From: Arie Verveer Subject: New Zealand Epicentre location. A Journey Date: Wed, 01 Apr 1998 07:50:08 +0800 Hi, I thought it may be fun to identify the location of an event, so here is my journey. I selected David Nelson's recent M5.0 with a probable location SW of New Zealand. The files are 980331B22.DNN and 980331B22.DNZ. Then using the origin time (17:17:51.9) from these files, I loaded in the my data and performed a 1 hertz High pass filter. To my surprise I found many phases but was unable to identify them. Then using Dave's station location / time as a first approximation, I identified the "P" and "LQ" phases. No "S" phase was found but there was a large phase between the P and LQ phases that wasn't account for. That phases was eventually identified via the IDC data base as a "P" wave from Nepal. NEPAL Ml4.0 17:19:18.1 27.90N by 85.43East at 17:30:00 UTC The New Zealand "P" wave was located and the "S" marker was moved until the "LQ" wave was located. A first approximation location was found using the program "Mapit", via the new distance from my location and Dave's estimates of the location. The epicenter location was re-entered into my data and a new distance and time was extracted. The data was updated in both files and the "Mapit" program was run to identified the final epicenter. Though in Dave's files, I found that the time information was out. So entering a time correction of -70 seconds the phases were aligned. Both stations magnitude estimates were within 0.4 mag. the final epicenter ? 51.14South 170.81East at 17:17:52.0 UTC March 31/ 1998 File : 980331b.au3 The journey ends or maybe it should have never started. Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: New Zealand Epicentre location. A Journey Date: Wed, 01 Apr 1998 21:43:56 +1200 Though in Dave's >files, I found that the time information was out. So entering a time >correction of -70 seconds >the phases were aligned. Arie explain what u mean by that ????? my clock accuracy is better than 0.5 of a second Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: PSN recordsection of the 29 Mar 98 M6.4 Fiji Earthquake Date: Wed, 01 Apr 1998 05:41:48 -0700 PSN- The 29 Mar 98 M6.4 Fiji Earthquake was recorded by several PSN stations world-wide (NOTE: in my haste to get this on the Web, I absent-mindedly forgot to include several other excellent PSN records of this event: I apologize for that, and I will try to do better next time) and by a portable autonomous digital seismograph (PADS) equipped with a Guralp CMG-40T broadband (0.03-20 Hz) three-component velocity sensor being tested in the basement of the USGS Geologic Hazards building in Golden, Colorado (i.e., the location of the NEIC). The raw, unfiltered timeseries of the P-waves of this event (77 s are displayed) as recorded by 6 PSN stations and by the USGS PADS are shown in the pseudo-recordsection. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Recordsection of the M6.4 Fiji Earthquake Date: Wed, 01 Apr 1998 05:48:41 -0700 PSN- Having forgotten to include the URL of the recordsection website http://groundmotion.cr.usgs.gov/PSN/M6_4Fiji/29mar98.htm I am posting this message again. The 29 Mar 98 M6.4 Fiji Earthquake was recorded by several PSN stations world-wide (NOTE: in my haste to get this on the Web, I absent-mindedly forgot to include several other excellent PSN records of this event: I apologize for that, and I will try to do better next time) and by a portable autonomous digital seismograph (PADS) equipped with a Guralp CMG-40T broadband (0.03-20 Hz) three-component velocity sensor being tested in the basement of the USGS Geologic Hazards building in Golden, Colorado (i.e., the location of the NEIC). The raw, unfiltered timeseries of the P-waves of this event (77 s are displayed) as recorded by 6 PSN stations and by the USGS PADS are shown in the pseudo-recordsection. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Re: New Zealand. Apology Date: Wed, 01 Apr 1998 21:57:50 +0800 Hi Dave, Please accept my apology if I offended you. It was an attempt to locate an epicentre and my only solution to the problem was to change your timing to fit my interpretations. It fitted very well but I was totally incorrect. There is lesson to be learnt, and I've just learnt it. What happened, was I missed the true event that fitted my data. It was an event at 17:19:16.3 UTC 51.842S by 156.7557E that was just north of Macquarie Island plus the Nepal event. I didn't record your event and assumed they were the same. The posting was written as an explanation on how the results were derived and no bad interpretations were meant. So please again, accept my apology and if you ever see me walking across a road, don't hesitate to run me over in your red Ferrari. All the Best. Arie > Though in Dave's > >files, I found that the time information was out. So entering a time > >correction of -70 seconds > >the phases were aligned. > > Arie explain what u mean by that ????? > > my clock accuracy is better than 0.5 of a second > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Hello from Daly City Date: Wed, 01 Apr 1998 10:51:25 -0700 Bob- I apologize for taking so long to get back to you. First of all, please check out the following site http://groundmotion.cr.usgs.gov/PSN/Ogburn/DalyCity.htm which is incomplete, but it gives you some idea of what I was trying to do. I decided to use the opportunity raised by your questions as an exercise in learning more about what is available on the PSN. I found out that there is alot that I didn't know. Larry's program WINQUAKE is really excellent at looking at teleseismic data, something I have had little experience with. I am used to studying events within about a source-depth of their epicenter. John Lahr is used to looking at regional distance records. WINQUAKE has alot of teleseismic phase and traveltime info that I did not recognize at first. Anyway, I then got lost in Web consciousness, and I have run out of time to finish my response to you because I am leaving for Australia for three weeks this evening. I am very interested in your attempt to record in such an urban environment as Daly City, and I will get back to you more about noise and gain levels. By the way, what happened to your vertical sensor? Good luck! -Edward bob ogburn wrote: > > Hi... > > Thanks again for the meeting at Menlo Park, and I believe that USGS has > decided to stay there... > > I have records of what I believe are these events: > 4.8 98/03/05 21:49:40 36.07N 117.65W 5.0 17 mi ENE of LITTLE LAKE > 5.2 98/03/05 21:47:40 36.08N 117.62W 0.7 20 mi SSW of PANAMINT > SPRING > > Since my S-G sensor is 'lightly coupled' through the condo structure, > the records do not look that good, but they have a time signature and > energy pattern that to my untrained eye indicate that the may be these > events. > > The sensor is positioned as an E-W device. > > If I send the records (Ted Blanks format) could you look at them and let > me know what you think? > > Thanks > > Bob Ogburn > (650) 594-9700 X19 > Satake Research Institute > San Carlos, CA -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: PS. Re: poster etc. Date: Wed, 01 Apr 1998 11:33:54 -0700 Sean- I wanted to say that I am very impressed with your seismometer. When you got on the PSN-L at Xmas, I was going through my winter solistice spiritual doldrums and could not keep up with the complex technical background to the device. I am not much sharper now, but I am feeling more confident about understanding the system after you went over it at John Lahr's last fortnight. As I said in my previous email, you should definitely take your machine to the IRIS meeting in Santa Cruz this July. -Edward S-T Morrissey wrote: > > Ed, > I want to thank you for your support and interest in the PSN/school > seismometer project. Its' taken me all week to get back to you > about it, but I came back here to about a dozen "by the end of > the month" things that weren't on my list when I left. > > I noticed some information about an April poster presentation, > which seemed to be an internal USGS affair if I read it correctly, > but I was wondering IF you wanted my poster material to contribute, > or if it was even appropriate. If you want to use it, let me know. > Or if you want to post it near your AGU poster there at the USGS, > let me know, and I will mail it. > > The university here is continuing to support the idea of getting > patent protection for the hardware store seismometer, so that we > can make sure it remains available to everyone. It has been > suggested that if we agree to let a commercial company make the > sensor, that for every unit they sell at a commercial price, they > must make one unit available at cost to the E&O and PSN programs. > How to draw the line may be problematic; some schools DO have > lots of "science" money. Any suggestions? > > So I have been writing up a 15-page or so "Patent Disclosure" about > the seis. One interesting aspect is the question of "witnessing" > the progress of an invention in time; it so happens that an > operating seismograph does it just by recording earthquakes, > which are always unique in time. So the first "witnessed" > existence of the seis is the VBB record of the M7.5 Santa > Cruse Isl. (SW Pacific) last April 20, the day after I made > the prototype, when it was operating on the wooden garage floor. > > I also never got around to asking you want research you were > involved in there other than the PSN support, which I assume > is not specifically supported by the USGS ... or is it? > If you get a minute, fill me in. > > Thanks, > Sean-Thomas -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Conti Claudio" Subject: TELESEISMIC RECORDING Date: Wed, 1 Apr 1998 20:55:32 +0200 I RECORDED A TELESEISMIC TRACE AT 18 09.50 UTC PKP a.t. 18 09 50 arr.2 SK s 18 19 20 UTC. Small Phase L . Regards Conti Claudio Syracuse (Sicily) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: The April 1st 1998 Seismograph Date: Wed, 01 Apr 1998 11:53:30 -0700 The April seismograph is finally nearing non-completion as of this date. The following is a description of the component parts of this magnificient machine. The base plate measures 3' X 6' and is 3" thick and is solid titanium. Machining of the plate was done with afew dozen diamond bits of various sizes. The urpright mast is of the same material for proper temperature co-efficient effects and was cast as one piece at a local refinery along with the base plate. The boom is made from a long extruded synthetic red ruby bole, of a diameter of 2" and 5' long. Proper cooling was done to alleviate minor 3" cracks across the diameter. The pickup and damping coils are made of solid gold #98 wire, with a thin teflon coating to prevent shorts. The coils themselves are 6" in diameter by 1" thick. The coils are encompassed by two 340 pound neodymium magnets spaced 1/2" apart. Its wise to not wear any kind of metal when servicing these units, and as a precaution food intake is severly watched for iron content. So far 346 seismologists have made the mistake of wearing steel belt buckles while checking out the magnets. The scrap iron is a visually distracting nuisance. One seismologist wore an opposing magnetic belt buckle, and some other physicists tried to spin and levitate the poor fellow over the magnets. The servicing technicians fondly call these magnets "the black holes", although they are gold plated to alleviate oxidation. Other sensors have been comtemplated but they are non-traditional. The leveling screws use rather large geared down motors which are coupled to a computer which has a program to instantly orientate the platform level. The screws rest on diamond squares. The pier is a solid block of optical grade quartz from Brazil and measured 20' X 40' X 10', and was polished by a collaboration of 459 companys in Redeye, California. The El Nino effects accelerated polishing work by the recent constant rains. The finished block measured 20' X 40' X 10', and took 24 years to complete. The polishing process was tedious and called for engineer correction calculations and surface grinding marks directly on the rough block. Subsequent correction erasures gradually polished the block over geological time. Work came to a halt when a child bumped into the optically clear block and threatened to sue them all as a public nuisance. The coil output is fed into a large computer using a 78 bit A to D card with room for 680 more inputs. The computer automatically configures all data and prints out earth maps with all depth features in 20 meg bits per inch clarity. The display continually shows on a giant screen, and with a hand held remote it is capable of displaying the instant location, magnitude and various other data relating to any earthquake in the world down to a magnitude -.00056 with a gain of one. Attenuation efforts are proceeding. Occasionally the women use the device to check out which shopping center is having a sale. The unit is so sensitive that distant supernovas will occasionally show up, due to the EMF aspects between here and there. More work needs to be done to filter out these frivilous solar system disturbances. Astronomers are not allowed into the control room. The housing for this unit emcompasses a two square mile outer shell building. Within the building are other progressively smaller building around the seismo...roughly 340 buildings or insulated "boxes" is a guess. The temperature is maintained to within ..00000023 of a degree by control electronics. Servicing is a open and shut case. Nevertheless, engineers are constantly at work upgrading the system...and hopefully next year we shall be able to report more significant and meaningful improvements. And then..............I woke up. Happy April Fools Day. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Mark & Margaret (Re: NZ) Date: Wed, 01 Apr 1998 13:15:54 -0700 Dave- I have been paralyzed by not being able to find a suitable reference about the quantitative effect on noise and sensitivity of going downhole. These guys, Ralph Archuleta & Co., U.C. Santa Barbara Institute for Crustal Studies: http://www.crustal.ucsb.edu should have the info, but their website server is down. In the meantime, there is no question in my mind that going down about a meter will decrease the noise above a few Hz by a factor of two (sufficiently qualitative?). Even better is to plaster or cement the sensor to competent outcrop. I am glad you had a chance to meet Mark & Margaret and expose them to the antipodal PSN. I apologize for my belated reply. Have continued to be very busy preparing to leave for Australia for three weeks which I will tonight. Mostly I will be going to see my mother in Adelaide. Three years ago, I went with Anya & Olya and had to explain to my aged relatives why I had a Russian wife & stepdaughter -- now I have to explain to them why I don't. -Edward David A. Nelson wrote: > > At 08:36 AM 3/14/98 -0700, you wrote: > >Mark & Margaret & Dave - > > Good to hear from you. I should have left before you split, because > >everyone's questions to you have been redirected to me. I am really > >going to get started on Dave's poster today! So have a good time away > >from the orifice and enjoy NZ! > > Dave - I still haven't forgotten your question about the effect on > >seismic noise of going downhole; I haven't found any good info on the > >subject yet, perhaps, I'll hear something at the SSA meeting that starts > >Monday in Boulder. We are going to have a sort of small PSN dinner at > >Johh Lahr's house on Thursday because S-T. Morrissey will be in town for > >the SSA meeting. Good of you to be such a gracious host to M&M. > >-Edward > > Hi there, > Mark and Marg. left here 1/2 an hr after sending the mail. > they left Dunedin city the following morning heading south down the scenic > coast road. Unfortunately the weathere turned sour so they may have spent > more time in the car keeping dry than out sightseeing. > > ok on the seismometer burial Ed. i am still interested to see if it is > worth puttting the 3 - 4 ft down rather than virtually rite at the surface > as they are at present. > Hey no prob. having M&M here im pleased u let me know they were > coming this way. At least they know a bit more abt NZ tectonics and > seismology. He loved my wall maps of new zealand showing events over the > last 100 yrs or so. and quickly noted and commented on the seismic gap > along the central Alpine Fault in the South Island. This length of fault > ~300 km, is deemed likely to rupture in the next 30yrs odd if the avg > rupture time between events is upheld. > > take care hope u can visit one day u would be most welcome to stay a > few days at home here. can always find a spare bed. > > Cheers > Dave > > Co-ordinator: > New Zealand > Public Seismic Network > Dave A. Nelson ZL4TBN > 24 Jensen St., > Green Is., Dunedin, > South Is.. New Zealand. > > http://psn.quake.net/dave/home.htm > > IF there indeed are other parallel universes... I can now rest in the > knowledge, that in at least one of them, I am filthy rich and drive a red > Ferrari -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: boom centering motor Date: Thu, 02 Apr 1998 12:25:01 -0600 At 06:53 PM 3/30/98 -0600, you wrote: >Meredith, > >The boom centering motor has to turn a fine thread (eg 8-32) screw >with an eccentric (so it won't turn) weight of 10 to 50 grams hanging >on it oriented along the axis of the boom. The Edmund Scientific >catalog has some nice miniature geared-down DC reversible motors >that weigh an ounce or two and draw less than 100 ma. In particular, >look at the motor part number J41331, a 2RPM, 31 inch-ounce laboratory- >grade (=$25) motor that runs on 8 milliamps at 12 V unloaded and is >1.75" dia x 1.75" long. > >THe motor can be mounted over the centerline of the hinges so as >to minimally affect the boom and the feedback coil/magnet. THere is >no problem with powering it via a pair of the fine coiled wires that >convey the signals over the hinges (I have two extra pair installed). >The fine #38 wire that I use can handle 2.5 amperes before it melts, >so a few hundred ma won't be a problem. > >The above motor can be controlled manually with a DPDT switch, and will >run quite nicely on a 9-volt battery; one could also set up an >auto-zeroing system using the integrator (= mass position) output >of the VBB feedback to control it via a meter relay (hard to find a >center-scale meter relay) or electronic comparators and cmos switches. > >I am also experimenting with electronic centering to extend the >operating temperature range. To do this, I integrate the mass position >output again with an extremely long (gt. 1000 seconds) time constant >and apply it through a limiting resistor to the auxillary 25-turn >coil above the main feedback coil. I am using a passive filter (ie >very large capacitors) to avoid adding noise. I have yet to evaluate >the change in the overall response. >regards, >Sean-Thomas Friends, If I understand the problem here correctly, it amounts to a minor trimming of the weight position to keep the horizontal beam of the seismo preperly centered and balanced. Since I think at least the leaf spring is magnetic, let me suggest a possible technique I have been using with some of my experiments. This is to use a ceramic magnet up to a foot away as a cheap and dirty and very easy to implement fine force trimmer. You position the magnet carefully back and forth until the chart output is within scale. In this way, I have been able to make external delicate beam adjustments on somewhat similar instruments mounted inside styrofoam coolers for purposes of temperature stabilization. Of course the magnetic fields involved are fairly linear at some distance and not necessarily much greater than the earth field, and so should not usually be expected to cause unexpected difficulties aside from slight temperature drift in the magnet or beam. Your motor could move the trimming magnet externally. And now my own question which is off topic for the PSN list, but likely to be known to somebody on this list, who can then respond to me privately: Does anybody know an easy way using my PC (and without spending $1000) to take a raw series of bytes representing a 256 step grey scale, like the scan lines of a TV picture and reconstruct an image? Or better yet by using my raw analog scan stream. Optical scanners do this all the time with lots of inscrutable code, but I am not a programmer and am generating the data stream at my own sweet slow rate with no coding attached except for the natural scan line breaks. Whats the simplest easy way for a relative cyber-klutz like me to turn this data into a picture -- for the purpose of my amateur friendly design for a scanning microscope? Or maybe there is just the right list to join, out there somewhere, and somebody here knows where it is. --Yours, Roger Baker _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: boom centering motor Date: Thu, 2 Apr 1998 20:54:42 -0600 (CST) Roger, A known problem with ferro-magnetic (until we find a non-magnetic spring that is not a thermometer) leaf-spring vertical sensors is that at high gain they are sensitive to geomagnetic storms and have to be shielded in mu-metal enclosures. They have even been known to shift in output from other temporary ferro-magnetic disturbances like a large hunting knife, steel-shank boots, and analog multimetres. (also, BTW, geomagnetics is the reason we use moving COIL rather than a much simpler moving magnet design for velocity sensors). I would hope that refinement of the STM design will allow low noise operation and require magnetic shielding, so the internal center- of-mass trimming motor (which WILL cause a temporary transient when it is activated) will be needed. The current STM design with sliding trim masses on the boom requires about 5 grams/centimeter/deg C adjustment when it its near the center of the boom. I will use someting like 32 grams for the moving trim weight, so the 2 RPM motor and the 8-32 threaded rod will adjust for 1 deg C in about 1 minute. The 1 deg C figure is the current operating range for an integrator output voltage limit of 6 volts. (without any other thermal compensation). Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: Re: SPIDER WIRE AND STAINLESS FISHING LEADER Date: Thu, 2 Apr 1998 22:47:32 EST TO: ANYONE I would like to purchase the boom suspension wire for a Lehman seismo that I am building. I have read some good things about a product called "Spider Wire" in the PSN archives. Has anyone had definitive experience with this product and if the experience was good what weight Spider wire should I purchase. According to the above referenced archives, this product, which is really not metal, does not stretch and is super strong. I also read about stainless steel fishing leader. Based on your experience what are its properties and what size(s) or weight and brands have be utilized for a boom suspension. Jim Allen Cerritos, Ca. U.S.A. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: ANOTHER BIG EVENT IN CENTRAL ITALY Date: Fri, 3 Apr 1998 12:00:30 +0200 7.27,16 UTC Mb 5.0 7.59.54 utc Mb 4.5 Located:=20 43.29N 12.67E =20 43.23N 12.58E =20 Francesco Nucera - Osimo, Italy
7.27,16 UTC  Mb = 5.0
7.59.54 utc     = Mb=20 4.5
 
 
Located:
43.29N   = 12.67E =20
43.23N   = 12.58E =20  
 
 
 
Francesco Nucera   - = Osimo, =20 Italy 
From: Arie Verveer Subject: FIJI Island Epicentre Date: Fri, 03 Apr 1998 21:03:08 +0800 Hi, After my last very poor effort in locating an epicentre, I thought that the FIJI Island quake might be a good event to study. I don't give up that easy. I used four stations each with very well defined "P" and "S" phase and plotted the information using the program "Mapit". Station .bue 10158km from event 30.112N .. 97.891W .lc3 8506km 37.496N 122.241W .ko1 4825km 19.723N 115.991W .au1 6638km 32.008S 116.135E The point where the lines crossed, was difficult to resolve given the large distance between the stations, but the answer was reasonably close. True Event 17.4S 178.2 West Mapit's Location 17.9S 178.6 West The results are not really that bad, considering the error box in locating the stations and difficulty in finding the point at which, the lines crossed. The answer would be a great deal better with close event and a better distribution of stations. Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Darrell Collins Subject: Re: weather work Date: Fri, 03 Apr 1998 08:28:47 -0700 Is PSN going to be there?? Subject: Seismic Network April 2, 1998 PRESS RELEASE FIRST SEISMIC NETWORK FOR TORNADOES (SENETOR) WORKSHOP TO BE HELD 6 APRIL 1998 Seismologists and meteorologists will meet together for the first time at a workshop on 6 April at the Center for Earthquake Research and Information (CERI), University of Memphis to explore means of using existing seismic networks to detect tornadoes in real time. The workshop was organized by Dr. Frank B. Tatom of Engineering Analysis Inc., Huntsville, Alabama with CERI serving as host. Representatives from the U.S. Geologic Survey (USGS), the National Weather Service (NWS), the National Severe Storms Lab (NSSL), and the National Aeronautic and Atmospheric Administration (NASA) are expected to attend along with seismic network coordinators located in Tennessee, Alabama, Arkansas, Oklahoma and Missouri. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: boom centering motor Date: Fri, 03 Apr 1998 09:25:44 -0800 Sean-Thomas, With the continuing discussion of temperature compensating the boom I have to ask: In the good old days they had temperature compensated pendulums for clocks. It consisted of brass and steel rods -- you've probably seen it and if you didn't know, would think it was for decoration -- as it was done typically in a grill pattern. I'm pretty sure the steel they used was standard magnetic, but today there are several non-magnetic materials you could use. For instance using brass at 20 ppmTCE and glass at 8.7 ppm TCE you could get positive or negative 12.3 ppm depending on construction. The question is, "Is this enough compensation range if one were using a phosphor-bronze spring?" Another fascinating number is magnesium with a TCE of 29.8 ppm. Invar is essentially zero, but I don't know is its magnetic or not, if not, this gives a combination possibility of almost 30 ppm. If I do my back of the napkin calculations right, for the current steel spring I estimate you are adjusting with an equivalent coefficient for the mass center of the boom of about 10 ppm/ degree C. So this would be in the ballpark. Left field or not, is a different question. Regards, Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: SPIDER WIRE AND STAINLESS FISHING LEADER Date: Fri, 03 Apr 1998 17:58:24 +0000 RADIOTEL wrote: > TO: ANYONE > I would like to purchase the boom suspension wire for a Lehman seismo that I > am building. I have read some good things about a product called "Spider > Wire" in the PSN archives. Has anyone had definitive experience with this > product and if the experience was good what weight Spider wire should I > purchase. ..........................snip.............. Hi, I was recommended spider wire, but was unable to find it over here (GB). Erich kindly sent me some USA wire (not spider),and I have since found that pike fishermen use multi stranded steel lines of various breaking strains. They all seem to consist of 7 strands of hard (piano wire?) wire with an outer nylon cover. I am using such a line (24 lbs breaking strain), altho I consider that a 100% nylon line to be more flexible (but it keeps on breaking!). This 24 lbs has 7 strands, each one .004" dia, so it's reasonably flexible, and strong enough. Here, ALL fishing tackle shops stock this pike wire, so you shouldn't have any trouble in USA. If you do, I will send you a some yards, (enough for a few seismos ), if you let me have your mail address, (privately of course). Incidentally, I use HEAVY galvanised wire for most of the suspension run, only using the flexible wire for the LAST 2 inches. In this way, any stretch is reduced to an absolute minimum. I have tried NON steel lines, in this way, in order to get minimum stretch. Regards Albert Noble (England) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: SPIDER WIRE AND STAINLESS FISHING LEADER Date: Fri, 3 Apr 1998 09:21:49 -0900 Spider Wire is THE best fishing product for fish with many sharp teeth. I don't doubt it will be very good for boom suspension! Here in Alaska, Spider Wire is available in most fishing isles of drug stores and super- markets. I might also suggest another product for boom suspension: Phillystran is a kevlar guy wire used for antenna tower guying. It is very flexible, very strong, and doesn't stretch too much. It is available from Texas Towers (www.texastowers.com/philstrn.html). Bob APSN Fairbanks _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: STM-8 Electronics Date: Fri, 03 Apr 1998 13:18:09 -0700 Sean-Thomas, >From my limited electronics experience viewpoint, personally I think it is a much bigger problem than the mechanical sensor building aspect. Of course, that angle of viewpoint will vary with the individuals experiences. Overall...either mechanical or electronics can stop the successful completion by interested parties. I do think it would be a shame for either problem to halt the individuals project; as the seismometer has great potential. The seismo is a prototype and therefore, both mechanical and electronics will see a possible ever changing composition, which is normal and desireable for progress. Anyway...as I gather it, the electronics are a composite of borrowed and "standard modules", and (?) therefore are not a part of the ongoing patent process, or are they? Question...would it be better from a homebrew approach, to build and test the individaul schematics boards, rather than a all in one approach? To supplement this; is there simple tests known for each schematic/board? What would be a minimum pre-requistite in regard to electronic test equipment...i.e., voltmeter and DC oscilloscope? With a specific schematic; the amp/demod/filter/DC amp....I do have questions regarding unspecified values. 1. On the right top side, is the unspecified resistor......160K? 2. A1 amp....the prior input + & -, R & C, are they different for the gain of 100? 3. A5 amp....the prior input + & -, R & C, are they different? 4. A6 amp....+ input, opt R range & C value? 5. Schematic has two opposing caps, one under A1, 2 X 10uf, and another of 2 X 47uf between A5 and A6. These are polarized caps I presume? 6. The MC14066B integrated circuit with its criss-cross lines, may need "connecting dots", for absolute clarity for dummys like myself-ha. I'am not real sure...but I don't want to blow the IC, or have a potential unrecognized problem. Right off, I don't see any other problems with interpreting the other schematics. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: SPIDER WIRE AND STAINLESS FISHING LEADER Date: Fri, 03 Apr 1998 12:17:56 I have read some good things about a product called "Spider >Wire" in the PSN archives. Has anyone had definitive experience with this >product and if the experience was good what weight Spider wire should I >purchase. I tried it and even used 3 strands of the 12*24 and it broke. I went back to a gatar string, G I beleave. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: CVW Subject: Where do I start (building a PSN station)? Date: Fri, 03 Apr 1998 17:07:10 -0500 Okay, I finally have the resources to pursue a dream of seismic proportions-- I have a budget of $1000 to spend on equipment to set up a seismograph. Here's what I already have: 1. A PC running Windows 3.1, with standard I/O and sound card, that can be 100% dedicated to this project. 2. Some potential sites on our lot where I can bury sensors. 3. Enough knowledge to be dangerous, based on the PSN FAQ's. Here's what I don't have: 1. A seismometer 2. An op amplifier 3. An A/D converter (but doesn't the sound card work on the same principle?) Here are my ideal requirements: 1. Measure on 3 axes. 2. Data captured in PSN usable format. 3. Durable and reliable sensors. 4. Ability to bury the sensors 50-100 feet away from recorder. So, how close can I come to creating a fully functional station for under $1000? Better to try making home-made seismometers, or buying commercial geophones? (I'm OK with DIY, but my main objective is good measurement.) Any comments would be greatly appreciated. Thanks, Charles van Wynbergen Atlanta, USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Terence Dowling Subject: Re: Where do I start (building a PSN station)? Date: Fri, 03 Apr 1998 14:08:13 -0800 CVW wrote: > > Okay, I finally have the resources to pursue a dream of seismic > proportions-- I have a budget of $1000 to spend on equipment to set up a > seismograph. I'm in essentially the same position. If you get any direct replies (not on the net) that you feel comfortable in sharing I'd appreciate it. -- Terence Dowling (408) 536-3856 Adobe Systems Inc. dowling@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Seismology Bibliography Date: Fri, 03 Apr 1998 16:18:02 -0800 Hi Everyone, A few days ago Bob Barns sent me a bibliography document he had put together. I went ahead and made a web page out of it and places it on my system. A link to the page can be found on: http://psn.quake.net/infoequip.html and a direct link to the document is: http://psn.quake.net/bibliography.html If anyone has a book or article they would like to add, please send me the info and I will add it to the list. Thanks Bob. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Seismology Bibliography Date: Fri, 03 Apr 1998 19:29:32 -0600 Larry Cochrane wrote: > > > If anyone has a book or article they would like to add, please send me the > info and I will add it to the list. > > Thanks Bob. > > Regards, > Larry Cochrane > Redwood City, PSN > Here are a few books in my collection that I didn't see on the list. Elementary Seismology Charles F. Richter 1958 W.H. Freeman & Company Earthquake Interpretations A manual for reading seismograms Ruth B. Simon 1981 William Kaufmann Inc. Earthquakes G.A. Eiby 1980 Van Nostrand Reinhold Company -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: VRDT amp/demod Date: Fri, 3 Apr 1998 21:09:12 -0600 (CST) Meredith, Answering your questions: 1: it is 160k, as the other switch driver. 2: The amp A1 gets gain two ways: the 40.2k/4.02k input circuit, and the 10k/1k divider in the feedback, for x 100. 3; The inputs to A5 are the same. 4: At A6, the optional low pass filter is 2meg with 0.1 uf (as in the feedback). 5: When opposing capacitors are used, they are electrolytics wired positive to positive. 6: The synchronous demodulator MC14066 (erroneously labeled 4088) is a quad cmos switch connected as drawn. The convention is that leads or wires that cross do not connect UNLESS there is a dot at the crossing point. I will update the schematic and re-post it on the web. It is a recent re-drawing of the 1982 version, so I have not actually made anything directly from it. It had been converted to a printed circuit that works; maybe I should put that artwork on the web? Or make it available by mail or FAX. The oscillator also exists as a PC board. If I put the PC artwork on the web, do you think that the home practitioner could retrieve it and rescale it to dimensions with enough accuracy that the IC sockets, etc, would fit? And would a photo-copied transparency of it be dense enough to print on a photo-resist PC board? Of course, the long term goal is to integrate all of it into one package. The oscillator will drive three VRDTs, but each needs its own amp/demod. But A6 could be re-configured as the integrator for the VBB feedback (with a different amplifier). BTW: none of the electronics is subject to any patent disclosure. Also, thanks for your thoughtful suggestions for the April 1 seismometer. I'm glad you avoided trying to use superconducting magnets; liquid helium would get expensive compared to the two 340 pound rare-earth magnets. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: Where do I start (building a PSN station)? Date: Fri, 03 Apr 1998 20:46:59 -0700 CVW wrote: > Okay, I finally have the resources to pursue a dream of seismic > proportions-- I have a budget of $1000 to spend on equipment to set up a > seismograph. > > Here's what I already have: > 1. A PC running Windows 3.1, with standard I/O and sound card, that can > be 100% dedicated to this project. Opinion: Upgrade to Windows 95 for enhancements. Ditch the sound card if it is separate from the video card and you need a slot for the A/D card. > 2. Some potential sites on our lot where I can bury sensors. Sounds like a geophone preference. The Galitzin/Ewing/Columbia/ Lehman variety would give you the longer period phases OH's and AH's to check out and enjoy. > 3. Enough knowledge to be dangerous, based on the PSN FAQ's. > > Here's what I don't have: > 1. A seismometer > 2. An op amplifier Larry Cochrane has a 3 channel card. Beautifully made. > 3. An A/D converter (but doesn't the sound card work on the same > principle?) Larrys Cochranes A/D card seems to be in preference....via past email recommendations. Beautifully made again. People say they are a reliable item, which is very important. > Here are my ideal requirements: > 1. Measure on 3 axes. This is going to be the biggest time factor if you home brew, say a Lehman coil-magnet affair. The vertical will be the most difficult. > 2. Data captured in PSN usable format. Larrys programs again seen to be in preference. > 3. Durable and reliable sensors. The old and reliable coil-magnet affair is next to impossible to beat for simplicity and least cost factor. > 4. Ability to bury the sensors 50-100 feet away from recorder. Again, this sounds like a preference to geophones. A crawlspace or basement floor are much more accessible and weather protected. > > > So, how close can I come to creating a fully functional station for > under $1000? Realistically, it would give you a preamp and A/D card and maybe 500 for materials for the seismos. 2K$ over a period of time would probably be more appropriate. (I can hear the whistling spears being thrown now-ha.) I'am probably the cheapest person there ever was for this stuff....maybe 8K$ over some 34 years, but in many ways, the commercial stuff is ready made...and you don't have to STRUGGLE with acquiring every piece and part.... Personally I'd start with the Homebrew Lehman type first. Graduation with a STM-8 vertical may well be down the road of time. > > > Better to try making home-made seismometers, or buying commercial > geophones? (I'm OK with DIY, but my main objective is good measurement.) The reward with buying is a quicker result. The reward with building is learning, experience and ALOT of personal satisfaction. Being as you have the dream...you're already well on your way. Most important....have fun and enjoy it all...good and bad. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: VRDT amp/demod Date: Fri, 03 Apr 1998 23:22:20 -0700 Sean-Thomas, OK and thanks for the update on the schematic. A web or mail posting of the circuit board/s would indeed be a major step in accelerating home brew utilization. I for one, would certainly do the best I could in regard to rescaling etc. efforts. Circuit layout is a time intensive subject. I've never done transparencies, but I guess they have been around for years..... Obviously the total design is yours of course. I would think that with a possible OK from you that you maybe beseiged with willing minds toward more resolutions or possiblities. I suppose with multiple IC's available in one package, that the layout could be chopped down, although the accuracy could possibly suffer? Even the oscillator can be replaced from a 2 IC, to a one unit, I think. Anyway (even though I am no engineer), I would think it could be possible to reduce the specific IC's package units to maybe ~ 6 instead of the present ~ 10 or 11. Pure speculation. I think with time that your seismo will be a standard, and the circuit aspects can be enhanced to a degree of more managability for digital dummys like myself. P.S., perhaps next years April 1st seismograph may feature an anti-gravity mass that is stabilized in space and place. Such a device could be envisioned for cracking nuts during festivities with computer control upon command...besides serving as a seismometer?-ha. Hey...imagination knows no cost boundaries or practicality.... in the mind. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Frank Cooper" Subject: Re: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM Date: Sat, 4 Apr 1998 01:17:04 -0600 ---------- From: Frank Cooper To: PSN-L@............. Subject: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM Date: Saturday, April 04, 1998 12:47 AM I got my Lehman seismograph sensor up and running in January, 1997, using an Esterline-Angus chart recorder and home-brew amp. In april, 1997, I purchased Larry Cochrane's 16-bit A/D card with wwv correction and his amp/filter card. I also use Larry's SDR and Winquake programs in conjunction with his hardware and my 486 dedicated computer. The results have been extremely gratifying. It is pleasing to see earthquake events displayed on my crt and my chart recorder at the same time. Until a few days ago I felt I would never cease using the chart recorder because a three hour event could be displayed on a continuous sheet of chart paper while the computer seismogram was printed out on a single sheet of unimpressive 8 and 1/2 x 11 inch paper. I have been running the chart recorder at 12-inches per hour so a three-hour event would show three feet of continuous recording. This seemed to be a much more useful display than a single sheet of compressed data using winquake. This all changed a few days ago with the revelation that I can expand eq data from winquake and print it on more than one sheet of paper. Attaching the sheets of paper together makes a more readable seismogram as well as one that is very visually impressive --- even more visually impressive than events recorded with chart paper. On the chance that not everyone is familiar with this technique I am going to relate what I did. You will not want to read further if this is old hat to you. The recording part of my seismograph station can be seen at http://members.xoom.com/hatsatv/past.html --- look for Frank Cooper, W5VID. I used the compressed data from my 3/25/98, three hour BALLENY ISLANDS REGION (7.9 mag) event file (980325a.fc1) posted at Larry's PSN files site. I expanded the data, printed it and the result was a six-foot long very impressive record of the event. I then displayed it on the back wall of my seismograph room along with the many chart recordings. After displaying the Balleny file using Winquake, I changed the y-scale from -310 to -125 in order to increase the vertical amplitude for printing purposes. After the event was displayed with the new vertical scale I clicked on the 27:08 time marker on the far left dragging the vertical line to the next time marker 55:08. I unckecked TEXT under VIEW and then printed the expanded data. I closed the displayed event and then clicked on the file 980325a.fc1 again to re-display it. I again changed the y-scale from -310 to -125. I then clicked on the 55:08 time marker dragging the vertical line to 23:08. I again unchecked TEXT under VIEW and printed the expanded data display. I did the same thing for 23:08 to 51:08, 51:08 to 19:08, 19:08 to 47:08 and ended with 47:08 to 15:08. I now had six printed sheets. On the second printed sheet I cut closely along the first time line, matching it to the first sheet, and then taped the two sheet together with non-reflecting scotch tape. The event trace matched perfectly. I did the same for the other sheets. I ended up with a six foot long impressive display of the event that was easy to see changes in wave forms, etc. It is now possible to think about retiring my chart recorder. I displayed another of my event files, 12/05/97, 971205a.fc1, EAST COAST OF KAMACHATKA (7.7mag) on the well next to my BALLENY ISLANDS event and a three floot long display of my 3/29/98, FIJI ISLANDS REGION (6.4 mag). These expanded files from Winquake may eventually replace all of my displayed chart recordings. Larry, please don't tell me all this was in Winquake documentation. Regards, Frank Cooper W5VID Friendswood, Texas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Where do I start (building a PSN station)? Date: Sat, 4 Apr 1998 10:17:31 -0500 Charles, Since you live in Atlanta, a seismic desert like here in New Jersey, geophones or other devices which can be buryed will be a waste of effort.= = You need something which will detect teleseismic events. This means something with a period longer than 10 secs. Verticals with the same period have a better signal-to-noise ratio but are more difficult. So go= for a horizontal. After you get your feet wet with a Lehman is the time to think about verticals and force feedback rigs. The Lehman (Scientific American, July 1979, pp152-16) is easy to understand and build. Mine has a 30" boom (1/2" dia. aluminum) but I thi= nk that 24" would be better in that it would req. a smaller housing. A "dog= house" to eliminate drafts is essential. This can be made from 2" thick Styrafoam (from a lumber yard) cemented together with Elmer's. Put a heater (say 15 watts) in the top to stagnate the air in the box. Mine usually operates with a 20-30 sec. period. The sens. to teleseisms is proportional to the square of the period. My coil has 15,000 turns. The suspension wire is piano wire and I can give you all that you will ever need. = A sensitive leveling device is a great convenience--either a leg under the base with a screw having 80 tpi or a lever driven by a micrometer hea= d. The meter-movement calibrator described on Larry's home page is also a convenience in checking performance daily. Mine sits (not bolted down) on the basement floor. There is a fair amount of spurious signals from foot traffic in the house but this is no problem because these events are easily distinguished from 'quakes. I get a good recording about every 2-3 days (a dedicated 286 computer running 24 hrs/day). The farthest 'quake I have recorded was from the Indian ocean-very nearly 180 deg. from here. So I can see 'quakes anywhe= re in the world with a magnitude of ~5.5 or greater. Two or three axes woul= d be nice but I miss only a few with only 1 seismometer. I think that buying Cochrane's A/D board (and his amplifier if you don'= t know how to handle op-amps) is the only way to go because it allows the u= se of his magnificent SDR program (free) for recording. This also allows th= e use of the even more magnificent Winquake (also free) program. I operate with a sampling rate of only 5 samples/sec. This is plenty wi= th a low-pass filter at 0.08 Hz and makes the hard disk storage space reasonable (about 2 megs/day). A sharp low-pass filter is necessary to reduce the noise from microseims which peak at about 0.16 Hz. $1,000 is way more than needed. Call (908-464-6785) if you need more details. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM Date: Sat, 04 Apr 1998 10:51:14 -0800 Frank I like your idea. I have a tractor feed dot matrix printer. I wonder if one can suppress the formfeed to get the recording w/o the cutting? Barry Frank Cooper wrote: >..... > line, matching it to the first sheet, and then taped the two sheet > together > with non-reflecting scotch tape. The event trace matched perfectly. I > did > the same for the other sheets. I ended up with a six foot long impressive > display of the event that was easy to see changes in wave forms, etc. It > is now possible to think about retiring my chart recorder. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM Date: Sat, 04 Apr 1998 11:44:59 -0800 At 01:17 AM 4/4/98 -0600, Frank Cooper wrote: > [snip] > Larry, please don't tell me all this was in Winquake documentation. No, but it would be a nice feature to add.... -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Frank Cooper" Subject: Re: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM Date: Sat, 4 Apr 1998 13:48:28 -0600 Barry and others, I use a sheet fed laser printer so I don't know if you can use your dot matrix tractor fed printer as you indicated. Think it's worth a try. Perhaps someone else will know? Frank Cooper, Friendswood, Texas ---------- > From: barry lotz > To: PSN-L Mailing List > Subject: Re: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM > Date: Saturday, April 04, 1998 12:51 PM > > Frank > I like your idea. I have a tractor feed dot matrix printer. I wonder > if one can suppress the formfeed to get the recording w/o the cutting? > Barry > > Frank Cooper wrote: > >..... > > > line, matching it to the first sheet, and then taped the two sheet > > together > > with non-reflecting scotch tape. The event trace matched perfectly. I > > did > > the same for the other sheets. I ended up with a six foot long impressive > > display of the event that was easy to see changes in wave forms, etc. It > > is now possible to think about retiring my chart recorder. > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: printer seismograms Date: Sat, 4 Apr 1998 23:39:46 -0600 (CST) Frank, Barry, et. al. Re interesting seismograms: Having a paper copy of an interesting event is a real plus for the PSN practitioner. Since I am not using any of the current ADC hardware, SDR, or Winquake, etc, maybe my relatively primitive method might be of use to some in similar situations. I am using the Radio Shack RS-22-168 multimeter, mainly because I haven't had time to actually do something about the many other possibilities I have been evaluating. It provides one channel at 1 sample/second (teleseismic speed) data at 12-bits, with lots of verbiage written to a *.txt file. I use a simple C program to reformat the output into an array that Mathcad can feed on, and use Mathcad's rather flexible graphic capabilities to plot the data, either as a single line compressed time series, or a multiple line "seismogram" of between 1 and 4 hours of data, with 10 to 30 minutes per line. All these graphics print on a single page with any printer. These can be seen at the web site at: http://www.eas.slu.edu/People/STMorrissey/index.html look st the page showing recent data. For the future, I am trying to find or create a multiple channel ADC system that specifically addresses the output of a broadband sensor. Specifically, the output of a single VBB sensor would be digitized at a high sample rate (40 sps or greater) with event detection for logging short period data (1 to 20 hz), from which would be digitally derived (FIR filtered) a parallel 1 sample / second stream continuously recorded for teleseismic events, and even a 0.1 sps stream for VLP (very long period) data. Such digitizers are widely used in the University networks of broadband stations in conjunction with 24-bit digitizers, but are very expensive ($10K or more). I would hope that we can realize a similar capability for the PSN with broadband sensors. An alternate scheme would be to run parallel SDR processes on the output of the same sensor, but with different sample rates. Maybe Larry's ADC board and SDR and Winquake can support such. I am not familiar enough with it to know. If a PSN station wanted to share data with the professional scientific community, a three component broadband system would have channels (using the SEED (Standard for Exchange of Earthquake Data: the definitions/ nomenclature should be adopeted by the PSN) named: BHZ, BHN, BHE, LHZ, LHN, LHE, VHZ, VHN, VHE. Higher sample rates (80 sps) use the SHZ, SHN, SHE channels. There are definitions for almost any physical parameter and sample rate. Regards, Sean-Thomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: RE: VRDT amp/demod Date: Sun, 5 Apr 1998 00:05:48 -0600 (CST) Meredith, I should have thought of the PC artwork long ago. With it, making the VRDT electronics becomes a plug-and-play activity. Since I still have your SASE (and new film for the Polaroid), I will send you copies of the artwork; THe problem is that the original is black lines for circuitry, and I have always photo-reversed it since the PC photo-resists I have used need clear lines for conductors. I can try to photocopy the actual PC printing film to a transparency. Regarding suggestions for changing the circuits: the design is the end result of a long effort to achieve nano-radian stability for the tiltmeters they were designed for, so we might as well expect a similar best performance for our seismometers. IC chips are very cheap, so "simplifying" a circuit to reduce the number used is not worth considering. The individual amplifiers (LM308) actually become cheaper in quantity. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Update PSN San Jose Web site Date: Sun, 05 Apr 1998 00:35:25 -0800 I have updated the San Jose PSN WEB site. http://pw2.netcom.com/~shammon1/psnsj.htm There is a section with a number of photos of the new exhibt being dedicated on April 18th at the Randall Museum in San Franciso, Living with a restless earth. Sveral PSN members donated labor and parts to create a part of the technical features presented. If you are intersted in seeing an well developed display you might take a look. Regards, Steve Hammond PSN San Jose _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: MAKING A VISUALLY IMPRESSIVE SEISMOGRAM Date: Sun, 05 Apr 1998 09:22:01 At 01:48 PM 4/4/98 -0600, you wrote: >Barry and others, >I use a sheet fed laser printer so I don't know if you can use your dot >matrix tractor fed printer as you indicated. Think it's worth a try. >Perhaps someone else will know? >Frank Cooper, Friendswood, Texas A dot matrix printer with tractor feed will only sheet feed when told to. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: Update PSN San Jose Web Site Date: Sun, 05 Apr 1998 11:04:51 -0600 Wow.......the pictures are a impressive graphic expression not only of the display and its educational awareness of earthquakes, but also too me of the larger hidden background of the big generiousity of the people involved in its creation. I for one would say that the PSN, has a great number of people whose contributions are evident and all over the various web sites......ranging from their pictures, programs, references and yes, a big live part is the continuing event and especially the e-mail ongoing educational process contributors. Thanks too ALL! Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: Another Quake Hits Central Italy Date: Sun, 5 Apr 1998 13:08:02 EDT Another Quake Hits Central Italy ..c The Associated Press ROME (AP) - Fans fled a soccer stadium in a small Umbrian town and tourists hurried out of St. Francis Basilica in Assisi on Sunday when another sharp earthquake struck central Italy. There were no immediate reports of injuries or damage. The quake has a preliminary magnitude of 4.5, making it weaker than the 5.0 quake that jolted the region on Friday and damaged 300 homes. Friday's quake was the strongest in several months of aftershocks following two killer quakes in September. Some 1,500 fans rushed from Gualdo Tadino's soccer stadium when the quake hit Sunday just two minutes before the end of a minor league match. Sunday's quake did no apparent damage to the Assisi basilica, whose lower- level church was filled with Palm Sunday visitors. The basilica's upper-level has been closed to the public since Sept. 26, when its ceiling collapsed during a quake. Thousands of people have been sleeping in tents or trailers since the first quakes in September punched the region, leaving 10 dead. Many have refused to go back to repaired homes for fear of the aftershocks. AP-NY-04-05-98 1302EDT _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: CENTRAL ITALY Date: Sun, 5 Apr 1998 19:31:38 +0200 Another medium quake occurred in Central Italy (Umbria-Marche border = region) 15.52.18 Utc Mb 5.1 Ml 4.7 Many material damnages I.E.S.N. PSN ITALY Francesco Nucera
Another medium quake occurred in = Central Italy=20 (Umbria-Marche border region)
15.52.18   = Utc
Mb 5.1  Ml 4.7
 
Many material damnages
 
I.E.S.N. PSN ITALY
Francesco = Nucera
From: S-T Morrissey Subject: highpass output Date: Sun, 5 Apr 1998 13:11:45 -0500 (CDT) Barry; Regarding accomodating the thermal drift caused by the leaf spring: the current operating range is about + - 1 degree C before the integrator output saturates. Here is a review of the highpass output discussion: (from previous postings) Also: the VBB output now contains the mass position component. To connect this to a recorder or digitizer (unless you have a 24-bit ADC), a long-period high-pass filter is needed, and usually an additional amplifier. I use 1000 uf, NP, into 1 megohm to an amplifier with a gain of 2 as a buffer to remove DC drift; it still passes periods of 10 minutes or more; you may want a shorter period corner with the horizontal. (see the curves of the step calibration on figure 10 of the figures page). With the unit here, the VBB output can range from + to - 6 volts (I have a +-9v regulated supply), which I monitor with a meter near the recorder so I know when the sensor needs to be recentered. It will also have a large drift anytime the covers have been removed for any length of time, and may take 4 to 6 hours to stabilize again. But the normal output from the high pass buffer is microseims of 1 to 10 mv, and the RS digitizer range is only +-200mv. So the high pass connection is a must. This near-DC response is because although the VBB output is flat to velocity from Tn up to the short period corner, it is flat to acceleration below Tn, so tilt, earth tides, acoustic gravity waves, etc, will be present in the output. From a later posting: I looked at the figure I posted of the electronics block diagram for the high-pass output configuration that is needed to remove DC drift and other ULP noise. It is conspicuously missing! oops and sorry about that. I will amend the drawing to show the large capacitor between the VBB output at the displacement detector and the buffer or "line driver" amplifier, which has a 1 megohm input resistor, which I should also show. (the drawing has been corrected to show the high pass output; the response to a calibratoin step also shows the effect of the high pass connection.) Hopefully you will be acquiring data by now. BTW: if your recorder and/or ADC has a very high input impedance (like 1 meg), you can forgo the buffer amplifier,and just install the capacitance. (I use two 2200uf capacitors connected + to + to get the 1100uf non-polarized; for trials, any large value will do) Regards, Sean-Thomas .. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: boom centering for STM-8 Date: Mon, 6 Apr 1998 00:25:50 -0500 (CDT) Re motor zeroing THe first boom centering motor has been installed on the Beta version of the STM vertical seis. It has been kept very simple: The Edmund Scientific motor part number J41331, is a 2RPM, 31 inch-ounce laboratory-grade (=$25) motor that runs on 8 milliamps max at 12 V ( 3ma with a 9-volt battery) and is 1.75" dia x 1.75" long. The centering motor shaft is coupled to a fine thread 6-32 SS rod about 8" long that simply protrudes out from the motor face. The motor is clamped to the outward end of the upper hinge angle by one if its mounting tabs. The weight of the motor is behind the hinge axis, and the threaded screw is on the boom side; they were set up so that they just about balance, so very little mechanical recentering of the boom is necessary when it is installed. The recentering weight is a small piece of aluminum angle (3/4" x 3/4" by 1/2" long, 1/16" material) with a 8-32 hole threaded into the upper half of the angle; the larger hole lets it turn freely, and also be easily relocated along the 6-32 threaded rod. The angle hangs below the rod. (so it won't turn), and the offset keeps the threads engaged; it has a weight of about 10 grams. THere is no problem with powering it via a pair of the fine coiled #38 wires that convey the signals over the hinges (I have two extra pair installed). The above motor is controlled manually with a DPDT switch and powered by a 9-volt battery. I am considering an automatic auto-zeroing system using the integrator (= mass position) output of the VBB feedback to control it via electronic comparators and cmos switches. The problem with this idea is that there has to be a long (electronic) time delay between the comparator (trigger) and the control switch to make sure it does not auto zero during an earthquake. In operating the motor while observing the integrator (mass position) output, one drives the voltage toward zero, but because of the VBB time constant, one has to stop the motor when the voltage has decreased to about half the starting value, and let the integrator catch up. Ie: if the voltage is 1 volt, run the motor until it approaches 0.5 volt, then wait. A more elaborate zeroing system would temporarily switch the integrator to a very short period during zeroing. Now we can proceed with enclosing the seismometer within a pressure tight containment to reduce barometric noise. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Looking for some help... Date: Sun, 05 Apr 1998 23:49:44 -0700 Hi Everyone, I'm slowly getting the next version of WinQuake together. One of the things I want to do with this release is add online help. To do this I will be adding Help buttons to most of the 30 some odd dialog boxes used by WinQuake. The online help will be in HTML rather then in the standard WinHelp format. Dealing with HTML is a lot easier then Microsoft's Help files. What I'm looking for is some help proofreading and editing the Web pages I come up with. You don't need to know HTML, I'll do that part of it. What I need help with is the content like spelling, grammar, suggestion etc. If you would like to help out please contact me at cochrane@............... Thanks, -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: Update PSN San Jose Web Site Date: Mon, 06 Apr 1998 00:03:35 -0700 > > I for one would say that the PSN, has a great number of people > whose contributions are evident and all over the various web > sites......ranging from their pictures, programs, references > and yes, a big live part is the continuing event and especially > the e-mail ongoing educational process contributors. Thanks > too ALL! > > Meredith Lamb > I agree-- You may have noticed that I took John Lear's suggestion by adding a list of work PSN members have helped out to the web site. I started the list with things I remember. I'm sure there are a lot more. What I would like to do is have people send me one liners-- Who was helped and how. I just remembered a couple more. Ted Blank and I provide the amp and code to get two PSN stations going in a couple of middle schools in Russia. Ted traveled there and helped set them up. I also built part of a seismic system for a middle school in Wisconsin.The local science teacher built the seismograph. I also talked to Jan Froom last week, and he told me that he went back to the Jr. High school in Gilroy and spent two more days teaching seismology to 7th graders. Now there is real courage... And Ken N. ran the USGS BBS for more than a year. All stuff that should be added to the list. I need people to speak up. Please send me any info you have so I could add it to the list. Regards, Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: Looking for some help... Date: Mon, 06 Apr 1998 00:05:14 -0700 Larry Cochrane wrote: > > Hi Everyone, > > I'm slowly getting the next version of WinQuake together. One of the things > I want to do with this release is add online help. To do this I will be > adding Help buttons to most of the 30 some odd dialog boxes used by > WinQuake. The online help will be in HTML rather then in the standard > WinHelp format. Dealing with HTML is a lot easier then Microsoft's Help files. > > What I'm looking for is some help proofreading and editing the Web pages I > come up with. You don't need to know HTML, I'll do that part of it. What I > need help with is the content like spelling, grammar, suggestion etc. > > If you would like to help out please contact me at cochrane@............... > Larry I'll help. Send me the HTML and I'll proof it. Regards, Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: printer seismograms Date: Mon, 06 Apr 1998 01:51:37 -0700 At 11:39 PM 4/4/98 -0600, S-T Morrissey wrote: >An alternate scheme would be to run parallel SDR processes on >the output of the same sensor, but with different sample rates. >Maybe Larry's ADC board and SDR and Winquake can support such. >I am not familiar enough with it to know. SDR can record up to 6 channels at 100, 50, 25, 10, and 5 samples per second. Currently all channels have to be sampled at the same rate. SDR saves all data to disk creating daily record files in the ~6 meg per channel range at 50 SPS. It does have a trigger mode, automatically saving PSN formatted event files, but it uses the data saved to disk instead of data saved in RAM. When I designed SDR I decided to save all of the data to disk because I live near a freeway and I knew that I could not rely on triggered data. By saving everything to disk I could replay the data and see what I got. Since disk space is pretty cheep now a days, having a disk drive that can save 6 channels for several days is not that much of a problem. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Kenneth J. De Nault" Subject: Re: Looking for some help... Date: Mon, 06 Apr 1998 07:40:09 -0500 Larry, I would be pleased to help but will not have time until May. Hope all is well. We have had some lovely weather following the blizzard you missed. Buck is fine and has been visiting more schools. We went to Charlotte, N.C. to race over Spring Break. I did well and finished 3rd. Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: http://pw2.netcom.com/~shammon1/psnsj.htm Date: Mon, 6 Apr 1998 08:38:43 -0600 (MDT) Steve, Your web site looks great! Is your section on "PSN outreach activities and link to other PSN web sites resources " available for others to add items or links? You need to add a link there to your pages on the Randall Museum. JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### Geologic Hazards Team, MS966 ############################## PO Box 25046 #############################/############################## ############################/############################### Denver, Colorado 80225-0046 ################################ Phone: (303) 273-8596 ################################## Fax: (303) 273-8600 ################################### lahr@........ ##################################### http://www.aeic.alaska.edu/lahr http://www.lahr.org/john-jan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob ogburn Subject: Re: Looking for some help... Date: Mon, 06 Apr 1998 07:52:56 -0700 Larry, Please place me in the reviewer pool, thanks Bob Ogburn Larry Cochrane wrote: > > Hi Everyone, > > I'm slowly getting the next version of WinQuake together. One of the things > I want to do with this release is add online help. To do this I will be > adding Help buttons to most of the 30 some odd dialog boxes used by > WinQuake. The online help will be in HTML rather then in the standard > WinHelp format. Dealing with HTML is a lot easier then Microsoft's Help files. > > What I'm looking for is some help proofreading and editing the Web pages I > come up with. You don't need to know HTML, I'll do that part of it. What I > need help with is the content like spelling, grammar, suggestion etc. > > If you would like to help out please contact me at cochrane@............... > > Thanks, > > -Larry Cochrane > Redwood City, PSN > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Update PSN San Jose Web Site Date: Mon, 6 Apr 1998 09:39:11 -0800 Steve, Here is a list of PSN-related outreach I have done and would be glad to see it on your webpage: -created a k-12 science and math education project based on in-school seismographs in urban and rural Alaska. Four schools are currently involved. Each school uses EMON and WINQUAKE software. Continue to guide students and teachers in the teaching of seismology as part of this project. -created and maintain the Alaska Public Seismic Network (APSN) webpage. -helped 3 individuals get their own seismograph stations up and running. My caveat is that I do this outreach as a USGS geophysicist as well as a PSN member. Maybe there is a distinction, maybe not. If I wasn't with the USGS, I'd be doing it anyhow. Hope this is want you want. regards, Bob Hammond APSN Fairbanks _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Amateur Seismology Educational Contributors Date: Mon, 06 Apr 1998 13:16:42 -0600 Steve Hammon, or anyone interested in history..... The problem with time passing is that denotations of their specific contributions usually get more or less lost in various ways. This can be unfortunate for those presently interested in history roles of the subject. Yes....it would be wise to do it now, and hope that a list somehow survives longer than normal. Also involved seems to be the fact that historical figures usually would rather not be pointed out....they are givers and not preferential to basking in the spot light. Nature also finds a way to renew its human resource of contributors and is as it should be. I now wish I'd have kept alot of my earlier papers and references back to the 1960's....but I didn't. At that time there was a group of individuals who communicated via mail. Mail is a poor method of reaching out and communicating over the human population, unless the subject material is such that there is no other way. The web sites and email now, are a world apart from mail. The "tools" a contributor now can use is much better....uhh...perhaps with time, more drawings and etc., would enhance the present state of computer e-mail program technology. The only individuals I knew of that were contributors in the 1960's were: Elmer Rexin....amateur water well level indicators of strong world earthquakes. Deceased. Wisconsin. Worked as a maintenance engineer for a shoe company. Communication via Charles Cox at the time. Gerald Shea...a innovative and skilled seismograph user whose approaches were amazing creations of household materials. Indiana. Worked in a educational institution. Robert Barnard...instrumental innovation way beyond normal. Washington. Electronic engineer. Endless contributions. Charles Cox...A real educational promotion person, who devoted more effort to that than even developing his own seismograph. If I gave him equipment...he would give it away to another person for their use. Amazing. Deceased. Wisconsin. I miss him alot. Anyway....life goes on... However, your present group has great contributors all over the place. I've only been tapping into PSN for maybe 6 months...but your educators are in abundance. For example in the past week emails, information has been put forth by.....(do it in one breath-ha), Frank Cooper, Robert Barns, Steve Hammond, Larry Cochran, Sean-Thomas Morrissey, John Lahr, Bob Ogburn, Roger Griggs, Arie Verveer, David Nelson, Edward Cranswick, Roger Baker, Charles Patton, Albert Noble, Bob Hammond, Norman Davis, Barry Lotz......(whew!), besides all the gobs of event seismograms which are teaching tools, and any others I may have missed. My point is, that they are all conveying messages....information, and therefore education. If you were to go back further, you would expand the list a great deal. As a comparison to the 1960's mail and the present e-mail, your email in one week would cover perhaps a years worth of mail in the "old days". Each email alone will take the indivdual an amount of time to compose from their experiences or thoughts, and is really a contribution FOR others. Monster contributions like developing programs, teaching, traveling for such, or even maintaining a computer day in and day out, are really the ultimate in devotion heights probably. So....you have a rich wealth of people....whose contributions I appreciate very much. My problem is that I don't know the total history of the individuals efforts or accomplishments on PSN. It's been around for maybe some odd 3 years. I can read the email and see the programs, but I'am sure that alot was done before that time period. Getting those individauls to do their own versions would be very nice to see.....if they can be coherced or prodded enough-ha. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: temperature compensation Date: Mon, 6 Apr 1998 21:55:44 -0500 (CDT) Charles; There are lots of available materials to try to make a zero temp. coefficient leaf spring. The STS units have such, made with two dissimilar metals; the remaining problem is that the temp. coefficient itself is temperature dependant; however, it does improve the stability by a factor of ten or more. For the homemade sensor, we have to keep focused on the less exotic stuff; I'm drawing the line at what I can find in the McMaster-Carr catalogue and Edmund Scientific. I still "cheat" a bit because I have the resources of my laboratory of the last 28 years, and I AM a packrat. Of course, everyone will make the best of their resources, and for the VBB instrument, temperature is a noise problem, and does not affect the response described by the transfer function at all. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: rayv Subject: Re: Looking for some help... Date: Mon, 06 Apr 1998 22:09:48 -0400 Larry Would be happy to assist. Ray Villemarette >Larry Cochrane wrote: >> >> Hi Everyone, >> >> I'm slowly getting the next version of WinQuake together. One of the things >> I want to do with this release is add online help. To do this I will be >> adding Help buttons to most of the 30 some odd dialog boxes used by >> WinQuake. The online help will be in HTML rather then in the standard >> WinHelp format. Dealing with HTML is a lot easier then Microsoft's Help files. >> >> What I'm looking for is some help proofreading and editing the Web pages I >> come up with. You don't need to know HTML, I'll do that part of it. What I >> need help with is the content like spelling, grammar, suggestion etc. >> >> If you would like to help out please contact me at cochrane@............... >> >> Thanks, >> >> -Larry Cochrane >> Redwood City, PSN >> >> _____________________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email listserver@............. with the body of the >> message: leave PSN-L > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Long Period Horizontal Seismo Drift Date: Mon, 06 Apr 1998 21:25:45 -0600 Sean-Thomas, OK on the vrdt amp/demod circuit artwork. I'll give it a try. I'll be looking forward to results of your boom motor and pressure container info results. Actually...its irritating because for the moment,...I can't think of a question to ask (ha)...and you're going into a realm of instrumentation that very few people have entered, but it will be very interesting to hear about...and perhaps some day to follow. Perhaps...a tough question. With my horizontal Sprengether seis, (like a Ewing/Lehman etc.) they are capable of 20 second periods, and I've seen a period of 60 seconds once. Of course at some point with this they become grossly unstable naturallly, and drift all over the place, no matter how stable the pier or frame is constructed. Even a 20 second period will historically show need for a adjustment perhaps every couple weeks. I guess the real question is what is really necessary and would a shorter period like 15 seconds suffice? Big distant quakes will simply make the mass lag the subtle L wave tilt anyway....I think. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: Update PSN San Jose Web Site Date: Mon, 06 Apr 1998 21:32:31 -0700 Hi Bob-- got the not. I'll add it this week. Thanks for the input. Steve Bob Hammond (USGS-AVO Geophysicist) wrote: > > Steve, > > Here is a list of PSN-related outreach I have done and would be glad to > see it on your webpage: > > -created a k-12 science and math education project based on in-school seismographs > in urban and rural Alaska. Four schools are currently involved. Each school > uses EMON and WINQUAKE software. Continue to guide students and teachers in > the teaching of seismology as part of this project. > -created and maintain the Alaska Public Seismic Network (APSN) webpage. > -helped 3 individuals get their own seismograph stations up and running. > > My caveat is that I do this outreach as a USGS geophysicist as well as a PSN member. > Maybe there is a distinction, maybe not. If I wasn't with the USGS, I'd be doing > it anyhow. > > Hope this is want you want. > > regards, > > Bob Hammond > APSN > Fairbanks > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: new help files Date: Mon, 06 Apr 1998 23:18:33 -0700 Thanks John, I placed the documents I have so far on my PSN system. The following link can be used as a starting point: http://psn.quake.net/wqdocs/index.htm I now have 12 people offering to help, so I have plenty of help. -Larry At 09:00 AM 4/6/98 -0600, you wrote: >Larry, > >How about just putting the new help files on your web site with >a heading > 'Preliminary WinQuake help file under review' > 'Please forward suggestions or corrections to ...' >When the next version comes out, you can just change the >title and leave them there. > >Just a thought. > >JCLahr > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Where do I start (building a PSN station)? Date: Tue, 07 Apr 1998 00:32:48 -0700 Charles, Sorry for not responding sooner. I've been trying too concentrate on getting the next release of WinQuake ready...Some comments below. At 05:07 PM 4/3/98 -0500, Charles van Wynbergen wrote: >Okay, I finally have the resources to pursue a dream of seismic >proportions-- I have a budget of $1000 to spend on equipment to set up a >seismograph. > >Here's what I already have: >1. A PC running Windows 3.1, with standard I/O and sound card, that can >be 100% dedicated to this project. I recommend that people have two PC systems. One is dedicated too data logging, running SDR or EMON, and the other for general computer usage and WinQuake. The data logging system, if it is going to run SDR or EMON, only needs to have DOS running on it. Both program are DOS based so you won't need to have Windows on that system. The main system needs to have Windows, preferably Win95. If you want to get real fancy, you can network the two together so event files will show up on the Windows system's hard disk. This way you won't need to use a floppy to transfer event files between the two systems. >Here's what I don't have: >1. A seismometer You will need a long period sensor. A geophone is fine for local events, but you will need LP sensors to record teleseismic events. To stay under the 1K limit you will need to build one. Or get very lucking in finding a used one. >2. An op amplifier >3. An A/D converter (but doesn't the sound card work on the same >principle?) As you know I have both available. My Web site has the current price and other info about my boards. > >Here are my ideal requirements: >1. Measure on 3 axes. I'm not sure you can get 3 LP sensors going for around $1K. Maybe one or two horizontal. You can buy used 3 axis geophone for under a few hundred dollars, but they won't work very well in your location. >2. Data captured in PSN usable format. You will need to run SDR or EMON for this... >3. Durable and reliable sensors. Thats a hard one... depends on how well you can make your sensor. I find that my SG sensor is more reliable because I don't need to re center it as often. >4. Ability to bury the sensors 50-100 feet away from recorder. The problem with home built LP sensor is they need to need monitored and adjusted now and then. If you bury it, make sure you can get at it pretty easily. > >Better to try making home-made seismometers, or buying commercial >geophones? (I'm OK with DIY, but my main objective is good measurement.) Do too cost, I think you will need to go with the home-made sensor. Again, geophones are not going to work very well in your location. You will be able to see the P wave of large teleseismic events with them, I see then on the USGS geophone sensors I monitor, but all of the low frequency wave information will be missing from your event files. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: Long Period Horizontal Seismo Drift Date: Tue, 07 Apr 1998 13:04:25 +0100 meredith lamb wrote: > With my horizontal Sprengether > seis, (like a Ewing/Lehman etc.) they are capable of 20 second > periods, and I've seen a period of 60 seconds once. Of course > at some point with this they become grossly unstable naturallly, > and drift all over the place, no matter how stable the pier or frame > is constructed. .......................... Hi Meredith, I have been considering the possibility of increasing the period of my seismos, by electronic means. (2 hor. currently about 20secs and 1 vert about 1.5 secs). Erich sent me an article published by Seismological Soc. of America, dated Oct 89. Volume 79 Number 5. page 1607........ Article entitled ,'A vertical equalisation circuit for increasing seismometer velocity response below natural frequency'. This describes a cct using LP filter plus an inverter with a summer, in series with SAME again, to allow a 1sec period seismo to have an effective response down to 10 secs! Only 6 op amps required. I am no great electronics wizz kid , but it should be possible, by suitable changes to C in LP filter to extend ANY seismo period, by a useful factor, without too much effort. The article shows the response from a short period seismo, used in Jemez mountains. The response includes 10-20 sec noise which an unconverted seismo would have been transparent to. You will be able to get a copy of this article from SSA no doubt. Not sure if this article has been mentioned on PSN before. Regards Albert Noble (England). _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: hand-held accelerometer Date: Tue, 7 Apr 1998 08:52:07 -0600 (MDT) Dear PSNers, Does anyone have any ideas re the question, below, raised by a San Francisco area teacher? I've never tried to measure acceleration while riding a wild ride, as I'm usually just holding on for dear life and laughing. (Hope this isn't too far off topic.) JCLahr > To: evans@.................... > Subject: home-built hand-held accelerometer > > Hi John, > > How is everything going in Menlo Park, and with your > accelerometer project(s)? > > I thought you might have some ideas for this teacher, > who wrote the question below to the pinhole listserver > of the Exploratorium. > > For Great America, I would think that measuring acceleration > to + or - 1 or 2 tenths would be sufficient. Electronic > means would be great, but may be overkill, unless you > have a hand held unit that they could borrow. > > Maybe just a clear plastic tube with two springs and a > weight? > > _______ > | S | > | P | - 1.g > | R | > | I | > | N | - 0.5g > | G | > | ^ | > | mass| > | v | > | S | > | P | + 0.5g > | R | > | I | > | N | + 1.0g > | G | > _______ > > > I think you can respond to pinhole@.................. > but if that fails, please cc me if you write to > Burt Kessler, as I'm curious too and will share your > response with the list. > > Thanks, > JCLahr > ################################## John C. Lahr > ################################# Seismologist > ################################ U.S. Geological Survey > ############################### Geologic Hazards Team, MS966 > ############################## PO Box 25046 > #############################/############################## > ############################/############################### > Denver, Colorado 80225-0046 ################################ > Phone: (303) 273-8596 ################################## > Fax: (303) 273-8600 ################################### > lahr@........ ##################################### > http://www.aeic.alaska.edu/lahr > http://www.lahr.org/john-jan > > > > From john-jan@........ Tue Apr 7 07:43 MDT 1998 > > X-Sender: jlahr@................ > > Date: Tue, 07 Apr 1998 07:43:16 -0600 > > To: "John C Lahr, Lakewood, CO " > > From: The Lahrs > > Subject: accelerometer > > Mime-Version: 1.0 > > > > Date: 6 Apr 1998 20:49:54 U > > From: bcomet@.......... (Burt C. Kessler) > > Subject: accelerometer > > > > One of the new teachers at my school is looking for instructions for > > building some simple accelerometers in preparation for physics day at Great > > America. Can anyone help? > > > > Burt C. Kessler > > > > A decision is an action you must take when you have information so incomplete > > that the answer does not suggest itself. - Arthur Radford > > > > > > -- > > > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: grc@............ (Gary Chantler) Subject: Re: hand-held accelerometer Date: Tue, 7 Apr 1998 08:23:46 -0800 Hi, Paragliders use variometers all the time. they keep track of place, time of flight, distance, rate of climb, etc - and are light and small as weight is a consideration. They are not to expessive if you get one used...if this helps at all. GRC *********************************************************** ***************************************** Gary R. Chantler Instructional Tech. II Washington State University (509) 335-5353 Webster Rm 922 gchantler@....... *#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: hand-held accelerometer Date: Tue, 7 Apr 1998 11:43:31 -0600 (MDT) I'll pass along John Evans' response on this. Also, Roger Baker suggested this as a good use for the "seismometer" that the Amateur Scientist column by Shawn Carlson in Scientific American carried a few years back. It wasn't sensitive enough to record any but the largest local earthquakes. JCLahr > From evans@.................... Tue Apr 7 10:59 MDT 1998 > Date: Tue, 7 Apr 98 10:01:07 PDT > From: evans@.................... (John Evans) > To: lahr@.................. > Subject: Re: home-built hand-held accelerometer > Cc: evans@.................... pinhole@.................. bcomet@.......... > > John, > > Finally solving the communications problems to get my prototypes into > the field. Took far longer than expected (doesn't it always?) and I > now know much more than I ever wanted to about TCP/IP/UDP and RS-232). > > I like your idea of the spring tube--very direct and visual and easily > built. Could be calibrated against gravity easily too. Might want to > use a chunk of scrap TEFLON for the mass so it will slide easily (add a > bolt through the center to secure the springs and increase the mass). > Teflon (R) works very easily (too easily), but NEVER get it really hot > (in other words, don't try to melt it)--LETHAL gasses result (envision > breathing through Teflon-coated lungs). A good plastics supplier or Si > Valley surplus house could supply bulk Teflon (R) for minor cost (or > free with a little talking?) in the small amounts needed. > > OSH has plenty of springs--you'll want sloppy ones. > > On the electronic side, I have one accel built for outreach--it could > be borrowed. It is nominally 1 V/g, but has a 0-g offset and has a > temperature dependent gain (and a temperature sensor to help). It is > VERY quiet (far quieter than they need on a roller coaster) but is a > bit tricky to use because of the offset and temperature dependence. > Also gets nonlinear somewhere between 2 and 3 g, so the wilder rides > might not measure accurately. > > For a more permanent (and less tricky) solution I suggest that they > talk to Analog Devices (contacts below) which I suspect would comp or > low-cost a few of their ADXL-05 or the newer ADXL-202 accelerometers. > These are 5-g devices. The latter may not be available yet--I have an > engineering sample sitting on my desk here. The -05 is a one-axis > accelerometer and the -202 a two-axis version, each with noise of a few > percent of g peak-to-peak over the frequencies of interest. Plenty > good enough for roller coaster physics demonstrations, and have been > used for that purpose. Would need power, a little wiring, and a > voltmeter to read the output. (Both my ICS-3028 box and the ADXLs are > micromachined silicon devices, and very tough--good for kids to use. > However, none would like being dropped onto concrete, since that type > of shock actually reaches thousands of gs, and these typically are > rated to 2000 g shock resistance (don't try this with an FBS-23!).) > > Analog Devices: > 804 Woburn St > Wilmington MA 01887-3462 > 617-937-1534 jim.doscher@.......... > 617-761-7436 christophe.lemaire@.......... > (You could tell either one that I sent you. My most recent contacts > are with LeMaire, who gave me this -202 sample.) > > Teflon (R): > Surplus house: HalTek Electronics, 1062 Linda Vista Av, Mtn. View > (650-969-0510) (101-->Shoreline-->toward mountains, away from > Bay--> left at first light-->down to Linda Vista Av-->left to > Haltek, which is on your left). They have scrap Teflon (R), > including some large chunks. Alternatively, try Commercial > Plastics and Supply Corp. in Santa Clara near 101 and De La Cruz > (408-988-6500). They might comp a scrap piece big enough (they > did comp part of the Teflon (R) I bought for the last Open > House--a urethane-foam fault model that needed a slippery > lower-crust and slide blocks). > > Good luck, > John > evans@................... > > Cc: Burt C. Kessler > pinhole@................. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: SETI Fw: Aether Tectonics: Alert: Merging Black Hole Predicted Date: Tue, 7 Apr 1998 11:42:39 +0000 Hello All, I am a member of the SETI-L reflector. This interesting post is thought provoking. Best Regards Walt Williams, 98.04.07 dfheli@.............. == Cross Posted From seti@....... == ------- Forwarded Message Follows ------- Reply-to: "Ron Blue" From: "Ron Blue" To: Cc: "Ross Tessien" Subject: SETI Fw: Aether Tectonics: Alert: Merging Black Hole Prediction; Date: Tue, 7 Apr 1998 01:55:45 -0400 Ross Tessien has asked for help in monitoring the likely black hole merger estimated to occur April 31, 1998. Any reports should be forwarded to him. Naturally, data before, during, and after would be useful. Also as a intuitive guess, if the timing is good, radio signals from your favorite SETI source could be stronger around this time. Ron Blue >>>>>> -----Original Message----- From: Ross Tessien To: Ron Blue Date: Tuesday, April 07, 1998 12:09 AM Subject: Re: Aether Tectonics: Alert: Merging Black Hole Prediction; >>I wish you luck Ross. Action is a rarer event than the merger of two back >>holes at least you will be able to sleep at night knowing that >>you make an effort. >>Would changes in radio signals occur as two black holes merge. I belong >>to SETI and would be willing to encourage support from the group? >>Ron Blue > >Yes. You ought to encourage any observations possible. The amplitude of >the radio energy is modulating on the order of 18 hours I think it is. You >could get frequencies and directions from astronomy groups and catalogues. >The galaxy name was in the original post, (I don't have it right now), Seyfert galaxy IRAS 18325-5926 >and >you can look that up on the Skyview Virtual Telescope by just typing in the >name, and the coordinates will come up. But I imagine that the guys >pointing the radio antennae know how to locate a galaxy. > >Anyway, any observations ought to be encouraged. > >Personally, I would give it a slim chance (but not zero), that we will >observe something really dramatic. ie, the ejection of a quasar from the >galaxy core. This is because black holes, IMO and according to the >fundamental models of forces means of transferring action via solitonic >interactions, leads to the conclusion that a BH has a core inside, and not >a singularity. Thus, a BH merger interupts the inflow of aether, ramming the >cores, and one or the other ought to breach! > >In any case, I certainly expect that fireworks are to be expected. If one >or the other is simply swallowed, I am not going to cry. But if some >radical things happen that cannot be explained I will have a smile on my >face ;-) > >Ross Tessien > From: baez@............ (John Baez)Newsgroups: sci.physics.research Subject: Merging black holes?Date: 5 Apr 1998 20:31:01 GMT Organization: Department of Physics - Penn State Univ.Lines: 73 Approved: bunn@...................... (sci.physics.research) Message-ID: <6g8pm5$q2t$1@..................> NNTP-Posting-Host: pac2.berkeley.eduContent-Type: textOriginator: bunn@pac2 Xref: oronet sci.physics.research:7648 Is anyone here familiar with the recent observations of the Seyfert galaxy IRAS 18325-5926 which could be interpreted as indicating a massive black hole binary system that would merge on or before April31st? Apparently in December 1997 researchers observed X-ray emissions with a period of 11 hours, significantly shorter than those seen previously in March 1997, and this February they saw a periodicity of 7.8 hours. They regard it as a priori "very unlikely" to stumble like this upon in-spiralling black holes right before they collide, but they raise the possibility because it would be very interesting if true. (Unfortunately LIGO is not yet up, but I hear that some prototype interferometric gravitational wave detectors will be used to try to detect this possible collision.) For more information, see the telegram posted by the IAU: http://cfa-www.harvard.edu/iauc/06800/06835.htmlas well as the following papers: > >>Mike what does you model say about these events? How about your model >Jerry? Would a tide wave of Aether have significant effect on earth even >though the distance is huge? >Ron Blue A post of mine was rejected from spr. this is my retort. In response to your question, it has already been measured that the earth is exposed to incessant free oscillations. These are not of earthquake origin, and so are either due to wind, waves, or gravitational wave excitation. No other sources are known. Will the earth be damaged, I think not. Is it possible that sensitive instruments might be able to detect the signals? I think so. do we have those instruments in place now? probably not but we have some instruments that might be barely able to detect these waves. Later, Ross Tessien I include ****paper abstracts below*****, a Stanford web site, and logic pointing out that you should post the ideas because they are valid and have already been attempted. The researchers, and others, may not be aware of the potential BH merger. It may well be that the amplitude of the resulting waves are below the sensitivity limits of any of these schemes. I am not saying that a run of the mill, "seismograph", has the sensitivity to detect a gravitational wave. I am telling you that the global network of seismographs, when the data is processed collectively create an interference pattern which can detect, in principle, graviational waves. There are a number of experiments that have attempted to detect gravitational waves using seismometers and the earths motions. These are not your run of the mill earth quake monitors or tecniques. Also, there are other superconducting seismographs that are more sensitive than most and perhaps these might detect a signal. The point is, it is unlikely that a black hole merger would occur again in our lifetimes. Thus, it is prudent to act now and ask questions later. If the idea is stupid, then fine, blame it on an ignorant crackpot and you are home free. But the fact is, physicists have indeed attempted to detect gravitational waves using high tech seismometers and by using the motions of the entire earth. I include also a commentary on the earth's free oscillations at the end so that you can see that the geo physicists have a lot of experience subtracting earthquake generated noise. So much so that they can monitor the earths incessant free oscillations. Now gravitational waves, would show up as incessant free oscillations, if they were originating from celestial sources that are orbiting one another **assuming that the waves were sufficiently large to induce the earths motions**. However, remember that when you excite a bell with a frequency that the bell is sensitive to, you are dealing with an underdamped resonance. Therefore, if the frequency of the BH merger oscillations passes through a normal mode of ringing of the earth, then the earth will behave as an underdamped oscillator, and the signal will be amplified. Ross Tessien In the following document, the knowledge of the direction and or timing of the source signal would help in detecting it from the noise. And improvements in the timing accuracies of the seismometers used could further improve the potential for detecting a signal. http://sepwww.stanford.edu/public/docs/sep75/ray1/paper_html/index.ht ml Detecting gravitational waves using seismic data Ray Abma Author has no known email address ABSTRACT Several years of seismic data acquired by the international deployment of accelerometers (IDA) are used in an attempt to detect gravitational waves radiated from low-frequency astronomical binary sources. These data were preconditioned with various combinations of earthquake removal, gain, and tapering. Directionally weighted spectra were calculated for 0.012 to 0.556 milli-Hz (one day to one-half hour periods) in 84 directions, one year at a time, with correction for the earth's rotation. While patterns similar to the synthetic response from a gravitational-wave source were observed, these patterns showed no consistency when compared between years. This inconsistency suggests that the patterns are noise and not the result of gravitational wave excitation by binary sources. And also see: Progress on low-frequency active vibration isolation for gravitational wave detectors. S. J. Richman, J. A. Giaime, D. B. Newell, R. T. Stebbins, P. L. Bender, J. E. Faller (JILA, University of Colorado.) The preliminary stage of a three-stage active vibration isolation system now includes sensors that measure the position of the platform with respect to the ground. We have developed a control strategy in which these new sensors dominate the feedback signal at frequencies below 0.3 Hz, and seismometers mounted on the platform dominate above 0.3 Hz. The preliminary stage now achieves the same isolation performance as previously reported, and is also tilt-stabilized against the first main stage actuators. These new sensors and new flexure ends for the first main stage support springs have allowed all control loops on the preliminary and first main stages to be closed simultaneously. Forced vibration transfer function measurements show isolation factors of at least 3\times10^3 from 1-10 Hz in both vertical and horizontal directions. The results of these measurements show agreement with our computer model of the performance of the stacked system. [K11.04] Low-Frequency Signal Extraction from Interferometers Using Balanced Heterodyne Detection Scheme with Orthogonally-Polarized Signal and Local Oscillator Beams Ke-Xun Sun (Apollonics Technology, 632 Des Moines Place, San Jose, CA 95133) Balanced heterodyne signal extraction schemes are proposed and analyzed for both Michelson and Sagnac interferometers for gravitational wave detection. In these schemes, local oscillator and signal beams are introduced in orthogonal polarization states, and mixed after exiting the interferometers. The local oscillator freqeuncy can be shifted for heterodyne detection by phase modulators. Extended from a previous measurement at a high frequency (91.9 MHz), low frequency signal extraction is experimentally demonstrated with a zero-area Sagnac interferometer. The local oscillator was frequency-shifted by a post-interferometer phase modulator. At a heterodyne frequency of 96 MHz, signals generated by displacing interferometer arm mirrors were detected in the frequency range from 50 Hz to 10 kHz. Detection of signal was robust against laser amplitude and frequency noises. Low noise interferometric seismometer readouts in an active vibration isolation system for gravitational wave detectors. J. A. Giaime, S. J. Richman, R. T. Stebbins, P. L. Bender, J. E. Faller (JILA, University of Colorado.) Within the frequency range of significant servo gain, our actively controlled seismic isolation platform's noise floor is limited by seismometer readout noise. A new Michelson interferometer readout has been designed and tested which should allow a displacement noise spectral density of approximately 3\times 10^-15m/\sqrtHz. Light for 12 readouts is supplied from a quiet laser though optical fibers, and corner-cube interferometer mirrors allow simple alignment and signal stability. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: W6JRF Subject: Re: SETI Fw: Aether Tectonics: Alert: Merging Black Hole Predicted Date: Tue, 7 Apr 1998 15:01:24 EDT Let's see, as I remember, the old grade school mind jogger went something like... "thirty days hath september, april, june and november..........April 31 huh? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: re SETI Date: Tue, 07 Apr 1998 13:28:58 -0700 If you drop the as off the end of the first link it works and the date there says april 21!!!!!!! If you add ml to the end of the second link it works and you go to the abstract!! SKM Pilot Hill _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: hand-held accelerometer Date: Tue, 07 Apr 1998 13:03:58 -0700 John Lahr posted: > > > One of the new teachers at my school is looking for instructions for > > > building some simple accelerometers in preparation for physics day at Great > > > America. Can anyone help? > > > > > > Burt C. Kessler I'd like to suggest something very simple. Take a piece of plastic strip like a 1" wide piece of a plastic divider from a notebook, or a vertical slice from a plastic milk bottle or pop bottle. A "straw" the diameter of pencil lead from a plastic broom is still another possibility. In any case, use one of these as a horizontal spring. Take a small cardboard box and cut a square hole in it. Tape one end of the "spring" in the box, horizontally across the hole with the end of the spring adjacent to the edge of the hole on the other side. Now depending on the strength of the "spring" you can add weights, such as pennies, marbles, lengths of wire, etc. one unit of weight is so much deflection, and then is marked on the edge of the hole opposite the "spring". 10 units is so much more. If you leave the 10 units attached permanently, you have just marked a scale in 0.1's of a G. Turn upside down and calibrate in other direction. Now you have a plus and minus G meter. Refinements are to cover the hole with Saran wrap in order to prevent drafts from bothering it -- those 30+ MPH winds on the roller coaster can play havoc with the calibration. Cutting the hole with a radius to match the "spring" will improve accuracy. Use of a strip of plastic rather than a "straw" will confine its reaction primarily to be perpendicular to the plane of the "spring", or even better, two "straws" spreading apart to the attachment point -- a triangle when viewed from above. The side rigidity would be excellent this way so sine/cosine vector resolution of forces could be attempted. Cheap, fast, needs no machining, test equipment, electric power, simle to calibrate, and uses materials found around the house. -------------------------------------- | box | | --------------------------- | | | | | | | | | | S | plastic | | | C | "spring" | tape| | A |==X========================XXXX| | L | X | | | E | weight(s) | | | | | | | | | | | --------------------------- | | | | | -------------------------------------- Regards Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Pinhole Listserv" Subject: Re: Re: hand-held accelerometer Date: Tue, 7 Apr 1998 15:31:18 -0700 (PDT) No action was taken on your mail by this listserver. This listserver supports the following commands. These commands should be the text in the SUBJECT field of your mail message. Make sure they are in the SUBJECT field!!! subscribe Your address will be added to the list of subscribers. You will then be able to send messages to this list that will be forwarded to all other list subscribers. subscribe digest Your address will be added to the list of subscribers who receive a digest instead of each forwarded message. You will be able to send messages to this list, and will receive a digest of accumulated messages once a day. digests A list of available digests will be returned to you. This command will only work if you are already subscribed to the list. unsubscribe Your address will be removed from the list of subscribers. You will no longer be able to send messages to the members of the list. This command will only work if you are already subscribed to the list. help This help message will be returned. -------------------- Original Message Follows -------------------- John Lahr posted: > > > One of the new teachers at my school is looking for instructions for > > > building some simple accelerometers in preparation for physics day at Great > > > America. Can anyone help? > > > > > > Burt C. Kessler I'd like to suggest something very simple. Take a piece of plastic strip like a 1" wide piece of a plastic divider from a notebook, or a vertical slice from a plastic milk bottle or pop bottle. A "straw" the diameter of pencil lead from a plastic broom is still another possibility. In any case, use one of these as a horizontal spring. Take a small cardboard box and cut a square hole in it. Tape one end of the "spring" in the box, horizontally across the hole with the end of the spring adjacent to the edge of the hole on the other side. Now depending on the strength of the "spring" you can add weights, such as pennies, marbles, lengths of wire, etc. one unit of weight is so much deflection, and then is marked on the edge of the hole opposite the "spring". 10 units is so much more. If you leave the 10 units attached permanently, you have just marked a scale in 0.1's of a G. Turn upside down and calibrate in other direction. Now you have a plus and minus G meter. Refinements are to cover the hole with Saran wrap in order to prevent drafts from bothering it -- those 30+ MPH winds on the roller coaster can play havoc with the calibration. Cutting the hole with a radius to match the "spring" will improve accuracy. Use of a strip of plastic rather than a "straw" will confine its reaction primarily to be perpendicular to the plane of the "spring", or even better, two "straws" spreading apart to the attachment point -- a triangle when viewed from above. The side rigidity would be excellent this way so sine/cosine vector resolution of forces could be attempted. Cheap, fast, needs no machining, test equipment, electric power, simle to calibrate, and uses materials found around the house. -------------------------------------- | box | | --------------------------- | | | | | | | | | | S | plastic | | | C | "spring" | tape| | A |==X========================XXXX| | L | X | | | E | weight(s) | | | | | | | | | | | --------------------------- | | | | | -------------------------------------- Regards Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Re: Re: hand-held accelerometer Date: Tue, 7 Apr 1998 17:44:13 -0600 (MDT) "From: "Pinhole Listserv" " "No action was taken on your mail by this listserver." Woops, looks like the pinhole list requires subscription. I'll send the psn suggestions in from my home account, which is subscribed. Thanks for the help! JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: VRDT osc ICs Date: Tue, 7 Apr 1998 19:25:54 -0500 (CDT) Meredith, I just checked the Newark catalog re the ICs: (800 463 9275; www.newark,com) On page 812; Harris Semiconductor.: CD4047BE Cmos oscillator $0.87 ea CD4066BE Quad switch 0.72 CD4018BE Counter/divider 0.97 Also: from Motorola: (look in price list) MC14018BCP $1.00 MC14066BCP 0.75. The Statek quartz oscillator was needed for the long-term (weeks to months) stability of the tiltmeters in Alaska, and is probably over-kill for the seismometer; use the 4047; I do believe that mechanical thermal noise will far ourweigh thermal drift of the cmos oscillator (but DO use 1% resistors and a polystyrene capacitor at pin 1 of the 4047.) Also, the last time I needed LM308As, Newark had them even though they were not listed. I will try to see if one of the Analog Devices "OP" series would be an affordable replacement (with FET inputs). regards Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: hand-held accelerometer Date: Tue, 07 Apr 1998 17:46:14 -0700 (My apologies if this went twice, but I received no response from the psn-l@............. address, so I'm re-sending to the webtronics address) John Lahr posted: > > > One of the new teachers at my school is looking for instructions for > > > building some simple accelerometers in preparation for physics day at Great > > > America. Can anyone help? > > > > > > Burt C. Kessler I'd like to suggest something very simple. Take a piece of plastic strip like a 1" wide piece of a plastic divider from a notebook, or a vertical slice from a plastic milk bottle or pop bottle. A "straw" the diameter of pencil lead from a plastic broom is still another possibility. In any case, use one of these as a horizontal spring. Take a small cardboard box and cut a square hole in it. Tape one end of the "spring" in the box, horizontally across the hole with the end of the spring adjacent to the edge of the hole on the other side. Now depending on the strength of the "spring" you can add weights, such as pennies, marbles, lengths of wire, etc. one unit of weight is so much deflection, and then is marked on the edge of the hole opposite the "spring". 10 units is so much more. If you leave the 10 units attached permanently, you have just marked a scale in 0.1's of a G. Turn upside down and calibrate in other direction. Now you have a plus and minus G meter. Refinements are to cover the hole with Saran wrap in order to prevent drafts from bothering it -- those 30+ MPH winds on the roller coaster can play havoc with the calibration. Cutting the hole with a radius to match the "spring" will improve accuracy. Use of a strip of plastic rather than a "straw" will confine its reaction primarily to be perpendicular to the plane of the "spring", or even better, two "straws" spreading apart to the attachment point -- a triangle when viewed from above. The side rigidity would be excellent this way so sine/cosine vector resolution of forces could be attempted. Cheap, fast, needs no machining, test equipment, electric power, simple to calibrate, and uses materials found around the house. -------------------------------------- | box | | --------------------------- | | | | | | | | | | S | plastic | | | C | "spring" | tape| | A |==X========================XXXX| | L | X | | | E | weight(s) | | | | | | | | | | | --------------------------- | | | | | -------------------------------------- Regards Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: Re: POSSIBLE EARTHQAUKE Date: Wed, 8 Apr 1998 00:16:06 EDT I am testing out my new verticle seismograph. I recorded, in the Southern California area, what appears to be a quake occuring about 17:46:11 UTC. I have checked the finger servers and they do not show anything occuring around that time. Did anyone else record anthing around the above referenced time period? Jim Allen Cerritos, California _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: MC14066 Date: Tue, 7 Apr 1998 23:54:23 -0500 (CDT) Meredith: Another typo !!! : the demodulator schematic lists the 4066 (a quad cmos switch used as a synchronous demodulator) as a 4088, (which is probably a mythical device.) I guess I expected a person assembling the electronics would look up the spec sheets on the devices used to see how they are used. Maybe I should have posted the original 1982 schematics rather than redrawing them. .. Also: the 4018 IS a 4018 on the oscillator here in my hand. I believe the 4016 is a similar device, but not the one used. Jim H. has pointed out an AD698 device that will run the VRDT (probably) all by itself. It is power hungry (+-15V at 15ma, or 0.45watt), as are other options, which is why I did not originally use them. (the whole tiltmeter system had to run from batteries for one year on a total power of 0.6 watts). Of course, this is not a concern for the seismometer. The AD690 costs $27 per; I'm not sure I would use it at this point. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: finger quake Date: Wed, 8 Apr 1998 00:03:22 -0500 (CDT) Jim, if it is any help, here is the latest NEIS list: qk_info@................. Updated as of Tue Apr 7 13:23:40 MDT 1998. DATE-(UTC)-TIME LAT LON DEP MAG Q COMMENTS yy/mm/dd hh:mm:ss deg. deg. km 98/04/04 22:52:35 50.97N 171.25W 33.0 4.4Mb B SOUTH OF ALEUTIAN ISLANDS 98/04/05 08:17:26 63.03N 148.69W 76.0 CENTRAL ALASKA 98/04/05 10:17:14 51.82N 174.84E 33.0 4.7Mb B NEAR ISLANDS, ALEUTIAN ISLANDS 98/04/05 15:52:20 43.02N 12.47E 10.0 4.6Mb A CENTRAL ITALY 98/04/05 20:14:54 37.96N 112.54W 5.0 3.4Ml A UTAH 98/04/05 23:52:26 41.07N 124.01W 30.0 3.4Ml B NEAR COAST OF NORTHERN CALIF. 98/04/06 05:28:52 27.94N 143.60E 33.0 4.9Mb C BONIN ISLANDS REGION 98/04/06 05:44:24 60.31N 153.45W 175.1 4.4Mb SOUTHERN ALASKA 98/04/06 13:10:53 24.40S 66.90W 150.7 4.3Mb B SALTA PROVINCE, ARGENTINA 98/04/06 14:25:04 61.82N 151.10W 67.0 3.6Ml SOUTHERN ALASKA 98/04/06 23:55:16 30.97S 71.04W 50.0 4.5Mb B NEAR COAST OF CENTRAL CHILE 98/04/07 00:27:07 34.26N 141.86E 33.0 4.9Mb C OFF E COAST OF HONSHU, JAPAN 98/04/07 13:12:42 14.27N 91.56W 66.9 5.0Mb A GUATEMALA ps: nothing says that this is complete. Regards, Sean-Thomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: boom centering for STM-8 Date: Tue, 07 Apr 1998 23:31:45 -0700 Sean-Thomas -- A couple of thoughts about automating your boom centering: I think your centering motor is functionally equivalent to a very long-period integrator driving the voice coil through a much smaller value resistor than the normal integrator in your VBB design. The small series resistor from this integrator would allow a greater force to be exerted by the voice coil, and be enough to overcome the mechanical drifts of the system. This new integrator could have a long enough time constant so as not to disrupt the normal VBB operation. Perhaps a period of hours. The op-amp used for it would have to be low drift (chopper?) so as not to introduce significant noise in the bandpass of interest. Another possibility is to use a timer that goes for an hour or two. When it expires, the voltage out of the usual integrator stage is used to determine how long to run the centering motor for, and the integrator polarity determines the motor direction. With a bit of trial and error, an on-time duration for the motor could be determined that would re-center the boom for a given integrator output. Ideally, the motor should re-center the boom slowly enough so that it is below the low-frequency cutoff of the VBB system, and not unduly affect the output. Just my $.02. Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: VRDT Schematic numbers ~ Date: Wed, 08 Apr 1998 02:09:48 -0600 Hi Sean-Thomas, I'am not all up with the electronics designations by various companies with their nomenclature for cmos over the years. I wish they would just say 4047, without the CD4047 or TC4047BP etc. Of course they have to identify their products, and this makes for a stumbling block for people like me. So....we only need a 4047, 4018, & a 4066, plus the LM308's or one of its derivatives, i.e., LM108 or LM208 or LM308 OR use a ? # Fet input type op-amp/s on what is shown so far. Talking about obsolete....I am thinking of using some LH0044 op amps in place of the LM308-ha....mainly because I have them, they may work better ....but its hard to get them anymore. They may work for the instrumentation amplifier also. Electronics is like new model cars every year & the accessories make for another designation ......whew! (I am not recommending the LH0044,..I don't have that kind of experience.) Don't know about the AD698. But Philips has an interesting LVDT signal conditioner/s...the NE/SA/SE5521 which sells for about 5-8 bucks, adj Freq of 1-20k, single or dual supply, 182mv power consumption, oscillator/sine converter/demod/amp in one package. LVDT, RVDT, bridge circuits...???VRDT use??? Interesting...came out in ~1987, by a company but absorbed by Phillips later. Not a crystal oscillator. Suggestion courtesy of my brother Robert Lamb. http://www-us.semiconductors.philips.com ...use search for spec sheets etc. To sum it up for digital dummy builders: beware the letters prior to the numbers, but make sure you don't order the microscopic sizes...ha. I've got afew electronics books....nothing with these numbers of course....uh...the circle dot in the corner designates pin 1 right? And if it has a half moon on one end...the pin to the left looking down at the top is pin 1? Somedays just don't go right....ha. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: VRDT Schematic numbers ~ Date: Wed, 08 Apr 1998 02:09:48 -0600 Hi Sean-Thomas, I'am not all up with the electronics designations by various companies with their nomenclature for cmos over the years. I wish they would just say 4047, without the CD4047 or TC4047BP etc. Of course they have to identify their products, and this makes for a stumbling block for people like me. So....we only need a 4047, 4018, & a 4066, plus the LM308's or one of its derivatives, i.e., LM108 or LM208 or LM308 OR use a ? # Fet input type op-amp/s on what is shown so far. Talking about obsolete....I am thinking of using some LH0044 op amps in place of the LM308-ha....mainly because I have them, they may work better ....but its hard to get them anymore. They may work for the instrumentation amplifier also. Electronics is like new model cars every year & the accessories make for another designation ......whew! (I am not recommending the LH0044,..I don't have that kind of experience.) Don't know about the AD698. But Philips has an interesting LVDT signal conditioner/s...the NE/SA/SE5521 which sells for about 5-8 bucks, adj Freq of 1-20k, single or dual supply, 182mv power consumption, oscillator/sine converter/demod/amp in one package. LVDT, RVDT, bridge circuits...???VRDT use??? Interesting...came out in ~1987, by a company but absorbed by Phillips later. Not a crystal oscillator. Suggestion courtesy of my brother Robert Lamb. http://www-us.semiconductors.philips.com ...use search for spec sheets etc. To sum it up for digital dummy builders: beware the letters prior to the numbers, but make sure you don't order the microscopic sizes...ha. I've got afew electronics books....nothing with these numbers of course....uh...the circle dot in the corner designates pin 1 right? And if it has a half moon on one end...the pin to the left looking down at the top is pin 1? Somedays just don't go right....ha. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: VRDT Schematic numbers ~ Date: Wed, 08 Apr 1998 06:23:31 -0500 Speaking of identifing chip part numbers. Have a look at http://www.twinight.org/chipdir/ They have an extensive reference of chip numbers and manufacturers. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Canie Brooks Subject: Re: POSSIBLE EARTHQAUKE Date: Wed, 08 Apr 1998 09:24:20 -0700 At 12:16 AM 4/8/98 EDT, you wrote: >I am testing out my new verticle seismograph. I recorded, in the Southern >California area, what appears to be a quake occuring about 17:46:11 UTC. I >have checked the finger servers and they do not show anything occuring around >that time. >Did anyone else record anthing around the above referenced time period? >Jim Allen >Cerritos, California There was this small one..: == PRELIMINARY REPORT OF SIGNIFICANT EVENT == Southern California Seismographic Network operated by USGS and Caltech (This is a computer generated solution and has not been reviewed by a human) Event Date and Time : 08-APR-1998 15:17:27.6 gmt (08-APR 07:17:27.6 pst) Preliminary Magnitude: 2.3 MLG Preliminary Location : 33 deg. 47.8 min. -118 deg. 44.7 min. -6.0 km depth Event ID #: 9050015 , 31 phases used, RMS = 0.48 ERH = 1.09 ERZ = 30.52 Region: Southern California 15 mi. SSE of POINT DUME 34 mi. WSW of LOS ANGELES 42 mi. SW of PASADENA 27 mi. SSE of CAMARILLO (quarry) 11 mi. SW of Malibu EQ (19 JAN 1989, 5.0) 15 mi. S of the MALIBU COAST FAULT > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Canie Brooks Subject: Re: POSSIBLE EARTHQAUKE Date: Wed, 08 Apr 1998 09:40:42 -0700 At 09:24 AM 4/8/98 -0700, you wrote: >------------------------------------------------------------------------ > >At 12:16 AM 4/8/98 EDT, you wrote: >>I am testing out my new verticle seismograph. I recorded, in the Southern >>California area, what appears to be a quake occuring about 17:46:11 UTC. I >>have checked the finger servers and they do not show anything occuring around >>that time. >>Did anyone else record anthing around the above referenced time period? >>Jim Allen >>Cerritos, California Sorry - I mis-read that!! - I thought it was this morning.... Canie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: VBB block diagram Date: Wed, 8 Apr 1998 20:46:38 -0500 (CDT) Jim, The block diagram is intended to illustrate the feedback concepts and was never intended to be a schematic, which is why it is incomplete. I don't actually use it as drawn; I'm recycling generic amp cards. At this point I have assumed that anyone creating the circuit would have enough electronics background to fill in the details. But.. A1 has a gain of 10 but is also a low pass filter. I believe the resistor from the inverting input to ground should be 23.2k for a gain of X20 (with 464k for the feedback R) since the input filter divides by 2. The resistor loading the output is 10k. The feedback resistor for the integrator input offset balance is 2meg. (I actually use a 3amp instrumentation configuration for the integrator). There is no problem with the integrator with temperature. any more than with any other low pass filter. It operates at unity gain to avoid any saturation that would limit the dynamic range. (it pegs out only when the displacement amp is also saturated, but, of course, for the time constant of the integrator). The integral feedback resistor of 107k is determined by the transfer function and shapes the broadband response. Its behavior is not a matter of supplying an independent current, but to shape the response by the ratio of the integral current to the proportional current through the 581k resistor and the differential current through the 24.1 uf capacitors. The feedback elements cannot be considered independently of each other. At least in this VBB configuration. regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Magnetometer going wild! Date: Wed, 8 Apr 1998 19:14:16 -0700 (PDT) Hi All: For most of the day I was fascinated with watching wild fluctuations in geomagnetic field strengths on my magnetometer! Does anyone have a clue to what's possibly causing this? For the last few weeks the readings were sort of erratic... But, today takes the prize! Frank Condon mailto: frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler Subject: Re: Magnetometer going wild! Date: Wed, 08 Apr 1998 22:55:23 -0400 Frank, GEOS also has had some adnormal readings today. Take a look at: http://sec.noaa.gov/today.html ELFRAD GROUP N 35 43.7336 W 80 48.4224 cplyler@............. Frank Condon wrote: > > Hi All: > For most of the day I was fascinated with watching wild fluctuations in > geomagnetic field strengths on my magnetometer! Does anyone have a clue to -- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Magnetometer going wild! Date: Wed, 08 Apr 1998 22:35:04 -0700 Frank Condon wrote: > > Hi All: > For most of the day I was fascinated with watching wild fluctuations in > geomagnetic field strengths on my magnetometer! Does anyone have a clue to > what's possibly causing this? For the last few weeks the readings were sort > of erratic... But, today takes the prize! > You're not the only one recording some fluctuations: http://dxlc.com/solar/index.html -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: Magnetometer going wild! Date: Wed, 08 Apr 1998 23:07:56 -0800 Wait till Mother's Day, full moon et al (may 10th for you orphans) Charles Watson wrote: > Frank Condon wrote: > > > > Hi All: > > For most of the day I was fascinated with watching wild fluctuations in > > geomagnetic field strengths on my magnetometer! Does anyone have a clue to > > what's possibly causing this? For the last few weeks the readings were sort > > of erratic... But, today takes the prize! > > > > You're not the only one recording some fluctuations: > http://dxlc.com/solar/index.html > > -- > ---/---- > Charles P. Watson > Seismo-Watch > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: new help files Date: Thu, 09 Apr 1998 08:59:19 -0700 Larry Cochrane wrote: > > Thanks John, > > I placed the documents I have so far on my PSN system. The following link > can be used as a starting point: > > http://psn.quake.net/wqdocs/index.htm > > I now have 12 people offering to help, so I have plenty of help. > > -Larry > > At 09:00 AM 4/6/98 -0600, you wrote: > >Larry, > > > >How about just putting the new help files on your web site with Larry I quickly read over the current HTML and the four help files. I see that you selected a style such as File menu and File List. Notice that menu is lower case. Another way to refer within a sentence is to italic the words and cap always havew two caps.. EM File Menu /EM or EM Save File /EM. re read the file. re as a prefex... the nuns will get you for this one-- How about reload the data. a SEED or PEPP data set volume... What is a SEED and PEPP data set and why do I need to know this? Looks good-- I'll keep reading. Regards, Steve > >a heading > > 'Preliminary WinQuake help file under review' > > 'Please forward suggestions or corrections to ...' > >When the next version comes out, you can just change the > >title and leave them there. > > > >Just a thought. > > > >JCLahr > > > >_____________________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email listserver@............. with the body of the > >message: leave PSN-L > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Velocity Period Enhancing circuits Date: Thu, 09 Apr 1998 21:22:04 -0600 Albert Noble, Picked up the article you mentioned afew days back; "A Vertical Equalization Circuit For Increasing Seismometer Velocity Response Below The Natural Frequency" by Peter M. Roberts in Vol. 79, No. 4, pp. 1607-1617, Bulletin of the Seismolological Society of America, in the Central Denver Public Library. I by no means followed all of the article, but it looks like it originally would be of interest to those with the short period seismos, to expand the response out to the intermediate period results. Electronically the original circuit uses LM312 op amps and its possible to use many other op amps of course, as trial replacements. Its nice to see the total circuit (which you have to 2 X) and it seems extremely simple, even for me-ha. Regardless, if you do try it out, or change it, by all means let us know the results. In many ways, however, I'am more drawn to the posted PSN article and circuit, "A Period Lengthening Device, Long Period Velocity Type Seismometers", by Allan Coleman, Nov 1995 that is on the PSN computer. I've managed to go through all of the past email messages over time, but....I don't remember seeing any mention of anyone trying it....nor is there any mention in the member/station lists. A strong part of my own interest is that I do have some 1500 ohm coils that could work-ha. Of course the Coleman circuit is a feedback circuit, and indicates the possibility of a much longer period, than the Roberts circuit. It would be nice to hear from anyone on the email list, who has tried the circuit? And, of course, their opinion? Failing that, I would presume no one has tried it.... people usually want strong confirmation before going ahead on their own. Technically, I couldn't begin to address any faults in either but the appealing idea of checking them out, is there anyway.... Raise the anchor and hoist the sails Mate!....ha. Thanks for the reference, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: ASCII data Date: Thu, 09 Apr 1998 23:54:11 -0700 Hi Everyone, I got this email today. Does anyone have a utility that Galileo can use to save a PSN event file in ASCII format? I get this question now and than and I plan to add this option to WinQuake in the next release, but that doesn't help Galileo now. Adding this feature to WinQuake is pretty easy, but I'm not sure what to do with the header information like file start time, samples per second etc. I can save the data set in ASCII form, but I would think that programs like MatLab and SAP90 (not sure what that is) would also need information like the sample rate and maybe the start time? Is there any "standards" for dealing with this? If not I was thinking of placing the start time and SPS on the first line and then the data set, one sample per line. The other thing that could be done is save the header info in a separate file. Any ideas??? -Larry Cochrane Redwood City, PSN >>>> Reply-To: "Galileo Tamasi" From: "Galileo Tamasi" To: Subject: Ascii data Date: Thu, 9 Apr 1998 17:37:05 +0200 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.71.1712.3 X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 ArialI have winquake program. How i can extract data ascii for dinamic analisys with SAP90 ? Thanks. Galileo Tamasi <<<<<<<< _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: More Earthquake Predictions Date: Fri, 10 Apr 1998 00:44:06 -0700 (PDT) Hi All: Here is another Web-Site I came across that is about predicting earthquakes. James Berkland Earthquake Prediction Web-Site http://www.syzygyjob.com/ Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: ASCII data Date: Fri, 10 Apr 1998 06:34:39 -0700 (PDT) One way that is fairly easy is to just use some BASIC code. There is sample BASIC code for loading a PSN file into memory in the file description on the PSN bulletin board. It would look something like this: DIM A(25100) DEF SEG(A(0)) BLOAD "C:\970101AN.XXX",varptr(a(0)) FOR I=100 to 25100 PRINT A(I) NEXT I You could precede the data (which starts at offset 100) by other print statements to print date, start time, etc. in whatever format was required by this program (SAP90). Make sure array A is DIM'ed AS INTEGER. Ted > > Hi Everyone, > > > I got this email today. Does anyone have a utility that Galileo can use > to save a PSN event file in ASCII format? > > > I get this question now and than and I plan to add this option to > WinQuake in the next release, but that doesn't help Galileo now. > > > Adding this feature to WinQuake is pretty easy, but I'm not sure what to > do with the header information like file start time, samples per second > etc. > > I can save the data set in ASCII form, but I would think that programs > like MatLab and SAP90 (not sure what that is) would also need information > like the sample rate and maybe the start time? Is there any "standards" > for dealing with this? If not I was thinking of placing the start time > and SPS on the first line and then the data set, one sample per line. The > other thing that could be done is save the header info in a separate > file. > > > Any ideas??? > > > -Larry Cochrane > > Redwood City, PSN > > > >>>> > > Reply-To: "Galileo Tamasi" > > From: "Galileo Tamasi" > > To: > > Subject: Ascii data > > Date: Thu, 9 Apr 1998 17:37:05 +0200 > > X-MSMail-Priority: Normal > > X-Mailer: Microsoft Outlook Express 4.71.1712.3 > > X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 > > > ArialI have winquake program. How i > can extract data ascii for dinamic analisys with SAP90 ? > > Thanks. > > Galileo Tamasi > > > > <<<<<<<< > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Sam Toon" Subject: Re: ASCII data Date: Fri, 10 Apr 1998 16:29:27 +0100 I have just written a program in Matlab to read in PSN format files. It can also read in the header information if you are using version 5 of Matlab. If anyone wants a copy just send me an email, or it could possibly be put on Larry's website. I haven't thoroughly tested the program! I will also try and write a program to write the data back out so that you would be able to use Matlab to do some processing on the data and save it as a PSN file. Sam ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sam Toon serr15@......... Microseismology Research Group http://www.pcweb.liv.ac.uk/Microseis/ Dept of Earth Sciences Tel: +44 (0)151 794 5157 University of Liverpool Fax: +44 (0)151 794 5157 P.O. Box 147, Liverpool, L69 3BX United Kingdom ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -----Original Message----- From: Larry Cochrane To: psn-l@............. Cc: g_tamasi@........... Date: 10 April 1998 07:55 Subject: ASCII data Hi Everyone, I got this email today. Does anyone have a utility that Galileo can use to save a PSN event file in ASCII format? I get this question now and than and I plan to add this option to WinQuake in the next release, but that doesn't help Galileo now. Adding this feature to WinQuake is pretty easy, but I'm not sure what to do with the header information like file start time, samples per second etc. I can save the data set in ASCII form, but I would think that programs like MatLab and SAP90 (not sure what that is) would also need information like the sample rate and maybe the start time? Is there any "standards" for dealing with this? If not I was thinking of placing the start time and SPS on the first line and then the data set, one sample per line. The other thing that could be done is save the header info in a separate file. Any ideas??? -Larry Cochrane Redwood City, PSN >>>> Reply-To: "Galileo Tamasi" From: "Galileo Tamasi" To: Subject: Ascii data Date: Thu, 9 Apr 1998 17:37:05 +0200 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.71.1712.3 X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 I have winquake program. How i can extract data ascii for dinamic analisys with SAP90 ? Thanks. Galileo Tamasi <<<< _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) To leave this list email listserver@............. with the body of the message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: ASCII data Date: Fri, 10 Apr 1998 08:35:18 -0700 Larry -- I'd go with just including a header that contains the information in question, and put it at the start of the ASCII file. It's easy enough to remove it later with a text editor if it turns out it's not needed. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: ASCII data Date: Fri, 10 Apr 1998 11:18:11 -0700 (MST) On Thu, 9 Apr 1998, Larry Cochrane wrote: > Adding this feature to WinQuake is pretty easy, but I'm not sure what to > do with the header information like file start time, samples per second > etc. > I can save the data set in ASCII form, but I would think that programs > like MatLab and SAP90 (not sure what that is) would also need information > like the sample rate and maybe the start time? Is there any "standards" > for dealing with this? If not I was thinking of placing the start time > and SPS on the first line and then the data set, one sample per line. The > other thing that could be done is save the header info in a separate > file. Larry, I think getting an ASCII format going is a great idea, especially for transfering files over the net and e-mail! How about making the first line the start date, the second the start time, the third the SPS and then one line for each data reading... The advantage that I can see in doing this is that a person could easily go into the file and edit and/or remove those peices which could then be transferred to many different kinds of software that handle data in that manner... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: A Magnetic Spring Seismometer Description Date: Fri, 10 Apr 1998 16:48:09 -0500 Friends, A while back I posted a bunch of stuff on magnetic suspension seismometers of my own design. Actually I experimented with a whole variety of good and bad designs. This is a sort of progress report = of making a few stabs at the problem now and then--presented here in the spirit of revealing some of its more promising aspects in case I go on to something else entirely. Generally my best designs have been small and used the repulsion between two magnets as a spring force to balance the force of gravity rather than the metal spring more commonly used in verticals. Pretty quickly I discovered that an oiled steel razor blade edge attracted to another magn= et mounted behind a thin brass strip makes a great pivot mechanism for such = a design, while being rigid enough to only allow only one accurately define= d axis of movement (in other words little off-axis wobble or vibration). =20 Furthermore the Q of such a system is very high, meaning in effect that i= t is very efficient at capturing and holding mechanical energy with low losses. In other words when slightly disturbed, such a system can take three or four minutes to stop oscillating at several oscillations per second. Such high Q systems, even with short periods, are an excellent match for force feedback, because the low losses mean that it can efficiently integrate slow additions of mechanical energy of energy over long periods of time; much longer than its own natural frequency. This is what is needed to sense teleseismic events with physically small instrume= nts. Such a configuration may be built very compactly and, with suitable adjustments, can be used at any angle from the vertical. For example if such instruments are small and easy to build, three of them could be aligned along the edges of a triangular pyramid, and the traces used to calculate quake shocks as three-dimensional vectors of accelerative force. With computing power so relatively cheap, why not? After initial trials with a laser pointer, I decided that a bright red LE= D and phototransistor interrupted by a flag mounted on the beam is small, sensitive, and cheap enough to do the job nicely (at least down to the ambient higher frequency seismic noise levels where I live in the central city near lots of traffic). No trouble seeing lots of these. The obvious objection to such a design is that it is a little bit magnetometer, a little bit gravimeter, and a little bit seismometer. It falls between three stools, so to speak. There can be little objection to an instrument which is both gravimeter and seismometer, so long as it can be held within range of the daily earth tides. A seismometer usually look= s for the smallest possible accelerations, and gravity is physically the sa= me as acceleration, so gravimeters are merely DC versions of seismometers.=20 The only real problem with a gravimeter being used as a seismometer is that seismometers are designed to be so sensitive to acceleration that sl= ow DC drift and earth tides are likely to throw the readings off scale. A Lehman is a horizontally balanced instrument, designed to be nearly blin= d to gravity, and thus does not suffer from these complications.=20 Anyhow, while the same instrument can be both a first class gravimeter an= d a vertical seismometer at the same time if it can be kept within scale, magnetic fields are another thing entirely.=20 They are just plain bad, insofar as weak external magnetic fluctuations come in all frequencies and interact with the rather strong magnetic fiel= d used to balance the force of gravity inside the instrument. Since we are trying to balance and measure these opposing gravitational and magnetic forces to low parts per million if possible, natural magnetic storms can interfere with our data. One design that I have proposed to use strong ra= re earth magnets to balance gravity on the theory that a smaller stronger mo= re concentrated magnetic balancing force would be relatively blind to weak background fluctuations in the earth field.=20 The bottom line here is that assuming temperature can be controlled fairl= y well, relatively small cheap and sensitive instrument can be designed wit= h magnetic springs. I now think magnetic shielding is the best answer to th= is instrument design problem. Doug Crice posted a response some time ago in which he said that several concentric shields of permalloy and iron would probably do the job. I have finally got around to reading a good paper on the subject, and it looks as if the best way to shield an instrument is probably to wind a th= in tube out of a thin sheet (even a foil if it it is good stuff) of some ver= y high permeability ferromagnetic metal such as permalloy or mu-metal. If t= he ends of the tube extend beyond the instrument and the several layers of magnetic alloy are separated with any non-magnetic material such as cardboard before being wound into a tube, then an instrument placed insid= e the tube can be shielded by a factor of thousands. Iron or steel is chea= p but rather poor for shielding purposes, except to reduce fields of thousands of Oersteds down to the point that permalloy can take over. (Se= e W.G. Wadey; Review of Scientific Instruments, Nov. ,1956. p 910).=20 From what I know, one of the best mountings for such a compact vertical instrument would probably be to lower it into the bottom of a vertical ir= on pipe plugged with concrete at the bottom, buried perhaps six feet in the ground. This would tend to be a good seismic platform, while largely buffering temperature changes, (which are usually the main arch-enemy of instrumental accuracy). To reach some sort of closure to this long post, my latest design uses a stack of three ceramic ring magnets mounted on a vertical screw so they m= ay be raised or lowered by turning the screw with their magnetic axis remaining accurately vertical.=20 This force opposes and supports the short horizontal beam. The latter is = a fourth magnet glued to a utility knife blade with a two ounce lead fishin= g weight on top. This horizontal knife edge is attracted to a brass strip backed on the opposite side with two rare earth magnets. This forms a kni= fe edge pivot surface to one side. In other words the little beam is very stout and heavy and rocks up and down on a horizontal axis less than an inch to one side.=20 On the side of the beam away from the brass pivot rest, I looped a strip = of aluminum cut from a drink can so it extends the beam sideways several inches. This extension amplifies the motion of the center of gravity of t= he beam by a factor of two or three. This hold the little aluminum flag that interrupts a beam between the LED and the phototransistor. The latter hav= e most of their integral plastic lens cut away so the emitting and sensing elements can be mounted very close together surrounding the flag (which moves vertically with the beam) for best movement detection sensitivity.=20 Finally, there is a second stack of two ceramic magnets, mounted on anoth= er vertical brass screw, just over the beam. This latter stack is oriented s= o as to try to pull the beam upwards.=20 The end result is that we have a little beam that resembles a magnetic pu= ck rocking up and down on an axis near its side. Below it we have another magnetic puck that can be raised or lowered and which repels it. To the top we have yet a third puck that can also be raised or lowered to attra= ct rather than repel the beam. All these discs are coaxial. By adjusting the repelling and attractive forces, we can push the beam from below while pulling it from above. Some combination of these forces will be found to very nearly balance gravity -- in such a way that the net force which tends to restore the beam position is very weak.=20 As with a Lehman, this delicate adjustment has the effect of lengthening the natural period of the beam and increasing the sensitivity. Even if th= e period is still a second or a half second, which may not seem very good, the beam will move quite a lot in a response to a very small amount of force, which is what we are after (and which is also what the goodness of= a zero length spring is all about). At this point we have a very high Q vertically sensitive spring and mass and sensor combination. The last step is to add force feedback. This is done by winding a wafer of several hundred turns of thin magnet wire wet with epoxy so that it is about the size and shape of one of the ring magnets (about 1/4 inch thick and an inch across). This coil is mounted o= n a thin glass horizontal platform just below the magnet on the beam. Thus the coil is surrounded by the repelling magnet to its bottom and the beam magnet to its top and coaxial with both. In this way, the coil has maximu= m interaction with the magnetic force that supports the beam.=20 It appears that the output from just one little 324 op amp can supply the 20 milliamps at six volts and this is sufficient to stabilize the beam position, even though the resistance of the coil is fairly low at about 8 ohms. Obviously, however, if the forces that need to be balanced are significant, a few hundredths of a milliwatt of power is not going to be able to push around a 2.5 ounce lead-weighted beam in order to faithfully follow and balance the motions from strong or rapid accelerations. But there is no reason why this should disqualify such a setup from following teleseismic events, which are characteristically slow motions with little power involved. I assume that if one wants to extend the flatness of response to strong shocks or higher frequencies, it is best to raise the voltage (currently= 6 volts from four large dry cells) to twelve volts and put transistor power boosters on the zero potential terminal of the force feedback coil and al= so on the variable voltage terminal, but this should be quite easy. Currently, I use a very simple arrangement of a 10 MFD non polarized tantalum and a 1000 ohm pot in parallel to power the coil. These are between the coil and the op amp output. This is not a sophisticated force feedback arrangement at all, and does not reflect stability at high power levels, but it does tame pesky feedback oscillations when small forces ar= e involved.=20 Obviously I have concentrated mostly on the mechanical configuration in this discussion. I=92m a bit over my head in regard to the finer points o= f optimizing feedback circuitry, but a little trial and error along with simple resistor and capacitor and op amp combinations is one way to do th= e job in a workable if non-optimal way. The STM-8 circuit configuration wou= ld undoubtedly work too. Otherwise read Horowitz and Hill=92s =91Art of Electronics=92 or take a course in feedback theory. A few final points. The external dimensions of the sensor in its present prototypical form exclusive of its mounting (chiefly made from scraps of wood and glass and brass ) is about 3x4x6 inches, with its longer dimensi= on being vertical. Thus it is small and could probably be designed to be be lowered in a 4 inch ID pipe. I think it should be possible to wind a reasonably suitable cylindrical o= r rectangular magnetic shielding tube from a strip of permalloy or mu-metal foil if I knew where to get some. Anyone know?=20 My current prototype is mounted on a pine board with the batteries and circuit inside a plastic insulated beverage cooler along with a heavy chu= nk of iron for thermal ballast. In other words so that any temperature chang= e will be very gradual. Nevertheless, the instrument is a gravimeter and th= us very subject to slow DC drift which pushes it off scale. The rough scale recentering adjustment is done by turning the upper screw to raise or lower the upper attracting magnet, while smaller scale changes are made b= y pushing a stack of ceramic magnets around outside the cooler, as I watch the emerging chart on my computer monitor (I use a two channel WinDaq A/= D for charting). The biggest problem that I anticipate with the current set= up is to keep the trace centered. I think if you reduce the sensitivity enou= gh to have the daily earth tides move the instrument full scale (which also implies good temperature control, I think), then you have automatically reduced the sensitivity too much for it to be a very sensitive seismomete= r. So you need some way to recenter the scale, even if the instrument is perfect, unless the A/D output has very high resolution. I don=92t have any sort of formal site, or any formal graphic presentatio= n prepared other than this written progress report, but I can send a digita= l JPEG photo of my instrument in its modest current form (I think Dave Nels= on offered to host a picture on his web site a while back). I certainly don= =92t advocate that anyone should try to duplicate my design exactly in every detail. For me instrument design is always a work in progress, and I neve= r do seem to get to the polished brass knob stage that some find so appeali= ng. What I am most interested in doing is doing is communicating the basic principles of my rather unorthodox instrument, centered around being fair= ly easy and cheap to build by amateurs as a fundamental principle. All comments are welcome, with the caveat that the current configuration is suggestive but not a polished design.=20 It is completely uncalibrated, and I know that it is sensitive chiefly by walking past it on my concrete slab floor while watching the chart, stamping the floor from the other side of the room, and by studying the static influence of small magnets moved about slowly at a distance of a f= ew feet.=20 --Yours, Roger Baker =20 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: magnetic suspension Date: Fri, 10 Apr 1998 19:34:54 -0500 (CDT) Roger, Thanks for the description of your magnetic suspension seis. An instrument of this type was one of the first that I worked with back in 1969, called the Sprengnether S-7000. It is still manufactured today because of its robust qualities and total lack of spring resonances. It is rather expensive, though, and is about the size of a shoe box. The S-7000 uses a concentric counter-rotating magnet assembly that has a special alloy shunt that compensates the temperature change of the magnet's strength. Since the rotor magnet is completely inside the fixed or stator magnet, it is relatively immune to external fields, at least as a velocity sensor. The standard output of the S-7000 is from a velocity coil, with a period of 1.5 seconds. I have configured an old one for VBB feedback to operate at 150 seconds, which really pushes the magnetic and thermal stability envelope; it is acceptably stable at 30 seconds though, and uses the VRDT with picometer resolution as the displacement sensor, and the velocity coil/magnet becomes the feedback coil. I looked in some of my catalogues for info on magnetic shielding sheeting (permaloy, mu-metal) and currentlu draw a blank. I will make some calls on Monday. If your sensor detects small magnets from a few feet away, it certainly HAS a serious susceptivity problem. Maybe you could consider a design with the RE magnets working from WITHIN a large pot, ring, or U amgnet, which would be an environment much stronger than external fields. Re recording the displacement detector output: I use a 1000 second high-pass output (1000 uf-NP into 1 megohm) to remove the DC components (tides, thermal drift, atmospherics, etc) of the VBB output, which can vary by several hundred millivolts over a day; the "seismic" component runs about 1 to 10 millivolts for the 6-second microseisms, and I have to be good to my cheap 12-bit digitizer. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: equalizer circuits Date: Fri, 10 Apr 1998 20:34:30 -0500 (CDT) Meredith, We have made several evaluations of the P. M. Roberts circuit, especially trying to make a 4.5 hz phone act like an L4-C at 1 hz. It does work, but it is noisy, even with the best selection of amplifiers. (there was a recent BSSA article on the noise limits of seismometers and amplifiers, but I can't find the reference right now; it had an important table that matched the performance of selected amplifiers to the coil resistance of the seismometers). The problem with the equalizer circuit is that the gain of the 1-pole filter is about 20, so the two of them in series (to get the proper slope) have a gain of 400. This means that all the 1/frequency noise of the amplifiers gets amplified and summed into the output. VERY careful selection of the preamp can help, and narrow-band coupling of the stages also helps, but limits the response. I still cannot get very good spectral coherence between an L4 and an equalized 4.5hz phone when operating side-by side on a shake table. And the noise in the output runs at several millivolts in the 0.8 to 5 second periods, and is ten times that if you breathe on the amplifiers (we use LT1024s). So the equalizer is OK for low sensitivity applications, but don't connect it to a 24-bit digitizer! When I find the reference to the other article (probably in THE HEAP at home), I will post it. Maybe someone else has it handy. regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: not FET amps Date: Fri, 10 Apr 1998 20:44:14 -0500 (CDT) Brian, Thanks for the correction about the LM308 NOT being a FET input like the (correct me if necessary) LF356. I tend to get some of the better qualities of devices confused, and as you observe, National about breaks their elbo patting their back over how DC stable the 308 is; it doesn't even have an offset adjustment. It actually has many FET qualities but without the thermal, etc, problems that you mention. I will check out the LM112 a bit more, since the LM308 isn't always available from all suppliers. Maybe it is a bit more ESD resistant than the 308. I've had problems with ESD wiping out all 20 or so 308s in a single tiltmeter system. I appreciate your interest, and will correct the notation on the next round of drawing upgrades. Hopefully the PSN readers of the documentaion will see this. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Surplus store Mu-metal foil Date: Fri, 10 Apr 1998 20:34:24 -0600 Roger Baker, A possible source for mu-metal might be found in electronic surplus stores. These are canned donut shaped which were originally used for donut choke etc. coils...i.e., ferrite predominates now. In Colorado I've seen them in 3 out of 4 surplus stores. They seem to be mostly orange, but sometimes black and mixed in with the ferrite core stuff. The tip off is that on one side, on the rim it has the appearance of being like a grocery can lid edge. Some are made different, and can be pried open, or pulled apart. Inside is mu-metal rolls of foil, usually not too wide...varies ~ 1/4", but they can usually be rolled off readily to whatever surface...and glued...whatever. The prices really run a wide range, from cheap to fairly expensive...50 cents each on up to $3 each, depending on store. These maybe leftovers From the 60's or so. Diameters are ~ 1.25 to 1.50" usually, but some are bigger. I don't know how thick the foil is...I've never got one. For your deal, it may take several, and hopefully you can get them cheap. They are getting scarcer all the time, and never seem to be in much quanity at all. If it doen't look like ferrite, check it out. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Readers Digest Magnet Healing Article Date: Fri, 10 Apr 1998 20:37:02 -0600 Offbeat but interesting article on using magnets for pain reduction. April 1998, pg. 170, Magnets For Pain? Basically 2 institutions used magnets & placebos over pain areas on 50 patients, and the magnet postpolio patients reported a much higher ratio of relief than the placebo patients. No explanations made. Only a short 1/3 pg or so spot, in the news from the world of medicine. I don't think it would be in the Readers Digest if it wasn't a valid report. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: The care & feeding of a Sprengnether vertical Date: Fri, 10 Apr 1998 22:32:34 -0600 Sean-Thomas, Getting around to setting up my 40 odd year old, and abused vertical. As of today I dropped the mass and promptly broke and mangled all spring wires and pivot hinges. Never fear, later in the day, it was up and hanging again. As it turns out, scatch sending the vertical manual, as I do have it in my heap at home (ha). 30 years affect my sloshing memory. The manual didn't really apply much as everything has been moved or out of the factory setting anyway. Late today, it was bouncing around at 17 second period on the mother pier, before I quit for the day, with more stuff, to be done tomorrow. Am finding out that verticals are another world apart from the horizontals, and this "baby" indicates it will need significantly more maintenance care over a period of time. I can see the relativity with your STM-8 design more clearly. Have questions if the good doctor cares to inform the parent: The original pivot post has a groove slot for presumably #36 music wire or .025" diameter. When I got it I found that the previous owner had tried using a bunch of smaller gauge wires close together, and steel flat hinges 3/8" wide and .005" thick at some time or the other. Am using the flat spring steel hinges presently. It seems to oscillate forever...~ 20 minutes, before I can't see any more movement. Anyway....being as the original was wire, would you recommend going back to the wire or leaving it as is? I can understand horizontals, but this "childs", period adjustment kind of throws me. Level the base, and it has a 6 second period, then raise the front screw, and the period increases, but with mass position adjustments. The mechanism seems somewhat like the horizontal, but I'am sure not really grasping the basis with the vertical period scheme? The spring itself does exhibit the ringing visually and sometimes in the audio range when it hits the stops. You've mentioned this before. I installed acouple wood blocks under the boom back hinge for initial setup and as a form of stop for crashes again. Their height is less than the level of the hinges, and doesn't interfere with operation. This model has photocells and a boom motor mass position device, which will eventually be used...if they work...and I inprovise. Might you have any tips to pass along, other than my questions? Would appreciate it. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: Re: Surplus store Mu-metal foil Date: Sat, 11 Apr 1998 00:16:20 -0700 -----Original Message----- From: meredith lamb To: psn-l mailing list Date: Friday, April 10, 1998 7:41 PM Subject: Surplus store Mu-metal foil >Roger Baker, > >A possible source for mu-metal might be found in electronic >surplus stores. These are canned donut shaped which were I think what you are describing are tape wound torroid cores. The tape is not Mumetal. There are many different alloys used for these cores depending on the intended use. Some of the material is what is known as "square loop" material. It has a memory characteristic and stays magnetized in the direction it was last driven. This would not be suitable for shielding purposes. Other materials are more linear and can be used for making audio or power transformers. Another type has yet another characteristic and is supplied in matched quads for use in magnetic amplifiers. There are many variations of these three depending on the frequencys and power levels they were designed for. I think the best unmistakable source of Mumetal is found in old cathode ray tube shields. The electron beam in a CRT is easily deflected by earth field and leakage flux from transformers and power lines and must be shielded for an oscilloscope to work properly. Some of the newer shields use a newer, different alloy which is 2 or 3 times better than Mumetal. The best shields are made with 2 layers of Mumetal with layer of copper sandwitched between. They are seldom needed and are quite heavy. By the way, the shielding effect of Mumetal is greatly reduced by drilling or cutting it. If you need to cut it after it is heat treated use very sharp shears and minimize the shock imparted to the piece. I don't know the correct proceedure for annealing Mumetal but I know it is done in a hydrogen atmosphere and that the temperature is critical. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: frankcnd@.......... Date: Sat, 11 Apr 1998 02:52:49 -0500 (CDT) More Earthquake Predictions Hi KFrank, Thanks so much for this site. Might be very interesting. Does anyone know what Berkland's success rate is? Ran across another book, today, and it looks very interesting. I have only read a couple of pages. It is called "The Trembling Earth." It is written by Frederic Golden and is copyright 1983. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: frankcnd@.......... Date: Sat, 11 Apr 1998 01:07:41 -0700 (PDT) Hi Bonnie: Another book that I'm trying to find a copy of is "When the snakes awake." about animal activity as a pre-cursor to earthquakes. Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" >More Earthquake Predictions > >Hi KFrank, > >Thanks so much for this site. Might be very interesting. Does anyone >know what Berkland's success rate is? > >Ran across another book, today, and it looks very interesting. I have >only read a couple of pages. It is called "The Trembling Earth." It is >written by Frederic Golden and is copyright 1983. > > >Bonnie >the crafty crafter > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: Readers Digest Magnet Healing Article Date: Fri, 10 Apr 1998 22:09:36 At 08:37 PM 4/10/98 -0600, you wrote: >Offbeat but interesting article on using magnets for pain reduction. >April 1998, pg. 170, Magnets For Pain? Basically 2 institutions >used magnets & placebos over pain areas on 50 patients, and >the magnet postpolio patients reported a much higher ratio of >relief than the placebo patients. No explanations made. Only a >short 1/3 pg or so spot, in the news from the world of medicine. >I don't think it would be in the Readers Digest if it wasn't >a valid report. Tried one for my back and didn't notice any significant difference. One guy at work says it works great for him. I just don't know? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: Readers Digest Magnet Healing Article Date: Sat, 11 Apr 1998 08:32:57 -0700 (PDT) Hi Meredith: Wouldn't that be known as "bio-magnetism." Also, I've seen some advertisments of matresses with embedded magnets. Very interesting subject matter. Somewhere in my collection of periodicals I recall seeing a 20 year old journal about alternative healing with an article about the use of magnets. I'll see if I can find it and post what it tells. Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" >Offbeat but interesting article on using magnets for pain reduction. >April 1998, pg. 170, Magnets For Pain? Basically 2 institutions >used magnets & placebos over pain areas on 50 patients, and >the magnet postpolio patients reported a much higher ratio of >relief than the placebo patients. No explanations made. Only a >short 1/3 pg or so spot, in the news from the world of medicine. >I don't think it would be in the Readers Digest if it wasn't >a valid report. > >Meredith Lamb > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: frankcnd@.......... Date: Sat, 11 Apr 1998 08:57:16 -0800 Looking for predictors or the gifted? 98% close enuf? http://www.viser.net/~charking/story.html When studying this keep in mind today's "science" is tommorrows witchcraft. The strides in quantum physics is closing in on the bicosmic energies. The gift is something that the scientific method promoted by the 'analyst' (notice the ANAL) lends itself to never having a final answer, just the most convincing argument gathering the largest world of agreement. I've experienced this on both ends of study. When working in the black arts of EMF/RFI shielding, I got 'results' using what's known as the common intelligence, tapping in with stupid things like intention, but producing a shielding that passed all FCC testing for sure. This bothered all my superiors, with their MS degrees, and they spent six months attempting to figure out what I did, instead of enjoying the product that would beat everyone to the market. While intellectually J Offing this, a competitor got their product to the market and blew my co. off the marketing scene. So when you get some project subsystem working, keep going and don't go for the BOOBY PRIZE - Reasons...or results. I've found results more satifying. For Roger's project try reflective mylar (AKA space blanket material) and use the old 555 chips, they can work miracles...Keep it SIMPLE, genius is simple, as the Truth, out their is... bschafer@......... wrote: > More Earthquake Predictions > > Hi KFrank, > > Thanks so much for this site. Might be very interesting. Does anyone > know what Berkland's success rate is? > > Ran across another book, today, and it looks very interesting. I have > only read a couple of pages. It is called "The Trembling Earth." It is > written by Frederic Golden and is copyright 1983. > > Bonnie > the crafty crafter > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: ASCII data Date: Sat, 11 Apr 1998 08:05:35 -0700 Hi Larry I believe SAP90 is a dynamic building structural analysis program. Barry Larry Cochrane wrote: > > I can save the data set in ASCII form, but I would think that programs > like MatLab and SAP90 (not sure what that is) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: equalizer circuits Date: Sat, 11 Apr 1998 08:22:37 -0700 Sean Thomas There were a couple of articles in BSSA vol. 82 #2 ,pp 1071-1123 by P.W. Rodgers that talked about it ."Frequency Limits for seismometers as determined from signal to noise ratios". Is this what you were thinking of? Barry > When I find the reference to the other article (probably in > THE HEAP at home), I will post it. Maybe someone else has > it handy. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: S5000 LP vertical Date: Sat, 11 Apr 1998 12:32:41 -0500 (CDT) Meredith, The S5000 LP vertical IS an entirely different sensor from the S5000 series horizontals; the only thing they have in common is the coil/magnet assembly. I will push your request for materials to the top of the list next week. I will also send you some new hinge material and new spring suspension wire. Getting the seis to perform as advertised is difficult enough with the original design, and probably nearly impossible with substitutions. In particular, if the hinge crossover point moves at all wrt the upper end of the spring suspension clamp, the period will change radically as the boom position changes. About the best period linearity that can be obtained is 3% over a range of + - 2mm at the boom pointer. This means that if the period is 30 seconds at center, it can be 31 or 29 over the operating range. The adjustment of the upper spring attachment sliding assembly for linearity can take days, and is all for naught if some event stresses the hinges after it is done. When these S5000 were used in the WWNSS, they originally tried for a standard of 30 seconds (and a 90 second galvanometer), but eventually backed off to a 15 second standard because of the instability and linearity problems. I have just "tuned up" a set of 4 S5100s (the "high performance" successor to the S5000: it can actually operate at 90 seconds! .... under ideal vault conditions... ) for a project in India. It was neither fun nor rewarding, since I knew that my homemade VBB instrument could out-perform them 10 minutes after it is put on the pier. Re the period adjustment with the front leveling screw: this is the normal way to trim the period: raising the front makes it longer by decreasing the gravity vector wrt the mass and hinge point. Generally the screw is not turned more than 6 turns from where the base is level; otherwise, adjust the main spring tension screw. This is were there are two clamps on the piano wire, one of which must always be tight or the spring will collapse. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: frankcnd@.......... Date: Sat, 11 Apr 1998 10:48:55 -0700 (PDT) Hello there: Fear not... I've not ruled out the use of humans as sensitive indicators for earthquake prediction. I'm only stating that animals are also another area that needs more exploration and study. Thank you for reminding me about Charlotte's predictions. Frank >Looking for predictors or the gifted? 98% close enuf? > >http://www.viser.net/~charking/story.html > >When studying this keep in mind today's >"science" is tommorrows witchcraft. The >strides in quantum physics is closing in on >the bicosmic energies. The gift is something >that the scientific method promoted by the >'analyst' (notice the ANAL) lends itself to >never having a final answer, just the most >convincing argument gathering the largest >world of agreement. >I've experienced this on both ends of study. >When working in the black arts of EMF/RFI >shielding, I got 'results' using what's known >as the common intelligence, tapping in with >stupid things like intention, but producing a >shielding that passed all FCC testing for sure. >This bothered all my superiors, with their MS >degrees, and they spent six months attempting >to figure out what I did, instead of enjoying the >product that would beat everyone to the market. >While intellectually J Offing this, a competitor >got their product to the market and blew my co. >off the marketing scene. So when you get some >project subsystem working, keep going and don't >go for the BOOBY PRIZE - Reasons...or results. >I've found results more satifying. >For Roger's project try reflective mylar (AKA >space blanket material) and use the old 555 >chips, they can work miracles...Keep it SIMPLE, >genius is simple, as the Truth, out their is... > >bschafer@......... wrote: > >> More Earthquake Predictions >> >> Hi KFrank, >> >> Thanks so much for this site. Might be very interesting. Does anyone >> know what Berkland's success rate is? >> >> Ran across another book, today, and it looks very interesting. I have >> only read a couple of pages. It is called "The Trembling Earth." It is >> written by Frederic Golden and is copyright 1983. >> >> Bonnie >> the crafty crafter >> >> _____________________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email listserver@............. with the body of the >> message: leave PSN-L > > > >-- >Michael S.Healy internet: sunmanh@............ >1-503-355-3177 (voice) internet: wave3@........... >1-503-355-3367 (fax) (below RIP-aware as well) >1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Where's Fontana Trend Map? Date: Sat, 11 Apr 1998 10:54:38 -0700 (PDT) Hi all: I was searching all over the USGS (pasadena) Field Office Web-Site for the recent map that shows the Fontana Trend and how it relates to the recent series of earthquakes in the Inland Empire of San Bernardino county. I don't see it listed anymore. I will email them to see if they can repost it for us. Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: frankcnd@.......... Date: Sat, 11 Apr 1998 11:24:32 -0800 When designing electronics for seismo indicators, don't use Y2D non- compliants - ref da problems - http://www.garynorth.com/y2k/index.cfm Frank Condon wrote: > Hello there: > Fear not... I've not ruled out the use of humans as sensitive indicators for > earthquake prediction. I'm only stating that animals are also another area > that needs more exploration and study. Thank you for reminding me about > Charlotte's predictions. > > Frank > > >Looking for predictors or the gifted? 98% close enuf? > > > >http://www.viser.net/~charking/story.html > > > >When studying this keep in mind today's > >"science" is tommorrows witchcraft. The > >strides in quantum physics is closing in on > >the bicosmic energies. The gift is something > >that the scientific method promoted by the > >'analyst' (notice the ANAL) lends itself to > >never having a final answer, just the most > >convincing argument gathering the largest > >world of agreement. > >I've experienced this on both ends of study. > >When working in the black arts of EMF/RFI > >shielding, I got 'results' using what's known > >as the common intelligence, tapping in with > >stupid things like intention, but producing a > >shielding that passed all FCC testing for sure. > >This bothered all my superiors, with their MS > >degrees, and they spent six months attempting > >to figure out what I did, instead of enjoying the > >product that would beat everyone to the market. > >While intellectually J Offing this, a competitor > >got their product to the market and blew my co. > >off the marketing scene. So when you get some > >project subsystem working, keep going and don't > >go for the BOOBY PRIZE - Reasons...or results. > >I've found results more satifying. > >For Roger's project try reflective mylar (AKA > >space blanket material) and use the old 555 > >chips, they can work miracles...Keep it SIMPLE, > >genius is simple, as the Truth, out their is... > > > >bschafer@......... wrote: > > > >> More Earthquake Predictions > >> > >> Hi KFrank, > >> > >> Thanks so much for this site. Might be very interesting. Does anyone > >> know what Berkland's success rate is? > >> > >> Ran across another book, today, and it looks very interesting. I have > >> only read a couple of pages. It is called "The Trembling Earth." It is > >> written by Frederic Golden and is copyright 1983. > >> > >> Bonnie > >> the crafty crafter > >> > >> _____________________________________________________________________ > >> > >> Public Seismic Network Mailing List (PSN-L) > >> > >> To leave this list email listserver@............. with the body of the > >> message: leave PSN-L > > > > > > > >-- > >Michael S.Healy internet: sunmanh@............ > >1-503-355-3177 (voice) internet: wave3@........... > >1-503-355-3367 (fax) (below RIP-aware as well) > >1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program > > > > > > > >_____________________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email listserver@............. with the body of the > >message: leave PSN-L > > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: S5000 LP vertical Date: Sat, 11 Apr 1998 11:32:52 -0800 may be old hat to most but here's a ref book - ISBN - 0-07-025209-2 library 94-23110 /CIP "How To Build Earthquake, Weather, and Solar Flare Monitors" by Gary G Giusti and for you Bill Nye fans, the simplest - http://www.pacifier.com/~sunmanh/edd_tws.html Happy Hoppity Day S-T Morrissey wrote: > Meredith, > > The S5000 LP vertical IS an entirely different sensor from the > S5000 series horizontals; the only thing they have in common > is the coil/magnet assembly. > > I will push your request for materials to the top of the list > next week. > > I will also send you some new hinge material and new spring > suspension wire. Getting the seis to perform as advertised > is difficult enough with the original design, and probably > nearly impossible with substitutions. In particular, if the > hinge crossover point moves at all wrt the upper end of the > spring suspension clamp, the period will change radically > as the boom position changes. > > About the best period linearity that can be obtained is 3% > over a range of + - 2mm at the boom pointer. This means that > if the period is 30 seconds at center, it can be 31 or 29 over > the operating range. > > The adjustment of the upper spring attachment sliding assembly > for linearity can take days, and is all for naught if some > event stresses the hinges after it is done. When these S5000 > were used in the WWNSS, they originally tried for a standard > of 30 seconds (and a 90 second galvanometer), but eventually > backed off to a 15 second standard because of the instability > and linearity problems. > > I have just "tuned up" a set of 4 S5100s (the "high performance" > successor to the S5000: it can actually operate at 90 seconds! > ... under ideal vault conditions... ) for a project in India. > It was neither fun nor rewarding, since I knew that my homemade > VBB instrument could out-perform them 10 minutes after it is > put on the pier. > > Re the period adjustment with the front leveling screw: this is > the normal way to trim the period: raising the front makes it > longer by decreasing the gravity vector wrt the mass and hinge > point. Generally the screw is not turned more than 6 turns from > where the base is level; otherwise, adjust the main spring > tension screw. This is were there are two clamps on the piano > wire, one of which must always be tight or the spring will > collapse. > > Regards, > Sean-Thomas > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: S5000 LP Vertical Date: Sat, 11 Apr 1998 15:30:35 -0600 Sean-Thomas, Thanks for the rapid reply. Yes indeed I would be most interested in the new hinge material and spring suspension wire. This critter is tending to be much more difficult than I ever thought it would be. Unfortunately the manual lacks all the distance specs of the wires, hinges, etc., and my present setup is not looking proper at all. I do have one additional question, which is turning out to be a key to matching the magnets/coil alignment. The boom hinge spacing between the clamp blocks is unknown....do you know the distance? The manual references a setscrew on a clamping block as the spacer but this doesn't sound right, as the setscrew actually has two diameters with the head and the thread. I suspect the thread and the head would rest on the clamping blocks? Yes I expect a long time and effort will be put into this machine, from what I've seen and you have mentioned. Being as I'am not really going for professional results, it will serve the amateur results as best as I can manage for a velocity instrument, and perhaps down the road as a VBB conversion project. Eventually I'll be getting into your STM-8, but for the moment I'am doggedly pushing to set up what I have. I shall be glad when it is done as its taken months as is just to get where I am. My vault has been done for acouple weeks and the piers with the horizontals are seemingly to be very stable with no resetting of the zero of either after acouple days of settling in. The piers are set on a plastic cover which entirely covers the vault floor, and hence no moisture has been sensed, and little air humidity is deforming the piers apparently as the sides are painted with a latex/acrylic combo. The piers are 5 & 1/2 inches thick, X 32" X 32" and the floor joists barely allow cover removal for the horizontals...maybe not ideal, but they will have to work. Thanks again for the answers and the future materials...I will of course compensate. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: FILTER Date: Sat, 11 Apr 1998 18:29:23 EDT TO: LIST PARTICIPANTS I have just connected a Gould DC amplifier to my recently completed short period vertical seismograph (about 4 Sec. period) based on the mechanical layout developed by Sean-Thomas Morrisey. The amplifier has a built in filter that can be set for (1) no filtering (2) 5 Hz filter (3) 15 Hz filter. Since I live in Southern California where I understand there is a lot of quake activity, which one of the above filtering setting would be best? Jim Allen Cerritos, California U.S.A. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: FILTER Date: Sat, 11 Apr 1998 15:44:14 -0700 At 06:29 PM 4/11/98 EDT, Jim Allen wrote: >TO: LIST PARTICIPANTS >I have just connected a Gould DC amplifier to my recently completed short >period vertical seismograph (about 4 Sec. period) based on the mechanical >layout developed by Sean-Thomas Morrisey. The amplifier has a built in filter >that can be set for (1) no filtering (2) 5 Hz filter (3) 15 Hz filter. Since >I live in Southern California where I understand there is a lot of quake >activity, which one of the above filtering setting would be best? >Jim Allen >Cerritos, California U.S.A. I would go with the 15hz setting since you will be receiving local quakes. Local events have information above 5 Hz, and you need some filtering, so I would go with the higher value. At 15 hz you will need to sample the data at 30hz or higher. For teleseismic events you can use the filtering feature of WinQuake to remove any high frequency local noise. Sounds like an interesting Amp / Filter chip. What's the part number? -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: Re: FILTER Date: Sat, 11 Apr 1998 19:01:24 EDT TO: LARRY COCHRANE The amplifier that I am using is called a Gould Signal Conditioner cage with eight plug in dc amplifiers each having two filter settings and a selectable volts full scale from 5 to .025. C and H surplus (Los Angeles area) carries a lot of these in their warehouse. As I remember, I paid about $50.00 for it. I will take your advice and use the 15 Hz filter setting and use a sample rate of 40hz. Regards Jim Allen Cerritos, California U.S.A. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: low-pass filter Date: Sat, 11 Apr 1998 18:12:15 -0500 (CDT) Jim, I assume that the filter you have is a low-pass (to remove high frequency noise). the biggest problem anywhere is "cultural" noise: cars, trains, us,etc. The frequency content of local quakes peaks at around 10hz for the M=3.+ at distances of 10 to 100 km. So there isn't any defintive answer for the trade off between tuning out the cultural noise and seeing the near-field quakes. I can only suggest what I am doing here at the farm where the Beta seis is in the basement, the house is about 10 meters from the street, and the railroad is 1km away. For a countinuous monitor recorder I'm using an old Geotech "portacorder" modified for DC response and recording with a warm stylus on FAX paper at 15mm/min with 2mm trace spacing (gets me 2.5 days on one record). I have the low pass filter set at 5 hz, but I also have about 40db of filtering at 10 hz in the line driver amp from the VBB seis (the input to this amp is used for the 1000 second high-pass to remove DC signals from the recorder and digitizer). So what do I see: the passing cars and my dogs romping through the house make noises about 1 to 2 mm p-p. We had a little quake at New Madrid on Wednesday: a M=3.2 240 km from here: the p phase was about 4mm, and the s was about 8 mm p-p. Then we had a M=2.8 at 265 km from here, and I only saw the s/lg phase. Yesterday the VBB signal gave a nice record of the M 6.1 quake in the SW Pacific, showing the "trains" of 20-second surface waves from the long path through the thin lithosphere of the Pacific plate. So the bottom line is to experiment. Some level of cultural noise is usually present in most seismic data; it is "acceptable" during the day, and generally vanishes at night. Railroad noise comes and goes over a period of several minutes. Farming and construction have the peculiar signature that they disappear from 12:00 to 1:00, for lunch!. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: Re: low-pass filter and freq. resp. Date: Sat, 11 Apr 1998 21:42:43 EDT TO: SEAN-THOMAS, et. ALL I appreciate the input on filtering. BTW, I read the post of Sean-Thomas to the list regarding his evaluation of the circuit in the BSSA to increase seismometer velocity response below the natural frequency. Sean-Thomas indicated that in his test using LT1024s that 1f noise was a problem. Are there lower noise chips (CAZ) than the LT1024s that could possibly improve the signal to noise ratio? Would a chip that would automatically compensate for drift (and possible noise) help and if so do you know of one? What other changes would you suggest? If one could overcome the noise problem, this simple circuit seems a natural for my short period vertical. Jim Allen Cerritos, California _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: low-pass filter and freq. resp. Date: Sat, 11 Apr 1998 21:17:18 -0500 RADIOTEL wrote: > > TO: SEAN-THOMAS, et. ALL > I appreciate the input on filtering. BTW, I read the post of Sean-Thomas to > the list regarding his evaluation of the circuit in the BSSA to increase > seismometer velocity response below the natural frequency. Sean-Thomas > indicated that in his test using LT1024s that 1f noise was a problem. Are > there lower noise chips (CAZ) than the LT1024s that could possibly improve the > signal to noise ratio? Would a chip that would automatically compensate for > drift (and possible noise) help and if so do you know of one? What other > changes would you suggest? If one could overcome the noise problem, this > simple circuit seems a natural for my short period vertical. > Jim Allen > Cerritos, California > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Jim, A couple of IC's worth looking at are the Burr Brown OPA27 Ultra Low noise OP amp and the Linear tech LT1052 Chopper stabilized OP amp. Jim Hannon -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: low-pass filter and freq. resp. Date: Sat, 11 Apr 1998 23:04:02 -0500 (CDT) Jim, I guess that my bottom line and 2 cents worth of evaluation of the Roberts article is that if you have to go that way (equalization circuits), it is frustrating; I am certainly not suggesting it. We have evaluated many amplifiers, including CAZ designs and some of the best AD and Maxim amps, but they really cannot provide much improvement for high gains, like trying to get the sensitivity of a 5500ohm L4 ( about 300 V/m/sec) from a 4.5hz phone, and I don't think it is worth further pursuit. Of course, IF you have a mechanical sensor that can be configured for VBB feedback (a displacement transducer can be installed, the coil has a low enough resistance, etc.) you are way ahead of the equalization game by implementing the triple VBB feedback. THere are fewer amplifiers involved ( 3 (displacement amp, integrator, VBB output follower/line driver) vs 8 for a fully configured equalizer), and we aren't pushing any specs (unless one goes for a 300+ second integrator), and the result is predictable and calibratable. A 4 second sensor can easily operate at 40 seconds or 120 seconds or beyond. I would suggest this for the next step for your instrument. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Magnetic shielding Date: Sun, 12 Apr 1998 01:44:50 -0500 Friends, I found a good web page at Advance Magnetics (www.advancemag.com) and here is part of what they have to say about shielding. It looks like the best way to go is to buy a roll of their foil and wind enough layers to do the trick. The premeability of high nickel alloys is about 300,000 under optimum conditions, but goes down to 100,000 or less in about 100 Gauss fields, but this is still way, way better than scrap iron at about 100. On the topic of low noise op amps, Linear Technology makes about the lowest noise one, which is the LT 1028. It is made to match a very low impedance source like a coil. In this case, the coil should have a resistance of no less than about 100 ohms, up to 1000 ohms or so, and in this region, the 1028 operates very near the theoretical noise level of a resistor's Johnson noise. No transistor can hear the inherent resistor noise below about 50 ohms, so your coil should have at least this much DC resistance, and probably more. (See Horowitz and Hill). It might be better to obtain or wind a coil with a size and resistance optimally matched to such a premium op amp (and the magnet) rather than the other way around. You can even put such ultra low noise bipolar op amps in parallel if you want to match ultra-low input impedance, but no need here. The Linear Technology Corp. data books have great info on circuits that push the limits in various ways with their premium parts like the LT 1028, which you can order in single quantities through Digikey, which is a very useful and reasonable electronic parts mail order supplier. -Yours, Roger **************************************************************************** *Once the offending field source is identified, one practical approach in determining needed shielding is to order a small quantity of heat treated ready-to-use magnetic shielding foil from a shielding manufacturer. It is available for immediate delivery in various convenient widths, lengths and shielding strengths for high or low permeability requirements with a range of electrical conductivities. Foil is easily, quickly cut with ordinary scissors and hand shaped to the desired outline. It is ideal for R/D, hard-to-get-at places, or for small quantity or extremely compact applications. Many shielding problems thus can be solved quickly. After hand shaping around the component to be shielded, the foil can be held in place with simple adhesive tape. Thickness and number of layers can be determined by ordinary trial and error procedure, or a formula to follow may be requested from the manufacturer. Begin by using a single layer and then adding layers until the desired shielding effect is achieved. When using multiple layers in steady fields and at low frequencies, the low permeability layer should be closest to the field source. This tends to increase the flux density shielding capabilities. The low permeability layer diverts the major portion of the field, permitting the high permeability layer or layers to operate in a lower reluctance mode. If you need relatively few shields or are experimenting, foil is the swift, economical solution. Once foil shielding is functioning satisfactorily in either experimental or production applications, it is time to evaluate the economics. The cost of foil versus prefabricated shields for that particular application should be compared. A prefabricated shield is less costly in larger quantities and for certain complex applications. For designing and manufacturing prefabricated magnetic shields in-house, sheet stock may be ordered. Sheet stock may be formed by bending, stamping, drawing, finishing, etc. on ordinary sheet metal equipment and finished by plating, MIL spec painting, etc. For optimum magnetic shielding characteristics, shields must be heat treated after all forming, welding and machining operations. Your supplier will guide you in the use of the various available states of heat treatment, such as the one which permits ease of forming (mill annealed) or the treatment which assures the maximum mechanically stable permeability or the absolute maximum permeability (which is not necessarily stable mechanically or thermally in some high nickel alloys). High electrical conductivity and high magnetic permeability both contribute to the effectiveness of thin foils in fast-rising pulse shielding by reducing the skin depth. Distinctions have lately been made between the case where the foil thickness exceeds the skin depth and where it is greater. This type of shielding against pulse-type interference achieves the highest order of shielding effectiveness generelly obtained by any means. Attenuations between 300 dB and 1000 dB are not unusual. *************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: equalizer circuits Date: Sun, 12 Apr 1998 09:25:20 +0100 S-T Morrissey wrote: > > > We have made several evaluations of the P. M. Roberts circuit, > especially trying to make a 4.5 hz phone act like an L4-C at > 1 hz. It does work, but it is noisy, even with the best selection > of amplifiers........................ > The problem with the equalizer circuit is that the gain of > the 1-pole filter is about 20, so the two of them in series > (to get the proper slope) have a gain of 400. ................ Hi Sean, I am a little puzzled about your reply. The article's equations required a gain of 20 from each of 2 stages, for a 1Hz seismo's response to be extended down to .1Hz . Your own experiments appear to make a 4.5Hz seismo go down to 1Hz using the SAME amplification....... .....don't the equations require a different set of RC values for your experiment, and therefor a different amplification? If I read the article correctly, any natural period seismo which is NOT 1 sec.requires new amplification figues, based on the natural period of the instrument before equalisation, (which was 4.5 sec. in your experiment)........should not your amplification have been different then?? I daresay I have the 'wrong end of the stick', (or 'the wrong end of the beam') somewhere, but I am puzzled. Regards Albert Noble (England) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: frankcnd@.......... Date: Sun, 12 Apr 1998 01:24:27 -0500 (CDT) frankcnd@.......... Hi Frank, It seems that I have heard of this book but can't remember where. I will look at Braille and see if they have it. My reader advisor is a really neat guy and knows I like things concerning seismology so he is always willing to try and help. He was the one that found the book that I am presently reading. If I can get a hold of it I will let you know. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Giovanni Rotta" Subject: NORTH EASTER ITALY - INTERMED. QUAKE Ml. 5.5 Date: Sun, 12 Apr 1998 13:27:08 +0200 It was just under my chair... My sistem tilt out. Many mild and moderate quake now. Giovanni Giovanni Rotta rottag@.......... Via F. Pizzigoni, 10 33010 Resia (Udine) Italy Lat. 46.373N Long. 13.305E QTH Locator JN66PI _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: Earthquake Jolts Alps Date: Sun, 12 Apr 1998 12:34:30 EDT Earthquake Jolts Alps ..c The Associated Press LJUBLJANA, Slovenia (AP) - A strong quake shook a broad area of south-central Europe on Sunday, setting Venice and Vienna swaying and toppling dozens of chimneys in Slovenia, where several people were reported slightly injured. The earthquake was centered in the Alps in western Slovenia and had a preliminary magnitude of 5.5, according to Italy's National Geophysics Institute. The epicenter was in the mountains close to Triglav, a peak popular with climbers, about 15 miles from the Italian border. Slovenian radio said the worst-hit area was around Bovec, a town of 1,500 people where the roofs on about 200 houses were damaged. Part of a church steeple in the town of Kobarida also fell, Slovenian national radio reported. One person in Bovec, 53 miles west of the capital Ljubljana, died of a heart attack blamed on fright, officials said. The mountainous area was blocked off by rockslides touched off by the quake, and phone and electricity lines were down, limiting information from the affected area. Sunday's quake also was felt in Italy, Austria, Croatia, Hungary and southern Germany, although no damage was reported in those countries. People in Milan, Bologna and elsewhere in northern and central Italy jammed fire department switchboards with inquiries. Venice, packed with Easter tourists, rocked for 15 seconds, as did the Austrian capital of Vienna, where tall buildings swayed back and forth. Walls of some high-rise buildings shook slightly in Munich, Germany, about 170 miles to the northwest. A devastating quake ripped through the area just west of Sunday's epicenter in 1976, killing nearly 1,000 people in northeastern Italy. AP-NY-04-12-98 1145EDT _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: SETV- Fwd[2]: SETI Fw: Aether Tectonics Date: Sun, 12 Apr 1998 10:00:53 +0000 Caruso and all, The original post by Ross Tessien contains a typo, the corrected date is April 21, 1998. I would have posted this correction earlier, but was at NAB conference & show for the past week in Las Vegas, Nv. Walt Williams, 98.04.12 dfheli@.............. ================================================ ------- Forwarded Message Follows ------- From: Caruso Stephen To: Walt Williams Subject: RE: SETI Fw: Aether Tectonics: Alert: Merging Black Hole Predicted Date: Tue, 7 Apr 1998 23:57:00 +0300 aPRIL 31ST IS NOT A REAL DATE. ================================================ From: Walt Williams To: PSN-L Mailing List Subject: SETI Fw: Aether Tectonics: Alert: Merging Black Hole Predicted Date: Tuesday, April 07, 1998 2:42PM Hello All, I am a member of the SETI-L reflector. This interesting post is thought provoking. Best Regards Walt Williams, 98.04.07 dfheli@.............. == Cross Posted From seti@....... == ------- Forwarded Message Follows ------- Reply-to: "Ron Blue" From: "Ron Blue" To: Cc: "Ross Tessien" Subject: SETI Fw: Aether Tectonics: Alert: Merging Black Hole Prediction; Date: Tue, 7 Apr 1998 01:55:45 -0400 Ross Tessien has asked for help in monitoring the likely black hole merger estimated to occur April 31, 1998. Any reports should be forwarded to him. Naturally, data before, during, and after would be useful. Also as a intuitive guess, if the timing is good, radio signals from your favorite SETI source could be stronger around this time. Ron Blue ------------------ deletia ----------------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Earthquake Jolts Alps Date: Sun, 12 Apr 1998 10:00:00 -0700 Seismo-Watch issued this earthquake fax alert bulletin earlier this morning: An earthquake registering a preliminary magnitude of Ms 5.7 (NEIC) occurred at 10:55 UTC, April 12, in the Italy-Austria-Slovenia border region in southern Europe. The quake struck at 12:55 p.m. local time and was centered about 27 miles north of Trieste, Italy, and just inside the Slovenia border at the southern margin of the Julian Alps, near the small village of Kobarid. The depth was fixed at 10 km for quick processing and we do not have a Moment magnitude for this event as of yet. The quake knocked out power and telephone lines and caused several landslides. Some homes have been damaged a few people were hurt, none seriously. There have been numerous small to moderate aftershocks. The main jolt was felt as far away as Venice, Italy. A devastating earthquake registering M6.5 struck the same region on May 6, 1976, causing widespread damage and killing nearly a 1,000 people. That earthquake had a robust aftershock sequence which included five more quakes measured M5.7 or greater, including two more in the M6 range, a M6.1 on June 17, 1976, and a M6.3 on September 15, 1976. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration/Seismo-Watch P.O. Box 18012, Reno, Nevada 89511 Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: equalizer circuits Date: Sun, 12 Apr 1998 12:24:30 -0500 (CDT) Albert and co, You are correct in observing that we HAVE recalculated the values for the equalizer for our particular application to 4.5 hz phones; and we did believe that the resulting reduced gain requirement would spare us the noise problems. But a difference (reduction) of 2.5 in equalizer gain doesn't help much, especially when it is connected to a 24-bit ADC with a LSB of a microvolt. The gain values for the 1hz to 10 sec equalizer calculate up to 22.1 for EACH stage for a total gain of 488. For the 4.5 hz to 1hz we use a reduced gain, but not that reduced because the new target lower frequency is 2 seconds so that it will look like a properly (over) damped L4-C. THe gain is 14 per stage, or 196 total. But the little HS-1LT phone is well over damped, and has an output of about 20 v/m/sec. So it needs a pre-amp as well as an amplifier after the equalizer to get 300 v/m/sec. The gains of these amplifiers total about 20 (the follower is adjustable), for a total gain of about 4000. This actually is not an unreasonable number: it equals 72db, which is what we generally use for the pre-amp between an L4-C and the telemetry VCO in remote stations. But the telemetry itself has a noise floor of about a millivolt, so amplifier noise is not a problem. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: equalizer circuits Date: Sun, 12 Apr 1998 12:24:30 -0500 (CDT) Albert and co, You are correct in observing that we HAVE recalculated the values for the equalizer for our particular application to 4.5 hz phones; and we did believe that the resulting reduced gain requirement would spare us the noise problems. But a difference (reduction) of 2.5 in equalizer gain doesn't help much, especially when it is connected to a 24-bit ADC with a LSB of a microvolt. The gain values for the 1hz to 10 sec equalizer calculate up to 22.1 for EACH stage for a total gain of 488. For the 4.5 hz to 1hz we use a reduced gain, but not that reduced because the new target lower frequency is 2 seconds so that it will look like a properly (over) damped L4-C. THe gain is 14 per stage, or 196 total. But the little HS-1LT phone is well over damped, and has an output of about 20 v/m/sec. So it needs a pre-amp as well as an amplifier after the equalizer to get 300 v/m/sec. The gains of these amplifiers total about 20 (the follower is adjustable), for a total gain of about 4000. This actually is not an unreasonable number: it equals 72db, which is what we generally use for the pre-amp between an L4-C and the telemetry VCO in remote stations. But the telemetry itself has a noise floor of about a millivolt, so amplifier noise is not a problem. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Morrissey e-mail Date: Sun, 12 Apr 1998 20:38:03 -0700 Thanks Bob (and ST Morrissey for taking the time to write them!), I ZIP the file (62k) and placed it on my system at: ftp://psn.quake.net/info/stm-mail.zip There is a link to the file at: http://psn.quake.net/infoequip.html -Larry At 02:03 PM 4/12/98 -0400, you wrote: >Larry, > I have found the e-mail from ST Morrissey so enlightening on many >subjects that I have collected all his messages into a single file. I >removed all the header junk and many blank lines (to use less paper when >printed). I may have missed a few but I think that it is most of them up >to 4/8/98. > This file (193k, pure ASCII) is attached. If you think that it would be >of sufficient interest to the group, put it on your page somewhere and >announce it. I didn't want to send that monster to the whole list. This >info might be a convenient source for those building his vertical. >Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: George Harris Subject: Magnetic shielding materials Date: Sun, 12 Apr 1998 19:47:01 +0000 For those intersted in the characteristics of magnetic shielding materials the following is taken from a catalog from Spang Specialty Metals (Home in Butler PA - Office and warehouse in Los angeles). The best materials are Permalloy 80 and Mumetal. They are 80% nickel with the remainder iron. To work the best they must be annealed at very high temperature in hydrogen for 4 hours. Spang supplies a material called Mu Guard 80 which is annealed ready for use. It is available in thickness from .001 to .006 in widths up to 6 inches. As was stated previously, it must not be bent or deformed if the maximum shielding is to be achieved. About 6 years ago, I purchased about 3 feet of material 4 inches wide which I remember cost near $50 when I was experimenting with flux gate magnetometers. They seem to be willing to talk about small orders though there is a minimum. George Harris _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: STM-8 Instrumentation Amplifier Date: Sun, 12 Apr 1998 22:48:43 -0600 Hi Sean-Thomas, Think I have missed out on the instrumentation amplifier in regard to the gain, and perhaps any other pertinent data. I know you use 3 op amps, and have stated that about any opamp would work. Might a chopper op amp be preferred over others....and is there a particular opamp/chopper op amp you have a preference for over others, if you had your free choice as opposed to the best of the cheapest? P.S., any progress on the sealed container? Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: integrator amp Date: Mon, 13 Apr 1998 01:14:04 -0500 (CDT) Meredith, I assume that you are referring to the integrator amp; I use a 3 amp instrumentation configuration: 1: because I have a box of them left over from a self-potential experiment (the Greek VAN idea .... nothing but noise) and 2: it lets me try wild ideas, like 1000 second integrators. Actually a single quality amp will do, like the OPA111, for a reasonable time constant. THe integrator gain is one, connected as a non-inverting follower; for lowest noise, the follower connection (from the output to the inverting input) should be a resistor of the same value as the input. Regarding the barometric contaiment: I have been doing an interim experiment to try to counter the buoyancy of the mass/boom with sealed containers (pill jars) hanging out the other side of the hinges from the boom. I've estimated the volume of the mass etc. at about 100 cc, located 38 cm from the hinges, or 3800cm*cc. To counter this, I have three pill jars (with lids sealed with RTV) of 128 cc ea, mounted 8.5 cm outside the hinges, for a volume*distance of 3264 cm*cc. We have had very windy weather lately, and this reduced the wind noise by about a factor of 10. Since it is almost impossible to fine tune the volumes in this scheme, I don't think it is a full solution, so I will pursue the aquarium containment idea. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: We're not in Kansas anymore (Greetings from Oz) Date: Mon, 13 Apr 1998 10:39:18 +0800 Larry- I have spent the last couple of days with Arie Verveer touring Perth and vicinity. I have seen his beautifully crafted S-G paired NS, EW horizontals in the vault below one of the many observatories of the Perth Astronomical Observatory -- where he has coupled the movements of the stars to the movements of the Earth. We spent this afternoon with Alby Judge and his wife at their new homestead on top of the Darling Scarp (where the PAT also sits) that is equipped with a Wilmore vertical sitting on a concrete pad in the bush covered with an old freezer box for protection/insulation -- a major source of seismic noise is the coming and going of kagaroos. Arie and Alby are doing some very interesting work with the public and plan to do more. Are you still awake? -Edward _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: [Fwd: We're not in Kansas anymore (Greetings from Oz)] Date: Mon, 13 Apr 1998 10:41:24 +0800 Larry- I have spent the last couple of days with Arie Verveer touring Perth and vicinity. I have seen his beautifully crafted S-G paired NS, EW horizontals in the vault below one of the many observatories of the Perth Astronomical Observatory -- where he has coupled the movements of the stars to the movements of the Earth. We spent this afternoon with Alby Judge and his wife at their new homestead on top of the Darling Scarp (where the PAT also sits) that is equipped with a Wilmore vertical sitting on a concrete pad in the bush covered with an old freezer box for protection/insulation -- a major source of seismic noise is the coming and going of kagaroos. Arie and Alby are doing some very interesting work with the public and plan to do more. Are you still awake? -Edward From: Karl Cunningham Subject: Re: Magnetic shielding materials Date: Mon, 13 Apr 1998 10:39:47 -0700 A source of magnetic shielding materials is old dead oscilloscopes. Usually, the CRT is surrounded with a drawn and annealed metal shield. You can cut it with a pair of tin snips, but bending it will reduce its magnetic shielding properties substantially. Look at surplus stores for old junk scopes. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Taber Subject: Re: ASCII data Date: Tue, 14 Apr 1998 10:34:21 +1200 (NZST) Larry, I don't think there are any standards for storing ASCII versions of binary seismic data, but I think it works best to have the header info followed by the data in the same file. I like having text lables in the ascii version of the header so that it is easy for humans to read and edit if necessary. Here is an example of part of the ascii form of the ah format that is used by a number of seismology groups: station information code: W01 channel: spe type: L4 latitude: -41.000000 longitude: 174.750000 elevation: 0.000000 gain: 59499999232.000000 normaliztion: 1120.369995 calibration information pole.re pole.im zero.re zero.im 5.000000e+00 0.000000e+00 4.000000e+00 0.000000e+00 -1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 -1.332900e+02 1.332900e+02 0.000000e+00 0.000000e+00 -1.332900e+02 -1.332900e+02 0.000000e+00 0.000000e+00 -3.769900e+00 5.026500e+00 0.000000e+00 0.000000e+00 -3.769900e+00 -5.026500e+00 0.000000e+00 0.000000e+00 event information latitude: -40.60 longitude: 173.65 depth: 97.6 origin_time: 1991 11 7 16 47 51.75 comment: null record information ndata: 5458 delta: 1.000000e-02 max_amplitude: 1.834650e+02 start_time: 1991 11 7 16 48 5.440000 abscissa_min: 0.000000e+00 comment: null log: null data: 4.535000e+00 1.535000e+00 1.153500e+01 3.153500e+01 etc I'd recommend you include the same parameters in the ascii format that you have in the PSN binary format. That way you can go back and forth between ascii and binary without any loss of information. John Taber School of Earth Sciences Victoria University of Wellington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tony Carrasco Subject: VR-60 Date: Mon, 13 Apr 1998 16:02:04 -0700 Cal State LA is looking for any information on a seismic recorded - Sprengnether VR-60, specifically pictures/diagrams. According to them (via the company) we purchased one here at SDSU back in the mid-70's. Unfortunately, if we did purchase it, the recorder and any information about it is now long gone. If anyone can help I'm sure they would appreciate it. Thanks ***************************************** ***** Tony Paul Carrasco ***** ***** San Diego State University ***** ***** tcarrasc@................ ***** ***************************************** || || || /\/\ ///\\\ ////\\\\ /////\\\\\ //////\\\\\\ ______///////\\\\\\\______ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: benioff seis Date: Mon, 13 Apr 1998 18:12:58 -0500 (CDT) Bob, The Benioff is a rather narrow band instrument, even when it is operated well over damped. In the WWNSS configuration, the peak magnification (of about 150K) is actually at 0.6 seconds when the nominal magnification is 100k at 1 second. At 6 seconds, it is down to about 600, and it is about 100 at 10 seconds, and at 20 seconds, where teleseismic surface wave energy peaks, the magnification is about 15. So it takes a good size teleseism to see much from a Benioff seis. The sensor in the Benioff is a variable reluctance type. Rather than having a coil moving through an orthogonal magnetic field, the coils are wound around the pole pieces of a large H shaped (H is on its side) magnetic structure, where the vertical center bar of the H is the charged magnet. As the suspension moves the top and bottom bars with the coils wound around them, the gap between them, above and below the fixed magnet, changes, causing a flux change in the moving bars, inducing voltage in the coils. When it was first designed (in the 30's) it provided the strongest signal from the poor ferromagnetic materials that were available then. It also has a serious electronic variant that would make me hesitate to use it as a VBB fedback sensor (not that I wouldn't like to try: I have about 6 of them): it has a very large inductance, about 16 henries when all the coils (8) are in series for maximum output. Of course, for feedback, one would use a low resistance parallel configuration. It also has a rather large mass (~15 kg for the "portable" unit (100 kg for the "big" Benioff) ) that would be difficult to work with considering that the generator constant of the coils is rather weak because of the variable reluctance configuration. The output is 135 -150 v/m/sec with the 80 ohm coil connection (where the inductance is still 5+ henries because of mutual inductance). It would probably work with an equalizer circuit at 10 seconds, but this would mostly enhance the 6-second storm microseisms rather than any data of teleseismic interest: teleseismic surface waves run from 15 to 30 seconds. So I guess that if you want some real LP data, you will have to make a broadband sensor. Speaking of which, the VVB here just showed some very large barometric acoustic waves, about 50 mv p-p at 100 to 200 seconds, and the tornado sirens went off, and now the news reports a tornado lifted some roofs, etc, about 2 miles east of here. Regards, Sean=THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: VR-60 Date: Mon, 13 Apr 1998 18:29:37 -0500 (CDT) Tony, Sprengnether Instruments Inc. is still very much in business, and just made another round of VR-60 recorders. If you call them at 314 565 1682 about your missing recorder, they should have the info on it; they have records of everything that they have ever made. Not that they might know where it went, but I'm sure they could sell you a replacement. They should be able to provide a serial number to help your search. If you need additional info, contact me at sean@............ we use the VR60 as a monitor recorder at our broadband seismic stations located in public parks, etc. In addition to being an excellent educational tool, it is an instant diagnostic of whether the station is working; park personnel may not know what the record means, but they call me the minute is stops making wiggly lines. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: Where's Fontana Trend Map? Date: Mon, 13 Apr 1998 19:26:18 -0700 (PDT) Hi All: I've been working with Katrin, the Webmaster at SCEC to get navigation links in place for the chino98.GIF and crafton98.GIF files on their Web-site (now part of TriNet). Wouldn't it be nice if all interested persons could view the information included on those Map files, instead of only us seismic types. Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" >Hi all: >I was searching all over the USGS (pasadena) Field Office Web-Site for the >recent map that shows the Fontana Trend and how it relates to the recent >series of earthquakes in the Inland Empire of San Bernardino county. I don't >see it listed >anymore. I will email them to see if they can repost it for us. > >Frank Condon >frankcnd@.......... >"Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: S5000 & STM-8 Misc. Date: Mon, 13 Apr 1998 21:00:40 -0600 Sean-Thomas, OK on the instrument amplifier/integrator oneness...terminology. Have never heard of your pill jar barometric approach experiment. Sounds like a possible means in the future for noise reduction with those who may not use the sealed container. I'am presuming they were plastic bottles, and not glass? What if the volume*distance slightly exceeds the mass/boom? Alot of interesting Mu-metal/Permalloy talk. The S5000 uses what appears to be 2 steel plates between the magnets and the spring, as a form of weak shield or field containment. Have you ever used old oscilloscope mu-metal permalloy shields for similar seismo magnet/spring conversions or improvements? For the one I have, immediately after the shield went in, the mass rose....not sure if may have disturbed something else or not....or is repeatable, didn't take the time to remove/reinstall. Could be the shield created more field and raised the spring?...no gaussmeter here. The Mu-metal/permalloy sounds like a possible luxury item for the STM-8, if one is lucky enough to get an old oscilloscope shield per Al Allworth & Karl Cunningham mentions. Found the right clamping block and hinge distance, per using drill bits as spacers, which allowed the coils and magnets to fit. Takes awhile & some tricks to setting these S5000 verticals up. Could use a pulley & rachet mechanism for the spring extension-ha. Think I'am getting the HANG of it-ha. The finer points not just yet. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: magnetic shielding, baro comp. Date: Tue, 14 Apr 1998 00:17:28 -0500 (CDT) Meredith, I guess I have to chime in here about magnetic shielding, etc. My experience with it is that unless one wants to be an expert about it, it causes more problems than it solves. FOr my degree work I rebuilt a 3.2MEV cyclotron with at hugh (13 ton) electromagnet (that ran on 300VDC at 110 AMps, regulated to 0.001%), with a 30" pole face and a field of 13 kgauss across the 10 inch opening. So dealing with this field was a constant problem, and it was very dangerous. It would make a rattle out of a mechanical watch at about 3 feet. We had to operate our TV monitoring cameras via mirrors with telephoto lenses, after wasting a lot of time with trying to shield them with mu-metal, etc. We made magnetic quadrupole lenses to focus the particle beam, and keeping them from interacting with everything else and vv. was an endless problem. So I have been frustrating myself with magnetic shielding ideas for many years. As for any need for such for the STM8 seis, I don't see any, and haven't made any efforts to use any shielding. Because of the propensity of permaloy, mu-metal, etc.,, to become as useful as sheet metal if it is reformed (cut, bent, etc) after final annealing, only a professionally fabricated shield would be worth considering. The STS-1V has such a shield in the form of a box that fits over the sensor, but I don't know of any other sensor using such. The S5100 LP has no shielding, and counts on geometry and design to minimize the effect of the magnets on the main spring. As long as there is relatively little movement of one part wrt another, any magnetic effects would be static. Your experiment with your S5000 demonstrates that the spring IS attracted very slightly by the main magnets, and that this is modified by any intervening ferrous material, as you observed. There is no need to try to modify it, though; there are over 500 of those LPs operating as they came from Sprengnether; and in the later re-design, the shield plates were eliminated. Re the pill jar (plastic) barometric flotation compensation: as I mentioned, figuring out the volume*distance of all the mass + boom + coils + etc. is nearly impossible. And trial + error methods cannot approximate the complex integration. And I believe that other pressure-induced noise sources play a major role, like the breathing of the coil-magnet assembly with pressure change. I'm only seeing 10 to 20 mv of noise, which amounts to about 12 to 24 nanometers of displacement (with 400 mv/micron and 2x gain in the line driver output). I think that wherever the "sealed" wooden shelf board box breathes, it makes minute jets of air that blow the mass around. If I observe the high-gain output of the microbarometer, I don't see a consistently repeatable correlation with the noise. So the "counter-flotation" scheme may have some benefit, but is not a solution. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: magnetic shielding Date: Tue, 14 Apr 1998 16:17:36 -0500 Friends, To clarify the recent discussion about magnetic shielding, I think my seismometer definitely needs magnetic shielding while Sean-Thomas's probably does not for everyday use. While his uses the pure mechanical spring force of a steel spring (which is weakly magnetic), mine uses pure magnetic force, and is thus much more sensitive to magnetic fluctuations in the ambient field. Remember we are trying to measure a few parts per million change in the earth's gravity combined, in a seamless way, with some undetermined amount of accelerative force. Our only practical option is to measure this force by exactly balancing it against some other equal and opposite force like a metal spring or magnetic force while assuming that any slight momentary imbalance detected must be due to acceleration, since the earth's gravity only changes slowly and by a very small amount (or pendulum clocks would never work). So in contrast to Sean's design, mine sees such things as as magnetic storms and stray pocketknives much more easily. In addition, ceramic magnets such as those I use ($1.79 for five at Radio Shack) are decidedly sensitive to temperature. So my design has to be thermally regulated, as I am well aware. Currently it tends to drift out of range, but this is probably mostly due to fact that it doesn't currently have a feedback temperature control, as some earlier versions did. I anticipate this will be done in this case by evenly gluing a bunch of resistors and a thermistor to the metal shield and surrounding everything with styrofoam. The tradeoff, as I see it, is that my design is rather small and cheap and easy to build, and as a DC sensitive device, it may also be used as a gravimeter. Since it is relatively small, it can be sealed against barometric changes relatively easily also, by hermetically sealing it inside a glass jug. I have scrounged what is probably a mu-metal or permalloy high nickel alloy cylinder 2 1/2 inch in diameter and about eight inches long, seam welded and lead grey in color-- out of an ancient (circa 1950?) oscilloscope I had gathering dust. (Does anyone have a use for the ancient 3AP1 CRT that fit inside?). I think I can fit a slimmed down version of my currently operating vertical into this shielding tube. For other models, since the foil sold by modern shield suppliers is very thin, it requires little distortion when bent around tubes, which is its intended purpose. I anticipate the current materials would probably do a similar job at a cost of roughly $25. So the bottom line is that my instrument is small and in all liklihood needs to be pampered with a mag shield and most certainly temperature control, and is also a work in progress. Its too early to say how useful my work is at this point, without a good basis for seigmographic sensitivity comparison, but everything is pretty easy to duplicate. I can send anyone a JPEG of the model that I discussed the other day, which will make the mechanical principles reasonably clear, when combined with my recent posting. (Incidently, I'm pretty much off the wall when it comes to protyping technique. In the first go-round, I often try to use carefully cut pieces of window glass and silicone rubber to build everything, as well as other materials when I need to. Protypical devices and instruments built in this fashion may be built very fast (since the thixotropic rubber sets up in ten minutes or so at each stage). The result is very cheap, can usually be made as rigid as needed by proper bracing, lasts forever, and yet may be cut apart and modified very easily with a razor blade. I'm quite serious about how useful this method is for building prototype frames and fixtures and mountings rapidly.) --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: amp selection vs noise Date: Tue, 14 Apr 1998 17:42:43 -0500 (CDT) Barry and all, I finally found the article I referred to last week but could not find the reference: "Limits of Sensitivity of Inertial Seismometers with Velocity Transducers and Electronic Amplifiers" by M.A.Riedesel, R.D.Moore, and J.A.Orcutt; BSSA Vol 80, No 6, pp 1725-1752; December 1990. It makes an important contribution in showing the importance of the selection of the proper amplifier for a given coil (with damping) resistance. It shows in figure 3 (which has one axis mis-labeled as "frequency" when it should be labeled "coil resistance") such things as that using a OP-27 rather than a LT1012 (same as the dual LT1024) can reduce the noise when using an input of 400 ohms by an order of magnitude. It also shows that while a LT1028 is very quiet with a 80 ohm input, it is 1000 times noiser than a CAZ type when connected to a very high impedance coil like 30k ohms. It has a very low voltage noise specification, but at the expense of a very high current noise. The paper shows numerous instrumental measurements with various combinations of sensors, including a 4.5 hz geophone. Their bottom line is that for low frequency data (10 to 20 seconds) from small velocity sensors, amplifiers need to be improved by one to two orders of magnitude to resolve earth noise below 10 to 20 seconds. Their recommendation is to use fedback sensors with displacement transducers. However, these are fragile, "power hungry", etc., and not (yet) suitable for such applications as OBSs (Ocean bottom Seismographs). Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: amp selection vs noise Date: Wed, 15 Apr 1998 07:24:11 -0500 Sean, You said "It also shows that while a LT1028 is very quiet with a 80 ohm input, it is 1000 times noiser than a CAZ type when connected to a very high impedance coil like 30k ohms." I am not familiar with the term "CAZ", could you explain? Thanks, Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dewayne Hill Subject: Re: amp selection vs noise Date: Wed, 15 Apr 1998 08:26:31 +0100 Lately I've seen a few posting about amp's. My I suggest one. Check out the following URL. I use amp and I'm very happy with the preformance. It is very stable (NO drift - none - nata) and to me it seem very quite. I made one modification and that was in the offset adjustment circiut. To allow for a more precise adjustment I replaced the 100k ohm pot with a 2.5k ohm pot and added two 51k ohm resistors, one on the in coming -12v and the other one the in coming +12v. I used all metallized film caps. Here is the URL www.info2000.net/~aloomis/seisfilt.htm James M Hannon wrote: > > Sean, > You said "It also shows that while a LT1028 is very quiet with a 80 ohm > input, it is 1000 times noiser than a CAZ type when connected > to a very high impedance coil like 30k ohms." I am not familiar with the > term "CAZ", could you explain? > > Thanks, > > Jim Hannon > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Dewayne (n0ssy) & Linda (n0uqf) Hill Westminster, Colorado USA 39.83569n 105.06270w. Elev 5660ft. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Velocity Coil Placements on "U" Shaped Magnets Date: Wed, 15 Apr 1998 11:43:21 -0600 Most amateur coils and magnets use coils placed between the poles of "U" shaped magnets...usually alnico magnet varietys. Another type use a speaker type arrangement with the coils entering into the central hole of donut like magnets with a steel core opposite pole field mechanical "intensifer". There are also coils going around the outside of the magnet pole/s ends with whatever shape. My limited experience in comparing coils, suggests that the coil around the outside of the magnet pole/s, would be a more efficient use of say a "U" shaped magnet than one coil between the poles, for a majority of home brew builders. Obviously, one "U" magnet could then have 2 coils for sensing and or possible damping or two outputs if another method of damping is used. My own available coils are usually round relay coils of various wire sizes and resistances. I do also have some square coils retrieved from old meter movement chart recorders. The square coils will crudely fit over the individual poles of some of my magnets, and seem to crank out a voltage much more higher than my round coils between the poles. Roughly the difference in like ohm coils seems to climb up to 10X difference. Only have 3 different square coils, two with 1500 ohm ranges, and they would peak around 2 volts. The 60 ohm coil would peak around 200mv. I do have some round coils that generate well, but they tend to be small gauge and their resistance climbs up into the 5-10 K range, and seem to be rare surplus finds overall. The pole surrounding coils seem to be a much better approach for higher output ratio and less wire useage, perhaps....a best way for managing the coil to fit the op amp desired. Logic says (too me) that the pole covering coils actually are exposed too more total gauss via the coils surface than the generally smaller coils between the poles. The larger signal may also be a nice preamp reduction in gain and noise. Basically any coil can be made with a form and wound. I am only suggesting that if you are going to wind a coil, try a form that will fit over the ends of the poles, and see the results. Or, wind both variations and compare. I'am writing with almost nill authority here, but the subject keeps showing up on my crude results of comparisons. Thanks, Meredith Lamb .... the lunchbucket seismometrist _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Radio Emissions, Electrophonics and Earthquakes Date: Wed, 15 Apr 1998 11:02:36 +0000 Hello all, I found an interesting excerpt which I think some members of the PSN-L may find interesting. Please forgive any typos or spelling errors, a finger is wrapped in tape. Best Regards, Walt Williams, 98.04.15 dfheli@.............. http://www.pacificnet.net/~dfheli ===================================================== "Progress in Explaining the Mysterious Sounds Produced by Very Large Meteor Fireballs (bolide)" Excerpts taken from Journal for Scientific Exploration (JSE, Vol 7, No. 4, pp. 337- 354, 1993, Colin S. L. Keay, Dept Physics, University of Newcastle, N.S.W., Australia) ppg 350 "An intriguing phenomenon, which may also result in the direct transduction of ELF/VLF electromagnetic energy into sound, is the correlation often reported between strong radio emissions and subsequent earthquakes (Corliss, 1983). A number of reports mentioning a "rushing" sound preceding earthquake shocks were gathered by Milne (1841). More recent accounts of such sounds may be lacking because of greater incidence of similar man-made artifacts reducing public alertness to sounds of seismic origin. However, audio frequency electromagnetic disturbances associated with earthquakes have been discussed in this journal (Parrot, 1990), while laboratory studies mentioned by Johnston (1987), and others, show that rock fractures generate electromagnetic signals. Cress and his co-workers (1987) recorded signals peaking in the range from 900 Hz to 5 kHz. Field studies conducted by O'Keefe and Thiel (1991) during large rock-blasting operations revealed a series of electrical pulses with a repetition frequency as high as 5 kHz and an amplitude of several volts. The substantially greater energy release in an earthquake could be expected to generate signals many orders of magnitude higher in amplitude. The connection has yet to be confirmed between these experimental observations and the alarm frequently exhibited by animals immediately prior to an earthquake and of course, the sparse reports of earthquake sounds by human observers." and, ppg 351, "Lastly, it is essential for geo-scientists to take reports of audible phenomena more seriously in order that some progress can be made in identifying the physical mechanisms involved. The subject of electrophonic sounds from bolides is now considered respectable within the meteor science community (Keay, 1992b), and a similar shift is now overdue within the communities of auroral and seismic scientists." _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: CAZ amps Date: Wed, 15 Apr 1998 19:23:27 -0500 (CDT) Jim, The CAZ amplifiers are a form of chopper stabilized amplifier that has (theoretically) no 1/f noise. CAZ stands for "commutated autozero", which also reduces the effect of input offset voltages. I believe that they are discussed in Horowitz and Hill (I loaned my copy several years ago ... haven't seen it since). Since they are designed as DC amplifiers, they get very noisy above 1 hz. THey are also a poor choice for low impedance sources. They generally are NOT low power devices. (the BSSA paper by Riedesel et al mentions a GE type icl421) Regards, Sean-Thomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: coil design Date: Wed, 15 Apr 1998 19:24:15 -0500 (CDT) Meredith, Some of the mysteries of coil design are explained in the first appendix of the BSSA article I mentioned yesterday. Full design criteria can be found in the handbook "Reference Data for Radio Engineers" from the ITT press. In general, the output voltage increases with the square root of the number of turns or the resistance, or a 8000 ohm coil has only four times the output of a 500 ohm coil. OR, if I wanted to double the generator constant of my speaker coil of 160 turns, it would need 640 turns. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Radio Shack Speaker Date: Wed, 15 Apr 1998 19:25:43 -0500 (CDT) Karl, Thanks for the info on your speaker coil. I expect that there would be some variations in such a consumer product. But you list the RS number as 40-1359, which may be a better speaker to use if it has a greater constant. I don't have any catalogue info on it. My original speaker #40-1349 has a constant of 12.988 N/A. The Beta instrument (also a 40-1349) is 11.815 +,-0.02 N/A. Both were measured as installed on the seismometer, using the displacement detector as a null indicator (+.- 5 microns), and 1 and 2 gram weights to balance with a current read by a 4.5 digit DMM. About 2mm of the coil is visible above the face of the magnet pole. The specification sheet lists the flux density as 7.5 kgauss; I can borrow a gauss meter and compare the four speakers I have to see how much variation we can expect. We may also have to pay attention to the position of the coil. Re using the aluminum coil former/heat sink as a calibration turn, I would be concerned about it shorting to the pole in the event of slight mis-alignment. It may not be aluminum if you were able to solder to it, aluminum generally does not solder. I have also found some indication of mutual inductance (transformer coupling) between my 5-turn coils and the main coil, even though the cal coils are about 2mm above the main coil. The problem starts to show up when using sine wave calibrations above 1 hz or so. THis problem could be serious if the two coils fully overlap. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: Small event near Dodger Stadium Date: Wed, 15 Apr 1998 20:29:31 EDT I work in a highrise in Encino and didn't feel a thing! Mike ------------------------------------------------------------------------------ --------------------------------------- LOS ANGELES, April 15 (Reuters) - A minor earthquake measuring 3.2 on the Richter Scale jolted Los Angeles at lunchtime on Wednesday, but there were no immediate reports of injuries or damage. The National Geological Survey in Boulder, Colorado, said the tremor at 1:13 p.m. (2013 GMT) was centered three to five miles (five to eight km) north of downtown Los Angeles and was also felt in the suburban San Fernando Valley. A spokeswoman for the California Institute of Technology in Pasadena said the tremor was a fresh earthquake and not an aftershock to the 6.7 magnitude 1994 Northridge quake, which killed more than 50 people and caused an estimated $40 billion in damages. The Northridge quake has so far spawned about 14,000 aftershocks, most of which have been too small to be felt. REUTERS 19:19 04-15-98 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Morrissey mail compiled Date: Wed, 15 Apr 1998 21:20:41 -0400 Hi gang, I have learned a lot about many things besides the STM-8 from Morrissey= 's mail. I thought that the information would be more accessible if it were= made more convenient so I collected all the messages up to about 4/8/98 (= I may have missed a few) into a single file. I removed all the header junk= and a lot of blank lines (so it takes less paper to print). = It (62k of text) is avail. at ftp://psn.quake.net/info/stm-mail.zip Larry sez that there is a link to the file at = http://psn.quake.net/infoequip.html Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: VBB calibration Date: Wed, 15 Apr 1998 18:05:35 -0700 Sean Thomas In checking the calibration of my VBB vertical is the displacement gain (V/M) measured at the output of the VRDT or the "mass position" output? I want to measure it at the "broadband output" but I guess this is velocity. Does the "A1" amp have a gain of 10? With my displacement sensor the output of an instrument amp goes thru a highpass filter and directly into the "Broadband velocity output" junction. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Fiberglass-Epoxy Circuit Board Date: Wed, 15 Apr 1998 20:22:23 -0600 Sean-Thomas, Thanks for the BSSA & Reference Data for Radio Engineers suggestions for learning. I'am sure they will give alot more insight. Am looking forward to a copy of the BSSA soon at the library. In regards to your STM-8 and its aluminum angle brackets for the hinges...I've pondered the use of double or triple thicknesses of printed circuit boards with no copper, with support angles as a possible temperature co-efficient improvement on your unit? I suppose the electronics manufacturers may know more of its temperature coefficent, than I have any access too. I presume it is fiberglass and epoxy composition. Obviously, the top boards or hinge attachment sides could be copper plated to the hinges for signal, etc wires also. Just a thought without the tce data. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: VBB calibration Date: Wed, 15 Apr 1998 22:18:48 -0500 (CDT) Barry, The displacement output as used in the VBB transfer function is measured after the gain of 10 amplifier (that is A1) when the feedback elements are disconnected. In my instrument here it is about 370 000 volts/meter (10x 37 mv/micron from the VRDT). An important point of the VBB feedback is that this SAME output that BECOMES the broadband VELOCITY output when the feedback is connected. This is the voltage that needs to be buffered with your high-pass amplifier to remove the DC components of the signal that would saturate your recorder. The actual output of the instrument is then calculated by the transfer function itself, and is of the order of 1600 v/m/sec. Note that the VBB output voltage (befor your high-pass filter) and the mass position output will approach the same value when there is no major input to the sensor. I use the mass position voltage to determine when and how much remote zeroing is needed. I assume that your high pass filter is not within the feedback loop. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: VBB calibration Date: Wed, 15 Apr 1998 20:31:41 -0700 S-T Morrissey Thanks. The next step is outside! Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: A Magnetic Spring Seismometer Description Date: Wed, 15 Apr 1998 23:58:19 -0600 Roger Baker, With reference to your report of 4/10/98, via email. Thanks so much for the JPEG views of you magnetic instrument. I enjoyed the views, and was amazed at the clarity of the side view especially. I can appreciate the idea of your device as one which probably alot of people have speculated and dabbled in occasionally, usually with little sucess, in a variety of designs. Experimentation is usually a delight to see and do....fun stuff. I have to admit I have had to read your progress report several times, to grasp most of it. Anyway...I do have questions and/or speculations (take your choice), to present... 1. If...one were to use much larger diameter ferrite magnets and of course a larger mass, would not the period be lenghtened somewhat...or would it stay the same? 2. The utility knife pivot distance does not look like it could be lengthened, without collapse...or could it? 3. Would a Hall Effect sensor be much better, with its much larger range of motion, than the photocells? 4. Could the lead mass, be instead made of a copper coil, as part of the feedback control and perhaps do away with the coil underneath? Perhaps this way, the response might be more linear to disturbances. 5. Some varietys of stainless steel....#314 I think....will also do an assumed variety of repulsion, to a limited extent. With the mass being part 314 variety and part feedback coil, I would wonder if the magnetic influence noise would shrink somewhat, in comparison to the solid magnet? I have not seen any magnetic repulsion instrument like yours, and that I find it interesting. Keep up the experimentation. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: A Magnetic Spring Seismometer Description Date: Wed, 15 Apr 1998 23:28:58 -0700 At 11:58 PM 4/15/98 -0600, Meredith Lamb wrote: >Roger Baker, > >With reference to your report of 4/10/98, via email. > >Thanks so much for the JPEG views of you magnetic instrument. >I enjoyed the views, and was amazed at the clarity of the side >view especially. Roger also sent me picture of is sensor. I have placed a copy of it at: ftp://drnet.com/users/psn/info/dcp00494.jpg Its a 300K jpg file. I asked Roger about the camera he used to take the photo. Heres what I got back from him; "My camera is a Kodak 210 that sells for about $800 and takes frames with about 800x1000 pixels. This is a little better resolution than most, but others are still better, like the Olympus, which apparently has a big detachable lens for about $1,200." -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: A Magnetic Spring Seismometer Description Date: Thu, 16 Apr 1998 07:49:17 +0100 Larry Cochrane wrote: > > > Roger also sent me picture of is sensor. I have placed a copy of it at: > ftp://drnet.com/users/psn/info/dcp00494.jpg > > Hi Larry, I wonder if Roger could be persuaded to make a sketch, with the main relevant parts marked, and place a copy of that, on web? The photo above is so intrigueing, but I am not sure what I am looking at. (I know what a yellow croc clip is, but not the other items.) Regards, Albert Noble (England). _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Radio Shack Speaker Date: Thu, 16 Apr 1998 08:31:26 -0700 Sean-Thomas -- I made a typo. The RS cat. # should have been 40-1349, same as yours. I believe the coil form is aluminum, and I used aluminum solder flux. I also tested the constant while installed in the seismometer, using its displacement detector. I determined the spring constant by knowing the mass and measuring the undamped natural period. Your method with the small weights sounds more direct. I'll try it. I'm not sure where the 7.5 kgauss is measured. It may be between the pole pieces, in the gap -- might be hard to measure. I hadn't thought about the mutual inductance problem. But since the feedback coil is used only to create a magnetic field to force the system back to the null position (and not part of a detector circuit), and the calibration coil is also used to create a magnetic field, I'm not sure if it matters. But my knowledge of magnetics pretty slim. (What the world needs is a simple, intuitive way to understand electromagnetics.) -- Karl _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Seismo-Watch in San Jose! Date: Thu, 16 Apr 1998 09:07:33 -0700 It is with great pleasure to announce that on April 15, the San Jose Mercury News San Jose, California began featuring a weekly Seismo-Watch Newspaper Earthquake Report in the Tuesday edition of their Science and Technology section. The Mercury has chosen to show a basic black and which earthquake epicenter map mostly of the San Francisco Bay Area and Central California, from about Sonoma in the north to San Benito in the south, and the Pacific Ocean on the west to the Sacramento-San Joaquin Valley on the east. Weekly earthquake epicenters registering M1 or stronger are plotted on the map and a table summarizes the various magnitudes recorded. A brief discussion highlights the significant activity. An example of their graphic can be seen at the following URL: http://www.seismo-watch.com/EQNEWS/Newspaper/Newspaper.html The San Jose Mercury News is one of the four largest newspapers in the San Francisco Bay area, servicing several communities in the South Bay Area and central California region, with a potential readership of over 780,000 people. Several active faults cut the region, which not only provide abundant backgroud seismicity but a pose a significant risk to the residents from a major quake. While providing an exciting feature to watch from week to week, it is hoped the Seismo-Watch Earthquake Report will maintain an elevated sense of earthquake awareness and in turn, create a population attuned to effective earthquake hazard mitigation strategies. Since 1992, Seismo-Watch Newspaper Earthquake Reports have gained widespread public, professional and governmental appeal for transferring information from the earthquake monitoring centers to the public via a common, low cost media source. Weekly Seismo-Watch Earthquake Reports currently appear in 32 newspapers from 14 core media syndications within California and Nevada, and have a collective potential readership of over 2.6 million people. For more information on how your local newspaper can begin a Seismo-Watch Earthquake Report, see the Seismo-Watch web page or contact: -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration/Seismo-Watch P.O. Box 18012, Reno, Nevada 89511 Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: A Magnetic Spring Seismometer Description Date: Thu, 16 Apr 1998 12:54:48 -0700 At 07:49 AM 4/16/98 +0100, you wrote: >Hi Larry, > >I wonder if Roger could be persuaded to make a sketch, with the >main relevant parts marked, and place a copy of that, on web? The >photo above is so intrigueing, but I am not sure what I am looking at. >(I know what a yellow croc clip is, but not the other items.) > >Regards, > >Albert Noble (England). Roger sent me an illustration of his magnetic suspension sensor. The 10K gif file (he sent me a bitmap and I converted to gif) can be view at: ftp://drnet.com/users/psn/info/magseis.gif -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Answers to Meredith's questions Date: Thu, 16 Apr 1998 15:02:42 -0500 At 11:58 PM 4/15/98 -0600, you wrote: >Roger Baker, > >With reference to your report of 4/10/98, via email. > >Thanks so much for the JPEG views of you magnetic instrument. >I enjoyed the views, and was amazed at the clarity of the side >view especially. > >I can appreciate the idea of your device as one which probably >alot of people have speculated and dabbled in occasionally, >usually with little sucess, in a variety of designs. Experimentation >is usually a delight to see and do....fun stuff. > >I have to admit I have had to read your progress report several >times, to grasp most of it. > >Anyway...I do have questions and/or speculations (take your >choice), to present... > >1. If...one were to use much larger diameter ferrite magnets and > of course a larger mass, would not the period be lenghtened > somewhat...or would it stay the same? > Yes the period would lengthen, but a far better way to lengthen the period is just to adjust the two magnet heights with the screws. This will lengthen the period up to about a second, but since the beam length is so short, as short as half an inch, this is about the limit for stability -- and with 2 oz of weight this in itself represents a very close balance of gravity with magnetism, meaning it moves a whole lot with a small change in vertical force. It isn't designed to have a long period so much as a high Q, because a feedback force can, in effect, stretch the natural period. >2. The utility knife pivot distance does not look like it could be > lengthened, without collapse...or could it? > Yes, you can make the beam a lot longer and stretch the design in a horizontal direction in effect, and some of my earlier prototypes looked this way. And it may turn out that a long beam is better than a short beam, but I didn't like the air resistance reducing Q. But I might be wrong. But whatever you do, you definitly should have a thermal feedback regulated enclosure, to keep it from drifting off scale, and a magnetic shield, so this argues in favor of a smaller size. If you could figure out a way to very slowly add or subtract larger amounts of magnetic force than I do currently, it might be possible to pull it back into range that way, while retaining the teleseismic period sensitivity. In that case the slow thermal drift could be compensated for, perhaps. >3. Would a Hall Effect sensor be much better, with its much > larger range of motion, than the photocells? > No, force feedback can keep the beam nearly motionless, although I am using very little feedback power right now (but this isn't good, its just cheap and easy for right now). And a good optical sensor is very sensitive and small and cheap. Since you have very little motion on the short beam, you want the best motion detection sensitivity possible and a Hall effect transducer isn't really very good for sub-micron displacements. Its only virtue, so far as I can tell, is that it tends to work along any axis of motion. >4. Could the lead mass, be instead made of a copper coil, as > part of the feedback control and perhaps do away with the > coil underneath? Perhaps this way, the response might be > more linear to disturbances. > I wanted to get the electronics and springy wires all off the off the short beam. In fact the beam is very easily demountable, since the only thing holding it in place is magnetic force. Lead weight on the beam, rather than my copper and epoxy coil, also gives the beam less buoyancy in response to changes in atmospheric pressure. >5. Some varietys of stainless steel....#314 I think....will also > do an assumed variety of repulsion, to a limited extent. With > the mass being part 314 variety and part feedback coil, I > would wonder if the magnetic influence noise would shrink > somewhat, in comparison to the solid magnet? > My magnets should be strong and cheap and easily available. Radio Shack has them all including the rare earth magnets used to seat the knife edge for a few dollars. >I have not seen any magnetic repulsion instrument like yours, >and that I find it interesting. Keep up the experimentation. > Sean-Thomas says that the Sprengnether (sic?) uses a magnetic suspension, so at least some configurations of magnetic suspension are quite practical. I have submitted a black and white line bitmap schematic to Larry Cochrane of my arrangement that should make my setup a little clearer, although I'm not sure yet if he can post it, since the non-optimal way I did it made the file a little big. --Yours, Roger >Thanks, Meredith Lamb > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: More Magnetic Spring Seismometer Questins Date: Thu, 16 Apr 1998 22:38:31 -0600 Roger Baker, Thanks for the effort involved in the JPEG's and the magnificient GIF drawing of your instrument. I get the solid impression from the drawing that you have quite a bit of experience along the line, and it was done relatively fast. I sometimes wonder why I keep asking questions, and don't just hit the books more-ha. (Probably everybody is nodding yes-ha) More questions and speculations...... Going back to question 1 involving the size of the mass. If one can successfully raise the weight of the mass and...keep the present ratio of the pivot (Assuming larger donut magnets), the inertia weight would seem to keep it in one place in space better....and....perhaps the period would be longer, and the Q would seem to stay high. I would think that the magnetic noise would also have a hair less impact in disturbances, due to the higher weight. Perhaps the magnets/weight/gravity balance can be made known initially with a plastic cup and pennys thrown in, and later a lead substitute. I know....I'am throwing out the little magnet stuff-ha. Part of the added mass speculation is directly related to the period of the instrument....a very solid one second period would be much more attractive on the seismic use desireability. I suppose there would obviously be a need for an increase in the number of magnets to do the lift work primarily. The power regulation of the LED and the circuit would probably have to be very tightly controlled I would imagine? Do you intend to do regular or sporatic recording of the output at some time? I would think it would be very interesting to see a variety of results from it. Have you tried or considered using eddy current damping instead of a feed back approach? Anyway....the instruments potential capability of seeing a variety of effects, does have ALOT of appeal in it self. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: More answers Date: Fri, 17 Apr 1998 01:12:56 -0500 At 10:38 PM 4/16/98 -0600, you wrote: >Roger Baker, > >Thanks for the effort involved in the JPEG's and the magnificient >GIF drawing of your instrument. I get the solid impression from the >drawing that you have quite a bit of experience along the line, and >it was done relatively fast. > >I sometimes wonder why I keep asking questions, and don't just >hit the books more-ha. (Probably everybody is nodding yes-ha) > >More questions and speculations...... > >Going back to question 1 involving the size of the mass. If one >can successfully raise the weight of the mass and...keep the present >ratio of the pivot (Assuming larger donut magnets), the inertia weight >would seem to keep it in one place in space better....and....perhaps >the period would be longer, and the Q would seem to stay high. >I would think that the magnetic noise would also have a hair less >impact in disturbances, due to the higher weight. Perhaps the >magnets/weight/gravity balance can be made known initially with >a plastic cup and pennys thrown in, and later a lead substitute. I >know....I'am throwing out the little magnet stuff-ha. Part of the >added mass speculation is directly related to the period of the >instrument....a very solid one second period would be much more >attractive on the seismic use desireability. I suppose there would >obviously be a need for an increase in the number of magnets to >do the lift work primarily. > A longer beam could easily increase the period if the weight were mounted a long way from the pivot, but from my point of view, a long natural period is just not that great in itself, when separated from other tradeoffs. However it is very important if you are designing some other sort of instrument without force feedback like a damped Lehman. >The power regulation of the LED and the circuit would probably >have to be very tightly controlled I would imagine? > If you control the voltage, which is pretty easy to do nowadays, the main source of variation of an LED output is going to be temperature, which is another good reason you need a thermal enclosure. >Do you intend to do regular or sporatic recording of the output >at some time? I would think it would be very interesting to >see a variety of results from it. > I see lots of local high frequency urban noise when I don't filter the output, but thats not very interesting at all. I can make charts, but the current problem is that thermal drift throws the thing off scale long before a teleseismic event comes along. It will take a specially made heat control, sometimes called an oven in the trade, that will maintain the magnetic shield slightly above ambient to kill the drift. My earlier posts talk about how to do that. But all this means work and I'm sometimes lazy or easily distracted toward various other interests. This PSN work don't pay enough! >Have you tried or considered using eddy current damping instead >of a feed back approach? > Feedback control is in itself the best damping approach when well done, IMHO. >Anyway....the instruments potential capability of seeing a variety of >effects, does have ALOT of appeal in it self. > Have you ever heard the expression 'Jack of all trades, but master of none.' ;) But enough of all this. Now that I have gotten out the basics, lets have somebody else play with the approach and improve on it, or discredit it, and let me chime in when I think I have something important to add. --Yours, Roger >Thanks, Meredith Lamb > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Re: A Magnetic Spring Seismometer Description Date: Fri, 17 Apr 1998 08:03:34 +0800 >The power regulation of the LED and the circuit would probably >have to be very tightly controlled I would imagine? >>If you control the voltage, which is pretty easy to do nowadays, the main >>source of variation of an LED output is going to be temperature, which is >>another good reason you need a thermal enclosure. Hi Just 1 1/2 cents worth: If the LED illuminated two fibre optics cables, one illuminated the displacement photo transistor and other illuminated a inline photo transistor. If the outputs were differenced then final result should be independent of the "LED" temperature drift. Do you have any "Winquake" type outputs from your device, say 60 minutes worth? It would be interesting to see the frequency spectrum. Great design. Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: A Magnetic Spring Seismometer Description Date: Fri, 17 Apr 1998 06:28:21 -0500 Arie Verveer wrote: > Hi > > Just 1 1/2 cents worth: If the LED illuminated two fibre optics cables, > one illuminated the displacement photo transistor and other illuminated > a inline photo transistor. If the outputs were differenced then > final result should be independent of the "LED" temperature drift. > If you carry this one step further and have the boom interrupt both beams of light in such a way that one is being covered while the other is being uncovered (pushpull) you have the potential of reducing several sources of noise and increasing the sensitivity to boot. I bought a couple of photointerrupter modules from DigiKey to do just that. But I think Roger is trying to keep things a simple and inexpensive as posiible and the single phototransistor will work. Since thermal control is needed for lots of other reasons using one beam is not such a problem. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: A Magnetic Spring Seismometer Description Date: Fri, 17 Apr 1998 08:29:11 -0700 A while back I experimented with photo-interrupters for displacement detection. Of the schemes I tried, the best involved using a dual CdS cell with a slot cut in a vane so that the outside half of each of the pair was covered. The sum of the two outputs was used as feedback to the LED to keep its light output constant, and the difference between the two was used as the displacement signal. The best I could do was about 25 nanometers RMS noise in a 5Hz bandwidth. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: A Magnetic Spring Seismometer Description Date: Fri, 17 Apr 1998 13:23:43 -0500 At 06:28 AM 4/17/98 -0500, you wrote: >Arie Verveer wrote: > >> Hi >> >> Just 1 1/2 cents worth: If the LED illuminated two fibre optics cables, >> one illuminated the displacement photo transistor and other illuminated >> a inline photo transistor. If the outputs were differenced then >> final result should be independent of the "LED" temperature drift. >> >If you carry this one step further and have the boom interrupt both >beams of light in such a way that one is being covered while the other >is being uncovered (pushpull) you have the potential of reducing several >sources of noise and increasing the sensitivity to boot. I bought a >couple of photointerrupter modules from DigiKey to do just that. But I >think Roger is trying to keep things a simple and inexpensive as >posiible and the single phototransistor will work. Since thermal >control is needed for lots of other reasons using one beam is not such a >problem. >-- >Jim Hannon >http://soli.inav.net/~jmhannon/ >42,11.90N 91,39.26W >WB0TXL > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > Yes indeed, Jim has it right. You have as much sensitivity and thermal stability as you need already, perhaps. The phototransistor is put in series with a 10 K 1% metal film resistor, followed by a voltage follower made from a little 'jellybean' 324 op amp, $1.29 from Radio Shack, which I probably use excessively in my designs. I use two 324's in my simple circuit control and output circuit. I fine tune the position of the beam (the screw adjustments are rough and inconvenient) using a magnet outside the Igloo cooler that encloses the whole thing. If the beam is thus raised and lowered slightly, at some point it will let through just enough light that the resistance of the phototransistor equals 10 K and the voltage output will be be at the midpoint-- where the resistor equals the PT resistance, or three volts using my 6 v supply made from four dry cells. Then this midrange output, which needs attention to keep it there, is amplified by ten before it goes into the A/D converter and into the computer. This buffered output voltage is then passed through a resistor in parallel with a largish cap and then into the coil, which has a DC resistance of about 8-10 ohms for force feedback. But the current electronics is very simple and nowhere near optimized, especially in terms of feedback power. My instrument still rings at its natural frequency, somewhat. But there is a big difference with and without feedback in operation, even at low power. But as I said, I'm more interested in other aspects of design than the electronics and invite anyone to improve on what they see. If you wanted more optical sensitivity, you could use a red laser pointer beam, presumably mounted vertically so as to fit inside the shield with a little mirror to aim the beam horizontally at the tip of the flag. A laser beam is inherently more concentrated than an LED, so that a smaller motion of the flag on the end of the beam can influence more photons going into the phototransistor, by at least factor of at least ten, I would guess. And if you want the ultimate sensitivity, you can call in the heavy artillery, so to speak, with a capacitance micrometer. I would post the results if I had any to brag about, so I will describe the general result at present, rather than sending you a JPEG photo of a chart off my monitor screen. I can amplify the raw output and see a lot of high frequency local man-made noise, or I have been putting a simple one pole low pass filter on the output, but have not seen any teleseismic events that I know of. The output into my Windaq A/D converter looks like a jagged line that gradually drifts off scale due to temperature change. I think I have sometimes seen teleseismic response from ocean waves from the Gulf coast but am not absolutely sure. This looked like a slight but distinguishable sine wave with a period of five or six seconds imposed on the slow drift offscale. --Yours, Roger PS--I just read Karl Cunningham's post. You can imagine that if a clunky old CdS cell will give you 25 nanometers resolution, then a very bright concentrated light source near to a good phototransistor having a very small sensitive area will probably do a lot better. I am well aware of the advantages of optical bridge arrangements, they are not hard to homebrew with two phototransistors, and I like to use them sometimes, but the situation does not require one in this case. Or maybe it does, but I just don't know it yet. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: A Magnetic Spring Seismometer Description Date: Fri, 17 Apr 1998 16:11:16 -0700 Roger -- Actually, the dual CdS cell was an improvement in noise over dual phototransistors by perhaps 3:1. And using a laser pointer was worse than the LED. Although the overall light output of the laser diode (averaging the entire beam) was pretty constant, the distribution of light in the beam's cross section wasn't very stable with time or temperature. Optically diffusing the beam and then columnating it again helped, but it still wasn't as good as the LED. I found that with LEDs, the distribution of light across its beam wasn't very uniform (although it was constant with time), so again diffusing and re-columnating was a help. I'm sure this is quite variable between types of LEDs, and yours may be better in this regard. Roger, I don't want to dissuade you from your work on this ... I easily could have missed a much better approach. I only stopped work on the optical detector when it became apparent that making an LVDT would get my instrument running sooner. -- Karl >PS--I just read Karl Cunningham's post. You can imagine that if a clunky >old CdS cell will give you 25 nanometers resolution, then a very bright >concentrated light source near to a good phototransistor having a very >small sensitive area will probably do a lot better. I am well aware of the >advantages of optical bridge arrangements, they are not hard to homebrew >with two phototransistors, and I like to use them sometimes, but the >situation does not require one in this case. Or maybe it does, but I just >don't know it yet. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: EMON PRINT Date: Sat, 18 Apr 1998 03:21:37 +0200 Hi all. I use Quakevew with Emon for immediately analysis of the event before to = run Wq. It's possible to print from Qv ? Francesco Nucera - Italy -
Hi all.
 
I use Quakevew with Emon for = immediately=20 analysis of the event before to run Wq.
It's possible to print from Qv = ?
 
Francesco Nucera   - Italy = -
From: S-T Morrissey Subject: optical displacement detectors Date: Fri, 17 Apr 1998 20:22:45 -0500 (CDT) Roger, I am concerned about your statements about the resolution of a vane or light-beam-interrupting type optical displacement detector. While it does exhibit interesting sensitivity, it is not used in sensitive geophysical sensors because of an inherent limitation: the wavelength of light. One of the rude rules of physics is that one cannot measure a quantity with more accuracy than the ruler that is used. In this case, the red LED has a wavelength of about 600 nanometers (nm), and even though you cannot see them on your detector, the shadow line of the vane is a series of diffraction fringes separated by that amount, all superimposed because of the diffuse nature of the LED source (a LED lasar would show them clearly). The photocell output is an average of this output. Even in the natural world, the limit of our visual resolution is the wavelength of light. This is why we had to invent electron microscopes to see sub-micron objects. The world of micro-positioning detectors uses complex optical encoders and digital interpolation to push the resolution, but the best available is 70 nanometers. (from Dynamics Research Corp, model LB with 64x interpolation). (BTW: I send for lots of literature on such detectors for possible use in strainmeters and tiltmeters ... but not in seismometers) But the resolution we need for seismic instruments is of the order 1 nanometer and less. Right now the sensor here has the normal background noise of microseisms of about 3mv amplitude, which at my current gains (3240v/m/sec) is a ground motion of about 1 micron at 6 seconds. On the power spectral density noise model this is about normal at about -140 db. But if we are interested in someting small and local, like a magnitude 3.0 at 200 km, it will have a peak amplitude of about 100 nm (using Mblg = 3.75 + log(distance in degrees) + log A (microns)). But I can easily resolve 0.1 mv at 10 hz, which is a ground motion of 0.5 nanometers, or about -170 db in power spectra. The smallest event I have recorded is a Mb 2.7 at 265 km, which had a peak motion of 34 nanometers at 3 hz. Early seismic instruments DID use optical detectors, but always employed the principal of optical levers, where the ground motion sensed by the seismometer rotated a small mirror that reflected a light beam over a distance of a meter or more to photographic paper for analog recording or to a differential detector (split photocell) for amplification. Currently optical measurement techniques use incremental encoders or lasars and interferometers, but are still limited by the wavelength of the light used. This is why a the best lasar strainmeters are over 500 meters long. A good discussion of optical displacement detectors can be found in "Strainmeters and Tiltmeters", by D.C.Agnew, (Reviews of Geophysics, Vol 24, No 3, pg579-624, August 1986.) It also has an extensive treatment of capacitive and LVDT-type displacement transducers. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek Subject: little question Date: Sat, 18 Apr 1998 04:12:34 +0200 (CEST) Hello all, I do not want to interfere in the interesting discussion about the new design from Roger, but there is one point in this design wat's very interesting for me.I'm now for sometime busy with a horizontal seismometer that's small (15 cm)but with a long (20 sec) period. I made my first rough instrument and it seems to work good. it's a re-design from the old Wieger-instrument (I just love the old stuff,can't help it) It's a design that's using the unstable principle , also I use 2 pick-up coils , and the magnet is inside and outside the coil, they are realy great ( took them from a scrap heart-plotter. What i need is a magnetic-shield to cover the instrument and there is my question. The mass and pendulum is "floating" on 2 small magnets and 2 very thin springs, there is no friction. The first rough edition i tested with a small mirror and a laser gave me a good performence it's now next to my "good old" Bosch (still working) and i'm still testing it Now busy with the new design and when i've finished it i'll put a photo and the drawing (cad) on the net. Hope someone can help me with a "simple" solution about the magnet-shield. Greetings, Kees Verbeek , Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: EMON PRINT Date: Fri, 17 Apr 1998 22:48:39 -0700 Yes you can print from QV. The help text is listed on the banner page. Just enter QV without a file name to display it. In short, in DOS mode enter the GRAPHICS command one time. Then display the file. Press the shift-prtsc (print screen) to print the file. Rgeards, Steve Hammond PSN San Jose Francesco wrote: > > Hi all. > > I use Quakevew with Emon for immediately analysis of the event before > to run Wq. > It's possible to print from Qv ? > > Francesco Nucera - Italy - _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Wieger seismometer/seismograph Date: Sat, 18 Apr 1998 10:40:38 -0600 Kees Verbeek, Can't offer help on the magnetic shielding, but do have a question on the wieger-instrument you are basing your design somewhat on. Is it like the Wiechert pendulum, an inverted pendulum, mass on top, pivot down towards earth, springs on the side? Difference in name or totally different? Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek Subject: Re: Wieger seismometer/seismograph Date: Sun, 19 Apr 1998 01:45:55 +0200 (CEST) At 10:40 18-04-98 -0600, you wrote: >Kees Verbeek, > >Can't offer help on the magnetic shielding, but do have a question >on the wieger-instrument you are basing your design somewhat on. > >Is it like the Wiechert pendulum, an inverted pendulum, mass on >top, pivot down towards earth, springs on the side? Difference in >name or totally different? > >Thanks, Meredith Lamb > Meredith, Indeed, its the same one. I saw one when i was visiting the"dutch seismo survey"(KNMI) (the "small" one, with a mass of 200 kg( the big one had mass of 1000!!!! kg)) and then they explained it to me , because it is a very complicated but smart seismograph , that was a completely mechanical seismograph and no longer in use . I was there to "investigate" and see the "bosch-seismograph" , the one I build after that visit. The "Wiechert" never did left my mind because I did think there was a very clever basic-idea .I think its the only way (because of the inverted pendulum) to let gravity help the system , in all other horizontal seismographs gravity is against the system. The gigantic weights of the old models were in those days necessarily to overcome the friction between the pen and the paper( and all the other mechanical frictions )That part was also a big problem in the "Bosch-model". Nowadays we have other ways to record so we can do with smaller models, but I wanted to look if it was posible to build a small seismograph with a inverted pendulum , I think its going to work!!. But i also did learn to be very reserved and first look at other ways before yelling that the work is done. So I'm now in the last phase of drawing (after a rough working-model) and after that i can make a start to build for real. Let you know how things are going. Greetings Kees Verbeek , Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: A Magnetic Spring Seismometer Description Date: Sat, 18 Apr 1998 22:52:29 -0600 Roger, In regard to the feedback coil ..... With the small donut magnets you are using, it maybe possible to use a small speaker (using just the magnet and coil, not the frame), for the upper magnets replacement, and use the coil in the speaker for the feedback coil. Of course the coil would have to be made to NOT move, and still be in the gap of the original speaker, and pointed down toward the mass. Of course, one could make the coil extended down and into the center hole of the mass also. There would be no attachment to the mass for this. Of course this is an old idea, but it might save winding the coil for some. I suppose one would at least need an 8 ohm or larger speaker, which is size adequate to the task. Of course a larger donut magnet unit could take larger sizes of speaker feed back, and one could arrange various kinds of attached or non-attached coils from speakers....either going thru the holes of regular donut magnets, or permanently set therein. Alot of people have small cheap junk type speakers that might work and accelerate completion. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: A Magnetic Spring Seismometer Description Date: Sun, 19 Apr 1998 01:39:43 -0500 At 10:52 PM 4/18/98 -0600, you wrote: >Roger, > >In regard to the feedback coil ..... > >With the small donut magnets you are using, it maybe possible >to use a small speaker (using just the magnet and coil, not the >frame), for the upper magnets replacement, and use the coil >in the speaker for the feedback coil. Of course the coil would >have to be made to NOT move, and still be in the gap of the >original speaker, and pointed down toward the mass. Of course, >one could make the coil extended down and into the center hole >of the mass also. There would be no attachment to the mass for >this. Of course this is an old idea, but it might save winding >the coil for some. I suppose one would at least need an 8 ohm or >larger speaker, which is size adequate to the task. > >Of course a larger donut magnet unit could take larger sizes of >speaker feed back, and one could arrange various kinds of >attached or non-attached coils from speakers....either going >thru the holes of regular donut magnets, or permanently set >therein. Alot of people have small cheap junk type speakers >that might work and accelerate completion. > >Meredith Lamb Meredith, et al, The way I make my coils is to take something like a pencil and wind it up with masking tape until two donut magnets will just barely fit over the increased diameter. I cover the facing sides of two such magnets with masking tape before jamming them on separated by a distance of approximately one magnet width. This makes a sort of bobbin on a stick, and you wind the coil between the two masking tape-faced magnets under a few ounces of tension. You need to secure the wire first of course by winding a few turns on the pencil and tape it over the rim of one of the magnets. The wire I use is the finest of the three spools of magnet wire you get for a few bucks at Radio Shack, measuring .010 inches by my micrometer. But in addition, I wind my coils wet with epoxy (don't use the quick setting kind!) so that when they are wound up to the diameter of the magnets, and the epoxy has set, the whole thing can be warmed up to loosten the adhesive on the masking tape and the bare coil removed. Made thus they have a DC resistence of around ten ohms. This is good for a force coil, but too low for a sensing coil. If you wanted to wind the latter this way, it would be better to use finer wire so as to get a resistance of a few hundred ohms to match a low impedence bipolar op amp like the LTC 1028, I believe. Making your own coils has the advantage of being able to custom fit the other parameters of seismo design. On the interesting topic of sensitive displacement transducers, I poked around in the UT physics library today, searching for review articles. Optical interferometry can sense displacements down to about .1 nanometer, as can linear variable differential transformers or LVDTs. For much more sensitivity, way way down to one hundred thousandth of a nanometer, capacitance micrometers are the way to go. The best overall review article I found was 'Microdisplacement Transducers' by P.H. Sydenham, Journal of Physics E, Scientific Instruments, Vol 5, p721-33, 1972. This has the disadvantage of being an old article, but has some good insights. The best non-interferometric optical method they cite was 20 nanometers sensitivity, but an optical lever system is cited that could do one nanometer. I did find one more recent article; "Real-time, high resolution optical beam position-sensing device' in the Jan. 1991 Review of Scientific Instruments, p 217 that uses a dual gap lead chromate sensor to detect a 543 nanometer laser beam displacement of 5 nanometers, said to be limited by the noise of the laser beam. I think somewhere I have seen references of LED-photodiode or phototransistor displacement transducers that can do in the low nanometers, or several times better than the latter. My current instrument has the center of gravity about three-quarters of an inch from the pivot and the flag extending outwards several inches farther on the beam beyond this so this should mean that any motion is mechanically amplified by three or four times. So I don't really know if I am at the one nanometer sensitivity needed for a good instrument, according to Sean-Thomas, but if not I am not far off. Maybe I can find more recent references that discuss the limits to the sensitivity of my type of transducer. Right now I suspect its photon noise between emitter and detector, which is why you should mount the two as close together as possible and drive the LED hard, or so I think.(Believe it or not, there are now many references to single photon counting with avalanche photodiodes operated at rather high voltage in what is known as the Geiger mode.) --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Saving PSN event file to ASCII file. Date: Sun, 19 Apr 1998 00:30:55 -0700 Greetings, I got an other request from someone that wanted to convert a PSN event file to a text file the other day. Since WinQuake is on a feature freeze, until I get the current version documented and released, I wrote a 16-bit DOS program that will save the PSN event file to an ASCII test file or display the data on the screen. I will add this feature to WinQuake in the next release. The program is called Psn2Text and it can be download at: ftp://psn.quake.net/software/psn2text.zip The "C' source code is include in the zip file. From then readme.txt in the ZIP file: PSN2TEXT Program This 16-bit DOS program converts a PSN Binary event file to an ASCII text file or displays the information on the screen. Usage: psn2text [ /d or /h ] InputFile [ OutputFile ] /d = dump or display data only. /h = dump or display header only. If no output file is specified, output will go to the screen. If neither /d or /h are specified, both header and data will be dumped or displayed. [] = Optional. Files in this package: PSN2TEXT.EXE 16-bit DOS Program file. PSN2TEXT.C C source code. PSNHDR.H Header file for PSN2TEXT.C 980403A.LC8 Example PSN event file. OUT.LC8 Output of PSN2TEXT using 980403A.LC8 as the input. format.txt Documents the PSN binary format. readme.txt This file. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Fwd[1]: A Magnetic Spring Seismometer Description Date: Sun, 19 Apr 1998 00:32:46 +0000 Hello Roger Baker, To what recording device do you connect your Magnetic Spring Seismometer (MSS)? Or is this just an experimental instrument for testing? Is your MSS fairly portable, more rugged? Thank you. Walt Williams, 98.04.19 ================================================= ------- Forwarded Message Follows ------- Date: Sun, 19 Apr 1998 01:39:43 -0500 To: PSN-L Mailing List From: Roger Baker Subject: Re: A Magnetic Spring Seismometer Description Reply-to: PSN-L Mailing List At 10:52 PM 4/18/98 -0600, you wrote: >Roger, > >In regard to the feedback coil ..... > >With the small donut magnets you are using, it maybe possible >to use a small speaker (using just the magnet and coil, not the >frame), for the upper magnets replacement, and use the coil >in the speaker for the feedback coil. Of course the coil would >have to be made to NOT move, and still be in the gap of the >original speaker, and pointed down toward the mass. Of course, >one could make the coil extended down and into the center hole >of the mass also. There would be no attachment to the mass for >this. Of course this is an old idea, but it might save winding >the coil for some. I suppose one would at least need an 8 ohm or >larger speaker, which is size adequate to the task. > >Of course a larger donut magnet unit could take larger sizes of >speaker feed back, and one could arrange various kinds of >attached or non-attached coils from speakers....either going >thru the holes of regular donut magnets, or permanently set >therein. Alot of people have small cheap junk type speakers >that might work and accelerate completion. > >Meredith Lamb Meredith, et al, The way I make my coils is to take something like a pencil and wind it up with masking tape until two donut magnets will just barely fit over the increased diameter. I cover the facing sides of two such magnets with masking tape before jamming them on separated by a distance of approximately one magnet width. This makes a sort of bobbin on a stick, and you wind the coil between the two masking tape-faced magnets under a few ounces of tension. You need to secure the wire first of course by winding a few turns on the pencil and tape it over the rim of one of the magnets. The wire I use is the finest of the three spools of magnet wire you get for a few bucks at Radio Shack, measuring .010 inches by my micrometer. But in addition, I wind my coils wet with epoxy (don't use the quick setting kind!) so that when they are wound up to the diameter of the magnets, and the epoxy has set, the whole thing can be warmed up to loosten the adhesive on the masking tape and the bare coil removed. Made thus they have a DC resistence of around ten ohms. This is good for a force coil, but too low for a sensing coil. If you wanted to wind the latter this way, it would be better to use finer wire so as to get a resistance of a few hundred ohms to match a low impedence bipolar op amp like the LTC 1028, I believe. Making your own coils has the advantage of being able to custom fit the other parameters of seismo design. On the interesting topic of sensitive displacement transducers, I poked around in the UT physics library today, searching for review articles. Optical interferometry can sense displacements down to about .1 nanometer, as can linear variable differential transformers or LVDTs. For much more sensitivity, way way down to one hundred thousandth of a nanometer, capacitance micrometers are the way to go. The best overall review article I found was 'Microdisplacement Transducers' by P.H. Sydenham, Journal of Physics E, Scientific Instruments, Vol 5, p721-33, 1972. This has the disadvantage of being an old article, but has some good insights. The best non-interferometric optical method they cite was 20 nanometers sensitivity, but an optical lever system is cited that could do one nanometer. I did find one more recent article; "Real-time, high resolution optical beam position-sensing device' in the Jan. 1991 Review of Scientific Instruments, p 217 that uses a dual gap lead chromate sensor to detect a 543 nanometer laser beam displacement of 5 nanometers, said to be limited by the noise of the laser beam. I think somewhere I have seen references of LED-photodiode or phototransistor displacement transducers that can do in the low nanometers, or several times better than the latter. My current instrument has the center of gravity about three-quarters of an inch from the pivot and the flag extending outwards several inches farther on the beam beyond this so this should mean that any motion is mechanically amplified by three or four times. So I don't really know if I am at the one nanometer sensitivity needed for a good instrument, according to Sean-Thomas, but if not I am not far off. Maybe I can find more recent references that discuss the limits to the sensitivity of my type of transducer. Right now I suspect its photon noise between emitter and detector, which is why you should mount the two as close together as possible and drive the LED hard, or so I think.(Believe it or not, there are now many references to single photon counting with avalanche photodiodes operated at rather high voltage in what is known as the Geiger mode.) --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Web Page update (Western australia) Date: Sun, 19 Apr 1998 20:51:53 +0800 Hi, for those who are interested, the web page at http://www.iinet.com.au/~ajbv/ now contains some information and images of the seismograph vault. It also has a simple page for the last local event and a map for the general reader. More to come. Arie Western Australia Station AU* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: VBB operation Date: Sun, 19 Apr 1998 08:45:58 -0700 Sean Thomas Well I put my VBB vertical in the garage and was attempting to "zero the mass position". I have been having the problem of the system working for a while(what appears to be reasonable ground noise) then the system output goes flat. It appears that either I am saturating the amplified output or the mass is gradually drifting to one end of it's travel. My question is: is the "mass position zero" close to the zero position of the system without the feedback? The zeroing process is time consuming in that one needs to move the zeroing mass and wait for the system to become stable then repeat the process. I have a highpass filter just after the displacement sensor. The other possible problem is that until I am happy with the circuit I have it on a solderless breadboard. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: zeroing the VBB Date: Sun, 19 Apr 1998 13:16:56 -0500 (CDT) Barry; Re: zeroing the VBB sensor: It sounds like you are running out of voltage for your feedback system. When the mass touches, the feedback starts to fight it and makes a lot of noise. I have +,- 9 volt supplies, and my unit goes "dead" at about +,- 7 volts at either output. Having 15 or 20 volt supplies would help. When I have to do a gross rezeroing of the sensor, I disconnect the signal to the feedback coil (the green clip lead if you can see it in the photo of the electronics box) and look at the meter connected directly to the output of the displacement detector. Then what you see is what you have, and you can adjust your trim masses accordingly. Once it is zeroed, reconnect the feedback coil. I actually have three meters connected: one to the detector output, one to the VBB out, and one to the mass position. As you center or zero the sensor, the mass position will slowly try to catch up with the VBB signal (which, remenber, is also the detector output X10 when the feedback is disconnected). If there is a large difference between these when the feedback is re-connected, the VBB voltage will temporarily take off in the "wrong" direction until the integrator catches up. When I use my remote centering (from upstairs here, near the PC and the monitor recorder), I run the motor until the voltage is within about 0.5 volts of zero, then let the integrator catch up. The remote zero is really handy when we get a cold wind that cools off the basement. You are really being brave in putting your sensor outside in the garage with what is probably a serious temperature problem. Until I can reduce the temperature sensitivity by 10 or 100, I'll live with noise of the basement of the house. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: NO BITMAPS, JPGS, etc Date: Sun, 19 Apr 1998 13:55:37 -0500 (CDT) TO ALL: Some of us are not reading mail in a browser environment!!!! Repeat above PLEASE!!! I read mail in a unix environment, either on a Sparkstation or here at home on the old PC. When someone sends a bitmap or JPEG or whatever, it clogs our mail server, and all I get are endless pages of characters and ciphers. The only way out is to kill the mail process, the dialup, etc, then go back in and clear the hugh file out of my mbox. If you want to make an image available, sent the ftp or internet path to it. Thanks, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: optical interferometers Date: Sun, 19 Apr 1998 13:59:40 -0500 (CDT) Regarding "optical interferometry can sense displacement down to 0.1 nanometer" I don't believe that this is the case for displacement measuring interferometers. There are thin-film interferometers that can for example, measure the thickness of mica sheet layers at 2 nm using blue-green light at 500nm and being able to phase lock to 1/250 of lambda because of the fringe separating techniques. There are also many techniques to sharpen the fringes by manipulating the qualities of the silvered surfaces (see "concepts of Classical Optics, by J. Strong, Freeman press, page, 255 &ff, and appendix A and B, which describe many types of interferometers and applications, including polarizations, but always conclude that the resolution of a distance measuring interferometer is about 0.1 lambda, or 200 nm for green light.), as is evident from what is available commercially. Interferometry involves the interference of two wavetrains of light that have traveled paths of different lengths (one is the fixed or reference path), producing bright or dark lines, fringes, or spots, depending on the design, if the waves interfere constructively or not. Interpolation methods can determine fractions of fringes, with phase lock techniques getting down to a hundredth of a wavelength if sufficient time averaging is done. But averaging kills the frequency response. So the manufacturers who push the resolution (Burleigh, Melles Grott, Dynamics Research, etc.) don't claim better than 100 nanometers repeatability, for reasonable frequency response, even though their micro-positioners (stacked piezo, etc) can easily make repeatable displacements of 0.1 nm. Perhaps the best current practitioners of optical detection methods for geophysical instruments are the people at UCSD at La Jolla, and their instruments at the Pinon Flat Observatory. They use interferometers both for the 750 meter strainmeters, but also for the "optical anchors" that reference the surface piers to consolidated bedrock at depths of 10 to 30 meters. They have just published a paper on using single-mode fiber optics as interferometers for the optical anchors. Regards, Sean-Thomas ... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: debris in magnet Date: Sun, 19 Apr 1998 15:22:21 -0500 (CDT) Barry, I only caught a glimpse of your message about stuff in your magnet because the bitmap (Please don't send!) cleared it all out. I find that masking tape can nicely clean out the magnet gap, as well as the gap in the VRDT, where I have found lint and very fine dog hairs (the dogs always supervise at the seismometer!). On occassion, I haven't even able to see anything, but sweeping the gaps (including the inside if the coil former) with tape has solved an annoying glitching problem. Fortunately, my box enclosure has excluded the spiders, etc, that this old house is fond of. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: VBB operation Date: Sun, 19 Apr 1998 15:38:49 -0500 (CDT) Barry, I just noticed that you said that you have a highpass filter "just after the displacement sensor". I hope you mean that it is between the VBB output and your recording system, and not INSIDE the feedback loop. I cannot imagine that the feedback would be stable if the displacement was high-passed before the feedback components, especially the integrator. However, it sounds like your VBB mass position is reacting properly. It is common, though, to need some amount of low-pass filter after the detector to keep the loop from ringing. Mine audibly "humms" at about 300 hz without a small 50 hz filter. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: VBB operation Date: Sun, 19 Apr 1998 15:54:08 -0700 S-T Morrissey You are correct in both statements. It is before the integrator and it seems unstable (drifts). I will relocate it at the "broadband velocity out position". I thought one would put it before the integrator to eliminate the DC accumulation of the integrator. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: integrator connection Date: Sun, 19 Apr 1998 21:18:45 -0500 (CDT) Barry, You mention a "DC accumulation" at the integrator. I hope that you have configured the integrator as a one-pole low pass non-inverting filter as shown in the (incomplete) block diagram of the VBB system, where the 10x detector output is connected via a large resistor (like 1 or 2 megohms) to the + input, the large non-polarized capacitor (like 2 x 200 uf connected + to +) is connected from there to common, and the unity gain feedback is via a resistor of the same value as the input connected from the output to the - input. (I should update that drawing so it is clearly workable). The integrator output voltage should follow the displacement voltage by the time constant of the integrator. If the displacement is zero, the integrator voltage should go to zero. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: integrator connection Date: Sun, 19 Apr 1998 21:43:45 -0700 S-T Morrissey It's amazing when one gets things hooked up correctly! I plan to heavily insulate the outside of the grounded aluminum enclosure with some R30 rigid insulation,maybe double thick. Also I want to fill the inside air space as much as possible with foam, as Larry has mentioned with his SG . I think that may eliminate some of the low frequency component. The response to ambient vibration looks good. I need to wait for an event now. Thanks again. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Soul of a Circuit Date: Mon, 20 Apr 1998 08:27:31 +0000 What is it that makes circuits work? See Below | | V Answer: It's smoke. Because once the smoke comes out and is all gone, the circuit doesn't work anymore. ;) Cheers Walt Williams :-{) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: ALERT: PROTON FLARE AND POLAR CAP ABSORPTION ALERT - 20 APRIL] Date: Mon, 20 Apr 1998 12:46:05 -0700 FYI: Received this alert earlier this morning. Looks to be fairly remarkable. -- ---/---- Charles P. Watson Seismo-Watch From: Roger Baker Subject: On Sensitive Optical Displacement Sensors Date: Mon, 20 Apr 1998 15:36:54 -0500 Friends, In my opinion the topic of the achievable sensitivity of sensitive optical displacement sensors is important. Important because of the fact that if it IS indeed possible to use some some combination of easily available photodetector and LED to achieve nanometer sensitivity, (i.e.--four bucks a pair from Radio Shack) then its liable to be a lot cheaper and simpler to build than competing alternatives. And, accordingl= y, it is likely to be a good sensor for small, cheap, easy-to-build seismometers, where you want to detect a DC displacement -- rather than acceleration, for which you want a coil. Coil/magnet combinations tend to lose sensitivity where very slow teleseismic changes are involved, since not as many magnetic lines of force are intercepted per unit of time so t= he physics tends to favor static displacement detectors, I think. This consideration does not apply to differential transformers used as detectors, however, since they are sensitive to static displacements. But the fact remains that capacitance micrometers although somewhat troubleso= me to build, can be hacked by amateurs, and nothing comes close to them in terms of practically achievable sensitivity if one wants to push the limi= ts of displacement detection. By far the best general reference for the latter, including an illustrati= on of the quite accidental detection of an earthquake by such a capactive sensor, is given in the article 'The design and some applications of sensitive capacitance micrometers' by R.V. Jones, Journal of Pysics E, Scientific Instruments, vol. 6, p 589-600. Also I described a hackable version built out of Radio Shack parts in a recent issue of the Society f= or Amateur Scientists Bulletin. Since I love physics and hacking instruments, let me present my analysis = of the situation as gleaned from the literature. Somewhere, there is a discussion of this very topic in the optical engineering literature, but = I have not found it yet. By far the best one source on the leading edge of optical technology I know of are the hundreds of volumes of SPIE, or the International Society for Optical Engineering, each on leading edge topic= s. There are two general alternatives to use when measuring optical displacement. One is interferometry, and the other is what we might call photon counting. I use the latter. Where interferometry is concerned, it is apparent that it is practical to measure down even to .01 nanometer, but the apparatus gets quite expensiv= e and always uses lasers, etc. (see =91Interferometric metrology: current trends and future prospects=92; SPIE, vol. 816, p 2-18, 1987). In other words, this would take a lab full of stuff that would negate the characte= r of hackable amateur science. But microdisplacement sensing by photon counting is a whole =91nother ball game. In this case you have a flood of fairly easily detectable photons totalin= g up to 16 milliwatts of energy, either red or near infrared photons, being emitted by an LED out of an area of less than one square millimeter.=20 This crosses a short gap of several millimeters chopped by a horizontal knife edge mounted on the seismo beam, which decends across the beam like= a horizontal guillotine blade. The detection area of the sensor is a phototransistor with about a one mm surface area, essentially a photodiod= e with a transistor output built in. If the detector is sensitive enough t= o detect one millionth part of the photons being emitted by the LED, it implies that you could choke off all but a millionth of the photons crossing the gap defined by the seismo beam and still detect what manages to get across the gap defined by three horizontal knife edges attached to the LED, beam, and phototransistor, respectively.=20 If you can detect one millionth of the photons crossing the gap, then the one square millimeter area of the LED divided by a million is a beam of light one millimeter across and one nanometer tall, which fits our requirements to be able to detect a displacement of one nanometer.=20 If the knife edge is at the top end of its travel it will only shave off = a millionth part of the top edge of the light beam passing across the gap a= nd we will never see it. However if the knife edge is instead intersecting t= he last millionth of the photons able to pass across the gap, it will result in a detectable output. I think that one can detect one millionth of the output, and the proof is that if one places the phototransistor four or five feet away from the L= ED in a dark room, even with the focusing lens filed off, they can still detect each other even though the photon flux between them is now reduced by a factor of millions. Now as Sean-Thomas has pointed out, light wavelength is a consideration, because light does not really travel in a straight line but rather will tend to diffract around the knife edge defined by the seismo beam. In oth= er words, if everything is set up properly and scattered light is almost totally eliminated, the phototransistor signal as the last of the light i= s blocked off should be a series of diffraction maxima and minima diffracti= ng around the beam=92s knife edge with a spacing determined by the wavelengt= h of light being used. This does not mean, however, that we cannot detect such displacement far smaller than a wavelength of light, if only enough photo= ns are involved to give a detectable signal in the phototransistor. The most hacker-friendly article I have yet found on this topic is titled =91A simple optical transducer for the measurement of small vibration amplitudes=92 in Measurement Science, 1985, p 947 (I think; my photocopie= s do not give the exact origin of the reference). This describes a simple dual photodiode setup sensitive to tens of nanometers displacement, but nowher= e near optimised in regard to trying to maximize displacement sensitivity i= n consideration of the factors discussed above.=20 For those trying to hack my sensor configuration, may I also suggest putting a tiny square of masking tape over the sensitive areas of the LED and phototransistor after cutting away most of the plastic case as per my illustration. Then spray them all over with black spray paint paint to se= al out almost of the stray light before peeling away the tape to make a litt= le window over the sensitive areas and then mounting them behind their knife edges. The latter edges should define and block off the lower 50% of the beam that passes between them. Very probably any work spent getting the three knife edges accurately lined up parallel to each other will be rewarded as added displacement sensitivity. =20 --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: PROTON FLARE AND PCA ALERT - 20 APRIL Date: Tue, 21 Apr 1998 09:30:13 +1200 At 12:46 PM 4/20/98 -0700, you wrote: >FYI: Received this alert earlier this morning. >Looks to be fairly remarkable. Charles P. Watson SATELLITE PROTON EVENT ALERT > ISSUED: 16:00 UTC, 20 APRIL > ** EVENT CRITERIA HAS BEEN MET ** >ATTENTION: > > A text-book perfect long-duration class M1.49 proton flare was observed >with a maximum x-ray time of near 10:21 UTC. The event appears to have unfortunate that it waited till the active region had rotated out of view before this event happened. othewise there would have been a change of good auroral activity. An M1.5 flare is quite small and as we move closer towards solar maximum in 2000 these events will become more regular and stronger. On the othere hand there is a large Coronal hole region crossing the face of the sun at present and over the next few days there is a good possibility of auroral activity from it. So people hight than 45 deg latitude (nth or sth) should keep an eye on their nthrn/southern skies for aurora. Aurora produced by coronal holes tend to be less intense than those from flares but they are usually more persistant..... often lasting 3 + days. Cheers Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: Soul of a Circuit Date: Mon, 20 Apr 1998 14:25:12 -0800 That's 'spirimentin' sayeth T.Edision 10,000th test of light bulb. keep on oh spark trician ! Walt Williams wrote: > What is it that makes circuits work? > > Answer: > > It's smoke. > Walt Williams :-{) > Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: [Fwd: ALERT: PROTON FLARE AND POLAR CAP ABSORPTION ALERT - 20 APRIL] Date: Mon, 20 Apr 1998 14:32:45 -0800 Holy sun screen! Should we get SPF 1000 or what, charles? 8 ) ^ sunglasses > SATELLITE PROTON EVENT ALERT > > ISSUED: 16:00 UTC, 20 APRIL > > /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: integrator connection Date: Mon, 20 Apr 1998 22:24:22 -0600 barry lotz wrote: > S-T Morrissey > It's amazing when one gets things hooked up correctly! I plan to > heavily insulate the outside of the grounded aluminum enclosure with > some R30 rigid insulation,maybe double thick. > Barry, good deal on the STM-8 going online. Question regardingthe grounding you mentioned. Real copper rod grounding, or circuit ground? Electrostatic prevention? Sounds like a good idea with real earth grounding. Don't remember anyone doing this. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: grounding Date: Tue, 21 Apr 1998 00:00:19 -0500 (CDT) Barry, Meredith, Good idea to be concerned about proper grounding and shielding. Grounding can never be taken for granted. Here at the farm, since the seismometer is sort of distributed from the far basement corner to the PC here to the monitor recorder over by the door, I use the cold water pipe as protective ground. The electrical common of the VBB seis electronics is floating and not grounded, but the case is grounded to the aluminum frame of the seis and to the copper pipe, as is the green ground wire in the AC to DC power supply. as is the chassis of the monitor recorder. I have 5 pairs of shielded data cable running up from the basement; I ground the shields only, not the common of each pair, which are in fact all connected to the electronic common in the electronics box. One wants to make protective grounds one-way streets to drain AC noise, static, etc. Avoid closing the loop anywhere, or currents flowing in the ground loop will induce voltage noises in the data. I consider the copper pipe to be the lowest impedance ground available here. The ground of the house AC electrical system is less desirable. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: optical displacement detectors Date: Tue, 21 Apr 1998 00:22:19 -0500 (CDT) Re: optical displacement detectors: I am concerned about recent statements about the resolution of optical displacement detectors that could be used for seismic instruments. I am concerned that those who are trying to build a working homemade seismograph are being misled into thinking that there is a cheap and simple optical method for measuring sub-micron displacements (better than ~10^-7 meter), or even down to sub-nanometer (to 10^-10 meter) displacements. The more serious concern is the implication that ALL of science and engineering (and seismic instrumentation specialists) have been blissfully ignorant or oblivious to this possibility for the past 50 years. Obviously, if we could be doing it (even at any expense), we would be doing it. And the major suppliers of micro-measurement and manipulating tools and hardware would be selling such devices. And, for example, why would we be struggling with 750 meter evacuated tube lasar strainmeters tracking 1/8 lambda interferometers (resolving 1/8 wave of a ~600nm lasar or 75 nm) so we can accurately measure 10^-10 earth strain? If interferometers could resolve 0.01 nanometer, as has just been claimed, our strainmeter could be a few meters long. I find that the claims being made for optical displacement detectors are speculative and not supported by the fundamentals of physics and/or any engineering data. And curiously, the claimed resolution for interferometric measurements improves daily. On 4/16 it was a reasonable "sub-micron" (eg. 10^-7 m), but on 4/18 it jumped to 0.1 nanometer (10^-10 m), and today it is " practical to measure down even to 0.01 nanometer", or 10^-11 meter, which is half of the first Bohr atomic electron-orbit radius of 5.29 x 10^-11m, or ~4 times the Compton wavelength of an electron (2.426 x 10^-12 m), which is the serious limit in electron microscopes (just to put the numbers into perspective). (I also have a serious problem with the curious notion of a "beam of light"... "one nanometer tall" when light propagates as a quantum waveform uniform in ALL directions, and the wavelength is 400 to 700 nanometers, and, btw, photons themselves are not particles.) I urge restraint on the part of anyone considering a plan to utilize such devices for seismic instrumentation. As observed above, if we could, we would, but we cannot, and it is not because we are ignorant and unaware. And if these claims could be supported by actual data, certainly an attempt would have been made. There is a wide range of proven displacement measuring technology for nanometer resolution at reasonable response times (to 1 khz) via reactive and/or resonant technologies (capacitive, LVDT, VRDT) that the home-made seismologist (who, btw, would probably prefer not to be considered an "amateur hacker") can readily apply to a broadband sensor. And Jim H. has pointed out a single IC , the Analog Devices AD 690, that will totally run such transducers (if +,- 15 volts is available) for $27, from Newark, although its noise floor has not been evaluated ... yet. The noise of capacitive transducers (at 1 hz bandwidth) is about 10^-10m, with the best reported as 10^-12 (1 picometer) at diurnal periods. (see D.C Agnew's paper) One of the best LVDTs (used in the Streckeisen STS-1) has a noise floor of 6 x 10^-11 m. The VRDT is not as quiet, but has the advantage of minimal force being applied to the moving element, great ease of assembly and adjustment, and general immunity to capacitance change noise due do lead movement. The VRDT can resolve the minimal earth noise model of 10^-9 m at 1 hz. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: optical displacement detectors Date: Mon, 20 Apr 1998 22:36:41 -0700 Excellent discussion Sean! -- ---/---- Charles P. Watson Seismo-Watch S-T Morrissey wrote: > > Re: optical displacement detectors: > > I am concerned about recent statements about the resolution of > optical displacement detectors that could be used for seismic > instruments. --snip-- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: NBC Dateline-Earthquakes Date: Tue, 21 Apr 1998 02:06:43 EDT For those of you interested, Tuesday, April 21 10:00pm PST NBC Dateline (Channel 4 in L.A.) Subject: Earthquakes, with Dr. Lucy Jones Mike O'Bleness Northridge, CA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: Earthquake felt over much of NZ's North Island Date: Tue, 21 Apr 1998 02:10:42 EDT Earthquake felt over much of NZ's North Island WELLINGTON, April 21 (Reuters) - A deep earthquake measuring 6.3 on the Richter scale rocked much of New Zealand's North Island on Tuesday but little damage was reported. The Institute of Geological and Nuclear Sciences said the quake, which occurred at 11.34 a.m. (2334 GMT), was centred about 33 km (20 miles) southwest of Taumarunui, in the central North Island. The shaking, lasting about a minute, was enough to make the city clock in Hastings, 260 km (161 miles) away, chime out of sequence. The quake, which was 245 km (152 miles) deep, was felt as far south as Christchurch in the South Island, and as far north as Hawke's Bay 360 km (225 miles) north of Wellington. The Earthquake Commission said it had received 12 claims for damage, mostly for such things as cracked walls. Some Wellington residents could not contact relatives following the quake because phone lines became overloaded. REUTERS 01:16 04-21-98 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: optical displacement detectors Date: Tue, 21 Apr 1998 05:09:53 -0500 At 12:22 AM 4/21/98 -0500, you wrote: >Re: optical displacement detectors: > >I am concerned about recent statements about the resolution of >optical displacement detectors that could be used for seismic >instruments. > >I am concerned that those who are trying to build a working homemade >seismograph are being misled into thinking that there is a cheap >and simple optical method for measuring sub-micron displacements >(better than ~10^-7 meter),... ************************************************************************** Response: See yesterday's post which described how to detect displacements down to tens of nanometers with very simple equipment which wasn't particularly optimised for detection sensitivity, titled 'A simple optical transducer for the measurement of small vibration amplitudes'; Measurement Science and Technology, p 947, 1985. ************************************************************************** ....or even down to sub-nanometer (to 10^-10 >meter) displacements. The more serious concern is the implication >that ALL of science and engineering (and seismic instrumentation >specialists) have been blissfully ignorant or oblivious to this >possibility for the past 50 years. > >Obviously, if we could be doing it (even at any expense), we would >be doing it. And the major suppliers of micro-measurement and >manipulating tools and hardware would be selling such devices. >And, for example, why would we be struggling with 750 meter >evacuated tube lasar strainmeters tracking 1/8 lambda interferometers >(resolving 1/8 wave of a ~600nm lasar or 75 nm) so we can accurately >measure 10^-10 earth strain? If interferometers could resolve 0.01 >nanometer, as has just been claimed, our strainmeter could be a few >meters long. > ***************************************************************************** Response: There is a world of difference between fringe counting at 750 meters, which is now possible under stringent conditions, and measuring short distances optically. Obviously the optical techniques one uses to count laser fringes at such a very long distance are completely different than those one uses to measure sub-nanometer displacements on the top of lab benches, which would be more suited, in theory at least, to seismometers where the total displacements are only millimeters or less. To quote quite specifically from 'Interferometric metrology: current trends and future prospects' by P. Hariharan, SPIE, vol 816; Intereferometric Metrology,1987; p 2. 'One of the beams is focused to a small spot (~2 micron diameter), while the other illuminates an area with a diameter of about 50 microns. With this arrangement a useful measurement sensitivity of .01 nm has been achieved' (from page 10). The primary reference for this is 'Optical hererodyne profilometer' by C-C Huang, Optical Engineering, 23 (4), 365-370, (1984). Yesterday I had not found the reference above (which claims .01 nm) but was basing my statement on another article entitled 'A complete high performence heterodyne interferometer displacement transducer for microactuator control'; Review of Scientific Instruments, vol.63, Jan 1992, which says in the abstract 'This article describes a laser heterodyne interferometer-based transducer which resolves displacements to .12 nm (standard deviation) locally, in a scanning range of 10 mm or more, in a 1 Hz to 10 kHz bandwidth under normal laboratory conditions.' Another paper, entitled 'Recent advances in displacement measuring interferometry' by N. Bobroff, Measurement Science and Technology , vol. 4, 1993, p 907 -926 affirms .1 nm in its introduction. But as I made clear, I don't think these setups are appropriate for homemade seismometers. I do think my current sensor is very good, although the sensitivity has not been determined. I do believe it is appropriate to analyze what aspects of physics probably limit the ultimate sensitivity of sensors like mine. ***************************************************************************** >I find that the claims being made for optical displacement detectors >are speculative and not supported by the fundamentals of physics >and/or any engineering data. And curiously, the claimed resolution >for interferometric measurements improves daily. On 4/16 it was a >reasonable "sub-micron" (eg. 10^-7 m), but on 4/18 it jumped to 0.1 >nanometer (10^-10 m), and today it is " practical to measure down >even to 0.01 nanometer", or 10^-11 meter, which is half of the first >Bohr atomic electron-orbit radius of 5.29 x 10^-11m, or ~4 times the >Compton wavelength of an electron (2.426 x 10^-12 m), which is the >serious limit in electron microscopes (just to put the numbers >into perspective). > >(I also have a serious problem with the curious notion of a "beam >of light"... "one nanometer tall" when light propagates as a >quantum waveform uniform in ALL directions, and the wavelength is 400 >to 700 nanometers, and, btw, photons themselves are not particles.) ***************************************************************************** Response: Photons share some of the properties of both particles and waves. They can be counted as individual units by both cooled photomultipliers and cooled avalanche diodes, however, if one wants to go to the trouble, and uncooled avalanche diodes would be a good choice if one wants to push the limits beyond what a photodiode will do. I DID go on to say that if one tries to block a light beam with a knife edge, the shadow will be a diffraction pattern with maxima and minima, rather than a sharp edge, which is quite according to optical theory. The real question to ask here is probably how the function of light falling on the sensitive area changes with displacement of the optical sensor, and what is the ultimate limiting factor in terms of instrument noise. The paper I cited yesterday (Review of Scientific Instruments, Jan 1991, p 217) with a resolution of 5 nm, used a dual lead chromate photoresistor, which I suspect does not have a very good quantum yield. The limiting factor in resolution under these conditions was said to the laser noise. In other words, the resolution was about one hundredth of a wavelength of the light used, but the light was very bright and the sensor likely not very sensitive. I presume most junction LEDs are fairly quiet compared to lasers, and photodiodes, are very sensitive indeed to red and near infrared light. So the photodiode (inside the phototransistor chip) sees a series of diffraction patterns as the knife edge on the beam intercepts the beam. The limiting sensitivity in this case would appear to me to be the accuracy of light measurement or photon counting at low light levels when the beam is very narrow, almost completely cut off, and exhibiting diffraction at the knife edge. If not, then can somebody suggest what would be the ultimate limiting factor in terms of the physics involved? We do know that the limit is at least as small as a twentieth of a wave from the article I cited yesterday without using very optimal conditions, and from what Karl Cunninham posted the other day (25 nm). We also know that scanning atomic force microscopes routinely sense such small displacements on the order of one nm and probably less using laser light reflected from cantilever probes. I'll try to find out the exact sensitivity of this arrangement and post it later *************************************************************************** > >I urge restraint on the part of anyone considering a plan to utilize >such devices for seismic instrumentation. As observed above, if >we could, we would, but we cannot, and it is not because we are >ignorant and unaware. And if these claims could be supported by >actual data, certainly an attempt would have been made. > ***************************************************************************** In the spirit of open discussion of technology which is what I love about this list, I don't think you should discourage others from trying out some elements of my design. If so, why? We won't really know until some others try it and see for themselves, right?. Its really easy to build for about $20, not counting the proposed permalloy shield and thermal enclosure. Admittedly, it does drift in its present incarnation, but I have made no claims I can't support. I can send JPEGS of the output trace, which is now a slanted line with lots of seismic noise. Maybe I'll be lucky enough to catch a quake. Response: Aside from slow thermal drift, (this despite being presently enclosed with a large block of iron in an Igloo cooler), and the fact that I must presume also magnetic noise in the absence of a model that fits into a permalloy shield, my instrument seems seems to work well, or I wouldn't have posted what I did. The feedback circuit is not optimised with a power booster, so that it rings a little. It is sensitive enough to see high frequency local seismic disturbances, and slower sine wave disturbances on the order of five seconds as the trace slowly drifts off the chart due to thermal drift. I can send both the current circuit I am using, which is very easy to build, or the thermal feedback circuit I built for an earlier prototype, and which may be of general interest to others wishing to build thermally regulated enclosures, or ovens maintained slightly above abient. **************************************************************************** >There is a wide range of proven displacement measuring technology >for nanometer resolution at reasonable response times (to 1 khz) >via reactive and/or resonant technologies (capacitive, LVDT, VRDT) >that the home-made seismologist (who, btw, would probably prefer not >to be considered an "amateur hacker")... ***************************************************************************** Response: I write a regular column titled Science Hacker, for the Society for Amateur Scientists Bulletin, and nobody has complained about my calling myself an amateur hacker up to now. The editor, Jack Herron, is a member of this list. **************************************************************************** *...can readily apply to a broadband >sensor. And Jim H. has pointed out a single IC , the Analog Devices >AD 690, that will totally run such transducers (if +,- 15 volts >is available) for $27, from Newark, although its noise floor has >not been evaluated ... yet. > >The noise of capacitive transducers (at 1 hz bandwidth) is about >10^-10m, with the best reported as 10^-12 (1 picometer) at diurnal >periods. (see D.C Agnew's paper) One of the best LVDTs (used in >the Streckeisen STS-1) has a noise floor of 6 x 10^-11 m. The VRDT >is not as quiet, but has the advantage of minimal force being applied >to the moving element, great ease of assembly and adjustment, and >general immunity to capacitance change noise due do lead movement. >The VRDT can resolve the minimal earth noise model of 10^-9 m at 1 hz. ***************************************************************************** Response: The article I cited yesterday by R.V. Jones on sensitive capacitance micrometers estimates the short term sensitivity of their capacitance micrometer at 10 to the minus eleventh mm, or ten to the minus fourteenth meters, in their abstract. But it is true that over the period of a day, drift reduces the accuracy to 10 to the minus twelfth mm, in close accord with your information. This is far less than the diameter of a hydrogen atom (see your comments above) and is only meaningful because this small displacement is averaged over a substantial area. Meanwhile, there is what seems to me to be a good analytical comparison of capacitiative and inductive displacement sensors by A.L. Hugill in the Journal of Physics E, Scientific Instruments, vol. 15, 596-607, 1982. The conclusion: 'It is concluded that capacititive transducers are most suitable in applications requiring high levels of accuracy, stability, and discrimination and low power dissipative and excitation forces. In situations where these requirements are not so stringent, both inductive and capacitative transducers are suitable'. ***************************************************************************** > > >Regards, >Sean-Thomas > ***************************************************************************** To sum up: I'm not without scientic credentials. I have had articles published in various peer-reviewed journals as the lead author including the Journal of Applied Physics, the Review of Scientific Instruments, the Journal of Chemical Education, and had THREE articles in Scientific American under the legendary old Amateur Scientist columnist C.L. Stong (on ultrathin layer chromatography, homemade transistors, and an infrared imaging device). Most importantly, I do not make up facts. I ask only a fair trial of my seismometer elements and do not claim to have it fully developed. I presented it quite specifically in the form of a progess report. It is remarkably easy to duplicate in its essentials, and it seems to me that only empirical evidence is a fair basis for passing judgement. --Yours, Roger Baker _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: grounding Date: Tue, 21 Apr 1998 10:20:37 -0500 I want to second the comment about not having ground loops. In communication facilities I have worked in there is only one earth ground for the entire building. All sorts of precautions are taken to avoid other paths to ground including things like placing the equipment racks on insulating platforms off the concrete floor. A final test of the building ground system is to open the lead to the single ground and measure the resistance to ground of the building ground system. I have seen this resistance as high as 100000 ohms for an entire building full of communications equipment including connections to hundreds of underground phone lines and data cables. If the resistance is too low we had to go through the building until we found the problem and fixed it. Not only will having multiple gounds cause noise problems. It can increase the chances of lightning damage. I am having this sort of problem at home right now. So far two modems and a surge protector have been destroyed by lightning strikes nearby even though the phone line is underground all the way back to the office. There are separate grounds for the phone and power in my house and I suspect that one of the grounds is inadequate. This causes voltages induced in one system to go to the ground of the other system through my modem or surge suppressor. It is possible that if you bury your sesimograph or ground it too well that all you will do is provide a better path to ground for lightning, right thru you equipment! Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: optical displacement detectors Date: Tue, 21 Apr 1998 08:50:22 -0700 Just a note about the AD690. We evaluated it at work for a commercial LVDT conditioner product, and its noise floor was about 2 millivolts peak out of 10 volts peak full scale. It appeared to be an output noise effect, independent of input levels, etc. One could increase the gain of the system to get desired resolution, but this noise represents a real signal-to-noise ratio limitation. In constructing my horizontal force-balance, I built an LVDT demodulator using a handfull of IC's that has an SNR of better than 2x10^5 and a noise floor of about 0.3 nanometers RMS, and less in reduced bandwidths. I agree that variable differential reactance transducers are the way to go. I'm experimenting with a differential capacitor transducer that has a noise level of about 1 nanometer peak-to-peak, and I have quite a few ideas to improve it still. This differential capacitor device is easier to build than the LVDT, and seems to have a bit less noise, and the electronics are simpler. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: cas Subject: Paranormal/Magnetic/Earthquakes - Off Topic Date: Tue, 21 Apr 1998 08:57:14 -0700 (PDT) -----BEGIN PGP SIGNED MESSAGE----- In order to conserve list bandwidth I have placed an article that appeared in our local paper at http://www.ncal.verio.com/~cas/ It is somewhat 'off-topic', but similar threads have appeared on this list and might be of interest to some of you. -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: noconv iQCVAwUBNTzB7dE8bAS3aqZxAQEekwP+MzUKNR3lOlCgF51t8d9lY19uxW3qNZX6 meywOD0xbHXzvswHGAFt09HNgxsQKu1LI1T4pDzmUgcrpMGJLjRY7NlDYb2oTA8V 3dB1wwqujw7mvpcFylv1sWrlq2ECa+KE0UEXyqcFv/QsRqKrqsAH2a5BMlbuCj/d x1rahbfDdbY= =QGLT -----END PGP SIGNATURE----- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: optical displacement detectors Date: Tue, 21 Apr 1998 10:10:37 -0700 For at least one more data point. As Roger said, there are two ways to look at the measurement system. As a fringe counting scheme and as a beam occultation "weighing" system. HP makes systems of both types. Currently they have an interesting one capable of 0.3nm resolution you can look at at: http://www.tmo.hp.com/tmo/datasheets/English/HPE1720A.html The method employed in the system is that a grating scale is illuminated with a laser diode, the diffraction pattern that forms in space several millimeters away is directly imaged on a multiple photocell array that is part of a custom IC with a pitch equal to the diffraction pitch. Patents I have looked at indicate there are three groups of cells -- somewhat like paralleling every third spoke of a picket fence. Then electronic processing derives the position. It may actually be two sets as the output I observed was quadrature. These things are real, and we're using them to replace a bunch of the standard HP interferometers of the fringe counting variety because these have more resolution in a smaller space. Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Analog Devices 690...AD690 Date: Tue, 21 Apr 1998 11:21:36 -0600 Minor note, keep seeing reference to the AD690, but have checked twice over time and am not finding it. Curiosity thing. Analog Devices does not give any reference to the AD 690 on its website. Perhaps too new? Not found in Newark catalog per that number. AD598AP is listed at $28.75 in 98 catalog. The price always goes up-ha. There is however 3 LVDT signal conditioners called the AD598AD, a 20 pin CerDip, a AD598JR, a 20-pin SOIC, and a AD698AP, a 28 lead PLCC & CerDip packages, all on page 803 on the bottom. Analog Devices does have data on the AD598 and AD698 on its web site. Presume someday it will show up on internet Analog Devices site. What is the difference between the AD598/AD698 and AD690, being as I have no reference....major, minor? Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Scientific American The New Backyard Seismology, April 1996 Date: Tue, 21 Apr 1998 14:55:05 -0500 Larry Cochrane's comments to the SAS forum on the ADXL05 sensor SA article finally got posted to the NEW SAS forum below is the author of the SA article's response. See http://psn.quake.net/adx05chip.txt and http://web2.thesphere.com/SAS/ The response was posted to the SAS forum. Shawn Carlson - 05:49am Apr 20, 1998 PDT (#3 of 3) I agree with everything Larry says about the sensitivity of the device described this article. Unfortunately, I didn't have the space to place the new sensor in perspective. (God, how I hate the 1200 word-limit!) The article was intended to provide an inexpensive entry-level instrument into the field of seismology, like a relatively inexpensive telescope provides an avenue for amateurs to get their feet wet in astronomy, without the full potential of a top-of-the-line instrument. These detectors are inexpensive, they can be monitored directly by any home PC, and they allow the amateur to sense three axies of motion simultainsly. And, they are, in my view, an important part of the next generation of amateur seismology. The accelerometer chips, which as Larry correctly points out, were first developed as crash sensors, are now being used in many other areas. As a result, market pressures (including for commercial seismographs) are driving developers to create ever more sensitive sensors. In fact, in the time since the article first appeared the sensitivity of the chip used in this project has increased by more than a factor of 50, which reduces the possible detection threshold brings us from mag 5.0 to mag 3.5 or so. This increase in sensitivity was achieved by lowering the noise floor. Other accelerometer chips now boost even greater sensitivity, and the next generation of these silicon marvels will bring even more subtle motions into easy reach of amateurs. Will they ever compete with the most sensitive devices used by amateurs today? I think that they will, and soon. In fact, I suspect that within the next five years, many instruments on the PSN (a WONDERFUL resource for amateurs, by the way) will be based on silicon-chip accelerometers. Shawn Carlson _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: AD698, not AD690 typo Date: Tue, 21 Apr 1998 17:49:37 -0500 (CDT) Meredith, MY TYPO (again): it is a AD698, not a 690. Sorry for the confusion. Did you see Karl C.s review of it (he inadvertently passed on my typo there too: right device, wrong number)? Unfortunately I don't have the literature here at home (some viral flu or cold has laid me low for the last few days). I recall the review from AD comparing the 598 with the 698 says that the demodulation in the 598 is by rectification, so it cannot handle phase errors like VRDTs produce; the 698 uses synchronous demodulation that reduces phase errors. The circuit I use for tiltmeters is also synchronously demodulated with the 4066; you can notice the two amps that drive the switch as "hard" as possible: these are designed to minimize any phase error in the switching. Karl reports a noise level of the AD698 of 2mv with a 10 volt range, which is only 74db, and we need 120db. I guess the chip has too many compromises built in. I don't think Validyne has adopted it for their VRDT pressure transducers. I have bought quantities their osc/demod/amp module for use with the Schaevitz 005MHR LVDT to make 100mv/millibar microbarometers. It also works with the transformer coil based VRDT at 50mv/micron (at a 2mm gap). For the tiltmeter osc/demod/amp (that I use for the seis VRDT,) the tiltmeter noise was less than 0.5 nanoradian at 25mv/microradian. When I use it with the VRDT at 100mv/micron, the ~10 microvolt noise level is 0.1 nanometers. The dynamic range (with a 7 volt maximum) is 117 db. A so barring further evaluation, it looks like the AD698 won't suit our needs. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: grounding Date: Tue, 21 Apr 1998 17:58:53 -0500 (CDT) Jim, You make a good point (which I should have mentioned) about burying the seismometer so that it is the ultimate earth ground for lightning. You can imagine the problem with a seismic telemetry station, with an antenna 100 ft in the air on the highest hill in the county. Often we would use a cheap natural tower: a suitable tree with a 20 ft. pipe in the top to push up the yagi antenna; (Cypress trees are the best, because the limbs grow like ladder rungs. ) Even with the "best" of lightning suppression, we have had some real smokers. At a station near Paducah the ligntning exploded every device in the radio transmitter, and got onto the shield of the seismometer cable and down to the buried L4-C, which was sealed in a 1/4" ABS pipe with the electronics (amp/vco/DC-DC/calibrator) in a 2.5" aluminum tube above it. It blew a hole in the ABS pipe, a hole in the case of the L4, and a big melt/burn in the side of the L4 mass. Curiously, it "went around" the electronics cannister, which was still operational, probably because the rest of the lightning suppression DID work, where there are probably 20 or so Varistors at work in conjunction with delay inductances and gas discharge devices. You also mention the central grounding for comm. facilities. One of my first tasks here in 1969 was to try to salvage a strainmeter project in a lead mine south of here. We had 100 ft fused quartz rods, (actually 2" dia tubes) for the reference lengths, and capacitive displacement transducers for continuous data, and for calibration we had 3-color (Fabry-Perot Mercury line) interferometers that took a photo of the fringe pattern every hour. (In the pre-Nova3 computer days, interpreting these kept several undergrads busy). The signal processing and recording electronics was at the surface in the lift house, about 1/2 mile from the underground sensors. The problem was that we could only get noisy data in the four hour period BETWEEN mine shifts. During the shifts the data was useless. I finally investigated and found that the electric railroad in the mine was leaking about 100 amperes at 300 volts, and the current would peg at 500 amps when a train moved. I could actually see the voltage gradient (400 ft down in the mine where the instruments were installed) with clip leads over several meters with the old Simpson 260 meter. So the mining company ran a continuous INSULATED ground cable (about 1/2" dia) from the surface, down the shaft, through the drifts; and I connected it to copper bars in an array of porous ceramic pots with copper sulfate in them. At the surface, we did as you did: put everything, even the electronics racks, on 3/8" plexiglass insulators, and referenced all grounding to the new cable. Then it looked like our data was "dead", so we turned up the gains and saw the earth-tides, free oscillations, etc, that we were seeking. At the array of porous pots, I had to keep refreshing the copper sulfate, because the ground currents were plating out the copper onto the bars. SO even the installation of the home seismograph needs to be done carefully with respect to grounding and lightning protection. If lightning comes in on the PC modem's phone line, and tried to find ground at a buried seismometer, the main path is through the PC and the ADC card. Insulating the seis from the earth is probably an effective approach, with a ground cable of about #6 size (possibly with a green jacket to mark it as ground) back to wherever the "master ground" is located. And in general, grounding cables MUST be insulated, so that they do not result in multiple ground paths. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: AD698, not AD690 typo Date: Tue, 21 Apr 1998 18:15:39 -0500 S-T Morrissey wrote: > The circuit I use for tiltmeters is also synchronously > demodulated with the 4066; you can notice the two amps that > drive the switch as "hard" as possible: these are designed to > minimize any phase error in the switching. > > Regards, > Sean-Thomas > I am just about ready to publish my design for a VRDT drive circuit. It features a small number of inexpensive parts, crystal controlled frequency and digitally adjustable phase of the demodulator drive. I am hoping that the phase adjustment will be usefull in "tuning" the circuit for best performance. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: VBB zeroing Date: Tue, 21 Apr 1998 19:30:03 -0700 Sean Thomas Well I'm having problems with the zeroing of the system. The mass position output wants to slowly drift off to the rail. I can zero the instrumentation amp(displacement output) when the integrator etc is not connected. I can (I think) zero the system without the feedback coil in the loop. But I have trouble with the system all connected. BTW the feedback has the correct sign. I tried to connect it the other way and the beam went more quickly to the rail. The system acts like it's in unstable equilibrium. When I am adjusting the mass should I wait more than an hour for the integrator to stabilize? If I set the mass output to slightly positive the voltage will appear stable, but overnight or during work (about 8 hr period) it will drift off. With the output slightly negative it will slowly drift that way. I am wondering if the integrator cap is charging without a discharge path. My instrumentation amp goes thru a single pole highpass filter directly into the integrator. Should there be a load resistor in there? I assumed the IA output was a low impedence path to ground.??? Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Grounds & VRDT Date: Tue, 21 Apr 1998 22:08:38 -0600 Sean-Thomas, Jim Hannon, Karl Cunningham and everyone interested, OK on the vrdt chip number correction....it did, seem like a form of COLD-con-FUSION ,ha. Interesting that there doesn't seem to be any equivalent chip to replace the number used by yourselves. Actually all the talk on the grounding stuff, will be useful to myself and a bunch of people, not really acquainted with all the aspects of it. I'am really draggggging out my seismo/computer preparation stuff, so the ground aspect data will really be of value now. My house was build in 1951, so half of it doesn't have electrical grounds, and when I got around to the room with the computer and other stuff; it really nosedived the glitchs occurance by maybe 99%. The other 1%, was a dying flickering light bulb, making a brief surge till shut off, then of course no more. Very good recent grounding email talk stuff useful to everyone with seismology interest! Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: VBB zeroing Date: Wed, 22 Apr 1998 18:26:10 -0500 (CDT) Barry, I am confused again about your use of a high pass filter, which you say is now at the input of the integrator?? If this is the case, the integrator is not getting the displacement information that it needs, so I would expect that the seis would be unstable. There are NO high pass filters used WITHIN the VBB feedback configuration. The ONLY place one can be used is between the VBB output and whatever you have for digitizing and recording, and the only reason it is necessary is to remove the near DC signals (thermal thru tides) from your (ours too) limited dynamic range recorder or 12-bit ADC, (unless one happens to have a 24-bit ADC that can handle the dynamic range.) You need to make sure your circuit conforms exactly to both of the block diagrams on the web site. Some of the values used are 2 meg for the integrator input resistor to the + amplifier input and the unity gain feedback from the output to the - input. The integrating capacitor is two 200uf polarized low leakage (ie. not TAGs) connected + to + from the integrator + input to common. (unless you have some quality non-polarized capacitors). But if I assume you have it connected correctly, the other problem that hasn't been solved is thermal drift. The units here will drift off scale with about a 2 degC temperature change. The TIME response of the integrator at the mass position voltage output is no longer than the integrator time constant. A drift of an hour to a day is probably thermal. When I zero the seis here with the manual trim weights, I do it quickly, looking at the displacement output with the feedback disconnected, then I get the cover/insulation back in place. Even body-heat radiation will effect the spring, which relaxes as it warms. That is why the motor-controlled zeroing is so handy. I have plans A thru at least P to try to reduce the thermal drift, but haven't tried them. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: VBB zero revisited Date: Wed, 22 Apr 1998 16:33:10 -0700 To All I was having problems with my first VBB vertical sensor zero. Previously STM had mentioned thermal drift as a concern. At the time I thought that was an interesting "second order" effect. Well..... As Sean Thomas mentioned on his recent posting , it isn't! I thought I would go back to basic principles and check the the magnitude of the drift. The Bouyancy force on an object is the weight of an equal volume of the surrounding media. If we assume a 1 lb aluminum sensor mass @ 168.5 pcf (excuse my use of english units). The volume would be 0.0059347 cf. Air @ 70 degrees F = 7.5E-2 #/cf Air @ 80 degrees F = 7.35E-2 #/cf Therefore the weight change of 0.0059347 cf of air between 70 and 80 degrees F would be 9E-4 lbs or 0.41 grams. If my math is correct, this is a significant weight change to the system. My sensor is indicating this. This morning the mass position reading was +3.47 v (higher position at the coolest part of the day). After work the sensor was reading -1.47 vts(lower position at warmest time). It's time to install the insulation and zeroing motor. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: X-ray interferometer Date: Thu, 23 Apr 1998 11:21:10 -0400 Hi gang, Here's a footnote to the optical interferometer displacement transducer= discussion. Some year's ago (20?), Dick Delattes at NBS wanted to improve the accuracy of the wavelength of copper k-alpha X-rays (1.540562... Angstoms= ). He built a simultaneous optical and x-ray interferometer (using a dislocation-free Si crystal) so that the no. of x-ray fringes could be determined in terms of the optical fringes. As I remember, he used a Lamb-dip stabilized He-Ne laser for the light. The wavelength of this is= known with high accuracy. Building an x-ray interferometer which can be moved in steps small enou= gh to count fringes while maintaining fringe contrast is one hell of a trick--but it worked. I saw this thing--it was in a room in a room in th= e basement (for vibration isolation). All this work was published but I no= longer have the reference. It greatly improved the accuracy of the X-ray= wavelength. Since the x-ray wavelength is about 4,000 times smaller that the optica= l wavelength, an X-ray interferometer makes a sensitive displacement transducer. I once set up an optical interferometer and I shudder at the= difficulites of making a device which is 4,000 times more fussy. I hesitate to recommend this scheme for a seismometer. Bob Barns Mind like a steel trap-rusty and illegal in 37 states. = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Sperry tiltmeter Date: Thu, 23 Apr 1998 11:21:07 -0400 Hi gang, I recently had an interesting time exploring a tiltmeter. My friend Bi= ll Scolnik has this tiltmeter and he found a fascinating paper "Use of a bubble tiltmeter as a horizontal seismometer", by Miller, Geller & Stein,= Geophys. J.R. astr. Soc., vol 54 1978 pp 661-668. This describes a Rockwell Intl. Part No. 67380-301 biaxial tiltmeter and its performance a= s a seismometer. The same 'quake recorded with a broad-band seismometer and the tiltmete= r showed essentially perfect correlation--"wiggle for wiggle"--on a teleseismic event. Correlation with a short period seis was also excellant. Amazing stuff from a small device. The transducer in this device is two resistors in a bridge circuit and = a Parr lock-in amplifier was used to amplify the signals. Bill's tiltmeter was obvoiusly not the same in that the output was a DC= voltage. (He managed to get a print of the pin-outs of the connector fro= m Sperry but no other info.) There was no access to a bridge circuit. Bill's device:Sperry Flight Systems Part # 00283, Sensing element Model= B. It has an associated box of electronics and a read-out which is Part = # 02020-00-01. The tiltmeter is a short (maybe 2 1/2" hi) cylinder painted= white about 5" dia. with a hemispherical dome. This is to a 1/2" thick Al base plate and I saw no hope of getting inside. Attached t= o the dome is a fancy, military quality multi-pin connector. There are connections for + and - 6VDC and a ground and signal wire. This is clear= ly a single axis device since there is only one output. = I built a 20" long tilting table with a micrometer head (smallest div. = is 10 microns, I don't have a differential micrometer) as one leg. Mounted = on this, the tiltmeter seemed to output either +3 or -3 V and anything betwe= en was nearly impossible. It seemed to be bi-stable. In desperation, I mounted the tiltmeter upside-down on the table and it worked fine!! Well= , sometimes wild notions pay off. I ran a calibration curve of output voltage vs. tilt (calculated from micrometer settings). The device was powered with two 6V drycell batteri= es and the output voltage was read by a Radio Shack DMM (which has an RS-232= port). Between -2.5 and 0.6V out (angle range of about 4 arc mins), the plot was nearly linear and a least-squares line gave mins of tilt =3D= (voltage + 4.807)/0.7793 = This is 2,700V/radian, a figure I find astonishing. The least count on= the DMM is 0.1mV which is 0.02 arc secs.! ( 1 micro-radian =3D .21 arc secs.) This tilt is what you would get if you placed a 0.001" shim under= one end of a beam 850 feet long. It looks like the time constant is abou= t 1 min. (to reach 67% of the final value). The tiltmeter was placed on the basement floor near my Lehman and connected thru Larry's amp. to the second channel of his A/D and both wer= e recorded with SDR. The signal from each sensor was passed thru a sectio= n of the Rockland low-pass filter set at 0.08Hz. I got a 'quake from Oaxaco Mexico on both the Lehman and the tiltmeter= =2E = The SDR files will be posted to the archives:980203C.RB1 is the Lehman an= d 980203c.RB2 is the tiltmeter. The records are similar but the noise level of the tiltmeter is poorer than the Lehman. P was not vis. in either and S was relatively stronger = in the tiltmeter record. I don't know what caused (maybe foot traffic) the monster spikes before and after the 'quake but the tiltmeter responded mu= ch more strongly . This performance was not as good as that described in th= e Miller, et. al., paper but it is a different device and with a much less sophisticated electronics. The very informative review paper by DC Agnew, "Strainmeters & = Tiltmeters", Rev. of Geophys., vol 24, no. 3, Aug. 1986, pp 579-624 contains a world of information including a detailed discussion of bubble= tiltmeters. (A paper by Morrissey is cited.) Agnew advises not to try = to build your own bubble meter and also sez that tilt-feedback systems work.= = A sensitivity as high as 38,000V/radian is cited so perhaps the figure above is not completely ridiculous. Agnew suggests that bubble position could be sensed with external plates and a capacitive bridge which makes building a bubble much easier and avoids all electrolysis problems. A quick look in Thomas' Register showed that there are dozens of manufacturers of bubble tubes for levels. All this raises some questions: 1. Why was Bill's device built to work upside-down? My guess is that it= was designed for monitoring tilt in buildings or bridges or something. 2. Agnew sez that bubble tiltmeters have been widely used so there must = be some in dead storage. How can us poor people acquire these? 3. Is this the sort of device that the PEPP is working to distribute as= an "electrolytic" sensor? = 4. Why are bubble tiltmeters so much rarer than horizontal pendulum sensors? Bob Barns = PS: I was playing around with a 4.5Hz geophone. I connected it to an amplifier made from an Analog Devices AMP01 instrumentation amplifier wit= h the circuit on a proto board . It seemed to have much more low freq. noi= se than I thought it should. I remembered an admonition in the AD data sheets about avoiding thermoelectric effects when using hi gains so I simply draped a Kleenex over the circuit and the noise went way down. = Draft-free amplifiers is a new concept to me. PPS:OK, so what's the speed of dark? = = = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Mammoth Times & Seismo-Watch Date: Thu, 23 Apr 1998 09:29:55 -0700 Guys, I am just too wigglie to contain myself. I just received a message from the Mammoth Times editor who has accepted my new and upgraded earthquake report for their newspaper. Check it out here: http://www.seismo-watch.com/EQNEWS/Newspaper/NewspaperGraphics/MTSeismo.New.jpg Oh, golly, this is going to be fun! -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Sperry tiltmeter Date: Thu, 23 Apr 1998 13:40:48 -0700 Bob -- I wonder if an optical or capacitance position sensor could be adapted to a machinist's bubble level, and if it would be sensitive enough. These are available for (as I remember) the <$50 range from the cheapie machinists supply houses (ie. Enco, etc.). As far as the spikes at the ends of the trace.. Sometimes digital filtering can introduce artifacts at the beginning and end of a trace that's been filtered. Is this a possibility? Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... At 11:21 AM 4/23/98 -0400, you wrote: > The tiltmeter was placed on the basement floor near my Lehman and >connected thru Larry's amp. to the second channel of his A/D and both were >recorded with SDR. The signal from each sensor was passed thru a section >of the Rockland low-pass filter set at 0.08Hz. > I got a 'quake from Oaxaco Mexico on both the Lehman and the tiltmeter. >The SDR files will be posted to the archives:980203C.RB1 is the Lehman and >980203c.RB2 is the tiltmeter. > > The records are similar but the noise level of the tiltmeter is poorer >than the Lehman. P was not vis. in either and S was relatively stronger in >the tiltmeter record. I don't know what caused (maybe foot traffic) the >monster spikes before and after the 'quake but the tiltmeter responded much >more strongly . This performance was not as good as that described in the >Miller, et. al., paper but it is a different device and with a much less >sophisticated electronics. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: tiltmeters:Sperry, Rockwell,etc Date: Thu, 23 Apr 1998 14:11:07 -0500 (CDT) Bob, THe tiltmeter you initially describe (the Rockwell/Autonetics) is the one that the USGS tried to deploy widely in the mid '70s for earthquake prediction research. It is the one used by Stein et al. as a horizontal seismometer. I was given 10 of these to use at New Madrid, and 10 for the Aleutian project, and a few etcs. The New Madrid project (they just don't work in the alluvium) was moved to So. California to the "Palmdale Bulge" in the western Mojave, and some were moved to the Crustal Deformation Observatory of UCSD at Pinon Flat for comparison with the long-baseline fluid tiltmeters. I guess I have the worlds stock of them here, about 24 sensors. Long ago we gave up on "improving" the Kinemetrics/Rockwell electronics and built our own to reduce the thermal sensitivity by a factor of 100. We have a standard output of 25mv/microradian (25 000 Volts per radian) with a noise level of 0.5 nanoradian. In operation, we use the earth-tide data at 0.1 microradian p-p to verify our calibration; we have programs that can model the tilt tide. THe most stable instrument we ever operated drifted only 0.32 microradian per year, but 1 to 2 urad/year was more typical. The final status of the borehole tiltmeter project is that the instrument lives up to expectations, but the surface of the earth is too unstable, mostly from meteorological influences. This is at the 3 meter depth that we were installing the sensor, which has no mechanical zeroing so has to be installed by hand to an initial level of one microradian. To solve the surface noise problem, we had developed a method to install the sensor in 30m boreholes with a detachable motor-driven pre-leveling device, but the funding ran out when everyone thought that GPS would answer all our crustal deformation questions, which, naturally, it hasn't. UCSD is still operating long-baseline fluid tiltmeters with "optical anchors" to reference the surface piers to bedrock at depths of 10 to 30 meters. THe "final" paper about borehole tiltmeters is: "Shallow Borehole Tilt: A Reprise"; by F.K. Wyatt, S-T. Morrissey, and D.C. Agnew; Journal of Geophysical Research, Vol 93, No B8, Pgs 9197,9201; August, 1988. The current interest in the electrolytic bubble tiltmeter is for correcting the aiming of large telescopes in the period between tens of seconds and an hour, in order to keep galactic images centered on the ends of optical fibers that lead to spectrometers. The natural earth-tides and wind blowing on the telescope, as well as thermal gradients in the support structure are the problem. There are several sources of electrolytic tiltmeters available, but only the Rockwell bubble has the stability and resolution needed for this application.. Regarding your Sperry tiltmeter: I have one here; it has a white ABS end cap cemented to an aluminum plate. It is designed to be mounted with the plate vertical, as on the wall of a tunnel inside a dam. I believe it has a "Frederics" bubble inside, which can produce an output when it is sideways, depending on how it is mounted. Somewhere I have all the literature about it. It was not useful for crustal deformation studies. Your other questions: 2: The Rockwell sensor has been found in surplus stores: they were originally used for the platform "pre-aim" for ICBMs. It is useless without the bridge circuit and the electronics; if you apply an ohm meter to the electrodes, they plate off into the electrolyte and the sensor is immediately ruined; they must be run only with an AC bridge. 3: It is not the sensor used in the PMD seismometer that is being considered/used for the PEPP project. That electrolytic sensor works on an entirely different (proprietary) principle. 4: Why aren't they used for horizontal seismometers: only the Rockwell sensor has a low enough noise level for teleseismic sensitivity. Stiction of the bubble and electrode contact surface irregularities are the main noise in other bubble sensors. And the last time a price was put on the Rockwell sensor, it was g.t. $5000 per, and they aren't made anymore. For a compact horizontal sensor, a miniature "garden gate" design (eg: 5cm boom, 200gm mass, To = 1 sec.) can be made with a VRDT displacement sensor and VBB feedback that, while not meeting the MTQ noise expectation (M*T*Q > 1), can resolve the mid-range of the earth noise models (at PSD of l.t. -150db at 30 seconds). Unfortunately, it is also a very good tiltmeter, and requires a well prepared site. This brings up the next problem: tiltmeters that are NOT seismometers. An interesting converse to the problem is that the current seismic broadband horizontal sensors ARE very sensitive to tilt noise, which even on piers situated on bedrock limits their usefulness. We are evaluating a tiltmeter that is NOT sensitive to horizontal acceleration to try to remove the tilt noise. It needs to be MUCH quieter than the seismometer, which is the challenge. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: The S in SG sensor... its a small world.... Date: Thu, 23 Apr 1998 17:54:28 -0700 Hi Everyone, Got this email from Barry Shackleford today. He's the S in the SG sensor name...Portola Valley is only a few miles from me. More info about the SG sensor can be found at http://psn.quake.net/sgsensor.html. -Larry >Date: Thu, 23 Apr 1998 17:37:50 +0000 >From: Shackleford >Reply-To: pecora@.......... >X-Mailer: Mozilla 3.01-C-MACOS8 (Macintosh; I; PPC) >To: cochrane@.............. >CC: pecora@.......... >Subject: S-G seismometer > >Dear Larry, > >I must say that I was surprised and delighted to see that the >seismometer that Jim Gundersen and I put together back in the >'70s still lives on through your excellent implementation and >seismic home page. > >I noticed that you are living in Redwood City. I'm close by in >Portola Valley, working at HP-Labs. As the Japanese say, "It's >a narrow world." > >We should chat sometime. > >Best regards, > >Barry > >Barry Shackleford >Hewlett-Packard Labs, 3U >1501 Page Mill Road >Palo Alto, CA 94304 > >email: b.shackleford@............ >tel work: 650-857-7537 >tel home: 650-234-1208 > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Geophone Help Date: Fri, 24 Apr 1998 05:23:42 +0800 Hi, I'm planning to set up a small station at home to complement my two SG seismometers some, 11 kilometers away. I hope to do some epicenter locating on the larger local events. The problem is that my house is located in a suburb and subject to the typical manmade induced, ground noises. I hope to keep the complexity as low possible and had intended to use a vertical geophone as the sensor. To that end can anyone recommend a good quality 4.5hz geophone? Is a 1 Hz geophone, available? My long term plan is to upgrade my primary station with a sensitive vertical seismometer. Thanks for your time. Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Geophone Help Date: Thu, 23 Apr 1998 23:15:50 -0700 (MST) Arie, From personal experience I have learned that vertical data is not good in local events. The reason vertical data is bad for local events is because the waves are travelling to your seismometer at a low angle to the surface, and because displacement in P-arrivals is in the same direction as the velocity they will move things from side to side a lot more strongly than up and down, making horizontal sensors more effective for first arrivals. Also, background noise, especially in suburban areas will have a high vertical component, thus masking almost entirely the P-arrival, or at least making it extremely difficult to nail down. Even so, 11 km separation will produce nearly simultaneous arrival times due to the fast speead at which waves travel. The combination of these two problems will defeat your purpose of epicenter locations... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Re: Geophone Help Date: Fri, 24 Apr 1998 20:46:12 +0800 Hi John Thanks for explaining the problem. Your advice sure makes sense and I'll redirect my efforts. Its a real problem in identifying the real local events against noise and mine blasting (150km) away. One of our seismic active areas is also about 150 km away. Has anyone had any success with identifying the quakes direction with a X,Y,Z axis seismometers? Arie > From personal experience I have learned that vertical data is not good > in local events. The reason vertical data is bad for local events is > because the waves are travelling to your seismometer at a low angle to the > surface, and because displacement in P-arrivals is in the same direction > as the velocity they will move things from side to side a lot more > strongly than up and down, making horizontal sensors more effective for > first arrivals. Also, background noise, especially in suburban areas will > have a high vertical component, thus masking almost entirely the > P-arrival, or at least making it extremely difficult to nail down. Even > so, 11 km separation will produce nearly simultaneous arrival times due to > the fast speead at which waves travel. The combination of these two > problems will defeat your purpose of epicenter locations... > > > John Hernlund _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Abreviations Date: Fri, 24 Apr 1998 13:41:29 +0100 S-T Morrissey wrote: > per year, but 1 to 2 urad/year was more typical. > > > 3: It is not the sensor used in the PMD seismometer that is > being considered/used for the PEPP project. That electrolytic > sensor works on an entirely different (proprietary) principle. > > > MTQ noise expectation (M*T*Q > 1), can resolve the mid-range of > the earth noise models (at PSD of l.t. -150db at 30 seconds). > Unfortunately, it is also a very good tiltmeter, and requires > a well prepared site. Hi Sean and OTHERS, I wonder if you would mind if I mention the subject of abbreviations. Many of us on PSN (some Americans TOO no doubt ), are sometimes no conversant with all the abbreviations that many use on PSN from time to time. I hope that I speak for many folk, who may struggle to follow the gist of a discussion, in which their understanding is further hampered by the use of abbreviations not understood by them, and who do not wish to ask. (I may be speaking for the 'silent majority' out on PSN.) I do not wish to point at your letter as the only example, but merely use it as an illustration of what I mean. For example, I confess that I don't know what "M*T*Q" is, nor can I fathom "PSD of l.t.", (altho' I DO know what "db" is .) "urad", also puzzles me. Maybe I should know what "PEPP" is (already refered to ?), but this eludes me as well........ Aren't I an ignorant cuss! . At times maths are used, and again, I am not sure what the multiplying/division/squares/roots etc. signs used in ASCII mean....perhaps there are standards for these, if so, maybe you/someone can mention a source of these so that I/we may be able to check. No offence is meant Sean or others . I thoroughly enjoy all this discussion on PSN, but it would be nicer if sometimes folk use FULL terms instead of abbreviations, which they may assume all 270 odd PSNers understand, and which many may not. Hope no one minds me bringing this up. TTFN !!! ("Tat Ta for now" ) Regards. Albert Noble (England). _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: Mammoth Times & Seismo-Watch Date: Fri, 24 Apr 1998 09:27:39 -0800 congratulations ! Charles Watson, your wiggling may set up anomalies. -- Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) internet: wave3@........... 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp) 8N1 FULL DOS terminal program _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Abreviations Date: Fri, 24 Apr 1998 11:40:47 -0500 (CDT) Albert, A very good point about abbreviations. I sometimes worry about being too "wordy" in spelling things out, but if an abbreviation is gibberish, the communication fails anyhow. re your specific questions: 1. M*T*Q = Mass(in kg) times the period (in seconds) times the Quality factor, which is often considered the inverse of the mechanical damping, but a value of 1 can generally be assumed. 2. g.t.; l.t., etc: = greater than, less than (from old Fortran) 3. urad = microradian 4. PSD = Power Spectral Density: which is a universal scale used to measure or compare of the seismic signal levels from any seismometer system. It is scaled in db = decibels, which, for power levels, is a logrithmic scale of 20 times the log of the signal level. 5. PEPP = Princeton Earth Physics Project, an Education and Outreach effort to get more earth science education in schools, and includes a program to place live seismic stations in high schools. Various "inexpensive" seismometers with digitizers are being considered. As I mentioned above, your point is well taken. I hope this answers some of your questions. Regards, Sean-THomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Abreviations Date: Fri, 24 Apr 1998 11:40:47 -0500 (CDT) Albert, A very good point about abbreviations. I sometimes worry about being too "wordy" in spelling things out, but if an abbreviation is gibberish, the communication fails anyhow. re your specific questions: 1. M*T*Q = Mass(in kg) times the period (in seconds) times the Quality factor, which is often considered the inverse of the mechanical damping, but a value of 1 can generally be assumed. 2. g.t.; l.t., etc: = greater than, less than (from old Fortran) 3. urad = microradian 4. PSD = Power Spectral Density: which is a universal scale used to measure or compare of the seismic signal levels from any seismometer system. It is scaled in db = decibels, which, for power levels, is a logrithmic scale of 20 times the log of the signal level. 5. PEPP = Princeton Earth Physics Project, an Education and Outreach effort to get more earth science education in schools, and includes a program to place live seismic stations in high schools. Various "inexpensive" seismometers with digitizers are being considered. As I mentioned above, your point is well taken. I hope this answers some of your questions. Regards, Sean-THomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Geophone Help Date: Fri, 24 Apr 1998 10:19:30 -0700 (MST) On Fri, 24 Apr 1998, Arie Verveer wrote: > Thanks for explaining the problem. Your advice sure makes sense and > I'll redirect my efforts. Its a real problem in identifying the real local > events against noise and mine blasting (150km) away. One of our seismic > active areas is also about 150 km away. Has anyone had any success > with identifying the quakes direction with a X,Y,Z axis seismometers? I haven't had much luck with just a single station. Since the waves could be arriving from any direction it is difficult to look for some of the characteristic polarization of the waves that would indicate fault nucleation and slip, although a close study of the seismograms is probably likely to produce some idea this would probably require a high-resolution seismograph... There are books out there on some methods for doing this kind of analysis, I remember seeing one written by Bruce Bolt on methods for telling a nuclear explosion apart from an earthquake; maybe that would be useful... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Quake in Nevada Date: Fri, 24 Apr 1998 10:28:23 -0700 Got several calls from a M4.4 jolt near Hawthore this morning. -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: Abreviations Date: Fri, 24 Apr 1998 13:32:18 -0500 Sean, Your description of PSD seems to be missing something. Unless it is used differently in seismology. Since it is a density it needs to be "per" something such as Hertz. Normally dB is a ratio so I would expect this to be dBm or with respect to some other signal level. This would make your -150 dB become -150 dBm per Hertz. Taking 20 log base 10 of a signal level in volts does not give you anything that you can use to compare with another instrument. Jim Hannon sean@........... on 04/24/98 11:40:47 AM Please respond to psn-l@............. To: psn-l@.............. psn-l@.............. cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: Re: Abreviations 4. PSD = Power Spectral Density: which is a universal scale used to measure or compare of the seismic signal levels from any seismometer system. It is scaled in db = decibels, which, for power levels, is a logrithmic scale of 20 times the log of the signal level. Regards, Sean-THomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Re: Sperry tiltmeter Date: Fri, 24 Apr 1998 20:18:58 -0400 Karl, = My remark about finding many makers of bubble levels was intended to inspire someone to experiment with capacitance pick-ups. The Rockland filter used here is an analog filter which should not introduce spikes. Bob Barns = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert L Barns <75612.2635@..............> Subject: Tiltmeters, reply to ST Morrissey Date: Fri, 24 Apr 1998 20:18:56 -0400 Sean-Thomas, Lots of interesting info in your epistle on tiltmeters, thanks. In your reference to the Sperry tiltmeter:apparently I still don't have= it right--it should be used with the base plate vertical??? I can't imagine what a "Frederics" bubble can be and work (at least reasonably well) when mounted 90 deg. from the proper way. I note a mention of the Frederics in Agnew's paper but no description of how it works. Could you describe this more thoroughly or suggest where I can find the= detalis? Also, if I send a SASE, could you send me a reprint of the Wyat= t, Morrissey, Agnew paper? (And maybe a copy of the literature on the Sperr= y if you can find it.) Bob Barns I love defenceless animals, especially in a good gravy. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: PSD definition Date: Fri, 24 Apr 1998 20:06:39 -0500 (CDT) Jim, There I went again: abbreviating a description for the sake of being brief, and causing more confusion, and mis-stating the fact that power ratios are 10 x the log, not 20 x, as for voltage ratios. Regarding PSD (Power Spectral Density): The standard units used for instrumental/earth noise PSD are in DB = 10 * log [(meters ** 2 / second **4) / hz ] A PSD plot is actually a modified plot of the FFT (fourier Transform) of the data sample, where each term of the FFT of the velocity output voltage is divided by the data calibration constant (volts/meter/sec or counts/meter/second). Then for every term of the FFT, this number is squared and then divided by the corresponding frequency in hz. Then the log of each term is multiplied by 10 and plotted on a log-linear scale. For example, if the value of the term for 10 seconds in the FFT is equal to 0.01 millivolts (a representative noise level of the instrument in my basement), and the instrument constant is 3280 volts/meter/second (the Beta version of the STM8), then 0.00001 volts divided by 3280 equals 3.05 x 10^-9; this squared is 9.3 x 10^-18; it is then divided by 0.1 hz, and the log of that value is -16.03, and 10 x that is -160.3 db. (db with respect to 1 meter**2/second**4/hz). This is the value of the PSD before averaging over a 5-point running mean. This approximate estimate can be seen in figure 4a of the .....Data... page on my web site. As you can see, the constants of the instrument, the digitizer (and any filters, etc.) have been deconvolved, so we can now compare this data with that of any other sensor or site. Or we can compare the PSD of the same event between various sites with completely different instruments. I hope this clarifies the PSD picture. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Tiltmeters, reply to ST Morrissey Date: Fri, 24 Apr 1998 20:52:43 -0500 (CDT) Bob, It may be that your Sperry unit is meant to bolt to a cieling. The one I have here has a pair of blue arrows over the word "TILT", and a fine screw adjustment that rotates it in the direction of the arrows, which is a vertical plane rotating about a pivot pin in the upper right corner. I haven't opened the ABS case to see exactly what sensor is inside, so I may be remembering wrong about the Fredericks bubble. We did evaluate some "high resolution" Fredericks units in the late 70s, but they were not as good as the Kinemetrics/Rockwell (a real thermal problem at the microradian sensitivity). Fredericks current line only indicates a null repeatability of 0.2 arc-minutes. (email: Francis Kull: fkull@.................. The Fredericks sensors are small slightly curved glass vials or tubes, about 1/4" dia and and inch long, with electrodes arranged out each end and one through the center. They are partially filled with a conductive electrolyte that looks like iodine. AC excitation is applied to the end electrodes, and the differential signal is sensed by the center electrode. (The electrodes are platinum, so the price is highly variable.) Different shapes of the vial give different sensitivities. If the vial is rotated 90 degrees about the long axis, it will still work, but with a different (and probably non-linear) sensitivity. Of course, I guess I will have to break open the Sperry sensor to see what is inside. Something to do next week .....? I can send you a copy of the paper if you send a SASE. Even greater fortune would let me find the Sperry literature. Regaards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: VBB Date: Fri, 24 Apr 1998 19:13:42 -0700 Sean Thomas I have uploaded two VBB files for the Hawthorne event. I noticed that the unfiltered event has a large low frequency component. When I ran it thru a single pole high pass with cut off @ at about the natural freq of the sensor I got a great record(flat log FFT response for low frequencies). Is this a coincidence or would a single pole high pass help? Have you noticed a similar response? I noticed your step response plot had higher than predicted response at low frequencies. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mark Robinson Subject: Re: Tiltmeters, reply to ST Morrissey Date: Sat, 25 Apr 1998 15:28:22 +1200 S-T Morrissey wrote: > The Fredericks sensors are small slightly curved glass vials or > tubes, about 1/4" dia and and inch long, with electrodes > arranged out each end and one through the center. They are partially > filled with a conductive electrolyte that looks like iodine. > AC excitation is applied to the end electrodes, and the > differential signal is sensed by the center electrode. > (The electrodes are platinum, so the price is highly variable.) > Different shapes of the vial give different sensitivities. > If the vial is rotated 90 degrees about the long axis, it > will still work, but with a different (and probably non-linear) > sensitivity. Of course, I guess I will have to break open > the Sperry sensor to see what is inside. Something to do > next week .....? > These sound to be exactly the same as the electronic level sensors used in Steadicam IIIAs. They may be available from Cinema Products as spare parts. In the steadicam they are driven using a National Semiconductor LVDT (Linear Voltage Something Transform :) chips. Cinema Products address is buried, I can dig it out if any is interested. They are unlikely to be cheap ! regards Mark _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Fredericks tilt sensors Date: Sat, 25 Apr 1998 01:57:08 -0500 (CDT) Mark, Your observation is correct. In fact, the latest Fredericks catalogue has a front page insert advertising the use of their sensors in the Steadycam. And I have little doubt that a LVDT driver chip would make them work nicely, since all they are is an AC bridge. The ones I evaluated here for geodetic studies worked with several AC bridge oscillator/amp/demodulator systems. For short term, relatively large amplitude tilt sensing with 12 arc-second repeatability (the "<0.2 arc-minute" specification from Fredericks), they should be pretty good. For reference, 5 arc-seconds is about 1 microradian; in geodetic studies, we need 0.001 microradian. I don't know what the current costs are from Fredericks, whether a second source might be better. But I don't think they have the resolution/noise level we would want for using them for horizontal seismic sensors. But I haven't run any numbers either. THe main problem is stiction of the bubble against the glass vial and irregular contact between the electrolyte and the electrodes. I have copies of all the research into these problems that was done by Rockwell/Autonetics in the early 70s. Lots of equations. (the references to Cooper et al are in D.C.Agnew's paper on straimeters and tiltmeters). The paper discussed earlier by Stein et. al. used the Rockwell sensor and a rather high quality amplifier/ filter setup.. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Metal Film Versus Wire Wound Resistors? Date: Sat, 25 Apr 1998 16:22:53 -0600 Hi all, Seems like the 1% metal film variety is the builders choice with most circuits anymore. Precision and low temperature drift I think. I hear that wire wound resistors are electronically noisy compared to other varietys....but to what degree I don't know. Have more endless questions..... I do have some precision wire wound resistors which I am hoping to use in the integrator of S-T's circuit down the road of time. These are 100K, with +- .0025% tolerance. I could paraell another to reduce the resistance to 50K if necessary. The resistors seem to be a very big part of the instrumental/integrator op amp accuracy. So...would using these be a bonus or detriment in regard to noise in the circuit? At this time, I could go with one op amp, or go with the "standard" 3 op amp with its 6 resistors, which may be much better in regard to this CMRR stuff? Am seriously considering using the Harris (old Intersil brand), ICL7650, a chopper op amp; because it is so cheap ~$2. Am perhaps overdoing the circuit question, but I think that this part is very important. No engineer experience here. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: Metal Film Versus Wire Wound Resistors? Date: Sun, 26 Apr 1998 11:42:46 +1200 At 04:22 PM 4/25/98 -0600, you wrote: >Hi all, > >Seems like the 1% metal film variety is the builders choice with >most circuits anymore. Precision and low temperature drift I think. > >Have more endless questions..... I do have some precision wire >wound resistors which I am hoping to use in the integrator of S-T's >circuit down the road of time. These are 100K, with +- .0025% >tolerance. I could paraell another to reduce the resistance to 50K >if necessary. The resistors seem to be a very big part of the >instrumental/integrator op amp accuracy. So...would using these be >a bonus or detriment in regard to noise in the circuit? >Thanks, Meredith Lamb No Meredith its the makeup of the metal film resistors that make them low noise. Low tolerance of ur wire wound resistors DOES NOT imply Low noise. Stay with metal film resistor for the best results. they are sooooo cheap anyway why bother using something else that is a worse performer. cheers Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Metal Film Versus Wire Wound Resistors? Date: Sun, 26 Apr 1998 09:05:07 -0700 Meredith -- In seismometers, noise that matters can be low-frequency enough for resistor people to call it drift. I believe a well-made wirewound resistor is usually quieter than a film resistor. But notice the disclaimer WELL-MADE. From what I understand, it's not easy to make them -- some of the problems: Thermal emf's generated due to temperature gradients across the bulk of the resistor (up to 10's of microvolts); Strains imparted to the wire due to stress on the leads (resistance change up to 10 parts per million (ppm)); Long-term drifts due to slow stress relieving of the packaging (10 ppm resistance change); Pickup of stray magnetic fields like 60Hz from nearby transformers etc. due to the fact it's a coil of wire (10's of microvolts & up, depending on the field strength and way the resistor is wound). There are other problems like resistance change with applied voltage, drift due to self-heating, drift due to current-induced migration of the resistance material, etc, etc, etc. And these are in addition to the problems of tolerance and temperature drift. At work, we have some precision dividers made of card-wound wirewound resistors (wire wound around mica cards) that are checked regularly, and are always much better than 1ppm -- year in and year out. But film resistors have their problems too. It wasn't until the last 15 years or so that even the best films have been able to match everyday wirewounds in temperature drift and long-term stability (read "noise" in seismometers). Perhaps someone else knows more about this, but I think the nature of the resistive material in films has more noise than the resistance wire of wirewounds. Some of the best resistors made are metal foil and card-wound wirewound resistors. Wirewound resistors are usually made from Evenohm (sp?) or other proprietary alloy, and connecting to copper leads generates thermal emfs. This is always a problem. Back to reality... I don't think the tolerance of the resistors used in Sean-Thomas' VBB design is very critical. I'm quite sure that 1% or even 5% values would work fine. But low thermal emf generation is definitely a concern, unless your temperature stability is good. Use as few op-amps as possible to get the job done (goes for resistors too). Each one introduces some noise and the fewer the better. You shouldn't need any common-mode rejection (CMR) in S-T's circuit, as (if I understand it correctly) it's all referenced to ground. Chopper op-amps are very good for 1/f noise and temperature drift. But be sure to synchronize the chopper with all other oscillators in your system (use one master oscillator) or you're sure to get intermodulation problems (beat notes between them). And don't let the chopper frequency get near 60Hz or a multiple of it, or you'll have the same problem. The newer chopper op-amps may produce less chopper-frequency noise at their outputs than older ones. Enough for now. Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Metal Film Versus Wire Wound Resistors? Date: Sun, 26 Apr 1998 12:12:25 -0500 (CDT) Meredith, Karl, and co. I think Karl addresses the problem of resistor noise and thermal drift quite accurately, and thanks Karl for the details. I would sum it up in saying that one has to read the specifications: you get what you pay for. We have bought some "now noise" resistors for as much as $10 per. And chip resistors are a whole different game. We do have some very old standard decade boxes with wire-wound on mica cards as Karl describes; I just assume that they are still good: they agree with the 4.5 digit DMM at room temp; we don't have the money to send them out to be calibrated again. THe few places I have seen wirewound Rs used in our applications are for the bridge resistors in the tiltmeters, where the temperature coefficient somewhat matches ONE of the thermal characteristics of the bubble bridge. Some of the commercial seismic feedback systems use very high quality metal film, selected for each configuration. (The european 1% resistors have so many color bands I never know which way to read them from.) A last note about amplifiers for the integrator: The OPA111 has been used successfully for this, even as an inverting integrator. I don't know what it costs. And my philosophy about costs: cheaper is not better. If a $10 amp will do the job without pushing the specs, it is to be preferred over a $5 amp that "might" work. We are not in a "dollar-saved, dollar-earned" situation, unless one is planning a bake sale featuring homemade siesmometers. If I find a device or hardware that clearly will fill the bill, (and obviously, not a HUGH expense), I buy it; or actually, I buy two or three, especially ICs, since I may ruin one, or the expected performance is not achieved because the one I tried was defective. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Marnie Gannon Subject: LA quakes Date: Sun, 26 Apr 1998 11:56:08 -0600 Hi Charles, Thanks for all your helpful posts on recent quake activity. I do have a question: These 3 recent LA quakes, 10 Miles NE of downtown, are described by Lucy on the Trinet site, as being in the NW aftershock zone of the Whittier Narrows quake. The 3.2 in LA on April 15 was described as being 4 miles NW of downtown and probably centered on the Elysian Park thrust and fold belt, which is also associated with the Whittier quake...Do you think these recent ones are on the same fault zone? Comments? Thanks, Marnie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: LA quakes Date: Sun, 26 Apr 1998 11:41:56 -0700 Marnie Gannon wrote: > > Hi Charles, > Thanks for all your helpful posts on recent quake activity. I do have a > question: > > These 3 recent LA quakes, 10 Miles NE of downtown, are described by Lucy > on the Trinet site, as being in the NW aftershock zone of the Whittier > Narrows quake. The 3.2 in LA on April 15 was described as being 4 miles > NW of downtown and probably centered on the Elysian Park thrust and fold > belt, which is also associated with the Whittier quake...Do you think > these recent ones are on the same fault zone? Comments? > Lucy has been looking at earthquakes in Southern Colifornia for a lot longer than me and I would tend to agree with here, sort of. The quake did fall close to the northern extent of the Whittier aftershock zone but I was not aware of the aftershock activity extenting this far past the Romona Freeway. This recent M3.8 triggered up at I10 near Garfield Ave. about 4 miles away. So it is close but not quite. Then again, she may have been talking spatially rather than tectonically. The M3.2 near Dodger Stadium was centered near the intersection of the NW-trending Elysian Park thrust and fold belt and ENE-trending Hollywood fault system. What I have seen of detailed studies of the area is that it is pretty cracked, and the quake could have triggered on either system. I haven't seen the focal mechanism for it yet. As for the association of the Elysian Park thrust and fold belt system with the Whittier fault system... well they both are in Southern California. :> There has been some speculation that the Whittier fault zone extends NW-ward into the Elysian Park thrust and fold belt. They are both thrust-slip fault systems, just the Whittier is more developed - like it should be. But you know, I went to the TriNet page and could find anything from Lucy regarding the Alhambra quake. But I did find a bunch of info from Kate Hutton at the SCEC page: http://flint.gps.caltech.edu/eqreports/comments/April1998.html Moreover, they have a new auto system of determining Mercalli intensities. I'm baffled it registered MMI IV 'cause nothing was shaken from tables or shelves. ta-ta, I'm off to enjoy the nice weather... -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Marnie Gannon Subject: Re: LA quakes Date: Sun, 26 Apr 1998 12:52:57 -0600 Charles Watson wrote: >But I did find a bunch of info from Kate Hutton at the SCEC page: Sorry, my mistake. It WAS Kate I was quoting..Thanks for the info. Marnie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Resistors, Fleas, Illusions and Op-Amps Date: Sun, 26 Apr 1998 17:03:44 -0600 Karl, David, Sean-Thomas and everyone, Thanks for the responses. My original msg was only concerned with wire wound resistors use in the instrumentation amplifier portion of the STM-8; i.e., 2 to 6 resistors, not, for the total circuit package...the government could afford that, but not me. The wire wound resistors I am considering using are surplus flea mart type purchases of long ago. All are around 30 years old, and mostly salvaged off big old circuit boards, for like 2 cents each. Nevertheless, they seem to very well built...plastic coil inside, plastic fire resistance cases, springs on each end, air separation of the coil from the case. The place I got them at is no longer in business...they probably didn't know what they had. So....the price is right -ha. I suppose I should have spelled it out better in the original message. I'am fully for surplus scrounging bargains, alot of fun if you strike gold once in awhile. Trivia. Karls assessment of wire wounds was most interesting, I could even check afew responses like the emf with a magnet and some cigarette lighter thermal resistance drift. Saw ~ 8mv with magnet, and perhaps 1/1000th resistance drift. Interesting stuff...kind of wish he would have kept on with the message further. I see no real crisis in using wire wound resistors instead of metal film in any aspect......now. Hmmmm...maybe I ought to check out those old fat wire wounds with low ohmage for use as pickup magnet/coils. Karls chopper op amp logic says it all, in the sense of a chopper op amp is no good for the STM-8 circuit, with its other oscillator running. Scratch the chopper for this specific circuit. Instrumentation amplifiers seem to need a reasonably close resistance matching tolerance especially for the unity or gain of one amplier involved in the STM-8 package. I suppose one could check a number of like resistances and get a fair match, with a suitable bridge or DVM, if they have the stuff, and wanted to go that far. My only reference is those I see in electronics linear manuels, most of which hit around 1% variation or better is appropriate. I know....the STM-8 is meant for electronics professionals, and I'am trying to compete where I don't belong at all. Trouble is, the electronics IS the WHOLE key to using the STM-8 or any other seismographs, the mechanics are interesting and varied but they are usually not complicated or hard to replicate fairly. I think the STM-8 circuit should be more open to amateurs with alittle less experience...it looks too good! I suppose the real solution will be someone coming out some day with the ready made circuit....which is a hard reality for a realistic majority I think. Have checked the OPA111 on the internet. Allied sells it for about ~ $11 to ~ $23, according to offset rating of typical 250 to 500 microvolts in a TO5/TO99 package. The maximum offset of these goes about 3 times higher, per Burr-Brown data. One would need a 10K trim pot also. Perhaps the bigger question is the maximum input offset allowed for the design, or the average temperature drift, and then one could go accordingly to the massive open market variety and pocketbook? Reckon I've gained from the answers you folks from generiously provided. Thanks. Electronics is a real pain.... Meredith Lamb P.S's, Robert Barns,...thanks for the tiltmeter data and grams...very interesting too see. Will we see more? Would like to see a bigger quake and teleseism record personally..... Sean-Thomas,...hope you are totally over the flu like stuff. No fun at all. Aftereffects can drag on for some time.... David Nelson,...hope you are better from the surgery and perhaps hopping around much better. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: STM-8 expectations Date: Sun, 26 Apr 1998 22:15:08 -0500 (CDT) Meredith, (and company): There seems to be too much concern about the electronic requirements for the STM-8 seismometer. I need to point out that one of the attractive features of the triple VBB feedback seismometer is that just as there are no special demands on the mechanical system, other than it is stable, the same is true of the feedback electronics. I am using recycled amplifiers that are more than 15 years old for the prototype here, mainly because I happen to have them leftover from the tiltmeter projects. Everything is based on the LM308A, a very reliable "low noise" but not particularly special amplifier, other than its DC stability is well known. Even where the OPA111 is used as an integrator, it is not even necessary to compensate it. (ie: just ground pin 8). For the feedback elements themselves I am using ordinary 1% components, like resistors that cost less than $1. I have made sure that the feedback capacitor and the integrator capacitors are low leakage, by testing them with a DMM. Again, nothing special. Since the VBB output signal IS in fact the output of the displacement detector, that is where we have to be concerned about electronic noise and drift. But thermal/mechanical noises in the detector itself can be of equal concern. Fortunately, the VRDT has such a large output (50 to 100 mv/micron with a 2mm range), we have lots of signal to work with, so we are well ahead of the electronic noise. But the VRDT, unfortunately, IS a "wirewond" device, so it does have a real temperature problem, especially if the two coils are not very carefully matched (for inductance AND resistance) before it is assembled. "Hand winding" the coils of a VRDT or an LVDT is especially demanding in this respect. Temperature compensation of the VRDT can be done by paralling the coils with a differential thermistor bridge, or shunting one coil with an appropriately thermal responsive resistor. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Equalising article again Date: Mon, 27 Apr 1998 15:13:09 +0100 Hi, Regarding the article in Bulletin of Seismological Soc. of America, Vol. 79, No 5 Oct.1989, " A Versatile Equalization Circuit for Increasing the Seismometer Velocity Response below the Natural Frequency", by Peter Roberts, which was previously mentioned on PSN................ .................... I have made this cct. up to try out on one of my beams. It became a little tiresome working thro' the equations on page 1610.........so I now have a PC software patch that calculates the values for the amplification required for each of the two stages, and also the values of R*C ( R2 and C1 in cct diagram on page1612). Below are some values for some typical seismo configurations. It's now easy to see that if one is greedy and attempts to lower the natural freq. of a seismo by more than a factor of about x5, the amplification required becomes very high, so we should heed Sean Thomas's recent warnings on PSN about the noise problem associated with this method. Noise is also mentioned in the article. The last example serves only to illustrate this. The damping factor (Zeta) in the equations don't have a significant effect on the values for RC, nor gain required. (The table is based on a value for Zeta of .7) RC = value of R2 and C1 in Megohms and Microfarads. A = amplification required from EACH of the 2 stages... .....adjusting R1 in order to obtain this. (As A=R2/R1) (Overall amplification will be A*A) Natural freq. New Equalised freq R*C A of seismo to be obtained (seconds) 1Hz .2Hz (1/5th) 1.59 x10 1Hz .1Hz (1/10th) 3.18 x21.3 .5Hz .1Hz (1/5th) 3.18 x10 .5Hz .05Hz (1/10th) 6.37 x21.3 .1Hz .02Hz (1/5th) 15.9 x10 .1Hz .01Hz (1/10th) 31.8 x21.3 .06Hz (15secs) .012Hz (1/5th) 26.5 x10 .06Hz .006Hz (1/10) 53.0 x21.3 .06Hz .003Hz(1/20th) !! 106 !! x43.7 !! The last example is to illustrate ONLY that the greater the reduction in natural freq.attempted, then the greater the amplification required. (x43.7 amp factor for EACH stage is x1909 total...example ONLY) One can also see from this table that the A value is solely dependant on the reduction ratio. (A = 10 when equalised freq. is 1/5th of natural freq. of beam, and A = 21.3 when 1/10th) TRIALS........... As I have 2 seismos (facing EW and NS) I thought it would be an interesting experiment to equip one beam with this equalising cct. and compare it with a NON modified beam. I reduced BOTH beam periods to 12 secs, and used new cct to equalise to 60 secs. on the EW beam. Amplification required for each stage in order to achieve this is x10, and LP filter is 20 secs. (R*C=20). I cannot see any noise generated by the new cct., but this may well be because my normal LP filters used after the new cct are lowish at 5Hz. Incidentally, the new cct.is just a lash up using 6 - 741 op amps!!! (I ran out of 8 pin sockets, so 2 op amps are in ONE 8 pin socket!) However, storm microseisms etc. on the modified beam are now more frequently superimposed on lower freq. data, whereas the unmodified beam doesn't show these lower freq. to such a degree. In fact, my trace sometimes resembles the trace shown on page 1613 of article (a teleseismic event in Jemez mountains superimposed on 10-20 sec wind/ocean tremor). I sat 4ft away from beams with a magnet in my hands. Once the beams had settled, I turned magnet VERY slowly back and forth (about once per minute) in my hand!!..... ...... (the things we do for seismology) It was very apparent that the equalised beam had the greater o/p of sine wave (well, a rough sine wave), compared to the normal beam, and this seemed to indicate that a 12 second beam equalised down to 60 secs was more sensitive to LF. I shall do some more experiments on this system . If anyone wishes to read Peter Robert's article it is available from the American Seismological Society, and some members of PSN have also obtained copies from their own local University Libraries. As the Author of the article, Peter Roberts, said in his conclusion, to his article................ "The simplicity of the design procedures makes it readily understandable and easily modified and implemented without extensive knowledge of electronics." Now, that last statement, is ME to a T Regards Albert Noble (England) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 1998 09:02:03 -0800 Do any of you have schematics for building a proton-precession magnetometer? I'm aware of the Sci Am article from 1968 on building such but wonder if there is anything newer (ie, digital)? Or, do any of you have leads on a used Geometrics proton-precession magnetometer for sale or trade? thanks, Bob Hammond APSN Fairbanks _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Instrumentation Date: Mon, 27 Apr 1998 12:00:29 -0500 Friends, Interesting discussion on resistors. Actually, I think the reason metal film resistors are generally to be preferred over carbon film resistors is primarily their lower temperature cooefficient and more precise vlues rather than noise. You can use a DVM to select metal ones that are matched to one part in a thousand, or make your own by soldering two in parrallel. In any case, metal films are indeed slightly less noisier but the difference in price is so trivial that it makes little sense to use carbon (A 50 pack of nickle-chromium film resistors are about $2.50 at Radio Shack). Carbon composition resistors may give noise well up into the microvolt range, but they're rather uncommon nowadays except in old circuits or for power, I think. The noise contributions of 1 k carbon film resistors is about 50 nanovolts, metal film 40 nanovolts, wirewound with crimped endcaps 30-10 nanovolts, and wirewound with welded ends 10 nanovolts. This from p 277, John Linsey Hood's 'Art of Linear Electronics', 1993. Compare with this the low noise circuit by Jim Williams in Linear Technology's Applications guide, 1987, which parallelled three LTC 1028s (their quietest) to an get extra low noise level of 30 nanovolts. Thus we can barely see the inherent noise from a carbon film resistor, even with such a low noise circuit. An op amp like the OPA 111, which is a precision low bias current JFET input device has a noise level of a few microvolts, so with this you would never see the noise in a carbon film I think. The main objections to carbon would then be thermal drift and matching accuracy. At any rate, you want to put your best efforts into the front end where the signal comes in and where noise and drift get in before the signal is amplified so that less demanding electronics can take over. John Hood's book is particularly excellent at discussing the important topic of the inherent properties of individual components and how this physics relates to front end design. **************************************************************************** Recently a retiring professor friend at the University of Texas gave me his copy of 'Building Scientific Apparatus', 1983, by Moore, Davis, and Coplan. Its a great book for science hacking, and reasonably up to date as the second best book that I know about. The best, the standard old classic in the field of homebrew scientific instrumentation in my opinion, is John Strong's 'Procedures in experimental Physics', published in the thirties, I think. Back in that era, everyone tended to build their own equipment, and Strong told you exactly what you needed to know to do it right and all the pitfalls using easily accessible equipment and materials. Another classic in the field of homebrew instrumentation is Robert W. Wood's 'Experimental Optics'. An interesting fellow who roamed the world, and settled down at John Hopkin's University some time around the turn of the century. He invented the spinning parabolic mercury mirror, the quartz ultrasonic generator, and many useful methods and techniques in optics. Wood had the knack of building amazingly sophisticated optical instrumentation with odds and ends and he explains how to duplicate everything yourself in exceptionally well-written detail. --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: PR for Gulf Islands earthquake] Date: Mon, 27 Apr 1998 10:29:28 -0700 FYI -- ---/---- Charles P. Watson Seismo-Watch From: Robert L Barns <75612.2635@..............> Subject: Resistors, Fleas, Illusions and Op-Amps Date: Mon, 27 Apr 1998 15:35:44 -0400 Meridith, Sorry, there will be no more 'grams from that tiltmeter--it has been returned to Scolnik and he is using it to observe the tilt of a massive pier on which one of his high precision pendulum clocks is mounted. Maybe you could borrow Sean-Thomas' device and try it. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 1998 13:12:10 -0700 You can buy a used proton magnetometer from R.T. Clark, 405-751-9696 that ubiquitious purveyor of used geophysical instruments including geophones and drum recorders. Probably they won't be cheap enough to tempt you, but there should be more out there with the Cesium mags catching on. As far as schematics, the proton mags haven't really changed much in the last 30 years. Phase lock loops and counters are still phase lock loops and counters. Sure, now you can measure the period instead of the frequency and convert it to gammas (oops, nanoTeslas) with an embedded microprocessor, but so what? The paradigm shift has been to the Cesium mags which are a whole new ball game. I'm sure the geophysics department at the University of Alaska has an old G-816 knocking around, did you take a look at it? -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 Bob Hammond (USGS-AVO Geophysicist) wrote: > > Do any of you have schematics for building a proton-precession magnetometer? > I'm aware of the Sci Am article from 1968 on building such but wonder if there is anything newer (ie, digital)? > > Or, do any of you have leads on a used Geometrics proton-precession magnetometer for sale or trade? > > thanks, > > Bob Hammond > APSN > Fairbanks > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David Josephson Subject: Re: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 1998 13:42:50 -0700 (PDT) > Or, do any of you have leads on a used Geometrics proton-precession magnetometer > for sale or trade? Suggest calling Ross Johnson at Geometrics, see if he can put together a kit of pieces for an 801 (with tweaking, good to about 0.25 nT) or something newer. This would be called a "base station magnetometer" in their parlance, so sensor heading error would not be an issue. 1-408-954-0522 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David Josephson Subject: Re: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 1998 13:48:04 -0700 (PDT) Doug Crice wrote > As far as schematics, the proton mags haven't really changed much in the > last 30 years. Phase lock loops and counters are still phase lock loops > and counters. Sure, now you can measure the period instead of the > frequency and convert it to gammas (oops, nanoTeslas) with an embedded > microprocessor, but so what? The paradigm shift has been to the Cesium > mags which are a whole new ball game. That's all true, but for the frequency band of interest (0.001 - 0.1 Hz, if you take the conventional view) a good proton mag is almost as good. But I think if I were going to build one from scratch, it would indeed be a cesium mag; the electronics are much simpler. Maybe Al would give me back that cesium sensor. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: juggie@................... (Nick Tile) Subject: Re: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 98 21:49 BST-1 In-Reply-To: <199804271702.JAA10806@kiska> Bob, There was a cct for a Proton Precession magnetometer published in a UK electronics journal nearly 20 years ago (Practical Electronics) - you could try phoning them on 1202 841 692, or e-mailing them on: editorial@...................... or visiting their web site: http///www.epemag.wimborne.co.uk. I can't recall the details, but I do recall that it was very large, very cumbersome and involved walking around with two coils, one on each end of a long pole :-) If you want to build a maggie, you could try a search on the web for the FGM-X series of chips and sensors from Speake 1873 811 281, or 1873 810 958 (fax) - they also have an american distributor who is on the web, (Bill Speake isn't YET )and has all their spec sheets and data sheets zipped up in downloadable form - I have a simple Maggie of theirs sitting in here now, showing that things are reasonably quiet, but a couple of days ago they weren't. Nick, Colchester, England _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Erich F. Kern" Subject: Re: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 1998 15:06:09 -0700 Hello, Speake & Co. has a U.S. distributor (yours truly). The data sheets, application notes and price list may be downloaded from our web site at: http://www.dconn.com/fatquarterssoftware When you visit this site, there's a link to Darrel Emerson's web site which will be of interest to those monitoring solar activity. Darrel's posted some very good plots of the geomagnetic field as detected with the Speake sensors and comparison plots from the Tucson Magnetic Observatory during the same 3 day period. Best Regards, Erich Kern ---------- > From: Nick Tile > To: psn-l@............. > Cc: juggie@................... > Subject: Re: Proton Precession Magnetometer circuits > Date: Monday, April 27, 1998 14:00 > > In-Reply-To: <199804271702.JAA10806@kiska> > > If you want to build a maggie, you could try a search on the web for the > FGM-X series of chips and sensors from Speake 1873 811 281, or 1873 810 > 958 (fax) - they also have an american distributor who is on the web, > (Bill Speake isn't YET )and has all their spec sheets and data sheets > zipped up in downloadable form - I have a simple Maggie of theirs sitting > in here now, showing that things are reasonably quiet, but a couple of > days ago they weren't. > > Nick, Colchester, England _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: WARNING: POTENTIAL MAJOR SOLAR FLARE WARNING - 27 APRIL] Date: Mon, 27 Apr 1998 16:17:48 -0700 Looks like it is time to rock 'n roll! -- ---/---- Charles P. Watson Seismo-Watch From: S-T Morrissey Subject: equalization noise etc. Date: Mon, 27 Apr 1998 18:22:03 -0500 (CDT) Albert, Roger, and co. Albert, Thanks for the discussion and calculations of the parameters for equalizer circuits, And putting 2 and 2 together, the timely review of resistor construction and typical noise levels by Roger is definitely appreciated. I would like to again suggest the article "Limits of Sensitivity of Inertial Seismometers with Velocity Transducers and Electronic Amplifiers" by M.A.Riedesel, R.D.Moore, and J.A.Orcutt; (BSSA, Vol 80, No. 6; pp1725-1752, December 1990). [ with the observation that the axis of Figure 3 should be "ohms" and not "frequency"]. This paper gathers all four of our concerns (amplifiers, resistors, seismometers and earth noise ) into a single discussion, with lots of experimental data. While the paper doesn't touch directly on the equalization question, it can provide some insights. The seismometer/amplifier noise figures can suggest the noise we will have to deal with in an equalizer with a total gain of 100 to 400, even with an optimal match between the seismometer coil R and the amplifier input characteristics. It also shows that to "equalize" a 4.5hz phone to the output level of an L4C at 1 hz requires an overall gain of over 10 000, even with high impedance coils. Figure 14 shows that the coherence between a 4.5 hz phone and the L4C will be very poor, like 0.3, at 1 hz because of noise considerations alone. Equalization will not change this, but actually adds to the noise, and the coherence is about the same, which we have confirmed here. this explains why we have had noise problems with our equalizer circuit evaluations, especially in the 1 to 10 second range, where we see 2 to 8 mv of noise, and much more if we look too closely and actually breathe on the input amplifier and resistors, an effect that someone mentioned recently. Regards, Sean-Thomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Instrumentation Date: Mon, 27 Apr 1998 16:40:37 -0700 To All As I was screwing the Aluminum portion of my sensor to the Brass Portion I began to wonder about the temperature sensitive potential that may be generated by the bymetal mechanical connection. Could it act like a thermocouple? I run my ground thru the composite boom from the displacement sensor to the amp. It saves me one wire and grounds the entire sensor. Am I developing a slight potential between ground and each connection? Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464 Subject: Book Availability Date: Mon, 27 Apr 1998 23:14:28 EDT Hello PSN Netizens (do you like that word?), Do I remember correctly, but did someone a few weeks ago say that they had difficulty in trying to locate a copy of Bruce Bolt's book titled Earthquakes and Geological Discovery? I came across 4 copies of it on the book shelf in the gift shop of the Nevada State Museum in Carson City, Nv a few days ago, their price was $32 each. I hope this helps someone. Allan Coleman, Edmonds, Washington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Quake alert by e-mail to pager? Date: Mon, 27 Apr 1998 22:01:47 -0700 (PDT) A new version of EMON is in the works. One new feature is the ability to execute a BAT file or command (EXE) when a quake file is saved. Since I got this new pager that lets people page me via e-mail, I wondered if there was any way to have a PC compose a message, dial a phone number, send an e-mail message and hang up. I suppose it would have to use an existing ISP account (like this one on netcom). This way the PC could page me if a large quake was recorded. I'm sure someone has tried this before, so if you have ideas you want to share with the group, or send me via private mail, I'd appreciate it. The new version also supports BAT/EXE file execution on a scheduled basis. For instance, if you want to run a BAT file to set your clock by dialing a time service every Sunday at 2:00 am, you can now tell EMON to do that. Up to two separate events can be scheduled in addition to the one which is performed after a quake file is saved. If anyone wants to try out the new version, let me know and I'll send a copy. It's been running for a week on my system. I'm also adding support for a new A/D card for Alby Judge, which is just about ready, just needs some testing. :-) Ted _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Proton Precession Magnetometer circuits Date: Mon, 27 Apr 1998 22:11:02 -0700 David Josephson said: >That's all true, but for the frequency band of interest (0.001 - 0.1 Hz, if you take the >conventional view) a good proton mag is almost as good. But I think if I were going to >build one from scratch, it would indeed be a cesium mag; the electronics ar e much simpler. >Maybe Al would give me back that cesium sensor. Sure the electronics may be simple, but blowing a glass cesium sensor is right up there with building superconducting gravimeters on the difficulty scale. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: FFT, grounds, etc Date: Tue, 28 Apr 1998 00:34:32 -0500 (CDT) Barry, I am still puzzling over your question of Apr 24 about high pass filtering of the VBB data, especially at the "natural frequency" of the sensor. Do you mean the mechanical period, or the electronic VBB period? I'm not sure what you are seeeing for the FFT. Is it a true FFT or a Power Spectral Density (PSD)? Regarding the high pass: I use a single pole far removed from the instrument response to remove the near DC data/drift from my recording. The corner is at 1000 seconds. In the plot of the PSD of the calibration step, this results in a steeper slope at the long period response. The slightly higher response near To of my step calibration is because I failed to adjust the Rp or damping resistor when I changed the mechanical period from 2 to 4 seconds, and the VBB response was under damped. Actually, the calibration step only gives the shape of the response. Playing with the math of it only backs out the value of Rp. The only way to truly calibrate the VBB instrument is with a tilt table. Fortunately, knowlege of the mechanical and feedback parameters yields a fairly accurate determination of the response via the transfer function. Regarding your concern today about grounding with dissimilar metals: it all just becomes part of the picture. If the connections are clean and low resistance, the slight EMFs aren't enough to worry about. I very frequently ground aluminum with copper or brass ground lugs. I am curious about your mention of a composite boom. My table of general coefficients of materials generally lists resin-based synthetics as having high thermal coefficients. Like formica is 170 (ppm/ degC), plexiglass is 90, etc,; whereas aluminum is 28, brass is 20, and iron is 12, etc. Maybe you are using a special composite or one with a high coefficient to counteract thermal problems? Regards, Sean-Thomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: STM-8 vrdt matching Date: Mon, 27 Apr 1998 23:37:05 -0600 S-T Morrissey wrote: > > > Since the VBB output signal IS in fact the output of the > displacement detector, that is where we have to be concerned > about electronic noise and drift. But thermal/mechanical noises > in the detector itself can be of equal concern. Fortunately, > the VRDT has such a large output (50 to 100 mv/micron with > a 2mm range), we have lots of signal to work with, so we > are well ahead of the electronic noise. > > But the VRDT, unfortunately, IS a "wirewond" device, so it > does have a real temperature problem, especially if the two > coils are not very carefully matched (for inductance AND > resistance) before it is assembled. "Hand winding" the coils > of a VRDT or an LVDT is especially demanding in this respect. > Temperature compensation of the VRDT can be done by paralling > the coils with a differential thermistor bridge, or shunting > one coil with an appropriately thermal responsive resistor. > > Regards, > Sean-Thomas > Sean-Thomas, The xfmrers or potential vrdt's I have experience with, most fall with a nice narrow range of like 212 to 225 ohms; with the majority (7) in the 217 ohm setting out of a bunch of some 20. This was a nice surprise. Its easier to match the total resistance than the inductance by far. Of the 7, there were only 2 close inductance matchs of .1mh and another of .2mh, of the 7 total available. The primary would usually range around 4.7 to 5.1mh, and the secondary would range around 58.2 to 60.0mh. An exact match would either be luck of the draw or buying a greater number of the Mouser transformers to convert. This was done with the 14 E core laminations in the coils. I was never successful in squeezing in more than 14 in any coil. I suppose the vrdt is alot like my Sprengnether coils in the sense that it is the most valuable part of the whole unit....replacing them is a very tough deal. Any more tips or tricks, or a reasonable inductance range of match other than perfect? I don't know... Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Resistors & Magnetic Spring Date: Mon, 27 Apr 1998 23:46:32 -0600 Roger, Thanks for the resistor and assorted reference information. Looks like I do have some ~ 10 nanovolt noise wire wounds..wouldn't have found out otherwise probably. Also, I found a round brass weight and by hand juggling it, I could get a more first hand (ha), picture of your magnetic spring device. The combined weight of the brass and magnets mass, came to a lifted weight of about 4 & 1/2 pounds I figure per bathroom scale. Parlor type appreciation approach, but interesting anyway. Makes me wonder how the Sprengnether model approach was done? Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond Subject: Re: Quake alert by e-mail to pager? Date: Tue, 28 Apr 1998 02:50:53 -0500 Ted, >A new version of EMON is in the works. One new feature is the ability to >execute a BAT file or command (EXE) when a quake file is saved. Since I >got this new pager that lets people page me via e-mail, I wondered if >there was any way to have a PC compose a message, dial a phone number, >send an e-mail message and hang up. I suppose it would have to use an >existing ISP account (like this one on netcom). This way the PC could >page me if a large quake was recorded. > >I'm sure someone has tried this before, so if you have ideas you want to >share with the group, or send me via private mail, I'd appreciate it. Exciting new features in your wonderful program! The folks at CERI are paged in a similar way when a big quake occurs, or one in the New Madrid area. I don't know the specifics of how the system is triggered, but could find you a contact there if you want any additional info. Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: equalization noise etc. Date: Tue, 28 Apr 1998 08:09:25 +0100 S-T Morrissey wrote: . It also shows that > to "equalize" a 4.5hz phone to the output level of an L4C at > 1 hz requires an overall gain of over 10 000, even with > high impedance coils. Hi Sean, I really hesitate to bother you....you seem to spend all your time answering questions on PSN! BUT, my calculations for a 4.5Hz seismo equalised to 1Hz gives an RC value=.318, and an OVERALL amplification of only 79 !! ........using the article by Peter Roberts in American Seismology bulletin, which I posted on PSN yesterday. How does this very LOW figure square with your 10,000 above??? I can well understand noise problems with gains of 10,000, but the Robert's cct. doesn't require such large values, EVEN WHEN equalising down by a x10 factor...(your own 4.5 - 1 is less than x5.) I realise my magnet experiment was unscientific (turning it slowly back and forth), but it did show nice o/p at 60secs, which the other unequalised beam didn't have, and no noise, even with 741's!! Now I know that, once again, I've got hold of the "wrong end of the beam somewhere".......but know not, I. Regards Albert Noble (England) > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: "Quakes" program on Discover Channel Date: Tue, 28 Apr 1998 07:42:56 -0700 (PDT) Last Sunday night Discovery Channel broadcast their program "Quakes". It has a lot of footage taken during quakes, the typical pans and scans of post-quake damage, plenty of footage of burning buildings, etc. However the hightlight was when they were visiting Waverly Person at the NEIC. You see him on tape excitedly pointing to each of a bank of drum recorders as a quake rolls in, saying "Here's the P wave on this one, and here's the P wave over here, we don't even know where this one is yet..." It's clear this is not rehearsed. There's a little bit of animation of plate movement but overall it's pretty weak on the science part in my opinion. Anyway, if anyone would like a copy just send me a tape and a paid return mailer and I'll copy it for you. 954 Foxswallow Ct., San Jose, California 95120. Ted Blank Please allow 4-6 weeks for delivery. Offer not valid where taxed. You may have other rights which vary from state to state. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Quake alert by e-mail to pager? Date: Tue, 28 Apr 1998 08:28:40 -0700 Ted -- My Internet Service Provider has a service (for a fee) that will forward email messages to an alphanumeric pager. I don't know any details, but you might check with your ISP. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... You wrote: >Since I >got this new pager that lets people page me via e-mail, I wondered if >there was any way to have a PC compose a message, dial a phone number, >send an e-mail message and hang up. I suppose it would have to use an >existing ISP account (like this one on netcom). This way the PC could >page me if a large quake was recorded. > >I'm sure someone has tried this before, so if you have ideas you want to >share with the group, or send me via private mail, I'd appreciate it. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JHammes@......................... Subject: Re: Book Availability Date: Tue, 28 Apr 1998 08:47:34 -0700 Regarding Bolt's book: it's available from www.amazon.com for $24. Jerry Hammes Palo Alto, California ______________________________ Reply Separator _________________________________ Subject: Book Availability Author: PSN-L Mailing List at CCSMTP Date: 4/27/98 11:14 PM Hello PSN Netizens (do you like that word?), Do I remember correctly, but did someone a few weeks ago say that they had difficulty in trying to locate a copy of Bruce Bolt's book titled Earthquakes and Geological Discovery? I came across 4 copies of it on the book shelf in the gift shop of the Nevada State Museum in Carson City, Nv a few days ago, their price was $32 each. I hope this helps someone. Allan Coleman, Edmonds, Washington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Magnetic Spring Thought Date: Tue, 28 Apr 1998 10:10:12 -0600 Roger Baker, Have a thought for your magnetic spring device. There are obviously mass center magnetic twisting torques when using your flat edge donut magnets per your initial device. Placement of material has to be somewhat adjusted around these by slideing your razor pivot or the positioning of the lifting magnets. How about the use of upward curved magnets (surplus motor magnets) for the lift; and, say a round bar magnet for the mass of appropriate length and diameter? I'am guess that alot of the torque around the mass center would disappear, except of course down toward the pivot direction. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Yet more instrumentation stuff Date: Tue, 28 Apr 1998 13:22:06 -0500 Well Merideth, et al, There's million different arrangements that should work OK. Mine was simple to set up and works too. Its hard to visualize your exact concept. Let me only say that a stiff razor blade with an oiled edge is is awful good at accurately defining an axis of rotation for the beam, when seated on a thin brass sheet with small rare earth magnets behind the brass to hold this edge in light contact. And the damping forces, which are the enemy of sensitivity in this case are very slight, leading to a very high Q mechanical system. The center of gravity of my very short beam does follow a short radius curve of a little over half an inch--in theory --but the force feedback force keeps the boom from moving much at all, assuming feedback power is sufficient to equal the acceleration forces encountered. That is the reason why I used a two ounce lead fishing weight on the beam -- and my wimpy little hundred or so milliwatts of feedback from just one little 324 op amp just isn't enough to completely damp the ringing from ambient urban noise. So anyone who wants to duplicate my setup should probably add more power, and in fact go for it with my blessing!, but I'm primarily interested in other details at the moment. Like what is the limiting sensitivity of my optical detector? Right now I am vibrating a dummy flag with a piezo transducer and am about to use lock-in to see if the sensitivity goes down to a nanometer DC displacement or better. My apparatus has a 20:1 aluminum lever and a micrometer so I can actually calibrate displacement pretty accurately I think. One thousandth inch displacement on the micrometer is somewhat more than one micron displacement of the flag. Then you vibrate the flag with an AC signal and you can compare the two magnitudes of movement. It looks like an AC signal of three volts on the piezo is equal in amplitude to about one micron of flag movement induced by the micrometer/lever. You can see the one micron displacement sine wave on the scope very sharp and clear, and I imagine that one can probably detect one hundredth or thoudsandth of this amplitude. But that may be premature for me to judge. Its best to use the resonant freq of the piezo. By now reducing the AC voltage into the piezo by a factor of one thousand, and seeing if it is still detectable with a lock-in, it should be possible to see if the sensitivity limit really is a nanometer or less. (Another option is a tuned bandpass filter). Lock-ins are tremendous little gadgets to use when you have a captive modulated signal to detect and want to add another decimal point in your favor to a signal to noise ratio. It may turn out that the most sensitive arrangement is to use some form of modulated LED and lock-in arrangement to detect displacement. Anyhow, this should all give me a pretty good feel for the limiting sensitivity of displacement detection setups with an occulted LED/phototransistor combination. Also, it has become apparent that one must accurately align the knife edges to be exactly parallel if diffraction is to be a limiting factor; otherwise the slope of the cutoff curve will be too gradual as a function of displacement. And so on and so forth; blah blah blah... --Yours, Roger At 10:10 AM 4/28/98 -0600, you wrote: >Roger Baker, > >Have a thought for your magnetic spring device. > >There are obviously mass center magnetic twisting torques when >using your flat edge donut magnets per your initial device. Placement >of material has to be somewhat adjusted around these by slideing >your razor pivot or the positioning of the lifting magnets. > >How about the use of upward curved magnets (surplus motor magnets) >for the lift; and, say a round bar magnet for the mass of appropriate >length and diameter? I'am guess that alot of the torque around the >mass center would disappear, except of course down toward the pivot >direction. > >Meredith Lamb > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: more equalization noise Date: Tue, 28 Apr 1998 13:36:44 -0500 (CDT) Albert, I guess I wasn't clear enough. THe gain figure I mentioned is estimated from figure 1 of the Riedesel et al paper., and as I said, it is what is needed to produce the equilavent output of an (their) L4C at 1 hz from a 4.5 hz phone. The gain figure is not just the gain of the equalizer, which in our design (for a corner somewhat greater than 1 second to stay in the more linear portion of the response curve) needs to be 12.33**2, or about 150, but the additional gain needed to get the 1 hz signal level of the equalized 4.5 hz phone up to that of the L4C at 1 hz. The Riedesel study uses special high-impedance coil seismometers, so the L4 output they show in figure 1 is about 800 v/m/sec (I think the Y axis scale of that figure is labeled wrong : it shows a power spectral density, rather than an output voltage due to acceleration). THeir L4 has a 33k ohm coil, and the 4.5 hz L15B has a 960 ohm coil. The output voltage of the L4C at 1 hz is about 10 000 times that of the L15B at 1 hz. I our application, we are targeting the output of a standard 5500 ohm L4C with an output of about 300 V/m/sec, trying to equalize a well over damped HS-1 with an output of about 9.4 V/m/sec at 4.5 hz, or about 0.9 v/m/sec at 1 hz. (I am estimating, since I don't have the figures here). So the equalization flattens the response out to ~1.3 seconds to a level of about 10 v/m/sec, with a total gain of 150. An additional gain of 30 is needed to match the L4C level, for a total gain of 4500. This additional gain can be either after the equalizer, or in a preamp before it. Either way, we have noise problems. They can be lived with for low gain applications, but clearly show up in the data from a 24-bit ADC. BTW: Your rotating magnet is a nice idea to induce a 60-second influence on your seismometer. Could you attach the magnet to the minute hand of an analog clock? One group has calibrated STS-1 sensors by gravitational attraction, by rolling a bowling ball past them on a wooden track. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: more equalization noise Date: Tue, 28 Apr 1998 13:36:44 -0500 (CDT) Albert, I guess I wasn't clear enough. THe gain figure I mentioned is estimated from figure 1 of the Riedesel et al paper., and as I said, it is what is needed to produce the equilavent output of an (their) L4C at 1 hz from a 4.5 hz phone. The gain figure is not just the gain of the equalizer, which in our design (for a corner somewhat greater than 1 second to stay in the more linear portion of the response curve) needs to be 12.33**2, or about 150, but the additional gain needed to get the 1 hz signal level of the equalized 4.5 hz phone up to that of the L4C at 1 hz. The Riedesel study uses special high-impedance coil seismometers, so the L4 output they show in figure 1 is about 800 v/m/sec (I think the Y axis scale of that figure is labeled wrong : it shows a power spectral density, rather than an output voltage due to acceleration). THeir L4 has a 33k ohm coil, and the 4.5 hz L15B has a 960 ohm coil. The output voltage of the L4C at 1 hz is about 10 000 times that of the L15B at 1 hz. I our application, we are targeting the output of a standard 5500 ohm L4C with an output of about 300 V/m/sec, trying to equalize a well over damped HS-1 with an output of about 9.4 V/m/sec at 4.5 hz, or about 0.9 v/m/sec at 1 hz. (I am estimating, since I don't have the figures here). So the equalization flattens the response out to ~1.3 seconds to a level of about 10 v/m/sec, with a total gain of 150. An additional gain of 30 is needed to match the L4C level, for a total gain of 4500. This additional gain can be either after the equalizer, or in a preamp before it. Either way, we have noise problems. They can be lived with for low gain applications, but clearly show up in the data from a 24-bit ADC. BTW: Your rotating magnet is a nice idea to induce a 60-second influence on your seismometer. Could you attach the magnet to the minute hand of an analog clock? One group has calibrated STS-1 sensors by gravitational attraction, by rolling a bowling ball past them on a wooden track. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: RE: Quake alert by e-mail to pager? Date: Tue, 28 Apr 1998 12:31:01 -0700 OK I'll bite...=20 I envision this as having four components:=20 1) Setting the trigger level and triggering. 2) Determining if there is more data (big event can create 8 or 9 event = files). 3) Creating a message and putting it in a sub-directory. 4) Sending the page message. Detail: (1) This is standard feature and already done by EMON. A test will need = to be added at trigger time if a pager message needs to be sent. Test = =3D true? , save the time_save, event_count_V_save, event_count_N_save, = event_count_S_save, go to step #2 =20 =20 (2) To be sure that you don't miss marginal levels of event data from = distant events, EMON needs to keep monitoring for a period after the = data set is saved. You want to be sure you capture event file number = 2~N. This will take some new code. The code would wait looking at buffer = A and B and count the number of discarded buffers. This could be a new = profile option: Number_of_buffers_until_call xx ; This values = can be determined in minutes based on the time it takes your system to = fill buffer A and B. (A value of 10 on my system would be about 30 = minuets.) Test =3D true? value reached. Go do step #3 (3) Format a message for the pager and save it to disk. time_save, = event_count_V_save, event_count_N_save, event_count_S_save taken from = the initial saved values in step #1. Save the formatted message file to = the EMON event file directory in a plan text format under the name = PAGER.TXT. Exit EMON and invoke PAGER.BAT step #4 and Return to EMON = monitoring =20 (4) PAGER.BAT invoke TELIX and uses the script function of TELIX to = dial the pager number and send it the PAGER.TXT file. This is pager = company dependent item, but I have a Skytel pager and sent the message = 174523231235258 (length in bytes time-6,vdata-3,ndata-3,sdata-3) and = the pager formatted it to look like 1-745-232-3123-5258 which worked for = me. We used the Telix script functions in the BBS days and they are easy to = create and dependable as long as you test for things like busy... These are my thoughts-- Comments? Regards, Steve Hammond=20 PSN San Jose, California -----Original Message----- From: Ted Blank [SMTP:tblank@........... Sent: Monday, April 27, 1998 10:02 PM To: psn-l@.............. Subject: Quake alert by e-mail to pager? A new version of EMON is in the works. One new feature is the ability = to=20 execute a BAT file or command (EXE) when a quake file is saved. Since I = got this new pager that lets people page me via e-mail, I wondered if=20 there was any way to have a PC compose a message, dial a phone number,=20 send an e-mail message and hang up. I suppose it would have to use an=20 existing ISP account (like this one on netcom). This way the PC could=20 page me if a large quake was recorded. =20 I'm sure someone has tried this before, so if you have ideas you want to = share with the group, or send me via private mail, I'd appreciate it. The new version also supports BAT/EXE file execution on a scheduled=20 basis. For instance, if you want to run a BAT file to set your clock by = dialing a time service every Sunday at 2:00 am, you can now tell EMON to = do that. Up to two separate events can be scheduled in addition to the=20 one which is performed after a quake file is saved. If anyone wants to try out the new version, let me know and I'll send a=20 copy. It's been running for a week on my system. I'm also adding=20 support for a new A/D card for Alby Judge, which is just about ready,=20 just needs some testing. :-) Ted _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: FFT, grounds, etc Date: Tue, 28 Apr 1998 15:23:47 -0700 Sean Thomas Well let's see if I can explain. My VBB sensor is very much like your configuration; however, I use a capacitor bridge to measure displacement. The output goes thru an instrumentation amp,a 44 hz single pole low pass, and into the triple connection point. The VBB output goes thru a 4700 sec single pole highpass,buffer, 11 hz single pole low pass, 1 sec single pole high pass, and into the output amp/line driver. The reason I included the single pole high pass with a cutoff freq of 1 sec was,in the FFT response to ambient vibration and a local event (250k away) there was an about 12 db/decade increase in response below 1 sec. It was saturating my output. With this slight filtering I was able to get a flatter response at the low end. The following are my MCAD parameters(sorry about the lack of subscripts):r=260900, t=1.7 sec, m=0.35, c=50E-6, rp=5.8E5, ri=1.07E5, rf=8, ti=39, and tn=91. I have heavily thermally insulated the sensor and circuit. I am getting an about 2 vt swing in the mass position output each day, which I attribute to temperature. I plan to set up a controller to measure temperature, time and mass position every hour for the day to get an idea of it's properties. The one other noticeable property of the sensor so far is that the ambient noise has the typical about 6 sec microseisms but also has an equally large 2 hz component(not seen with my Lehman). Could this be the vibration of the leaf spring? I haven't eddy current damped it yet. Barry PS The response I describe above I believe is an FFT which I get from Larry's fine program. My boom is made of the channel you used but the displacement sensor is a brass unit at the end. Finally, I think the unit maybe under damped since if I remember the damping coef is 0.46. Shouldn't it be around 0.7 like the Lehman? With a higher damping coef, the low frequency response drops off at a little higher frequency than with the lower damping. I could increase the ti to correct this. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Quake alert by e-mail to pager? Date: Tue, 28 Apr 1998 17:22:37 -0700 WOW! EMON sounds like a dandy program. Where did you say one could get some more information? -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Barrys' VBB Date: Tue, 28 Apr 1998 20:20:10 -0500 (CDT) Barry, I updated the info for the mathcad response you gave me some time ago, which indeed showed that yout VBB was underdamped at 0.48. Generally zeta should be greater than 0.707 (the critical value). The value of Rp is the principal control of the damping. I tried a value of 270k ohms to raise your damping to about 0.78. (conversely, if you raise Rp to 10meg, your seis will actually oscillate at Tn). But I noticed that the output is quite low at 553v/m/sec. I think it is because your Cp is much too large with respect to your mass of 0.35kg. I tried a value of 24 uf instead, and virtually put the rest of the C in the integrator to lengthen it to 80 seconds, to keep Tn at 90. Then the output just about doubles to 1153 v/m/s. I also changed Rp to 1.0 meg, but left RI to 107k. The damping is about 0.78. Of course, the possibilities are endless. I also use several poles of low pass filtering at about 5 hz to get the cultural (=traffic, my dogs, me, etc.; I have a railroad about 2 km away, and a 8-lane interstate about the same) out of the data. Someday I will put the sensor in the 10meter pit at the experimental seismic station in the back field, and reduce the noise filtering. In the meantime, I got a nice record of the Mblg 4.2 near Oklahoma city this AM (1413z), about 1000 km distant. Maybe some of our Colorado PSN stations recorded it? About your 2 hz noise: it may be real, but vertical, probably cultural, but not seen by your other (horizontal) sensor. My spring rings at a much higher frequency. I am unsure about your 1hz high pass corner. I think it will wipe out your broadband response. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: multiple responses Date: Tue, 28 Apr 1998 21:39:18 -0500 (CDT) Re multiple posts of mail responses: The multiple posts occurr because I don't always notice the multiple addresses in the mail I receive, especially from England. When I use rhe R command to reply, it replies to both addresses. Of course, I also receive multiple notices from the MAILER, but too late. Sorry for the inconvenience. Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464 Subject: Looking for the Best Integrator Date: Tue, 28 Apr 1998 23:17:23 EDT To all the PSN electronic wizzards, I would like someone to help me by answering my questions about integrators, as my knowledge regarding electronics is limited. After experimenting with different electronic integrators, used for converting an acceleration signal to velocity, I am wondering if I have finally found the best type for this particular application. I found that using either the "classic" type integrator circuit or a single pole low pass filter always showed a slight instability of the signal trace. Now using a state variable filter (center freq set at .03 Hz for example) utilizing 3 op-amps, I can pick off the band pass signal for a velocity response (drops off @ -6dB above .03 Hz) or I can pick off the low pass signal for a displacement response (drops off at -12dB above .03 Hz). Either response is much more stable than using other single op-amp designs. Below are my two questions: 1. Is the state variable filter a better circuit to use for a more stable response? 2. What should the "Q" value be, assuming I should use this circuit? Any feedback to my questions would be appreciated. Allan Coleman, Edmonds, Washington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: quake detectors? Date: Wed, 29 Apr 1998 00:19:30 -0500 (CDT) I have heard, recently, of an alarm, much like a smoke detector, that can be installed in someone's home to warn them of an impending quake. I think that is gives something like 30 seconds warning before the quake strikes. If this is available, where would I be able to learn more about it? I am also wondering how it would differentia between the vibration of a truck going by as opposed to a very minor quake. Interesting. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: more equalization noise Date: Wed, 29 Apr 1998 07:35:44 +0100 S-T Morrissey wrote: > > > I guess I wasn't clear enough. THe gain figure I mentioned is > estimated from figure 1 of the Riedesel et al paper., Hi Sean, It seems that we are talking at cross purposes, your article and the one I refered to by Peter Roberts!! So, I conclude that Robert's cct. was NOT the cause of the noise you refered to in your first comments, when I brought up the subject of Robert's cct., but was caused by Riedesel's designs. > Your rotating magnet is a nice idea to induce a 60-second > influence on your seismometer. Could you attach the magnet > to the minute hand of an analog clock? > One group has calibrated STS-1 sensors by gravitational > attraction, by rolling a bowling ball past them on a wooden > track. As I said, "The things we do for seismology" ........... ......I am going to mount magnet on a stepper motor whose rotational speed be controled by a pot. Then I will be able to examine ALL frequencies from say, 1Hz to .01Hz .etc. Trouble is, were do I get the time to do all these things ?. By the by, you mention in other letter about double posting, and you said, " from England"....I hope that I'm not doing anything wrong this end to cause you this trouble......I HAVE to reply to psn-l@.............. else none of my letters get thro' to PSN (who said,"A damned good thing too" ). Thanks for your time in clarifying the article mix up. Regards Albert Noble (England) > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Live SDR Image WEB PAGE Date: Wed, 29 Apr 1998 07:45:57 +0800 Hi, For a limited time only! My web page now contains a "LIVE camera" image of the display screen running Larry's "SDR" program. My employer is running a open day this sunday with a the "Science Theme" I would be most interested in all comments, from "I hate it" to "I really hate it". Web Page http://iinet.net.au/~ajbv I hope it works!!! Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "DAN SANSON" Subject: Re: Quake alert by e-mail to pager? Date: Tue, 28 Apr 1998 15:34:24 -0700 hello, my name Dan Swanson I am new to group. I have a computer pager program that lets you monitor any pager message it does not need to no the pager ID you can select the pager you want and have its messages re sent to you or as many as you pagers you want . it can also dial different paging companies. it also has a feature that allows you to have five triggered inputs N/C N/O .That will let you send a pre typed message, to alert you of the inputs being triggered. i.e. house alarm- fire alarm- door open- the message can be any length the system transmits POGSAG (over 90 percent of pagers) .alphanumeric message or just numerical message. YOU CAN EVEN MONITOR CAL BERKLEY EARLY SEISMIC PAGER WARRING and resound to you or as many pagers numbers you want to have called. if you want more info please contact Dan -----Original Message----- From: Charlie Rond +ADw-rond+AEA-ceri.memphis.edu+AD4- To: PSN-L Mailing List +ADw-psn-l+AEA-psn.quake.net+AD4- Date: Tuesday, April 28, 1998 12:52 AM Subject: Re: Quake alert by e-mail to pager? +AD4-Ted, +AD4- +AD4APg-A new version of EMON is in the works. One new feature is the ability to +AD4APg-execute a BAT file or command (EXE) when a quake file is saved. Since I +AD4APg-got this new pager that lets people page me via e-mail, I wondered if +AD4APg-there was any way to have a PC compose a message, dial a phone number, +AD4APg-send an e-mail message and hang up. I suppose it would have to use an +AD4APg-existing ISP account (like this one on netcom). This way the PC could +AD4APg-page me if a large quake was recorded. +AD4APg- +AD4APg-I'm sure someone has tried this before, so if you have ideas you want to +AD4APg-share with the group, or send me via private mail, I'd appreciate it. +AD4- +AD4-Exciting new features in your wonderful program+ACE- +AD4-The folks at CERI are paged in a similar way when a big quake occurs, or one +AD4-in the New Madrid area. I don't know the specifics of how the system is +AD4-triggered, but could find you a contact there if you want any additional info. +AD4- +AD4- +AD4- Charlie Rond -+AFw-/+AFw---Public Seismic Network-Memphis +AD4- rond+AEA-ceri.memphis.edu (901) 360-0302 +AFs- free BBS +AF0- +AD4- http://gandlf.ceri.memphis.edu/+AH4-rond http://gandlf.ceri.memphis.edu/+AH4-rond/psn +AD4- +AD4- +AD4AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXw BfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8AXwBfAF8- +AD4- +AD4-Public Seismic Network Mailing List (PSN-L) +AD4- +AD4-To leave this list email listserver+AEA-psn.quake.net with the body of the +AD4-message: leave PSN-L +AD4- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: Quake alert by e-mail to pager? Date: Wed, 29 Apr 1998 06:51:32 -0700 (PDT) The latest version is always on the PSN web page, under Data Acquisition Software. Documentation is available separately or bundled with the code. Ted > > WOW! EMON sounds like a dandy program. > Where did you say one could get some more information? > > -- > ---/---- > Charles P. Watson > Seismo-Watch > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Phil Giannini" Subject: GIF images Date: 29 Apr 1998 07:45:52 -0800 REGARDING GIF images Hi Larry, I sure like the "GIF Image" feature you have added to the recient files list on your web page. It saves a ton of time when comparing traces. You ALWAYS amaze us all with all your great work. Thanks, Phil SFN, SFZ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: Quake alert by e-mail to pager? Date: Wed, 29 Apr 1998 08:34:36 -0700 (PDT) I always think new function is easy until Steve designs it right! :-) Sounds good. I found a pager program (cpager95) which bypasses the need to have an ISP and email account, it dials the toll free number for pager access via modem (most companies have one) and sends a text string to your pager. Numeric if you just have numeric pager. It worked on my skytel alphanumeric pager. You can check it out on the web at www.pager95.com. Dan Swanson: your post didn't tell us how to get in touch with you. Ted _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Looking for the Best Integrator Date: Wed, 29 Apr 1998 08:19:41 -0700 I have used the state-variable, three op-amp filter for years in exploration seismographs, and they are quite stable and dependable. If you set the damping to 0.5 instead of 0.7, then you can use all three outputs simultaneously (lowpass, highpass and bandpass) with the same gains. A damping of 0.5 gives you a little peak at the natural frequency (or if you prefer, a little ripple in the passband) which I guess makes it a Tchebyshev filter instead of a Butterworth. The way to make damping 0.5 is to make all the gain resistors the same value (and of course equal C's), so the design gets really easy and the corner frequency is 1/2piRC and the passband gain is 1 for all functions. If you use a dual pot for R, then you can adjust the frequency. Then, if you sum the lowpass and highpass outputs (with a classic op amp summing circuit), you get a nice stable notch filter. For those low frequencies, you would need some high-impedance op amps and probably some big, high-quality, non-polarized capacitors like they have in most surplus stores. However, it doesn't feel intuitively correct to call this an integrator, nor does this seem like a good way to make one. Integrators need a slope of 6 db/octave, not 12, and even though the bandpass fits that definition for some range of frequency, it seems like a simple op amp with a nice C in the feedback loop and some R to take care of drift would be a better choice. Most introductry op amp books have an integrator early in the text. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Arie Verveer's Live Cam Date: Wed, 29 Apr 1998 10:43:04 -0600 Hi Arie, I think your live cam is the first from the PSN amateur group, and although it is temporary, I would hope it is on long enough to be able to discern some quakes around your area. Hope to reference the site afew times between now and ? shutdown time. I appreciate the cam view and even more, your nice "science discovery attitude", which is great. Understand that the Leonid meteor shower maybe having its best display in the Asian and Pacific Ocean Latitude, with a theoritical maximum around November 18th, 1998. Perhaps the display may be seen there with some intensity. Have you ever checked out any of the number of impact sites in Australia? Being as I'am on the subject of your station and yourself. Your seismometers look to be machine shop origin and very well done. Also liked your display of recent quakes and the refreshing map of the quake location. Perhaps some time, you might like to acqaint us with your area and environmental living conditions. I watch the Australian shows with alot of interest, but don't remember much about the western part. Years back, I remember some excitement in regard to discovery of some living "fossil", type trees somewhere in Eastern Australia, but the location was kept secret for the tree survival. I think they were similar to Pine trees but with a very thick bark, and supposed to have gone extinct some ~ 25 million years ago. Nothing since. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Re: quake detectors? Date: Wed, 29 Apr 1998 11:10:06 -0600 (MDT) The the crafty crafter writes: "I have heard, recently, of an alarm, much like a smoke detector, that can be installed in someone's home to warn them of an impending quake." In my opinion, this sort of device is marginal at best. One problem, as you suggest, is that it can not distinguish between a truck and an earthquake P-phase. It could only give you a 30 s warning if the earthquake were more than about 30*8 = 240 km away, as this is the distance at which the P phase leads the S phase by 30 s. There have been serious attempts at earthquake warning systems, but they are based on having a seismic network near the epicenter to detect the earthquake reliably and then to radio the warning to a more distant point prior to the S-waves arriving. Such as system was set up to warn rescue workers in Oakland of Loma Prieta aftershocks. JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### Geologic Hazards Team, MS966 ############################## PO Box 25046 #############################/############################## ############################/############################### Denver, Colorado 80225-0046 ################################ Phone: (303) 273-8596 ################################## Fax: (303) 273-8600 ################################### lahr@........ ##################################### http://www.aeic.alaska.edu/lahr http://www.lahr.org/john-jan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Just a test Date: Wed, 29 Apr 1998 11:19:18 -0600 (MDT) This is a test to see if I can send Email to psn-l@............. rather than psn-l@............... which has not worked in the past. JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: major solar flare Date: Wed, 29 Apr 1998 15:48:41 -0700 A major class M6.89 flare (large optical flare estimated as a 3B) was observed at 16:37 UTC. It was associated with a major CME (corona mass ejection). If ya all want the alert I received, let me know and I'll send it along. -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: quake detectors? Date: Wed, 29 Apr 1998 21:29:21 -0700 (PDT) Don't they also use the same type of a distant seismic warning system in Mexico City? >The the crafty crafter writes: >"I have heard, recently, of an alarm, much like a smoke detector, that >can be installed in someone's home to warn them of an impending quake." > >In my opinion, this sort of device is marginal at best. One problem, as >you suggest, is that it can not distinguish between a truck and an >earthquake P-phase. It could only give you a 30 s warning if the earthquake >were more than about 30*8 = 240 km away, as this is the distance at which >the P phase leads the S phase by 30 s. > >There have been serious attempts at earthquake warning systems, but they >are based on having a seismic network near the epicenter to detect the >earthquake reliably and then to radio the warning to a more distant >point prior to the S-waves arriving. Such as system was set up to warn >rescue workers in Oakland of Loma Prieta aftershocks. > >JCLahr >################################## John C. Lahr >################################# Seismologist >################################ U.S. Geological Survey >############################### Geologic Hazards Team, MS966 >############################## PO Box 25046 >#############################/############################## >############################/############################### >Denver, Colorado 80225-0046 ################################ > Phone: (303) 273-8596 ################################## > Fax: (303) 273-8600 ################################### > lahr@........ ##################################### > http://www.aeic.alaska.edu/lahr > http://www.lahr.org/john-jan > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: quake detectors? Date: Wed, 29 Apr 1998 22:59:30 -0700 Yes, they do, Frank. It actually works from a series of strong motion detectors within the Sierra Madra del Sur in the Michoacan-Guerrero-Oaxaca States. When a sufficently large quake occurs, it sounds a series of sirens in Mexico City and alerts radio and television station to begin a pre-planned emergency broadcast message. Residents are expected to get between 30 - 150 seconds of warning before the more damaging S-waves arrive. Obviously, that is enough time to do a number off things, including moving to a safer place, close bridges, overpasses and tunnels, and power up the lap top so you could record the temblor before the power goes off. They have had five tests since its instalation a few years ago, two have been failures, but the last two preformed perfectly. There is no question in my mind this kind of system could save lives here in the US and in other places in the world. Yet the social and financial impact of a failure would send the political and business interests into a tissy, thus you may never see this fabulous system deployed. *sigh* I hope it doesn't take us a quake similar to the M8.2 Michoacan earthquake to realize its benifits. -- ---/---- Charles P. watson Seismo-Watch Frank Condon wrote: > > Don't they also use the same type of a distant seismic warning system in > Mexico City? > > >The the crafty crafter writes: > >"I have heard, recently, of an alarm, much like a smoke detector, that > >can be installed in someone's home to warn them of an impending quake." > > > >In my opinion, this sort of device is marginal at best. One problem, as > >you suggest, is that it can not distinguish between a truck and an > >earthquake P-phase. It could only give you a 30 s warning if the earthquake > >were more than about 30*8 = 240 km away, as this is the distance at which > >the P phase leads the S phase by 30 s. > > > >There have been serious attempts at earthquake warning systems, but they > >are based on having a seismic network near the epicenter to detect the > >earthquake reliably and then to radio the warning to a more distant > >point prior to the S-waves arriving. Such as system was set up to warn > >rescue workers in Oakland of Loma Prieta aftershocks. > > > >JCLahr > >################################## John C. Lahr > >################################# Seismologist > >################################ U.S. Geological Survey > >############################### Geologic Hazards Team, MS966 > >############################## PO Box 25046 > >#############################/############################## > >############################/############################### > >Denver, Colorado 80225-0046 ################################ > > Phone: (303) 273-8596 ################################## > > Fax: (303) 273-8600 ################################### > > lahr@........ ##################################### > > http://www.aeic.alaska.edu/lahr > > http://www.lahr.org/john-jan > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: ALERT: MAJOR SOLAR FLARE ALERT - 29 APRIL] Date: Wed, 29 Apr 1998 23:10:56 -0700 Well golly guys, I received a number of request for the recent Solar Alert message, here it is below. BTW You can subscribe to this thing here: http://solar.uleth.ca/solar/www/sublists.html Their main web page is here: http://solar.uleth.ca/solar/ Rather a good find. -- ---/---- Charles P. Watson Seismo-Watch From: watson@................ (Charles Watson) Subject: Solar monitoring lingo guide Date: Wed, 29 Apr 1998 23:13:56 -0700 Oh, almost forgot, for those who need the glossary of solar monitoring terms, try this site: http://www.rnw.nl/realradio/solar.html -- ---/---- Charlie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: quake detectors? Date: Thu, 30 Apr 1998 05:54:13 -0700 Debating earthquake warning systems a litte, My understanding is that Mexico City is a little different than most earthquake country in that relatively distant quakes can cause severe damage. The foundation under Mexico city has a really high ground spectral amplification ratio (read jello) and the buildings fall down easily even from far off events. I don't think it would work (or be of much use) say here in California, where earthquakes far enough away to provide some warning don't cause significant damage. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: quake detectors? Date: Thu, 30 Apr 1998 08:13:21 -0700 Doug Crice wrote: > > My understanding is that Mexico City is a little different than most > earthquake country in that relatively distant quakes can cause severe > damage. The foundation under Mexico city has a really high ground > spectral amplification ratio (read jello) and the buildings fall down > easily even from far off events. > > I don't think it would work (or be of much use) say here in California, > where earthquakes far enough away to provide some warning don't cause > significant damage. To the contrary, the San Francisco Bay Area would be an ideal place for such a distant early warning system. While earthquakes in the mid M7's are rare for the region, they have occurred and would cause significant damage to the populated margins around the bay and in the delta region. Say the Peninsula and Northern segments of the San Andreas fault ruptures with a M7.4. The warning system is sounded and by the time the shock hits, residents of the east and south bays could get sufficently warning to DUCK, COVER and HOLD, or even move to a safer position. Granted, the soil/geologic condition are different than Mexico City but think of the advantages of a few 10's of seconds of warning. -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: quake detectors? Date: Thu, 30 Apr 1998 10:14:42 -0700 I'm not sure if it's good to tie up the net with debates carried on just for the fun, but what the heck-- OK, lets put a good sized earthquake in Marin County. It's about 60 miles or so to San Jose. Let's move the waves at 6 Km/sec. That means the first arrivals get to San Jose in 15 seconds. Now up in hot tub country, we have to detect the earthquake, automatically decide it's really big (without too many false alarms), and send the news to the alarms in San Jose. I guess that would take 5 seconds, so you would have 10 seconds to duck under the table. I guess that's enough time if the person understands what's happening. Of course, he only gets to do in once in his lifetime for real, so you would need monthly rehersals. Of course the real damage is from those rolling surface waves, that get there later. The P waves should actually provide the 10-second warning--did mother nature build in a system for us. Charles Watson wrote: > > > Say the Peninsula and Northern segments of the San Andreas fault ruptures with a M7.4. The warning system is sounded and by t he time the shock hits, > residents of the east and south bays could get sufficently warning to DUCK, COVER and HOLD, or even move to a safer position. > > Granted, the soil/geologic condition are different than Mexico City but > think of the advantages of a few 10's of seconds of warning. > > -- > ---/---- > Charles P. Watson > Seismo-Watch > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: quake detectors? Date: Thu, 30 Apr 1998 11:02:18 -0700 Doug Crice wrote: > <> > I guess that would take 5 seconds, so you would > have 10 seconds to duck under the table. ...or get out of the hot tub. :> -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: quake alarms Date: Thu, 30 Apr 1998 13:29:06 -0500 (CDT) Re quake detectors: A recent report on the Discovery channel describes a short term quake detector system in the SF Bay area that sends an alarm to all the firehouses and automatically opens their doors. When this happens, the firemen jump in their trucks and try to get them out onto the relative safety of the street. At least the doors are not jammed shut by the S-wave energy. I guess the data source is the USGS network; maybe Ed C. or John L. have more detials.?? I have seen several abstracts about very short term warning detectors. There is also an interest on the part of utilities to take preventative measures before communications get disrupted, like closing pipeline valves and isolating power grids. This is clearly a case where 10 seconds can make a difference. And a false alarm is really not a big deal. (Hey, someone close the doors, please!). Whether providing a short term warning to the general population is useful or safe (I tripped getting out of the hot tub and fell back in and drowned because the quake wasn't big enough to slosh all the water out of it!) is debatable. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: ERROR Live "PSN" Date: Thu, 30 Apr 1998 21:29:23 +0800 Hi, An error has been found when updating the "SDR" screen images via the web camera. It turns out that image file name doesn't change during each upload so the browser just calls the last cached image. This results in no updating of the image. For a quick fix, I've created a link to the image file and with the use of your browser's "RELOAD" button, the image should be updated. You'll need to update the web page that calls the link with a once only "reload". Then follow the link and use the reload button. The update time has been shortened to 6 minutes and the length of a drum line is now 1 hour. This gives a maximum of 4 hours on the screen. I'll try to improve the service this Saturday. Thanks for the mail response and please if you find any problems, drop me an email. Eventually something good may come out of this. http://iinet.net.au/~ajbv/ Thanks Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: quake alarms Date: Thu, 30 Apr 1998 13:14:43 -0700 S-T Morrissey wrote: > > Re quake detectors: > > A recent report on the Discovery channel describes a short term > quake detector system in the SF Bay area that sends an alarm > to all the firehouses and automatically opens their doors. > When this happens, the firemen jump in their trucks and try to > get them out onto the relative safety of the street. At least > the doors are not jammed shut by the S-wave energy. > Actually, I think the issue is opening the doors before the power goes off and before they jam from building distortion (both laudable goals). I doubt that the firemen will really move those trucks out fast enough. I remember some years ago when Bob Swain from Kinemetrics was wanting to sell an earthquake alarm for every firehouse (based on the seismic trigger from the SMA-1's). For you folks in St. Louis, here in California we have little earthquake valves to put on your gas line. There's a little ball that jumps off a pedastal and shuts off the gas automatically in response to acceleration. There's some debate among knowledgable users whether it is properly damped to have the right response. Of course, we arn't installing them on existing houses, but probably they are code for new homes. No politician seems to mind increasing the cost of a house for good reasons. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: best integrator Date: Thu, 30 Apr 1998 21:43:22 -0500 (CDT) Allen Re electronic integrators: I can only remark about them in the context of the VBB fedback seismometer. Most of current seismic data recording is of ground velocity. And most methods of analysis integrate velocity to displacement in the digital domain. The integrator used in the triple feedback VBB seismometer must be either a simple inverting configuration, with the capacitor as the feedback, or a non-inverting single pole low pass configuration. The point here is not to make an optimal integrator, but to satisfy the need of the transfer function, which needs a simple integral of the displacement voltage, with the phase response of a single pole. Regarding state-variable configurations: I have never found them particularly better than other filter configurations, which can more specifically address a given problem, like a multipole high pass that has a well constrained transfer function. The choice of the amplifier used can make a big difference. I am not sure what you mean by "more stable" in your discussion. Every amplifier or filter does have some noise present at the output that can be characterized by some peak-to-peak or RMS amplitude at a given frequency, or a power spectrum can describe the composite noise level. regards, Sean-Thomas ps your post was double addressed, so I re-addressed it to avoid duplication. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: watson@................ Date: Fri, 1 May 1998 00:23:59 -0500 (CDT) quake detectors? Hi, I think such a warning system would benefit Los Angeles as well. Much of the soil of the Los Angeles basin is very loose alleuvial soil with some of it having a high water table which could cause liquifaction. This system could give people time to at least go to a safer place--say out of one's kitchen. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: sean@............... Date: Fri, 1 May 1998 00:24:04 -0500 (CDT) quake alarms Hi, speaking of alarms and warnings--I have heard that if a quake were to occur on the San Andreas fault over a five magnitude a warning would be sent out to the public that a larger quake is possible? Also, is the method of A B and C alerts still being used? Has this new warning device been tested in the bay area? Yes, you are right in that ten seconds could make a great deal of difference. One quake caught me as I was making pancakes--not a good place to be. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: JAVA..LIVE PSN...Fixed Date: Fri, 01 May 1998 18:12:49 +0800 Hi, At last it appears the Web camera problem seems to be solved. A Java applet was created that updates the image. So every 6 minutes a new image is sent to the display web page. At the same time the "Java" applet then updates the image every 2 minutes. The upshot is the screen is updated. The whole thing now seems to work well and it even restored itself after a 1 1/2 hours communication failure. If you have used this service before you will need to update your cached web page. All you need to do is enter the display page and press the "Reload" or "Refresh" button. It will take a few moments to load the "Java" applet and the last screen image. From then on the screen will refresh itself. I will work on the screen resolution. After playing around with this sort of thing, it would be easy to a set up a system that would take a snapshot every time an event occurred. Do you think this would be a better option then displaying all the data ? Anyhow its been fun Regards Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Earthquake Alarms Date: Fri, 1 May 1998 09:02:50 -0600 (MDT) I checked with the Northern California Seismic Network folks in Menlo Park on this topic. Apparently there is not an alarm system operating at this time, although the new software that they are using, called "Earthworm, or EW," could be used in this way if the proper sensors were installed along with appropriate outbound communications. JCLahr > Date: Thu, 30 Apr 98 18:32:04 PDT > From: (David Oppenheimer) > To: lahr@.................. > Subject: Re: public inquiry > > Hi John, > > Al forwarded your inquiry to me. I am unaware of any such system in > the SF Bay region. I have no idea where the Discovery Channel got > their information. These ideas have been kicking around for a long > time, and the media will often ask about the possibility of early > warning. However, the NCSN doesn't have the capability. > > The EW software can now rapidly issuing such reports, but to be > reliable it would have to be based on digital acceleration data, and we > would need to have access to a private, dedicated broadcast system that > could blanket the entire SF Bay region. That's not on the horizon, as > far as I can see. > > -David > > > > > From psn-l-return@.............. Thu Apr 30 12:33 MDT 1998 > > Date: Thu, 30 Apr 1998 13:29:06 -0500 (CDT) > > Subject: quake alarms > > Re quake detectors: > > > > A recent report on the Discovery channel describes a short term > > quake detector system in the SF Bay area that sends an alarm > > to all the firehouses and automatically opens their doors. > > When this happens, the firemen jump in their trucks and try to > > get them out onto the relative safety of the street. At least > > the doors are not jammed shut by the S-wave energy. > > > > I guess the data source is the USGS network; maybe Ed C. or > > John L. have more detials.?? I have seen several abstracts > > about very short term warning detectors. There is also an > > interest on the part of utilities to take preventative measures > > before communications get disrupted, like closing pipeline > > valves and isolating power grids. > > > > This is clearly a case where 10 seconds can make a difference. > > And a false alarm is really not a big deal. (Hey, someone close > > the doors, please!). > > > > Whether providing a short term warning to the general population > > is useful or safe (I tripped getting out of the hot tub and > > fell back in and drowned because the quake wasn't big enough to > > slosh all the water out of it!) is debatable. > > > > Regards, > > Sean-Thomas > > > > _____________________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email listserver@............. with the body of the > > message: leave PSN-L > > > > > > ----- End Included Message ----- > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Re: JAVA..LIVE PSN...Fixed Date: Fri, 1 May 1998 09:33:41 -0600 (MDT) Arie, I like your web page real-time seismic display. A nice addition might be something like: Data displayed through xx:xx UT (yy:yy Local Time, Western Australia) Rather than only update the display after a trigger, you could also add the line: Time of last trigger: qq:qq UT JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### Geologic Hazards Team, MS966 ############################## PO Box 25046 #############################/############################## ############################/############################### Denver, Colorado 80225-0046 ################################ Phone: (303) 273-8596 ################################## Fax: (303) 273-8600 ################################### lahr@........ ##################################### http://www.aeic.alaska.edu/lahr http://www.lahr.org/john-jan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: technical info Date: Fri, 1 May 1998 18:16:35 -0500 (CDT) PSN menbers: ALbert has written me about the technical support that I have been trying to provide to the PSN. Here are excerpts: >I have only been on PSN for about 6 months. But >in that time I have noticed that only about 30-40 odd >folk regularly write to PSN. There must be some 200 + >who never say a word! I would guess that many of these >folk are not too interested in the subtle nicities of seismology, >nor do they understand all of the technical talk that goes on. >I certainly don't for one, (my own profession being very much >removed from seismology...that is, before I retired!). > >I believe that many are put off from trying out circuits and ideas, >by technical criticisms made by the seismo profesionals on PSN, >such as yourself, who, altho' are extremely generous in devoting >so much time to answering queries etc., are I believe, possibly >inhibiting some more of us inexperienced, into 'having a go'. .......... >But I now wonder how many have been put off by all this recent >discussion on noise etc.? Most BSSA articles, even if we can get >hold of them, are above our heads, (and back copies are pricey as >well!), >and only add to our inhibitions to build anything...... >all we read of in many cases, are problems and restrictions, and how >an idea is not quite perfect! (What is ever perfect in life? ). .......... > I have had private letters writen to me from some AMERICANS on PSN, >who do not wish to try anything unless proven, so too much about all >the problems associated with a circuit etc. (even tho' TRUE), can be >a 'real show stopper'. > >The recent appeal by me regarding all the abbreviations used on PSN >was another example of how those not fully conversant with them, >can be inhibited still further.....again, an AMERICAN wrote to me, and >thanked me for bringing up this subject on his behalf!! >I wish to emphasise that I was NOT specifically pointing the finger at >you Sean, in this regard, but merely used some of your own abbrevs as >an example..... >...there are VERY MANY on PSN who also use abbrevs which those >of us, less experienced in these fields, cannot fathom. Nor do books >always help in this. ........... >If there is some merit in something, then for them, words to this >effect may get them going, even tho' the drawbacks have been well >chewed over! A good word from someone such as yourself with such >great experience and knowledge, is all that they may need! > >Finally, I take this opportunity to thank you for all the time you >have devoted to answering all the various queries etc. these last >months. I have found it a 'great eye opener', and before PSN, >never realised how much there is to finding out how this old >Earth of ours, moves! My response is: Albert, There are two sides to every discussion, and the case here focuses on what some people want to know in great technical detail compared with what some people don't understand because their interest or background has had a different emphasis. and/or they do not want to try to gain more technical expertise. For the record, I did not get involved in the PSN technical discussions because I have anything to gain by it. I have been aware of the PSN for some time, and only recently got actively involved because of the consistent request that I do so from other professionals that are involved. Their emphasis was specifically on the need for a more technical forum so that some of the PSN who were building/operating instruments could post their questions and get some advice based on experience. I guess my 28 years of building seismic/geophysical instrumentation and running networks, etc., is experience. So I am not doing this for my own entertainment, and especially not for any "ego" value. Quite clearly I have little to gain, although on occassion I have to dig out a reference to refresh my memory. However, if someone posts a technical question, I will address it as professionaly as I would to my colleagues in the field. If this includes references to professional articles, so be it. They can be found in most good libraries, and if a PSN member wants the info, they can get it, but they don't have to either. I have also copied articles for some who have sent a SASE, as if I don't have enough to do. And there just isn't time to explain every abbreviation that might be common parlance within a technical discussion. As for criticizing some of the offerings for new seismometer ideas, I was asked to speak up when something was proposed that was "just too good to be true", but has yet to be shown to produce a record of an earthquake, before too many of the PSN thought that it would eliminate their need or quest for a more proven design. (Notice that I have never chimed in with my opinion, which I obviously must have, about other designs that are in use: the SG, Lehman, etc). Unfortunately, "having a GO at it" doesn't make poor physics work. And there are many ways to make a basic sensor (like take the spring out of an empty Polariod film pack, bend it inside out, fasten a rod about 10 cm long with a couple of ounces of fishing weight, and voila: a 1-second vertical seis; and then there is the one I made with an "erector" set...). The idea of "having a GO at it" also has another side: if the idea hasn't produced any plausible data, so clearly doesn't work, trying it can totally discourage an amateur from trying a more reliable and proven design. And I believe that most PSN members who want to build a seismograph want something that works in a predictable fashion from the start. And actually records earthquakes, rather than just responding to someone walking past it or the nearby freight train. The bottom line of the noise discussions has been to address what ground motion we would like to detect compared with the output of our sensors and amplifiers. I get considerable feedback about the technical discussions, ranging from "nice, I'll try that", to a detailed analysis that finds the flaws in my math. But the PSN cannot be split into separate forums, like one for technical support, one for prediction specualtions (notice that I haven't spoken out about my opinion about this one), solar flares ( nice info, but I erase the mail), the recent short-term warning discussion, the SDR Q and A (quite necessary for those who use it; we obviously have a considerably more complex system in the US National Network, so I don't follow the details that are offered with the SDR mail)., etc., SO all the PSN subscribers have to sort their email per their own preferences, just like I do when I stop by the trashcan on the way in from my postal mailbox. So if I get a consensus that I should stop responding to technical queries, I will do so. I cannot answer each privately; although in fact I often do get repeated questions about the same subject. Since I edit all my email "off line", I can often copy in a previous response. But when there seems to be a wider interest, I respond to the psn-l. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Re: technical info Date: Fri, 1 May 1998 18:20:27 -0600 (MDT) invlo To toss out my two cents worth on the PSN discussions, I think there has been a good mix of topics and levels of technical discussion and I wouldn't have it any other way. Although I'm a seismologist, much of the technical electronics discussion is way over my head and I'm sure I'm often just as lost as Albert -- life is too short to learn about everything. This doesn't bother me, as I expect that those who do understand will work out some good instrumental designs and eventually, when I get around to building a seismometer, I'll just have to carefully follow the "directions" even if I'm often in the same boat as Albert and don't understand all of the components in detail. I hope Roger and anyone else who is inclined to work on their own experimental designs will not be discouraged and will continue to contribute. There are a lot of levels at which seismology and the concepts of seismology can be addressed. Even an instrument that will never measure a teleseism can be useful in a classroom setting, or as an on-scale instrument during strong ground shaking! And who knows where a breakthrough might come from? Sean is developing a "home-built" seismometer that will rival the best commercial instruments in the world today. This, plus his comments based on years of professional experience, are a real asset to the PSN. I was one of those who encouraged him to make his design available to the PSN and I've been amazed at his depth of understanding of instrumental issues and pleased that he's taken the time to answer so many questions. I'm hoping that working with the more technical PSN members has been helpful to Sean also, to clarify the basis for his design as well as review the circuits and components involved. In any case, lets keep up the friendly exchanges and remember, none of us are getting paid for this, so it should be fun! JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### Geologic Hazards Team, MS966 ############################## PO Box 25046 #############################/############################## ############################/############################### Denver, Colorado 80225-0046 ################################ Phone: (303) 273-8596 ################################## Fax: (303) 273-8600 ################################### lahr@........ ##################################### http://www.aeic.alaska.edu/lahr http://www.lahr.org/john-jan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: quake detectors? Date: Fri, 1 May 1998 17:26:08 -0700 (PDT) A recent study reported on TV used a bunch of human-sized dummies which were placed around a building scheduled for demolition. The building was knocked down (can't quite remember how) and then all the dummies (adult and child size) were examined for damage. The most surprising finding was that all the dummies placed under furniture like tables and beds were badly "injured". The ones place next to the same objects were had only slight injuries. They survived in the space next to the crushed table or bed. There was a search/rescue guy quoted as saying that only voids let people survive, which makes sense. So if you Marin-ites can reach the phone from the hot tub and don't mind giving us a call when you feel the shaking, we'd be much obliged down here in San Jose. :-) But I'm getting next to the table, not under it. Ted > > I'm not sure if it's good to tie up the net with debates carried on just > for the fun, but what the heck-- > > OK, lets put a good sized earthquake in Marin County. It's about 60 > miles or so to San Jose. Let's move the waves at 6 Km/sec. That means > the first arrivals get to San Jose in 15 seconds. Now up in hot tub > country, we have to detect the earthquake, automatically decide it's > really big (without too many false alarms), and send the news to the > alarms in San Jose. I guess that would take 5 seconds, so you would > have 10 seconds to duck under the table. I guess that's enough time if > the person understands what's happening. Of course, he only gets to do > in once in his lifetime for real, so you would need monthly rehersals. > > Of course the real damage is from those rolling surface waves, that get > there later. The P waves should actually provide the 10-second > warning--did mother nature build in a system for us. > > Charles Watson wrote: > > > > > > Say the Peninsula and Northern segments of the San Andreas fault ruptures with a M7.4. The warning system is sounded and by the time the shock hits, > > residents of the east and south bays could get sufficently warning to DUCK, COVER and HOLD, or even move to a safer positio n. > > > > Granted, the soil/geologic condition are different than Mexico City but > think of the advantages of a few 10's of seconds of warning. > > > > -- > > ---/---- > > Charles P. Watson > > Seismo-Watch > > > > _____________________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email listserver@............. with the body of the > > message: leave PSN-L > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: PSN members - new book by John McPhee Date: Fri, 1 May 1998 17:41:37 -0700 (PDT) My favorite author bar none is John McPhee. When he got interested in=20 Geology in the early 80's he began writing about the plate tectonic=20 revolution with focus on the lives of scientists who were participants in= =20 the creation of (or sometimes outspoken critics of) the new paradigm. The books are Basin and Range, Rising from the Plains, In Suspect Terrain= =20 and most recently Assembling California. He has just completed a fifth=20 book called Crossing the Craton which completes the series, and all five=20 books have just been published under the title "Annals of the Former=20 World". I cannot recommend these books highly enough. If you have even=20 the slightest interest in basic geology, the plate tectonics revolution,=20 the geologic history of the NA Continent, you can't go wrong. Not to=20 mention that he writes beautifully. When he refers to the industrious=20 Dutch who reclaimed much of their country from the sea as having=20 "borrowed against unrecorded deposits" you realise you are in the hands=20 of a master. Amazon.com has it for $28. Here is a book review: Regards, Ted McPhee began studying the geology of the U.S. 20 years ago, cruising=20 Interstate 80 in the company of geologists and listening intently to=20 their decodings of the rock strata visible in road cuts. What look merely like colorful outcroppings=20 to the uninitiated are actually records of deep time and the stupendous=20 heavings, splittings, and crushings of the earth's crust. A strictly literary guy, McPhee was first= =20 drawn to geology by the poetics of its nomenclature and his love of land,= =20 but he found himself captivated as well by the personalities of the scientists he befriended=20 and soon realized that what he had conceived of as a good idea for a=20 single piece of writing was in fact the subject of a lifetime. He filled four books with accounts of=20 his geological journeys across North America, books now legendary for=20 rendering a technical discipline alluring enough for even the most science-phobic of readers=20 and for elevating creative nonfiction to the level of art: Basin and=20 Range (1981), In Suspect Terrain (1983), Rising from the Plains (1986), and Assembling California=20 (1993). Here he brings those four books, revised and updated, together=20 with one more, previously unpublished geological work, Crossing the Craton, a=20 study of the low-profile country of the heartland. The five volumes=20 together form a portrait of the continent--a magnificent narrative that not only tracks the drama of=20 North American geological history but also chronicles the rapid evolution= =20 of the theories and practice of geology itself and tells the intriguing stories of people for= =20 whom love of rocks has meant love of life.=20 Copyright=A9 1998, American Library Association. All rights reserved=20 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ralvarez@........ (Raul Alvarez) Subject: Re: technical info Date: Fri, 1 May 1998 19:03:16 -0600 (MDT) Hi All, I would like to add my comments to this thread. My thanks to Sean and the other seismo - tech gurus that give so much of their time to help us amateur seismolgist. Please keep up the good work and the information that has and is allowing us to make progress in our experiments with seismometers. Raul Alvarez ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ "My dreams are the seeds of my reality, ~ ~ nurtured in the womb of my soul" ~ ~ RJA, 1985 ~ ~ ~ ~ ~ ~ Raul J. Alvarez ~ ~ La Estrellita Observatory ~ ~ Bellvue, Colorado ~ ~ e-mail ralvarez@........ ~ ~ homepage www.frii.com/~ralvarez ~ ~ "The Renaissance Experimenter" ~ ~ doing research in: ~ ~ Radio and Optical Astronomy, Seismology, Weather, ~ ~ Computers, Instrumentation and Neat Stuff! ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: technical info Date: Fri, 1 May 1998 18:05:25 -0700 (PDT) I am one who must work on electronics in disguise, lest the chips see who is fiddling with them and begin to behave outside the laws of physics as they always seem to do when I approach. Nevertheless I have made my share of idiot mistakes, like trying to get both +12V and -12V out of two 6V batteries (to power the amplifier for my 1979 Lehman). I'm a bit better with mechanical devices, thank goodness. But don't ask me to fix your pacemaker. Fiddling with the Lehman for several years made me appreciate the engineering thought that goes into the design of a professional sensor. Most importantly, each component must be designed 1) to do its job well, 2) not to interfere with any other component trying to do its job well, and of course 3) to tolerate abuse by having a wide range of conditions under which it can continue to do its job well. It is HARD to design home made items that satisfy all three of the above conditions. Change one thing and something else breaks or more insidiously, begins to behave differently without warning. I find this interconnectedness the most frustrating part of actually trying to build something that works, because the non-obvious connections between parts is - well, not obvious. The only payment we all get is satisfaction, and a frustrating experience with recalcitrant parts can keep you off the air for weeks. So when I see the unintelligible babble flying around this list, I pretty much translate it into a satisfying feeling that I will someday benefit from someone's understanding of all these interconnections. I am sure it takes 30 years or so to get a feel for all these connections and be able to design something right the first time. Hopefully a design will pop out which will tolerate mistakes, different materials (type and thickness) and still deliver the signal while throwing away the noise. Even if I forget to wear my mask when I build it. :-) Ted > > invlo > To toss out my two cents worth on the PSN discussions, I think > there has been a good mix of topics and levels of technical > discussion and I wouldn't have it any other way. Although I'm a > seismologist, much of the technical electronics discussion is way > over my head and I'm sure I'm often just as lost as Albert -- > life is too short to learn about everything. This doesn't bother > me, as I expect that those who do understand will work out some good > instrumental designs and eventually, when I get around to building > a seismometer, I'll just have to carefully follow the "directions" > even if I'm often in the same boat as Albert and don't understand > all of the components in detail. > > I hope Roger and anyone else who is inclined to work on their > own experimental designs will not be discouraged and will > continue to contribute. There are a lot of levels at which > seismology and the concepts of seismology can be addressed. > Even an instrument that will never measure a teleseism can > be useful in a classroom setting, or as an on-scale instrument > during strong ground shaking! And who knows where a breakthrough > might come from? > > Sean is developing a "home-built" seismometer that > will rival the best commercial instruments in the world today. > This, plus his comments based on years of professional experience, > are a real asset to the PSN. I was one of those who encouraged him > to make his design available to the PSN and I've been amazed > at his depth of understanding of instrumental issues and > pleased that he's taken the time to answer so many questions. > I'm hoping that working with the more technical PSN members > has been helpful to Sean also, to clarify the basis for his > design as well as review the circuits and components involved. > > In any case, lets keep up the friendly exchanges and remember, > none of us are getting paid for this, so it should be fun! > > JCLahr > ################################## John C. Lahr > ################################# Seismologist > ################################ U.S. Geological Survey > ############################### Geologic Hazards Team, MS966 > ############################## PO Box 25046 > #############################/############################## > ############################/############################### > Denver, Colorado 80225-0046 ################################ > Phone: (303) 273-8596 ################################## > Fax: (303) 273-8600 ################################### > lahr@........ ##################################### > http://www.aeic.alaska.edu/lahr > http://www.lahr.org/john-jan > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: RE: technical info Date: Fri, 1 May 1998 19:23:39 -0700 -----Original Message----- From: S-T Morrissey [SMTP:sean@............ Sent: Friday, May 01, 1998 4:17 PM To: psn-l@............. Subject: technical info PSN menbers: ALbert has written me about the technical support that I have been trying to provide to the PSN. Here are excerpts: >I have only been on PSN for about 6 months. But >in that time I have noticed that only about 30-40 odd >folk regularly write to PSN. There must be some 200 + >who never say a word! I would guess that many of these >folk are not too interested in the subtle nicities of seismology, >nor do they understand all of the technical talk that goes on. >I certainly don't for one, (my own profession being very much >removed from seismology...that is, before I retired!). > Snip Snip I've been in the group from the start. (It started in my kitchen in 1990 = on a January Saturday morning) The PSN is a group with a lot of = different people and interests. We all share an interest in seismology = or other science. That's what makes it such a great group-- There are a = lot of folks out there that work 70-80 hours a week and read along as = the weeks go by. That doesn't mean they are not taking part... = Sometimes, you see real genius and some times you see somebody trying to = learn something new. I feel that if you got something to say, = contribute-- If you got a question, ask it-- If you just feel like = reading along, then keep on reading... Remember the laws of the PSN-- = there are no laws of the PSN other then to not have more than one = meeting a year, and never ever elect any officials. That's my 2C worth. = Have a great day. Regards, Steve Hammond PSN San Jose From: Kees Verbeek Subject: RE: technical info Date: Sat, 2 May 1998 05:31:47 +0200 (CEST) Hi all , Just my thoughts about the subject, Most of the information on this newsgroup is to much for me , But because every day reading the mails i've learned a lot off things . I just pick out the things i'm interested in . I like to learn from people who made there seismograph from some tape and good luck and also people who are very profesionel. Every day there is great information from and for all . I hope we can keep it that way.!!!!!! I hope nobody is afraid to tell his "story" So we all can learn and do all the "strange" things we just like to do. I think this P.S.N. group is a very good example for all. many greetings , Kees Verbeek ,Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Chuck Erickson Subject: Re: technical info Date: Fri, 01 May 1998 20:35:48 -0700 I, too, want to add my two cents to this thread. I relish reading each of the technical discussions/explanations that we find here on PSN-L. I especially want to thank Sean-Thomas for the significant amount of time he spends answering questions and giving us the benefit of his vast experience. Having the likes of Steve Hammond, Larry Cochrane, John Lahr, Ted Blank, Charles Young and all the other experienced gurus as regular contributors to these discussions makes every login a worthwhile learning experience. I am assembling the stuff to build a STM-8 and am close to finishing a S-G design (which I might modify to use ST's VRDT sensor). Were it not for the discussions here I would not be as enthusiastic and motivated to proceed!! And, I have been delightfully diverted by the magnetometer references and notes recently - another "score" for PSN-L in my book. So my vote as a silent reader is to keep up the good flow of information. And my bookshelf is looking a lot better now that the dust is off my amplifier and filter design books. Chuck Erickson Saratoga, CA Emailto: cee@............. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: technical info Date: Fri, 01 May 1998 22:32:41 -0500 Some of my rambling thoughts on the subject. I guess I am one of the persons guilty of creating some of the electro techno bable. For the most part I work and play with highly technical people so it is hard for me to remember that others are intimidated by techno talk. Back in the days when I did such things, a group of us have been know to empty a bar with a highly technical discussion :) I joined this list a couple of years ago in hopes of finding just the sort of information that has been discussed in recent weeks. Sean's knowledge of the requirements for a good seismograph design have really enabled me to feel confident that I can design and build an instrument that will work to my satisfaction. Sean's STM-8 represents a major increase in performance over many if not all of the other homebuilt seismographs. Anyone can build the STM-8 without knowing the technical details involved in it's design. So don't be afraid to build one even if you don't begin to understand the basis of it's design. The 150 or so members of this list who do not frequently post messages may be just sitting back absorbing the information that is flowing. I subscribe to three other similar lists and I don't post much to them but I do read the interesting stuff and delete the rest. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464 Subject: Re: Looking for the Best Integrator Date: Fri, 1 May 1998 23:58:38 EDT To Sean-Thomas and Doug, Thank you gentlemen for answering my questions regarding integrator designs. Your inputs made me go back and review my earlier integrator designs more closely. I eventually found that the velocity signal that I was recording was being influenced by the wrong op-amp selection for a down stream filter and not from a bad integrator design. The result of this poor component selection was a unsable looking signal trace. Now again using a first order low pass filter to integrate the acceleration signal with the components that it was originally configured with, everything is looking like it should. Thank you for responses, Allan Coleman, Edmonds, Washington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: W6JRF Subject: Re: technical info Date: Sat, 2 May 1998 01:11:45 EDT Dear Mr. Morrissey, Please count me as one who enjoys your presentations on the various topics you address. I must admit that, quite often it is miles above my level of knowledge, but then, so too was mans' knowledge of the surface of the moon, until he went there. At times, a topic you addressed tweaked my interest enough to send me to the technical journals and other sources so expand my own knowledge on the topic. Then too, there have been topics in which I had no interest at all, so I just scrolled by them. I, like a lot of others out there do not have a seismograph of my own (yet!), but find the material presented here to be both interesting and fascinating. Bottom line is, please keep it up. If you were to present your facts, postulates and other musings in a private arena, those of us who do not actively participate would lose. Thank you very much. Bob Pietruszka w6jrf@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: tblank@.......... Date: Sat, 2 May 1998 00:41:19 -0500 (CDT) quake detectors? Hi Ted, I found your message very interesting but rather puzzling. Wouldn't the moving furniture and flying objects account for numerous injuries to the dummies? I would imagine that in a demolition of a building there would be displaced objects. Also, how closely does this experiment resemble a real temblor? Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Magnets Mystery Date: Sat, 02 May 1998 00:24:08 -0600 Hi all, Have 4 circular donut magnets and a magnetic jumbo paper clip. When I finger center the paper clip over the hole of the 4 stacked pair, I'am seeing a different reaction as the paper clip is gently lowered in the "pile". Layer 1 thru 2, the paper clip lowest part will attach itself to the inside wall. When it reaches layer 3, it will go to the donut center and with further downward movement, it will again go to the hole wall for the rest of the journey down. Its possible to adjust the depth mechanically and see the paper clip hanging there non-attached to the magnet wall with only a wire holding the paper clip from going further inward. The inward pull is of course significant. I think I'am seeing a type of paper clip assumed magnetization and a repulsion effect. The "curvelinear effect", with the 3rd layer, suggests possibilities of a vertical mass mechanical amplification device, i.e., light, etc, or, even as a vertical or horizontal device in itself, with critical added weights on the end of the paper clip "plunger". No good for long period, but who knows any other use if any? Trying other metals of various lengths, so far has not yielded the same effect and suggests that the length of the "plunger", is critical. I have no smaller donut magnets and clips to compare. The magnets I used are 3.375" in diameter, 1.270" inside diameter hole and .425" thick. The paper clip is a "jumbo" size 1.975" long by some .400" width, and the paper clip wire is .050" thick, wrapped in the standard configuration. No answer necessary of course. Parlor toy device for the moment, but interesting. Very heavy doubt on anything new here overall. Thanks, Meredith Lamb P.S., In regard to the Technical Information message, people individually will go only as far as they want to go, but the information itself will nudge the critical ingredient...curiosity ....further along, but only, if its really there to begin with. Keep on nudging away.....gosh knows I really need it-ha. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: technical info Date: Sat, 02 May 1998 07:55:05 +0100 S-T Morrissey wrote: > PSN menbers: > ALbert has written me about the technical support that I have been > trying to provide to the PSN. Hi Sean and others!My letter to you was written privately. As I said in it, that if you didn't agree with my thoughts then you could ignore it. It was not about tech. support but bearing in mind the begginers on PSN from time to time......... Well, my only reason for writing was just to consider the less experienced from time to time! In my letter to you I HAD NO DESIRE, and nor DID I SUGGEST that all the tech discussion be simplified! On the contrary, I enjoy it, as do most folk.... It was just a plea that if there was any merit in a cct. or idea, (and I cited Robert's equalisation cct. as an example,) then you might say that, "this has disadvantages, but has some merit for beginners" etc. This would ensure that the less experienced on PSN could build the Robert's cct. safe in the knowledge that it would work, as you had given it some endorsement.... albeit with reservations. The less experienced would then feel able to 'have a go' at this, knowing that it does work..tho' not perfect. I think that you have been a little unfair to me, as my intentions were SOLELY to bear the less experienced PSNer in mind from time to time. I am very sorry that you don't take my letter in the spirit in which it was intended, maybe I didn't express myself too clearly. I also said that as I live thousands of miles away, I would happily accept your view if you thought, "I should mind my own business!" I can only repeat what some have recently said in reply, that we ALL want your input to PSN, and NOWHERE in my letter did I ever suggest otherwise. Obviously, My own beginners experience is not a reflection of other beginners. I need a little encouragement from time to time, in order to go to the trouble to build something. If tech. talk only mentions the snags and drawbacks, then I am inhibited from, 'having a go!' I cited the Robert's cct. as an example.......I very nearly didn't build it, because I thought that noise would be a problem, and that I was wasting my time on it....also I wasn't quite sure how it all worked, so couldn't really get it going if faulty on completion! Well, as no one agrees with my sentiments, then I MUST be in error.....I accept the democratic vote on this. Again, I am sorry that I ever wrote to you, as I thought that you may have taken my sentiments in a less severe light. I was only trying to help others! In vain it seems....I shall mind my own business in future Regards Albert Noble (England) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: tblank@.......... Date: Sat, 2 May 1998 06:31:58 -0700 (PDT) All good questions, it was the serious "getting squashed" kind of injuries that tended to happen to the dummies under furniture. The ones next to the beds and tables survived in the angular voids made when the ceiling came down and was kept up by the partially crushed furntiture. There's no guarantee, just playing the odds. Ted > > quake detectors? > > Hi Ted, > > I found your message very interesting but rather puzzling. Wouldn't the > moving furniture and flying objects account for numerous injuries to the > dummies? I would imagine that in a demolition of a building there would > be displaced objects. Also, how closely does this experiment resemble a > real temblor? > > > Bonnie > the crafty crafter > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Looking for the Best Integrator Date: Sat, 02 May 1998 07:20:49 -0700 So Allen, if you have one that works, why not post the schematic for the folks on the net. An integrator should be simple enough that you can draw it with ASCII characters. Be sure and mention the frequency range it works over. Sean-Thomas--I appreciate how much time it must take you to respond to these enquirys. Your contribution to the net is priceless. I see you still can't talk without abreviations and acronyms though--I figured out what an SASE was but some won't. Everybody--don't forget that folks in New Zealand, Australia, England and the USA don't speak the same language even though they have common roots. We automatically make allowances for the folks who obviously speak English as a second language, but we forget to when it sounds the same. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: quake detectors Date: Sat, 02 May 1998 07:32:06 -0700 Hey Ted, look at this way. Your walking down the isle of Costco, looking at all the stuff thy have piled three maybe four racks high. Items like canned goods, TV's, bags of BBQ charcole, lawn trackers, etc. And a strong earthquake strikes. The isles jammed with people and the hoards of shoppers at the check out stands break for the exits while the stuff begins to fall. Where would you go? Next to the rack of stuff? Not me, I'd dive under the first open rack I see. That lawn tracker three flights up is a risk I want to avoid and I'd take what ever protection I can get. But tall buildings are different animals. In many of the Northridge and Kobe studies, void space [survival space] in tall buildings was found near the support beams. If a quake strikes while you are in a tall struccture, head for the beams and hope it is one that doesn't shatter and send rebar and concrete through your chest. As the floor above you begins to collapse, watch for the way the beam falls and move with it, watching for the void space. Your right, a desk won't provide you much cover there. Whatever the case, the idea is to THINK first, then ACT; your first move could save your life. Now if I was in that Hot Tub... I just might stay there and watch the world tremble and reach for another Sam Adams. :> -- ---/---- Charles P. Watson Seismo-Watch Ted Blank wrote: > > All good questions, it was the serious "getting squashed" kind of > injuries that tended to happen to the dummies under furniture. The ones > next to the beds and tables survived in the angular voids made when the > ceiling came down and was kept up by the partially crushed furntiture. > There's no guarantee, just playing the odds. > > Ted > > > > > quake detectors? > > > > Hi Ted, > > > > I found your message very interesting but rather puzzling. Wouldn't the > > moving furniture and flying objects account for numerous injuries to the > > dummies? I would imagine that in a demolition of a building there would > > be displaced objects. Also, how closely does this experiment resemble a > > real temblor? > > > > > > Bonnie > > the crafty crafter mail listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Marnie Gannon Subject: Void space survival Date: Sat, 02 May 1998 09:15:01 -0600 Here's an article I found last year on how to survive inside collapsed buildings. When you get to the page, pick tip of the week, then pick collapsed buildings in the earthquake section in the left frame. Good anecdotal evidence from a man who searches for survivors in disasters. He agrees that determining the void space is most important for survival. Smaller objects can be dangerous, but I'd rather fight it out with a 40 pound TV than a two ton ceiling. Marnie http://TheEpicenter.com/tipoweek.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: technical info Date: Sat, 02 May 1998 07:41:00 At 06:16 PM 5/1/98 -0500, you wrote: >PSN menbers: >ALbert has written me about the technical support that I have been >trying to provide to the PSN. Here are excerpts: > I am one of those americans that don't talk much. Not because what is being discused is not interesting or nessary but because I have too many irons in the fire and cannot. I look at all this as data base. If and when I will start constuction on say a VBB I will be able to look at the archives and find all the background on the subject. This group seems to be a group of experamenter and that is what I do. There is an option that maybe some people have not explored. Unsuscribe.... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: more technical info Date: Sat, 2 May 1998 21:01:09 -0500 (CDT) Albert, Regarding your recent PSN post and your concurrent "private letter" to me. I believe I was acting properly in publishing relevant selections (47 lines) of your letter (of 117 lines) to the PSN because, as the excerpts indicate, you were repeatedly claiming to represent the opinion of all the members of the PSN in stating your concerns. Calling it a private letter to criticise me with you as a spokesperson for the PSN just doesn't work. I only omitted the portions that were not related to your criticism. I had no intention to "deliberately mislead" as you assert in your "private letter" today. The fact is that your two statements that you have "no desire to simplify all the tech. discussion" are inconsistent with the rest of your statements, where you want me to believe that the PSN doesn't want an unbiased technical discussion, but some watered down statements that mitigate the actual problems involved. You have accused me of "not very professional conduct"; I believe that if you want me to disseminate half truths, THAT is unprofessional, and I do not do it. If you claim to speak for a majority of the PSN, they should know about it. If you think you have been wronged, you are of course, free to post the entire letter. So I felt that if the PSN was in fact generally not interested and were "put off... by technical criticisms", I should find out from the PSN, and perhaps save myself a lot of time and effort. The inconsistency of your complaints compared with your statements that you "have no wish to simplify all the wonderful discussion" left me wanting to clarify the situation. As I saw it, you want me to 1: provide my professional opinion or experience relating to a technical matter; and 2: you want me to show "lieniency" by changing the facts of the situation so that what is in fact a serious problem with a design could be ignored to the point that someone will expect a performance or response that is unrealistic. Of course, option 2 is not possible for me to do; I will not blow sunshine on something just to make an inexperienced person try it. In your letter today you state: "In life, I have learnt to treat those less knowledgable than myself, with some degree of respect, and certainly with encouragement, and GOOD MANNERS. Apparently, you have yet to learn this lesson." I can only comment that you are entirely out of place in making such a statement. I think the level of and method of my contributions to the PSN speak for themselves. S-T.Morrissey St. Louis. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Mexican Volcanics Date: Sat, 2 May 1998 21:24:26 -0700 (PDT) Hello All: What's the chance of this being a new volcanic vent opening as opposed to=20 what is speculated about in the article? EL AJUSCO, Mexico (CNN) -- Under the shadow of what was thought to be an=20 extinct volcano, a group of peasants watch as scientists in masks and white= =20 coats study a hole in the ground from which pours intense heat.=20 "Imagine a pot of boiling gruel," says one woman. "That's what it looked= like."=20 The peasants are frightened, thinking they are witnessing the emergence of a= =20 new volcano. Or, worse, the beginning of the apocalypse.=20 "I think God has just lost his patience with us," says another woman. "There= =20 have been so many things. You don't think this is another way for God to=20 punish us?"=20 In an improvised cantina near the hole, everyone has an opinion.=20 "It is like you have a gas tank and you just open it up and everything comes= =20 rushing out," a man says.=20 It turns out the world is not coming to an end, and the earth is not spewing= =20 poisonous gases. But in a way, the phenomenon does have a link to volcanic= =20 activity.=20 LAVA TUNNELS TRAPPED HEAT FROM FOREST FIRE=20 About 2,000 years ago, the Iittle volcano erupted, sending rivers of lava=20 down the mountainside. As the lava cooled, it formed a system of tunnels=20 that eventually became covered by soil, grasses and other vegetation.=20 A few weeks ago, a forest fire raged through the area, which is south of=20 Mexico City, and some of the heat it generated was trapped in the lava= tunnels.=20 "We believe the tunnels extend to this area, and the heat they carried=20 started to seep out," says Luis Wintergertz, local director of civil=20 protection.=20 But the authorities wanted to make sure there was nothing else to the heat,= =20 so they used seismographs and radioactivity sensors to rule out any other=20 possibilities.=20 There are still some people living on the mountain, however, who are not=20 convinced. They expect to wake up one morning under the shadow of a new=20 volcano.=20 -------------------=20 MEXICO VOLCANO: POPOCATEPETL=20 As of the 30th of April, it has been reported to SWVRC direct from CENAPRED= =20 that at volcano Popocatepetl, during the last 24 hours, the volcano has=20 stayed stable showing a slight decrease in seismic activity. A very small=20 gas plume could be seen.=20 Regarding the other monitored parameters, no important changes were=20 recorded. The color of the volcanic alarm light stays on yellow.=20 =95 ****=20 Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: tblank@.......... Date: Sun, 3 May 1998 00:01:23 -0500 (CDT) tblank@.......... I wonder if this study will make the quake safety experts re-think what people are told to do during a quake. I can remember that in the '70's it was always sugested that when the shaking starts you head for a doorway. Now, of course, this is discouraged. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: reading new book Date: Sun, 3 May 1998 00:13:09 -0500 (CDT) Hi all, Just wanted to let you know about a book that I am reading. It is called Terra Non Firma by James Gear and Harich Shaw. I believe it was written around 1985. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: Re: more technical info Date: Sun, 03 May 1998 08:55:23 +0100 S-T Morrissey wrote: > Albert, > , you were repeatedly claiming to represent > the opinion of all the members of the PSN in stating your concerns. > Calling it a private letter to criticise me with you as a > spokesperson for the PSN just doesn't work...................... Hi Sean, I did not wish to waste PSN time on this, but I ONLY said,"I believe that many", and "I wonder how many". You are very unfair, once again ,for suggesting that I claim to be a spokesperson for PSN, and that I said "all". I do not speak for PSN, only myself. How could I, having been on it for but 6 months, and living 8,000 miles away? Again, you are showing VERY bad manners. You have not yet had the courtesy to answer ANY of my PRIVATE letters. You should answer me FIRST before publishing to all. That is the polite thing to do. No one else on PSN who I write to privately, does this, even if we are in disagreement. You cannot claim insufficient time, for a SINGLE letter to me explaining your viewpoint, would have taken less time, than the time you expended on your first post to PSN. That would have been the end of the matter! I wrote to you PURELY to, "try and help others"!! You have tried to make me look as tho' I wish to stop all tech. talk. You mislead by not mentioning my own desires, expressed in my letter to you, that I did not wish this...I refered to " All the wonderful tech talk" that goes on in PSN. TWICE I said that I had no wish to see this cease! Obviously, PSN is all about tech discussion, so no one wishes this to cease! I see no inconsistancies with good tech talk, and just now and again saying that something, altho' flawed, does have some merit for the beginner, such as myself. THAT IS ALL I WISHED FOR!!! What is so very wrong with that??? Why do you see the need to bother PSN with all this? Why not answer me privately, please? Why blazen a beginners original request all, 'over the front pages?' Did you not see that my first letter was only well meant? Only to try and help other beginners? I very am very saddened by your attitude towards a beginner, who, only had the best of intentions when writing to you at first, but now finds that he is unjustly accused of trying to suppress tech talk......the very, very LAST thing that I would ever desire! I shall not waste any more PSN time on this, and I look forward to your FIRST private letter to me. (something which, had you done courtesly in the first place, would have avoided all this). But no doubt you will have the very last word on this on PSN, showing everyone, 'How to demolish the beginner, once again ' Saddened (but wiser), Albert Noble (England) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: more technical info Date: Sun, 03 May 1998 02:54:45 -0700 Hi, I was hoping to stay out of this.... Albert, your last post is unacceptable. Sean-Thomas has spent a lot of time responding to our questions. Some of his answers have been very technical, a lot of it above my head!, but I don't expect him, or anyone else, to explain every little thing. If your not sure about something, lookup up in a book or ask for clarification. This is a technical list, and I want to keep it that way. Making a good seismometer is VERY technical thing....People who post info to this list can't be expected to write to the "lowiest common denominator". I hope we can put this thread to rest. Albert, and others, have a good point that we should all remember that there are 270+ members of this list with different backgrounds and English skills. Maybe using abbreviations like SASE (Self Addressed Stamped Envelope) would be better written out, but, and to take it to the other extreme, I don't expect people to us kilometers for km. Enough said.... -Larry Cochrane Redwood City, PSN At 08:55 AM 5/3/98 +0100, Albert Noble wrote: >Hi Sean, >I did not wish to waste PSN time on this, but >I ONLY said,"I believe that many", and "I wonder how many". >You are very unfair, once again ,for suggesting that I claim to be a >spokesperson for PSN, and that I said "all". I do not speak for PSN, >only myself. How could I, having been on it for but 6 months, and >living 8,000 miles away? > [snip] _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: wizard@......... (Rick Jerome) Subject: Re: technical info Date: Sun, 3 May 1998 05:34:37 -0700 Amen I say to that. Hope the discussion doesn't turn into a flame war. How is the new computer coming along? Spring is sprang here. Will have to attempt a visit again. Figure you are having fun there getting everything working. ---------- > I am one of those americans that don't talk much. Not because what is > being discused is not interesting or nessary but because I have too many > irons in the fire and cannot. I look at all this as data base. If and when > I will start constuction on say a VBB I will be able to look at the > archives and find all the background on the subject. This group seems to be > a group of experamenter and that is what I do. There is an option that > maybe some people have not explored. Unsuscribe.... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: prewar Subject: ASCII maths symbols Date: Sun, 03 May 1998 14:26:05 +0100 Hi all, From time to time on PSN various maths formula are discussed. I have never been sure what the correct ASCII codes are. Everyone knows what 'plus' and 'minus' and 'divide' are, but I'm never been sure of others. * means multiply, but is **2 the sq. of a number, and if so is **4 the forth power? Also, how does one write powers to the MINUS roots?? Then how does one write, for example, the sq. root of.........say X squared times Y cubed, then all divided by the sq root of C ?? The answers may be in the PSN archives, but I cannot find them. Maybe others on PSN would also like to know about all the above........can anyone enlighten us all, please? Regards. Albert Noble (England). _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Upgrade: Live PSN Date: Sun, 03 May 1998 22:24:19 +0800 Hi, There is a small possibility that the "Live" PSN page may continue for a little time longer. So armed with all your good suggestions, I'll change its format. Even if the service is discontinued, it was good fun and I think the principal is sound. Hopefully the new page will be finished and look something like this. The continuous display will be stopped and replaced with an immediate updated image of an "Event". The "X" and "Y" scales will be expanded and some timing's will be given. I'll have to work out the time delay between the alarm and the image. Maybe a set of 1 minute pictures while the alarm is on.? There may also be an archive of the last few events. Lets think, what MIGHT happen: Your system goes "BEEP" and with a quick reference to the "Live" page, you may see it arrive in Western Australia. Well, then again. Arie. http://iinet.net.au/~ajbv/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: technical info Date: Sun, 03 May 1998 07:48:48 At 05:34 AM 5/3/98 -0700, you wrote: >Amen I say to that. Hope the discussion doesn't turn into a flame war. How >is the new computer coming along? I sometimes can't help myself. I just had to get my 2 cents in on that one. > >Spring is sprang here. Will have to attempt a visit again. > >Figure you are having fun there getting everything working. Got everything up last weekend. Went though 3 motherboards before I found one that worked. This one is a feetech and seems like a real good one. On the fftdsp problem, It seemed like the system loaded so fast it could not always find the sound card. Taked to cook who could not figure it out eather. I then modified the fftdsp.bat and added mem /c twice to give it time to load the sound card drivers and it works everytime. Don't ask me why. Also got all the drivers loading in dos mode so it works in dos mode too. Been doing some yard work inbetween the rain. Got almost a half inch yeasterday. Have the uhf back up so will try and give you a call, maybe today and have a chat. Did you say you had a crack for cool edit pro. Got to playing with that last night and that is one neat program. Also have the max186 a/d converter going on the laptop. It is event driven but need some refinment on the display. Have been working with jim sky on that. He origanally made that for seismology but will work for radio astro too. The shuttle is going to land this morning and will try to get some meteor trace on that when it goes over. Norm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: ASCII maths symbols Date: Sun, 03 May 1998 08:37:32 -0700 Hi I use programming code to represent math: ((X**2)*(Y**3))/C**.5 or (X^2*Y^3)/C^.5 or even X^2*Y^3*C^-.5 Then how does one write, for example, > the sq. root of.........say X squared times Y cubed, then all divided by > the > sq root of C ?? Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: ASCII maths symbols Date: Sun, 03 May 1998 12:12:12 -0700 (MST) On Sun, 3 May 1998, prewar wrote: > From time to time on PSN various maths formula are discussed. > I have never been sure what the correct ASCII codes are. > Everyone knows what 'plus' and 'minus' and 'divide' are, but I'm > never been sure of others. * means multiply, but is **2 the sq. of a > number, and if so is **4 the forth power? Also, how does one write > powers to the MINUS roots?? Then how does one write, for example, > the sq. root of.........say X squared times Y cubed, then all divided by > the > sq root of C ?? The answers may be in the PSN archives, but I cannot > find them. Maybe others on PSN would also like to know about all > the above........can anyone enlighten us all, please? > > Regards. > > Albert Noble (England). That is a great question. Many people learn their own symbols usually due to the software they use, and how the software reads text. However, there is a standard used on the internet, believe it or not. Here are some examples: sqrt(x) = square root of x x^n = x to the "nth" power [x1,x2,x3] = proper vector notation e^(i*x) = e (the natural number) to the i*x power int(f(x)*dx) = indefinite integral of f(x) with respect to dx int(f(x)*dx){x=a,x=b} = definite integral from a to b dy/dx = Derivative of y with respect to x d/dx(dy/dx) = second derivative dy/dx + dy/dz = partial derivatives (no special symbol) sum(x^n/(n!)){n=0,n=inf} = infinite sum (recognize this one?) grad(f(x,y,z)) = gradient of f(x,y,z) (normally expressed with "del") A.B = dot product A X B = cross product (this one varies; also crossp(A,B)) F(x,y,z) = vector field, capital letter used div(F(x,y,z)) = divergence of F(x,y,z) curl(F(x,y,z) = curl of F(x,y,z) Aij = matrix Aij = [a,b,c] [d,e,f] [g,h,i] Aij*Bkm = product of two matrices Aij.*Bkm = dot multiply Aij.+Bkm = dot add Aij.-Bkm = dot subtract trace(Aij) = trace of matrix (sum of elements) det(Aij) = determinant of matrix trans(Aij) = transpose of matrix Aij^(-1) = inverse of matrix Some others I have seen but do not know if they would be standard: LaPlace(f(t)) = LaPlace transform Fourier(f(t)) = Fourier transform InvLaPlace(f(s)) = Inverse LaPlace Everybody might also be interested to know there is a new html language for math, called MathML. I haven't gotten around to using it, and do not know whether to recommend it or not. Also, about the only good thing that Microsoft Word 7 does is when you use the equation editor on a document you are writing and go to "Save as html..." it will automatically convert the equation to a .gif file. I have also figured out various ways around html problems with math equations by using tables and other tricks. I have been working on a page for a project in one of my classes at ASU titled "Analytic Geometry for Geology." It will be used for students in structural geology in the future as an educational aid. You can see a preview at the following URL: http://www.public.asu.edu/~hernlund/glgmath/ The page is incomplete, so don't e-mail me about broken links or image files that won't load. I plan on finishing it this week, but until then it is still under major construction! If you visit the page, and have any suggestions about additions to the sections I would love to hear them. Also if you find any mistakes please let me know... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek Subject: Quake!!! Date: Mon, 4 May 1998 02:09:53 +0200 (CEST) Hello all, A huge quake is coming in right now!! (also my rough testing-model has a big amplitude) Where? Greetings , Kees verbeek, netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tom Frey Subject: Re: Quake!!! Date: Sun, 03 May 1998 17:15:00 -0700 Here in Washington state also..saturating my system... At 02:09 AM 5/4/98 +0200, you wrote: >Hello all, > >A huge quake is coming in right now!! >(also my rough testing-model has a big amplitude) > >Where? > >Greetings , > >Kees verbeek, netherlands > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: Tsunami warning issued after strong quake hits Okinawa Date: Sun, 3 May 1998 20:23:09 EDT Tsunami warning issued after strong quake hits Okinawa ..c Kyodo News Service TOKYO, May 4 (Kyodo) - A fairly strong earthquake measuring magnitude 7.7 on the open-ended Richter scale jolted several islands in Okinawa Prefecture on Monday morning, prompting the Meteorological Agency to issue a tsunami warning along the coasts of the island prefecture and Kyushu and Shikoku, two of Japan's four major main islands. The agency said the quake occurred at 8:30 a.m. and registered 3 on the Japanese intensity scale of 7 in Miyakojima, Ishigakijima and Yonagunijima islands. The quake's focus was about 20 kilometers below the seabed about 260 km southeast of Ishigakijima, the agency said. AP-NY-05-03-98 2008EDT _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek Subject: Re: Quake!!! Date: Mon, 4 May 1998 02:30:45 +0200 (CEST) At 17:15 3-05-98 -0700, you wrote: >Here in Washington state also..saturating my system... Hi all again, That was the end off my testing -model!!!!! ( IT ALL BROKE DOWN ) this must be a big-one. Greetings Kees Verbeek. Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Magnets Mystery Date: Sun, 03 May 1998 17:49:03 -0700 Hi Meredith, I found your description interesting but too terse for me. Can you elaborate on the magnetic poling of your donut magnets. They sound like they might be speaker magnets which would be poled face-to-face, but if they were for a linear actuator, such as an old disk drive, they will be poled ID to OD. Then after you answer that question, how are they stacked? N to S or opposing, etc. Thanks, Charles R. Patton patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: Quake!!! Date: Mon, 04 May 1998 12:30:23 +1200 At 02:09 AM 5/4/98 +0200, you wrote: >Hello all, A huge quake is coming in right now!! >(also my rough testing-model has a big amplitude) Where? Greetings , >Kees verbeek, netherlands MONSTER looks like Wstrn Pacific or asian continent Tony in Hawaii got it b4 me Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: LIVE: Big Quake on "Live" Camera. Date: Mon, 04 May 1998 10:01:56 +0800 Hi, See LIVE camera image of a big quake. Arie. Http://iinet.net.au/~ajbv/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Live PSN (haemorrhage) Date: Mon, 04 May 1998 10:43:03 +0800 Hi, "Live" PSN has just had a brain haemorrhage. It doesn't seem to handle lots of requests at once. I'll look into it. Wait and see my hand. It will be about 3:15 UT. Next Time. Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: Magnets Mystery Date: Sun, 03 May 1998 21:27:18 -0600 Charles R. Patton wrote: > Hi Meredith, > I found your description interesting but too terse for me. Can > you elaborate on the magnetic poling of your donut magnets. They sound > like they might be speaker magnets which would be poled face-to-face, > but if they were for a linear actuator, such as an old disk drive, they > will be poled ID to OD. Then after you answer that question, how are > they stacked? N to S or opposing, etc. > Thanks, > Charles R. Patton > patton@......... Hi Charles, The magnets are surplus store, and probably quality control rejected speaker ferrite magnets, poled face to face, and stacked N-S-N-S etc. Guessing on the imposed reject label, but their is a very slight outside diameter difference, whereas the inside diameter is more consistent. If you use 3 stacked magnets you see no effect. With 4, their is a repulsion in the 3rd magnet down. With 5 stacked magnets, the repulsion is now the 4th magnet down. With 6 stacked magnets, now it gets more interesting; now the repulsion is still about 1 magnet thickness wide, but it starts the repulsion about in the middle of the 4th magnet and ends in the middle of the 5th magnet thickness. Same paperclip. Floppying magnets around the stack yields same stuff. Other same size paperclips yields same results. Actually, I acted on impulse with receipt of your msg, to check out more magnets in the pile, out of curiosity. Kind of glad I did with the weirder 6th magnet effect...thanks for question. Again....interesting thing....but useful for anything, I really don't know, but I would suspect very doubtful except for that repulsion/ curvelinear (?) field area, which suggests uses. Haven't got into exterranious magnetic influence stuff, adding paper clip non-magnetic weights etc. ............... Thus far, outside of the above, the use of ferrite donut magnets for the use in pickup coils as made a huge jump in appeal too me. I've always been brainwashed into using alnico magnets, but these do a hell of a job, and one can add magnets to increase the gap width and cover the coils used, if desired. Adding a top/bottom plate washer and a center pole bolt for the coil (if possible), is fairly easy to do. Essentially they are speaker type assemblys, but for a magnetic pickup use, the coil has a much larger resistance, smaller wire/gauge. Trouble may brew with using more than 3 stacked magnets? Think I should blame/credit John Lahr, as it all started with his desire to salvage magnetron magnets out of defunct microwave ovens. Never even considered that resource before. Afew days later, out in my alley was one of those critters....and curiosity building thereafter. Uhhh.....2 magnets in each microwave magnetron.....(personal disguises are OK...ha) Decidedly low...tech stuff...that I don't really understand, but interesting nevertheless. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: todays' quake Date: Sun, 3 May 1998 22:55:02 -0500 (CDT) Todays quake info from NEIS: Updated as of Sun May 3 19:10:38 MDT 1998. DATE-(UTC)-TIME LAT LON DEP MAG Q COMMENTS yy/mm/dd hh:mm:ss deg. deg. km 98/05/03 23:30:22 22.49N 125.30E 33.0 7.3Ms B SOUTHEAST OF TAIWAN Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: S-G Sensor & Lehman [was: technical info] Date: Mon, 04 May 1998 01:13:58 -0700 S-T Morrissey wrote: >(Notice that I have never chimed in with my opinion, which I obviously >must have, about other designs that are in use: the SG, Lehman, etc). I for one would like to hear your opinion on the Lehman and S-G design, having both types. I know that both are not perfect, but they do record earthquakes, so be gentle . I myself have problems with the Lehman, it's size is harder to deal with, and mine needs constant adjustments. Other PSN stations have less problems with theirs... I like S-G sensor design. Its much smaller and produces seismograms similar to the Berkeley (BKS STS1?) broadband seismometer that I compare my sensors to. The BKS sensor is the closest broadband sensor I have access to (I have an account on the Berkeley system so I can download data from their sensors), about 41km from me. Todays (5/03) event is another good example of how close the SG sensor can produce seismogram compared to the BKS sensor. I have posted event files to my system from my SG sensor (my *.LC3 files) and from the BKS sensor. There are three PSN files from that sensor. They have the file extension BKSN, BKSE, and BKSZ. My SG senor is point N-S so if you look at the BKSN and my LC3 file you will see a similar seismogram. One difference is the background noise. The P is just out of the background noise on the BKSN channel and is almost not visible on my sensors. Given that I live very near a freeway and my sensor is just sitting on the floor in a spare bedroom, and the BKS sensor in a vault somewhere near Berkeley, it makes me pretty happy that I can make something that can come close to a commercial system. From what I understand in your posts you are not running a Windows system so you can't look at our event files using my WinQuake program. Well now you, and others who aren't running WinQuake, can view them with any Web browser. I have added a new feature to my system that produces GIF images using WinQuake on my Internet gateway system. Each event file link produced by the "New Earthquake Data Files", "Eathquake Data Files", and the "Request Data" links, on the main Redwood City site (http://psn.quake.net) now has a "(GIF Image)" link at the end of each line. If you select one of them, WinQuake will return a GIF image of the event file to your browser. PLEASE EVERYONE!!! This uses up bandwidth on my 28K modem, each image is around 20 to 30K, so please limit your usage of this feature. Anyway, back to the S-G sensor. I have several specific questions about it... One is the method used to pickup the ground movement. You have commented on several types of displacement transducers. I don't think you have talked about the method the SG sensor uses before. It uses a RF transmitter, I use a 2.46 Mhz TTL oscillator with a ~3 to 4 volt square-wave signal, mounted on the pendulum. This drives a transmitter plate, I use a 1.5 inch square double sided PC board material, mounted on the end of the pendulum. The transmitter excites two receiver plates, the same size as the xmiter, that are mounted on the base plate. I use about an 1/8 of an inch spacing between the two receiver plates and the xmiter plate. The receivers are tuned, using a coil and the plate as the capacitor, too the xmiter freq. and have a diode and capacitor to rectify the RF to produce a signal. The two plates are in a push-pull configuration. One produces a positive voltage and the other a negative voltage. They are summed together and then amplified and filtered etc. From what I understand some commercial units used (use) this method. Is that true and what are your thoughts on using this method? Also I was wondering about the electronics that drives the sensor and the difference between how the SG and your VBB sensor works. Basically the SG sensor has the integrator outside of the feedback loop and your sensor has it inside. The SG sensor has active damping, with a magnet on the pendulum and a coil mounted on the frame, but the integrator is not part of the damping loop. What's the difference, and should the electronics be re-designed to have the integrator inside the loop? TIA (thanks in advance ) Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Modified Lehman - base plate mounting Date: Mon, 4 May 1998 02:02:54 +0000 Hello All, Regarding base plate used in PSN style Lehman (1979 Scientific American article) at: http://psn.quake.net/lehmntxt.html The documentation suggests using a metal base plate, 40 cm x 25 cm. I notice this is rather shorter than the full length of the 75 cm (~30 inch) boom. Also I notice the damping hardware, i.e., magnets, basin of oil, and etc., are located off of the base plate. Is this necessary to properly dampen boom? Please reference: http://psn.quake.net/lehman1.gif http://psn.quake.net/overall.html http://www.onr.com/user/ct/lehman1.html Thank you. Walt Williams, 98.05.03 http://www.pacificnet.net/~dfheli/seismo.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: S-G Sensor & Lehman Date: Mon, 4 May 1998 07:45:03 -0500 Larry, I want to comment on part of your question to Sean. One of the problems we are seeing here is the description of the operation of the S-G sensor is in my mind technically misleading. I think that this explanation was used in the SA article in attempt to make it understandable to the non technical person :) . Technically in order to "transmit" RF energy you must have generated electromagnetic radiation which is not happening in the S-G sensor. You have the electro part but not the magnetic part. A more accurate description of the sensor is a differential air variable capacitor. Knowing this you can use the equations for a parallel plate air dielectric capacitor to calculate the response ( displacement versus voltage) of the sensor. I did this sometime ago and found the response to be very nonlinear. In the S-G design the effect of this nonlinearity is somewhat reduced by the small displacements involved and the use of feedback, which is a good "fixer" of nonlinearity. I think Sean has mentioned some "proprietary" designs to reduce the nonlinearity of this type of sensor. Personally I also don't like the idea of mounting electronics on the boom. Because of these things I had switched to using a LVDT for my design until Sean came along with the VRDT which in my mind is mechanically and electrically simpler than the VRDT. Jim Hannon Larry Cochrane on 05/04/98 03:13:58 AM Please respond to PSN-L Mailing List To: PSN-L Mailing List cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: Re: S-G Sensor & Lehman [was: technical info] Anyway, back to the S-G sensor. I have several specific questions about it... One is the method used to pickup the ground movement. You have commented on several types of displacement transducers. I don't think you have talked about the method the SG sensor uses before. It uses a RF transmitter, I use a 2.46 Mhz TTL oscillator with a ~3 to 4 volt square-wave signal, mounted on the pendulum. This drives a transmitter plate, I use a 1.5 inch square double sided PC board material, mounted on the end of the pendulum. The transmitter excites two receiver plates, the same size as the xmiter, that are mounted on the base plate. I use about an 1/8 of an inch spacing between the two receiver plates and the xmiter plate. The receivers are tuned, using a coil and the plate as the capacitor, too the xmiter freq. and have a diode and capacitor to rectify the RF to produce a signal. The two plates are in a push-pull configuration. One produces a positive voltage and the other a negative voltage. They are summed together and then amplified and filtered etc. From what I understand some commercial units used (use) this method. Is that true and what are your thoughts on using this method? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: S-G Sensor & Lehman Date: Mon, 04 May 1998 06:48:04 -0700 Re: the differential capacitor that James Hannon mentioned ... I've had good luck with a differential capacitor constructed of coaxial tubes. Using two short lengths of pipe (say 1" dia, 1" long) butted against each other with an insulating film between to keep them from touching. Then put another (slightly larger) 1"-long piece of pipe over the other two such the outside one doesn't touch the inside ones. Then you can electrically drive the outside one and detect the signal on the inside ones, or drive the inside ones differentially and detect the signal (and its phase) on the outside one. You can also have the two outside the one. Referring to my first-year physics textbook for equations of coaxial capacitors, the output was fairly easy to predict. The output is fairly linear as the outside pipe slides back and forth over the inside ones. I am very interested in Sean-Thomas' comments about the Lehman and SG sensors. Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: S-G Sensor & Lehman Date: Mon, 04 May 1998 07:31:50 -0700 Re Capacitive Sensors: There is an excellent book from the IEEE Press called: Capacitive Sensors, Design and Applications by Larry K. Baxter ISBN 0-7803-1130-2 IEEE Press 445 Hoes Lane, P.O. Box 1331 Piscataway, NJ 08855-1331 http://www.ieee.org I'm still reading it snatches at a time. But it goes into both configurations already mentioned, plus more, including techniques to linearize either one, noise figures, back force, etc. Which brings me to that point -- back force. Capacitive sensors exert low force due to their measurement and can be made in certain configurations to not exert any while most inductive sensors exert more force in configurations where there is unbalance in the position, including, I believe, the one used in the VBB. LVDT's don't exert force if the coil is an air coil and it works into a high impedance. So I was wondering if this has any effects the VBB or not enough to change the choice since it is a simple sensor as currently used? Charles R. Patton patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: Modified Lehman - base plate mounting Date: Mon, 4 May 1998 16:09:13 -0700 (PDT) I never liked that design. I made my base out of 2 inch thick Oak, 12 inches wide and 24 inches long. All equipment, suspension, magnets, damping magnets, coil etc. was mounted on the base. Sorry, the base was 30 inches long. A cover fit over the whole thing. So don't worry, you can be creative with the base. Regards, Ted > > Hello All, > > Regarding base plate used in PSN style Lehman > (1979 Scientific American article) at: > http://psn.quake.net/lehmntxt.html > > The documentation suggests using a metal base plate, 40 cm x 25 cm. > I notice this is rather shorter than the full length of the 75 cm > (~30 inch) boom. Also I notice the damping hardware, i.e., magnets, > basin of oil, and etc., are located off of the base plate. Is this > necessary to properly dampen boom? > > Please reference: > http://psn.quake.net/lehman1.gif > http://psn.quake.net/overall.html > http://www.onr.com/user/ct/lehman1.html > > Thank you. > > Walt Williams, 98.05.03 > http://www.pacificnet.net/~dfheli/seismo.html > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: RE: Modified Lehman - base plate mounting Date: Mon, 4 May 1998 16:42:48 -0700 Not if you don't want to. Check the picture at the PSN San Jose = http://pw2.netcom.com/~shammon1/equip.htm=20 In this photo the base can be seen. I use three machine lags and bolt = the base to the cement. Silver duct tape is used for taping the damping = magnet and coil to the Cement floor.=20 What you don't want is any kind of flexing. You want it solid as = possible. Regards, Steve Hammond PSN San Jose -----Original Message----- From: Ted Blank [SMTP:tblank@........... Sent: Monday, May 04, 1998 4:09 PM To: psn-l@............. Subject: Re: Modified Lehman - base plate mounting I never liked that design. I made my base out of 2 inch thick Oak, 12=20 inches wide and 24 inches long. All equipment, suspension, magnets,=20 damping magnets, coil etc. was mounted on the base. Sorry, the base was = 30 inches long. A cover fit over the whole thing. So don't worry, you=20 can be creative with the base. Regards, Ted >=20 > Hello All, >=20 > Regarding base plate used in PSN style Lehman=20 > (1979 Scientific American article) at: > http://psn.quake.net/lehmntxt.html >=20 > The documentation suggests using a metal base plate, 40 cm x 25 cm.=20 > I notice this is rather shorter than the full length of the 75 cm=20 > (~30 inch) boom. Also I notice the damping hardware, i.e., magnets,=20 > basin of oil, and etc., are located off of the base plate. Is this=20 > necessary to properly dampen boom? >=20 > Please reference: > http://psn.quake.net/lehman1.gif > http://psn.quake.net/overall.html > http://www.onr.com/user/ct/lehman1.html >=20 > Thank you. >=20 > Walt Williams, 98.05.03 > http://www.pacificnet.net/~dfheli/seismo.html >=20 > _____________________________________________________________________ >=20 > Public Seismic Network Mailing List (PSN-L) >=20 > To leave this list email listserver@............. with the body of the = > message: leave PSN-L >=20 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Modified Lehman - base plate mounting Date: Mon, 04 May 1998 17:22:50 -0700 Hi Walt, At 02:02 AM 5/4/98 +0000, Walt wrote: >Regarding base plate used in PSN style Lehman >(1979 Scientific American article) at: >http://psn.quake.net/lehmntxt.html > >The documentation suggests using a metal base plate, 40 cm x 25 cm. >I notice this is rather shorter than the full length of the 75 cm >(~30 inch) boom. Also I notice the damping hardware, i.e., magnets, >basin of oil, and etc., are located off of the base plate. Is this >necessary to properly dampen boom? > >Please reference: >http://psn.quake.net/lehman1.gif >http://psn.quake.net/overall.html >http://www.onr.com/user/ct/lehman1.html My Lehman sensor uses two AL plates. One is the full length of the sensor. At the boom end is the pickup coil and damping. These parts are sitting on the main plate. The pickup coil is held down with a lead weight. I should bolt them down someday, but do to the small movements we are recording I don't think it matters. If the shaking gets to the point where the pickup coil starts moving on its own, the sensor will have saturated along before that. At the other end of the main plate is the upright support. This is a smaller plate that has the boom support on it. This plate also rests on the bottom main plate using three screws need to adjust the sensors period. None of this really has anything to do with the damping. That is up to whatever method you use. Damping can be oil, magnetic or electronic. The amount of damping you need will vary with the period you have your sensor running at. Hope this helps. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Looking for the Best Integrator (filters) Date: Mon, 04 May 1998 17:37:57 -0700 A discussion was going on about the best active filters. I haven't worked in this area that much, but while I was designing the Humphrey seismometer, I came across the application note: AB-026 A Low Noise, Low Distortion Design for Anti-Aliasing and Anti-Imaging Filters from Burr-Brown. The application note is available from; http://www.burr-brown.com/Applications/ABs.html Just page down to AB-026. The important comment was that GIC (Generalize Immittance Converters) were the filters of choice for compact disk players and high resolution A/D work because of: Low noise Low distortion Reasonable cost Easy synthesis So you might factor that application note into your thinking about possible filter configurations. Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: S-G Sensor & Lehman Date: Mon, 04 May 1998 18:32:12 -0700 Re: the differential capacitor that was mentioned: I've had good luck with parallel brass plate composites. The plates are 2" square and have a 1/8" gap between.Each composite is composed of 11-12 parallel plates. The plate capacitors are configured as half of a wheatstone bridge . The center double composite plate is GND and the outer two single direction plate composites are the differential output. Very sensitive and to air caps are around 170 pf (not to small). I use it with my VBB. Barry Karl Cunningham wrote: > > Re: the differential capacitor that James Hannon mentioned ... > > I've had good luck with a differential capacitor constructed of coaxial > tubes. Using two short lengths of pipe (say 1" dia, 1" long) butted > against each other with an insulating film between to keep them from > touching. Then put another (slightly larger) 1"-long piece of pipe over > the other two such the outside one doesn't touch the inside ones. Then you > can electrically drive the outside one and detect the signal on the inside > ones, or drive the inside ones differentially and detect the signal (and > its phase) on the outside one. You can also have the two outside the one. > Referring to my first-year physics textbook for equations of coaxial > capacitors, the output was fairly easy to predict. > > The output is fairly linear as the outside pipe slides back and forth over > the inside ones. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Modified Lehman - base plate mounting Date: Mon, 04 May 1998 18:43:23 -0700 Hi My Lehman is about 30" long. The "base" is composed of 1/2" copper water pipe soldered together. The reason "base" is in quotes is the base is composed of two vertical triangles (36"x12"). The 12" is the common vertical support leg and the 36" is the horizontal length. There is a cross tube at the end near the coil.Three leveling screws are used. The beam is composed of a soldered brass rod truss. I use a coil shunt resistor but I think eddy current is better. Larry Cochrane wrote: > > Hi Walt, > > At 02:02 AM 5/4/98 +0000, Walt wrote: > >Regarding base plate used in PSN style Lehman > >(1979 Scientific American article) at: > >http://psn.quake.net/lehmntxt.html > > > >The documentation suggests using a metal base plate, 40 cm x 25 cm. > >I notice this is rather shorter than the full length of the 75 cm > >(~30 inch) boom. Also I notice the damping hardware, i.e., magnets, > >basin of oil, and etc., are located off of the base plate. Is this > >necessary to properly dampen boom? > > > >Please reference: > >http://psn.quake.net/lehman1.gif > >http://psn.quake.net/overall.html > >http://www.onr.com/user/ct/lehman1.html > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: S-G Sensor & Lehman Date: Mon, 04 May 1998 22:05:05 -0500 barry lotz wrote: > > Re: the differential capacitor that was mentioned: > I've had good luck with parallel brass plate composites. The plates > are 2" square and have a 1/8" gap between.Each composite is composed of > 11-12 parallel plates. The plate capacitors are configured as half of a > wheatstone bridge . The center double composite plate is GND and the > outer two single direction plate composites are the differential output. > Very sensitive and to air caps are around 170 pf (not to small). I use > it with my VBB. > > Barry Barry, I am having a little trouble visulizing your capacitor configuration. Do the plates move closer and further from one another like the S-G or do they mesh like an air variable capacitor? A meshing arrangment should have much better linearity and less sensitivity than the other arrangment. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: comments on Lehman and SG Date: Tue, 5 May 1998 01:15:51 -0500 (CDT) Regarding the Lehman horizontal pendulum and the SG vertical pendulum seismometers: I think that they are good designs for the amateur seismologist, and can produce quality data depending on the technical skill and inventiveness of the builder. I guess my greatest concern is that they are old designs, and that I think we can do much better. The Lehman is a version of the 1950s Columbia-Sprengnether that is used in the WWNSSS (worldwide network of standardized seismic stations). (I believe that our friend in Denver, Meredith, is operating a set of them.) In my opinion the basic SA (Scientific American) designs are amenable to considerable improvement, some of which has been recognized by PSN menbers and even documented. I really don't want to discourge anyone from making them until I have the time to fully document what I think would be a significant improvement. I guess that my first concern is that they are horizontal sensors. In general, when a single sensor is used for earthquake monitoring, a vertical is used, since most of the phases will be represented. The P or primary wave is mostly vertically polarized for most quakes. What is seen by a horizontal depends on its relation to the focal mechanism (how the earth moved at the source) and the direction of the wave propagation from the source. For example, the S or shear wave oscillates at right angles to the direction of movement, so a North-South sensor will see little of a quake that is either north or south of it. This is why in the Aleutian network, we only had Vertical and East-West horizontals, since most of the quakes were in the trench south of the island arc. So I encourage the use of vertical sensors where a single seismometer is used. The plus points od the SA designs are: 1. They are well documented with drawings and technical support. 2. They are relatively easy to make, either with a moving coil transducer or the capacitive displacement transducer. 3. Construction materials are readily available. 4. The PSN provides good Q and A support from those who have built them. Some of my reservations and/or suggestions: 1. The mechanical designs, in my opinion, seem pretty unstable, with serious potential thermal problems, depending on how they are constructed. They seem to require constant adjustment when operated at longer periods, which might discourage the operator. As I look at the Lehman, I think "too many parts" and "many dissimilar materials". A design with a minimal number of parts and fastenings and made of mostly the same material, eg aluminum, should have better mechanical stability. Symmetry of the design also helps. (If I had to assemble the "plumbers delight" version of the Lehman, I would use 1" copper pipe with soldered fittings for the frame and 1/2" copper pipe for the boom). I don't know why the boom for the Lehman is longer than the base, since any period is possible by tilting the base along the axis of the boom. I would replace the "knife edge pivot" with a taught wire arangement. Damping should be done with a coil and magnet, rather than an oil dashpot (another mess to discourage the amateur). 2. There is considerable use of ferrous materials, like the steel rod boom of the Lehman. This presents problems with interactions with the necessary magnetics of the seismometer as well as susceptibility to external fields. Everything should be made from aluminum, brass, copper, or non-magnetic stainless steel. (most True-Value hardware stores have a good selection). I am fond of using the metal-bonding epoxy (the grey mix) to add absolute rigidity to permanent structural joints that may just be bolted together; be sure to sand the oxide or anodize off aluminum first. 3. The capacitive displacement sensor of the SG is a "rough" design and pretty non-linear, mostly because the gap is so large (1/8"?). This nonlinearity would be less of a problem in a VBB feedback configuration. The square-wave exitiation (if it is that) is a real problem, since the square wave contains lots of harmonics, each of which responds differently to thermal mechanical changes. Commercial VBB sensors with capacitive detectors are careful to use sine-waves of relatively low frequencies (10 to 50 khz) to avoid stray capacitance problems. And they also use synchronous demodulation (as the VRDT does) to avoid noise caused by phase errors. Diode rectification also involves the thermal problems of the diodes. My 1970 quartz tube (100 ft long) strainmeters originaly used capacitive sensors with tuned circuits, and the tuning was a major source of change in sensitivity and nonlinearity. The VRDT is an attractive alternate. Since it is not "driven" like a LVDT, forces on the sensing vane are minimal. It is a "reactive" bridge, similar to the capacitive sensor. A LVDT is driven with an excitation winding, whose signal is coupled to the outside windings by the position of the ferrous core, and its output is similar to a ratio transformer. (see D.C.Agnew's paper for a detailed discussion and the math). Several years ago I made a dual-axis vertical pendulum tiltmeter (that also is a dual axis horizontal seismometer) by mounting two sets of VRDT coils at right angles in a circle with about 1/2" clearance in the center. The pendulum consists of a fine wire with an AA battery as the mass, but the steel cylindrical case of the AA battery is also the sensing element for the orthogonal VRDTs. THe actual gap between the steel cylinder and each of the four coils is about 1 mm. With a 60 cm pendulum, the output was about 50mv/microradian. Maybe it could be considered as a dual axis version of the "SG". Regarding Larrys question about the SG integrator compared to the VBB use of an integrator: First of all, I think that the word "integrator" is a misnomer. It is really a low-pass filter that is coupled to the displacement output through a capacitor, which is a high-pass filter, and in this case a differentiator, converting the displacement output to a velocity.. One needs to differentiate the displacement output, which has units of, say, microns, to velocity, with units of microns/second. An integrator would be used for a direct force-fedback system, such as Karl C.s design, where the forcing current is proportional to acceleration, which has to be integrated to become velocity. However, the VBB system is a complex feedback system where each of three feedback paths (the differential, the proportional, and the integral) contributes to the shape of the response to make it flat to velocity when the values are properly chosen, which is why we use the math of the transfer function to determine the values we want for a given response. One parameter so determined is the damping of the feedback loop. The only way to realize the VBB response is to use the complete configuration, which requires a force transducer for the feedback. (With the coil mounted to the boom and the magnet to the frame; if the magnet is on the boom, as you describe for the SG damping, it makes it susceptible to magnetic noise.) I have been working on an alternate version of a horizontal seismometer to compliment the vertical VBB design, using the same speaker coil and magnet, and a vertical hinge of the "Press-Ewing" configuration. (It can also be used as a simple moving coil long-period sensor.) (a "pre-prototype" is pictured on the web page). I am currently refining a method to provide remote centering of the sensor. It was such a cinch to add to the vertical. Commercial systems use traveling wedges or differential micrometers. The idea I am working on will provide about 0.5 microradian per minute of centering using the 2RPM motor. It is not be the smoothest centering in the world, but it works. I will fill in the details later; it could even be applied to the Lehman and SG designs. Enough comments, etc, for now. Hopefully they are helpful. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: Re: S-G Sensor & Lehman Date: Mon, 4 May 1998 23:40:54 -0700 Jim and all, On the S G sensor, why not remove the electronics from the boom by using dual plates on each side of a metal plate attached to the boom. Drive one half of the dual plates from the oscillator and use the other half in the present push-pull configuration. The dual plates could be made from a rectangular piece of PC material with a strip of copper removed across the center. The moving plate should be insulated from the boom so it can act as a floating capacitor plate. Possible? Al allworth@.............. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Lehman: Base Plate Gauge? Date: Tue, 5 May 1998 04:40:29 +0000 Hello All, First-- thanks to Larry Cochrane, Steve Hammond, Barry Lotz, and Ted Blank. New question: base plates which I have tried were 16 steel, and 12 ga Al. They both flex front to back. May I ask what minimum ga of Al should be used? I notice in Steve Hammond's "operational measurements" picture at: http://pw2.netcom.com/~shammon1/equip.htm base appears to be quite robust. Thank You. Walt Williams, 98.05.05 http://www.pacificnet.net/~dfheli/seismo.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dewayne Hill Subject: Re: Lehman: Base Plate Gauge? Date: Tue, 05 May 1998 07:28:25 +0100 I use 1/2" 6061 aluminium. My base is 12"x36". Also everything that is attached to the base is drilled and taped. By taping everything into the base I never have to turn the unit over in order to make repair/adjust. All hardware other that the boom and boom support frame are non ferrious metal. I purchased the 1/2"x12"x36" base from a scrap yard for $70. Walt Williams wrote: > > Hello All, > > First-- thanks to Larry Cochrane, Steve Hammond, Barry Lotz, and > Ted Blank. > > New question: base plates which I have tried were 16 steel, and 12 > ga Al. They both flex front to back. May I ask what minimum ga of Al > should be used? > > I notice in Steve Hammond's "operational measurements" picture at: > http://pw2.netcom.com/~shammon1/equip.htm > > base appears to be quite robust. > > Thank You. > > Walt Williams, 98.05.05 > > http://www.pacificnet.net/~dfheli/seismo.html > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Dewayne (n0ssy) & Linda (n0uqf) Hill Westminster, Colorado USA 39.83569n 105.06270w. Elev 5660ft. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: S-G Sensor & Lehman Date: Tue, 5 May 1998 09:14:42 -0500 Al, Yes this will work, You would have to make the plates twice as big to get the same sensitivity. Jim Hannon "Al Allworth" on 05/05/98 01:40:54 AM Please respond to PSN-L Mailing List To: "PSN-L Mailing List" cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: Re: S-G Sensor & Lehman Jim and all, On the S G sensor, why not remove the electronics from the boom by using dual plates on each side of a metal plate attached to the boom. Drive one half of the dual plates from the oscillator and use the other half in the present push-pull configuration. The dual plates could be made from a rectangular piece of PC material with a strip of copper removed across the center. The moving plate should be insulated from the boom so it can act as a floating capacitor plate. Possible? Al allworth@.............. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: baseplates Date: Tue, 5 May 1998 11:55:16 -0500 (CDT) My experience with baseplates: My experience with baseplates has been mostly in the realm of tiltmeters, which are horizontal seismometers by another name. In this regard, thicker is better, with even the smallest designs using 1/2" aluminum plate. For the vertical VBB sensor, a base/frame made with aluminum channel and angle material 1/8" thick is adequate. This is because everything is moving in a vertical plane, not torqueing the base. When I use the same structure for a horizontal, it is not rigid enough, since the movement is across the plane of the base, including the centering adjustment which is applied to one corner. Even the slightest rotation or twisting of the base will affect the alignment of the transducers. So I use 1/2" aluminum plate (from McMaster Supply) under the inverted channel+angles of the base frame. I drill holes through both to fasten the seis components. Dewayne's idea of using a very thick plate with all tapped holes sounds like an excellent idea too. I would also suggest that only non-magnetic materials be considered for the baseplate, which probably means aluminum. I can also suggest that if the trip to the metal scrap yard yields a piece of aluminum baseplate that needs to be cut or squared up, I have been using a fine-toothed CARBIDE tipped table saw blade and a similar miter saw blade (60 teeth/10") to cut aluminum. THey make clean (shiney) cuts; please use all precautions, though. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Giovanni Rotta" Subject: GIF FORMAT OF WQ FILE Date: Tue, 5 May 1998 19:23:28 +0200 Hi friends ! I have a question: how it is possible to convert a WQ format file in a GIF format ? I see that all files in dbase are downloaded in GIF format. Thank you very much for your help ! Giovanni Giovanni Rotta rottag@.......... Via F. Pizzigoni, 10 33010 Resia (Udine) Italy Lat. 46.373N Long. 13.305E QTH Locator JN66PI _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: GIF FORMAT OF WQ FILE Date: Tue, 5 May 1998 13:09:02 -0500 Giovanni, There are probably other ways to do the conversion, but one way is to view the file you want to convert with Winquake and press the copy button on the tool bar. This will place the image in the windows clipboard. You then paste the copy (ctrl V) into your favorite image processing program and save the file as a GIF. There is information in the Winquake help about copying images. Hope this helps. Jim Hannon "Giovanni Rotta" on 05/05/98 12:23:28 PM Please respond to PSN-L Mailing List To: "PSN Mailing List" cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: GIF FORMAT OF WQ FILE Hi friends ! I have a question: how it is possible to convert a WQ format file in a GIF format ? I see that all files in dbase are downloaded in GIF format. Thank you very much for your help ! Giovanni Giovanni Rotta rottag@.......... Via F. Pizzigoni, 10 33010 Resia (Udine) Italy Lat. 46.373N Long. 13.305E QTH Locator JN66PI _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Unorthodox Base Plate Thought Date: Tue, 05 May 1998 14:42:19 -0600 OH NO! .... yes, the thought occurred to me, that its possible to use formed concrete, or stepping stones (concrete) as a base. Perhaps concrete drills for holes of the mast etc. Solid, heavy, and CHEAP. biggest expense might be the drill/s, and or epoxy filler. Sizes around here...18 to 22" square, probably other sizes in other stores. Heck....one could even consider bricks with their holes as the mast support Run threaded rod through the holes, washer and nuts, epoxy. Heavy, solid and cheap. OK....I don't know the temperature co-efficent ... ha. If its a velocity coil magnet unit, it won't matter very much, and the solid construction may yield less drift over time, than a mechanically weaker metal one. OK... not pretty, but if its tucked away, who's to notice? Its the output thats important. IF...I had one such a critter, I think I would paint it with a acylic/latex combo, to keep water/humidity out. Perhaps...we need...really need a ugliest seismometer contest? No fair to use pretty tiled inlays according to the rules of the west. I suppose you are going to erase this important message from your computer...aren't you? Ha. Meredith Lamb ....the lunchbucket masonry seismometrist _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: RFI radio interferance geting into dc amp. Date: Tue, 05 May 1998 15:26:45 Larry and the group. I have just about ideas. I have an amature radio tranmitter that transmits several times a min. some times. It is getting into the dc amp/filter. I have tried all the traditional aproaches to stoping it. beads, bypass caps chokes and ever time it fires it pulls the voltage up. Anyone got any ideas? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: RFI radio interferance geting into dc amp. Date: Tue, 5 May 1998 19:32:25 -0500 (CDT) Norman, I don't know what power level your transmitter is operating at, but maybe the AC line voltage is changing from the load of the transmitter. and affecting the power supply for your amplifier. I helped my father (W0ALY in Denver, KG6KG in CA) and others build killowatt level linear amplifiers, and keeping the AC line voltage constant for the rest of the equipment was always a problem. If you could key just the high voltage power supply into a dummy load (we used lightbulbs in series), it would show of the problem was the RF or not. Also, reducing the transmitter power level would show if it was spurious harmonics from limiting/distortion in the transmitter. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: RFI radio interferance geting into dc amp. Date: Tue, 05 May 1998 20:42:04 -0500 Norman Davis WB6SHI wrote: > > Larry and the group. > > I have just about ideas. I have an amature radio tranmitter that > transmits several times a min. some times. It is getting into the dc > amp/filter. I have tried all the traditional aproaches to stoping it. > beads, bypass caps chokes and ever time it fires it pulls the voltage up. > Anyone got any ideas? > Norman, Sean has some good ideas to try. The basic idea being to try and pin down a little more about what is actually happening. You also might want to try some things at the amplifier end of the problem. Such as temporarly running the amp on batteries or terminating the input with a resistor rather than the sensor coil. All these things to try fall under the heading of "divide and conquer". If you still can't solve the problem, ask again with some specifics such as transmitter power and frequency and the results of the experiments. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464 Subject: Earthquake Sites to Visit in Anchorage Ak Date: Tue, 5 May 1998 22:30:08 EDT Hello PSN, This August my family and I will be visiting Anchorage for 1 1/2 days in the mid-week. For those of you that live in this part of the world could you provide some information regarding earthquake related sites that we can visit. We know of Earthquake Park, is it worth the time to visit. Are there any good government organizations/centers worth seeing, and are they within an easy drive? Are there any local universities which have interesting displays etc? Thank you, Allan Coleman Edmonds, Washington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Seisguy Subject: Volcano Erupts in Costa Rica Date: Tue, 5 May 1998 22:43:01 EDT Volcano Erupts in Costa Rica ..c The Associated Press SAN JOSE, Costa Rica (AP) - The El Arenal volcano spewed molten lava and sent columns of ash and smoke into the skies Tuesday, prompting the government to declare an emergency and evacuate at least 400 people from the area. There were no immediate reports of injury. The Seismological Observatory reported three major eruptions from the 5,389-foot volcanic peak Tuesday afternoon. The region surrounding El Arenal , the country's tallest mountain, is a tourist mecca with the scenic village La Fortuna and some thermal baths and several hotels. The volcano, located 60 miles north of San Jose, was dormant for 450 years until June 29, 1968, when a violent eruption killed 95 people. The last big eruption in 1993 caused no fatalities. Authorities closed all access roads to the volcano on Tuesday as a precaution. AP-NY-05-05-98 2238EDT _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: RFI radio interferance geting into dc amp. Date: Tue, 05 May 1998 19:33:49 -0700 I have seen this problem in my exploration seismographs. It happens right at the first preamp when modulated RF gets into the input amplifier, the P-N junction rectifies the signal and turns it into low frequency audio and there there is no filtering it out. Solutions? Maybe think of the input wires as an antenna and try shielding and filtering the RF out of the preamp circuit. Maybe substitute an FET input preamp IC instead of a transistor input so you don't have a PN junction to act as a detector (if you can find one with good enough specs). -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: STM-8 VRDT Location Change? Date: Tue, 05 May 1998 21:38:18 -0600 Hi Sean-Thomas, Have checked past emails in regard to this question, but I see nothing specifically like it. Suppose your vrdt, was relocated to under the moving aluminum hinge of the boom. The movement there would be maybe 1/4 of that further out as it is used now. Aside from likely electronic circuit changes, would this be a possible way to extend the temperature range from the present 1 degree to maybe 4 degrees? Suspect the effort may cause more problems than desired, but it is a thought. Suspect you have already gone over this possibility in your mind before. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Earthquake Sites to Visit in Anchorage Ak Date: Tue, 05 May 1998 20:52:41 -0700 Try the Alaska Tsunami Warning Center in Palmer, the Alaska Division of the USGS in Anchorage, and the Alaska Bureau of Mines and Geology in Anchorage as well. Also look up this guy John Larr, he is kinda nuts about seismology. :> -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: GIF FORMAT OF WQ FILE Date: Tue, 05 May 1998 21:04:32 -0700 Giovanni, If you are running Windows 95 (or NT) you can download and try the new WinQuake beta release I just upload too my system. One of new features in this release is the ability to save an event file as a GIF image. A link to the new beta release can be found at http://psn.quake.net/software or you can download it directly at ftp://ftp.seismicnet.com/users/psn/software/wq32b251c.zip I will make a more formal announcement about the new release later tonight. Regards, Larry Cochrane Redwood City, PSN At 07:23 PM 5/5/98 +0200, you wrote: >Hi friends ! >I have a question: how it is possible to convert a WQ format file in a GIF >format ? >I see that all files in dbase are downloaded in GIF format. >Thank you very much for your help ! >Giovanni _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Earthquake Sites to Visit in Anchorage Ak Date: Tue, 05 May 1998 21:17:35 -0700 At 08:52 PM 5/5/98 -0700, Charles P. Watson wrote: >Try the Alaska Tsunami Warning Center in Palmer, the Alaska Division of >the USGS in Anchorage, and the Alaska Bureau of Mines and Geology in >Anchorage as well. Also look up this guy John Larr, he is kinda nuts >about seismology. :> I'm sure John can speak for himself, but he is now "hanging out" with Edward Cranswick in Colorado. He moved from Alaska a few months ago. -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Volcano Erupts in Costa Rica Date: Tue, 05 May 1998 21:30:10 -0700 Check out some spectacular photos of past Arenal eruptions here: http://www.cocori.com/photo/imaren/index.htm -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Earthquake Sites to Visit in Anchorage Ak Date: Tue, 05 May 1998 21:33:52 -0700 Larry Cochrane wrote: > > At 08:52 PM 5/5/98 -0700, Charles P. Watson wrote: > >Try the Alaska Tsunami Warning Center in Palmer, the Alaska Division of > >the USGS in Anchorage, and the Alaska Bureau of Mines and Geology in > >Anchorage as well. Also look up this guy John Larr, he is kinda nuts > >about seismology. :> > > I'm sure John can speak for himself, but he is now "hanging out" with > Edward Cranswick in Colorado. He moved from Alaska a few months ago. > > -Larry > Thanks Larry, I forgot. -- ---/---- Charlie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mark Robinson Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 16:36:48 +1200 Hi Norman et al, I have found that using folded dipole based antennas, well matched especially around the balun, instead of ground planes makes a huge difference to the amount of pickup in surrounding equipment. I suspect that this is because of earth currents from the ground plane's inherent unbalanced nature. Putting lumps of ferrite on the feeder especially at the top can reduce standing waves on the sheild as well. I suppose you have tried all this ! Mark Norman Davis WB6SHI wrote: > > Larry and the group. > > I have just about ideas. I have an amature radio tranmitter that > transmits several times a min. some times. It is getting into the dc > amp/filter. I have tried all the traditional aproaches to stoping it. > beads, bypass caps chokes and ever time it fires it pulls the voltage up. > Anyone got any ideas? > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: Re: RFI radio interferance geting into dc amp. Date: Tue, 5 May 1998 22:11:13 -0700 -----Original Message----- From: Norman Davis WB6SHI Date: Tuesday, May 05, 1998 3:50 PM Subject: RFI radio interferance geting into dc amp. Hi Norman and group, Things I would do to eliminate RFI in a seismo system: (I have been planning for this eventuality for when I also get more equipment operating here.) 1. Put all the seismo electronics in a sealed box made of thin brass or PC board material. (easy to solder) Ground the box with short, heavy shield braid to a separate earth ground. 2. Filter all input, output,control, and power connections with Pi filters. (cap to gnd., choke coil, cap to gnd.) use feedthrough capacitors and provide a separate compartment within the box and partitioned for each choke, capacitor combo. 3. Shield the input leads with a separate interference shield soldered only at the entrance to the box. This shield must be insulated from everything else and soldered very close to the input connections. 4. The use of a FET may not help very much because of the high gain following the input device. It might just amplify the interference and pass the problem to a later stage. 5. Use coax cable for all conections to the electronics box, connecting the shields only to the box. 6. If it is found that the output lead is injecting the interference, optical coupling or fiber optics might be a consideration. The first 2 steps should make a huge improvement. I hope you don't have to use the more exotic ones. What band are you using and how much power do you run. Also SWR in the antenna feedline can contribute to the problem. I hope this helps. Al allworth@.............. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Fwd[1]: Base Plate Date: Wed, 6 May 1998 05:32:13 +0000 Hello All, Re; base plate. Larry, there is consensus --thicker is better. Meredith ....concrete? Ha, ha. Sean, cool ideas-- cutting tools. When I fly R/C helicopters (very cool), the one thing that really bothers me is constant tuning and adjustments, some choppers are better than others in this respect. In science it is essential instruments remain calibrated, else the data is suspect. Some instruments are finicky. From what I have read in the FAQs and the archives as well as your comments and others, I gather the PSN style Lehman is not a modern design. Is it possible to to create a modern amateur instrument which is thermally stable, mechanically stable, able to produce useful science data (perhaps better resolution) and yet still be constructed by amateurs? Dewayne, I bought a tap set for the project. I need some stuff for my microbarograph at the metal scrap yard (I am not sure I can afford McMaster-Carr), now I have another item on the agenda. Re; magnetometers. Roger, I am studying those interesting references on magnetometers you mentioned to me last year, finally. Walt Williams, 98.05.06 dfheli@.............. http://www.pacificnet.net/~dfheli _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 05:54:53 >I don't know what power level your transmitter is operating at, but >maybe the AC line voltage is changing from the load of the transmitter. >and affecting the power supply for your amplifier. It is a level problem. I will take a look at the DC levels. That is a good Idea. It could be getting into the Powersupply/ voltage regulator.. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 05:59:49 At 08:42 PM 5/5/98 -0500, you wrote: >Norman Davis WB6SHI wrote: >> >> Larry and the group. >> >> I have just about ideas. I have an amature radio tranmitter that >> transmits several times a min. some times. It is getting into the dc >> amp/filter. I have tried all the traditional aproaches to stoping it. >> beads, bypass caps chokes and ever time it fires it pulls the voltage up. >> Anyone got any ideas? >> >Norman, >Sean has some good ideas to try. The basic idea being to try and pin >down a little more about what is actually happening. You also might want >to try some things at the amplifier end of the problem. Such as >temporarly running the amp on batteries or terminating the input with a >resistor rather than the sensor coil. Have dead shorted the input and it still does it. All these things to try fall under >the heading of "divide and conquer". If you still can't solve the >problem, ask again with some specifics such as transmitter power and >frequency and the results of the experiments. Power level is anywhere between 5 and 35 watts. Antenna it 70 feet up and the shift is worse at the higher levels. freq 144.35 mhz. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 06:02:03 At 07:33 PM 5/5/98 -0700, you wrote: >I have seen this problem in my exploration seismographs. It happens >right at the first preamp when modulated RF gets into the input >amplifier, the P-N junction rectifies the signal and turns it into low >frequency audio and there there is no filtering it out. > >Solutions? > >Maybe think of the input wires as an antenna and try shielding and >filtering the RF out of the preamp circuit. Maybe substitute an FET >input preamp IC instead of a transistor input so you don't have a PN >junction to act as a detector (if you can find one with good enough >specs). Was thinking of changing the 741 to something else. Problem though. It does it with the input shorted. Me thinks is is comming in via the power or output lines. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 06:03:39 At 04:36 PM 5/6/98 +1200, you wrote: >Hi Norman et al, > >I have found that using folded dipole based antennas, well matched >especially around the balun, instead of ground planes makes a huge >difference to the amount of pickup in surrounding equipment. I suspect >that this is because of earth currents from the ground plane's inherent >unbalanced nature. > >Putting lumps of ferrite on the feeder especially at the top can reduce >standing waves on the sheild as well. Nope but was going to rework the antenna anyway, if it ever stops raining. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 07:45:37 -0700 Norman: I was using a 741 when I saw the problem. Of course we had long twisted pairs of cables laying on the ground. These days we operate with floating differential inputs, with small caps between the inputs and also to ground from each input. Also some resistors leading to the outside world so the caps have impedance to work with. We never actually tried the FET's because the noise levels were higher, but the theory was that their common mode rejection (in a floating differential circuit) would filter the RF. Since the noise is still there with shorted input, that suggests a ground loop. Maybe you ought to look at where the ground is on you input. It's a really big deal in low-noise design. (More discussion available on request). Norman Davis WB6SHI wrote: > Was thinking of changing the 741 to something else. Problem though. It does it with the input shorted. Me thinks is is comming in via the power or output lines. > At 07:33 PM 5/5/98 -0700, you wrote: > >I have seen this problem in my exploration seismographs. It happens > >right at the first preamp when modulated RF gets into the input > >amplifier, the P-N junction rectifies the signal and turns it into low > >frequency audio and there there is no filtering it out. > > > >Solutions? > > > >Maybe think of the input wires as an antenna and try shielding and > >filtering the RF out of the preamp circuit. Maybe substitute an FET > >input preamp IC instead of a transistor input so you don't have a PN > >junction to act as a detector (if you can find one with good enough > >specs). > > Was thinking of changing the 741 to something else. Problem though. It > does it with the input shorted. Me thinks is is comming in via the power or > output lines. > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 08:45:25 -0700 Norman -- Be careful of RF getting into your measuring instruments too. Some handheld digital multimeters are susceptable to interference and the apparent dc level changes. You'll soon wind up chasing your tail with those kind of problems. At work, we've constructed a brass box to put a DMM in with a fine brass screen to be able to see the display, and feedthrough filters for the input leads. The lid slips on one end of the box and telescopes over it by about 3/4" to ensure a good RF connection. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: Earthquake Sites to Visit in Anchorage Ak Date: Wed, 6 May 1998 08:18:49 -0800 Allan, check out these places while in Anchorage: -The Alaska Volcano Observatory, 4200 University Drive (Alaska Pacific University campus) 786-7474 -The Alaska Tsunami Warning Center, Palmer (public tours on Thursdays when I worked there, about 40 miles north of Anchorage, very much worth the drive) 745-4212 -and especially check out The Alaska Experience Center in downtown Anchorage! (180 degree theatre for you to "relive the Great Alaska Earthquake") 276-3730 -The Imaginarium (science, nature, technology) 725 W 5th ave. Good coffee at Kaladi Brothers. Gwennies on Spenard has the best breakfast in town. Best bagels at Bagel Factory on 36th. I've never been to Earthquake Park so I can't tell you if it's worthwhile or not. Have fun! Bob ====================================================== Bob Hammond, Geophysicist US Geological Survey Alaska Volcano Observatory, Fairbanks ph: 907-474-5333 fax: 907-474-5618 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond Subject: Re: Base Plate Date: Wed, 06 May 1998 12:33:48 -0500 Hello All, Walt Williams wrote Wed, 6 May 1998... >In science it is essential instruments remain calibrated, else the data >is suspect. Some instruments are finicky. From what I have read in >the FAQs and the archives as well as your comments and others, I >gather the PSN style Lehman is not a modern design. Is it possible to >to create a modern amateur instrument which is thermally stable, >mechanically stable, able to produce useful science data (perhaps >better resolution) and yet still be constructed by amateurs? Larry Cochrane has noted his Lehman requires frequent adjustment. From pictures, his design is considerably modified (and apparently improved) from the original design in July, 1979 Scientific American magazine article. In support of the Lehman, mine is much closer to the original design, except for a particle board+wood base plate and oil damping. I check it about once a month and need to adjust it only about once ever three months - probably because of seasonal temperature changes. That adjustment is about a half-turn to one turn of one leveling screw. In my experience - and for the benefit of amateurs considering building a sensor - the mechanical stability of the old Lehman design can be quite good and is lately getting an undeserved bum rap. I have to confess, however, that my conscience made me go check it just then before I sent this. It's FINE and needs no adjustment :-) My two-cents worth.. Charlie Rond -\/\--Public Seismic Network-Memphis rond@................ (901) 360-0302 [ free BBS ] http://gandlf.ceri.memphis.edu/~rond http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Lyzenga Subject: Lehman design discussion Date: Wed, 06 May 1998 12:58:52 -0700 I'd thought I'd throw in my two cents' worth on the pros and cons of the Lehman design... from Charlie Rond: >In support of the Lehman, mine is much closer to the original design, except >for a particle board+wood base plate and oil damping. I check it about once >a month and need to adjust it only about once ever three months - probably >because of seasonal temperature changes. That adjustment is about a >half-turn to one turn of one leveling screw. > >In my experience - and for the benefit of amateurs considering building a >sensor - the mechanical stability of the old Lehman design can be quite good >and is lately getting an undeserved bum rap. I've been running my old Lehman now for about 7 years, and I tend to agree with this view -- with some qualification. My Lehman is of the "plumber's nightmare" variety, constructed of galvanized pipe. It's also oil damped and it also requires re-centering only every few months or so. Not bad. However from my point of view, whether you consider it an "adequate" instrument or not depends entirely on what you want to do with it. As a "hobby" means of detecting and recording a wide range of local events and teleseisms, it's a spectacular success. The value/cost and value/trouble ratios are hard to beat. On the other hand, if you want to do "hard" quantitative seismology with the waveforms it's probably not the way to go. Why? Well, even though it goes months between required adjustments, the gain is continually varying as the pickup coil drifts ever-so-slightly in its position relative to the magnet. Also the natural period of the pendulum is changing over time, I'm pretty sure. So as a result, I've never bothered to pursue a good calibration, because I knew it wouldn't mean too much. This leads me, however, to the latest debate I've been having with myself. What should be the design of my *next* seismometer? (Ask my wife that question, and she'll probably say one that doesn't take up any more garage space!) If I want a simple, mechanically stable, tried and true design that will give me earthquake records with good "ooh-and-aah" value, I'd be inclined to build an S-G system with Larry's hardware. On the other hand, if I want to step up the "seriousness" factor a notch, and think about doing real digital signal processing and such (sounds like work!) I have to think that a VBB design like Sean-Thomas' is the obvious way to go. My bottom line is that neither is necessarily *better* unless you can agree on the criteria by which you judge them. I'm not sure which side of the fence I'll fall on, but knowing me, I'll probably eventually build both :-) - Greg |Gregory A. Lyzenga *** (909) 621-8378 |Dept. of Physics, Harvey Mudd College *** fax (909) 621-8887 |Claremont, CA 91711-5990 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 13:21:38 -0700 Update: well tried a low gain 2x input and still same problem. Then tried the bifet input tl082 and still doing it. It is not the power supply or the meter as it also does it into the a/d converter. If I short it at the chip. It goes away. Just a short 1 " wire is all the antenna It needs. I think I will atack the transmitting antenna next. It must be where it is comming from. I mean the lead. If I remember right when I had the lehman in the shack it was ok. It must be riding the cabel in some how. Will check for a ground loop too. I'm thinking that if I use the opamp in larrys design the rf comming in on both leads would cancel each other out. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Thank you for your hospitality Date: Wed, 06 May 1998 14:23:16 -0600 Arie- Thank you very much for your hospitality while I was in Perth last month. I very much enjoyed the tour of the Perth Astronomical Observatory and the visits to the Perth Art and Natural History Museums (most Australians in the eastern states have never heard of a "chudich" or a "quoll" as it is sometimes called). I have never seen more beautifully machined seismometers, your paired SG's. I would like to get a copy of the tape of your TV program about the Earth from an astronomical and seismological perspective: as a point which moves through space and as the structure which moves internally. I apologise for taking so long to thank you -- I spend most of my time lost in a professional/personal fog -- but I wanted to tell you how glad I am that I decided to go to Perth and see you and Alby Judge. Thank you also for setting up our meeting with Alby. I hope you get the chance to visit us in Golden. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Thank you and your wife for your hospitality Date: Wed, 06 May 1998 14:56:33 -0600 Alby- I remember that afternoon last month sitting with you and Arie Verveer outside the shed on your property on the Darling Scarp, where you and your wife are building a home, and having a cup of tea that your wife so graciously brought us while we talked seismology. With your seismic vault in the bush behind the shed that is visited by the kangaroos, there is something that reminds me of "Waltzing Matilda". It makes me think of myself as a traveling wave or, at least, as the seismic swagman. I don't know why I had to go to Perth to find out about the PS-1 seismograph which you showed me (do you have an email address for it?). I am very impressed by your plans to set up the public seismographs and your comprehensive knowledge of the regional seismicity. I hope you get your SDR going soon and are able to start posting wiggles on the PSN and exchanging data with Arie. I look forward to hearing about your cooperative projects with him. Thank you and your wife very much for your hosptality, I wish you the best in the flourishing of your home and family. -Edward -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: BIG DISASTER IN ITALY !!! Date: Wed, 6 May 1998 23:09:32 +0200 Big geological disaster in southern Italy. Up to this moment the = victims are 30, 70 lost persons, around 1800 destroyed houses. It's the most serious catastrophe of the last years in Italy; more = large than the earthquake of central Italy. The catastrophe has happened in Campania, near in Naples.=20 After two days of intense rains, a river of mud is been disconnected = from a mountain; three countries have been submerged from the deposits. I.E.S.N. Francesco Nucera
Big geological disaster  in = southern Italy.=20 Up to this moment the victims are 30, 70 lost persons, around 1800 = destroyed=20 houses.
It's the most serious catastrophe of the last years in = Italy; =20 more large than the earthquake of central Italy.
The catastrophe has = happened=20 in Campania, near in Naples.
After two days of intense rains, a = river of mud=20 is been disconnected from a mountain;  three countries have been = submerged=20 from the deposits.
 
I.E.S.N.
Francesco Nucera
From: "David A. Nelson" Subject: Re: RFI radio interferance geting into dc amp. Date: Thu, 07 May 1998 10:39:01 +1200 At 06:02 AM 5/6/98, you wrote: >At 07:33 PM 5/5/98 -0700, you wrote: >>I have seen this problem in my exploration seismographs. It happens >>right at the first preamp when modulated RF gets into the input >>amplifier, the P-N junction rectifies the signal and turns it into low >>frequency audio and there there is no filtering it out. >> >>Solutions? i also suffer from this partic on 50 MHZ (6m band) i have tried almost every standard filtering shielding still no success i switch the alarm off and let it go if a quake happens too bad when we are using such hi gain preamps a long length of cable out the front (a perfect antenna) anything over ~20 W odd is going to cause hassles I 100W or so, into hi gain yagi antennae, on 144 and 50 MHz bands and it drives the seismo crazy on my drum recorded I put a switch across the input to the pen motor to stop it swinging wildly when I transmit Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: RFI radio interferance geting into dc amp. Date: Wed, 06 May 1998 17:37:30 -0700 Norman -- I think your best bet is to build the amplifier on a board with a good ground plane and use ceramic capacitors to shunt the RF directly to the ground plane right at the op-amps. Not an inch away, but right on the leads! Use the largest value of cap that doesn't mess up the signal, and use ceramic caps and keep the leads as short as possible -- 1/4" or less. Use chip capacitors without leads if you can. Put these on all of the op-amp leads -- inputs, output, and power supply leads. Then, if you have to, build foil boxes to put over the op-amps or use op-amps with metal cans. If you have a good, solid ground plane on the board, this should pretty much kill it. Don't count on the common-mode rejection of the op-amps to do much for you at these frequencies. At work we build low-level low-frequency instrumentation amplifiers that sometimes require common mode rejections to 100MHz, and let me tell you, it is a real pain. The amplifiers wind up looking more like RF power amplifiers in partitioned boxes with lids than they do normal low-frequency amplifiers. There are shields within shields. And they cost thousands per channel. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464 Subject: Re: Earthquake Sites to Visit in Anchorage Ak Date: Wed, 6 May 1998 21:22:29 EDT Thank you all for the feedback to my questions as to what I can see and do in regards to earthquake related things when I visit Anchorage. Should be a fun trip. Regards, Allan Coleman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: New WinQuake beta release. Date: Wed, 06 May 1998 22:18:49 -0700 Hi Everyone, Last night I uploaded a new 32 bit beta release of WinQuake. A link to the WQ32B251C.ZIP file can be found at: http://psn.quake.net/software or you can download it directly by using ftp://ftp.seismicnet.com/users/psn/software/wq32b251c.zip. Here are some of the new features in this release: WinQuake can now read some SEED (Standard for the Exchange of Earthquake Data) volume files. SEED volumes are used by some Institutions too store archived event files. I say some SEED volumes because the standard has many different ways (formats) to save the binary data. WinQuake currently supports only one decoding format called Steim2. The Berkeley system (http://quake.geo.berkeley.edu/) and IRIS system (http://dmc.iris.washington.edu) both have SEED volumes that WinQuake can read. The IRIS system is pretty neat. You can download the SEED volumes for an event over 5.?. The SEED volumes contain event files from selected broadband sensors located around the world. A typical IRIS SEED volume size is around 3 to 5 megs and can contain over 150 event files. A starting point for downloading data from the IRIS system is ftp://dmc.iris.washington.edu/pub/farm. I will add more decoders as I find locations on the net with different data formats. WinQuake can now read PEPP (Princeton Earth Physics Project) volume sets. Like the SEED volume sets, PEPP volumes contain two or more PEPP event files. People who send event files to the PSN archiving system (event@.............. can now send their event files directly from within WinQuake. After selecting the event file and an entering an email address, WinQuake will send the file as an email MIME attachment. This feature can be used to send event files to any email address, not just the archive system. WinQuake can now save an event file as a GIF image. To save an event file as a GIF image go to the Save File dialog box and select GIF Image for the save "Format". The beta release has the beginnings of the new Help documentation that I and the "WinQuake Documentation Team" (thanks guys!) are working on. This version has the dialog box help. Each of the main dialog boxes in WinQuake now has a help button. Using this button will bring up a short description on how to use the dialog box. WinQuake uses the default Web browser installed on the system to display the help files. Those are the main new features in this release. After unzipping the release file please read the README.TXT file on how to install this version on your system. You must have an earlier version of WinQuake already installed to use this beta release. Please let me know if you run into any problems with this new release. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: New WinQuake beta release. Date: Thu, 7 May 1998 05:52:44 -0700 (PDT) Larry, Do you think WinQuake will ever be ported to Linux? --Warner _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: New WinQuake beta release. Date: Thu, 07 May 1998 17:13:14 -0700 At 05:52 AM 5/7/98 -0700, Warner Lindholm wrote: >Larry, > >Do you think WinQuake will ever be ported to Linux? > >--Warner Don't hold your breath... I am not a UNIX / Linux fan, and, I don't have the knowledge, development tools and time need to port it over. Sorry... -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: rayv Subject: Geo Phone Date: Thu, 07 May 1998 21:12:16 -0400 Gateway Electronics is selling a Geosource geophone model MD-79 for $9.95. They call it a Geo sensor and include some parts for a simple amp/indicator. Gateway can be reached at 314-427-6116 or 8123-25 Page Blvd, st louis missouri 63130. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Geo Phone Date: Thu, 07 May 1998 19:51:53 -0700 The MD-79 is a geophone, specifically a velocity transducer of the moving coil and magnet variety. Geosource was a pretty big company in 1980. They made geophones in Texas and also owned Sensor in The Netherlands. Geosource was merged with Texas Instruments and that equipment business sold to Halliburton Services, and then again to Input Output. The domestic geophone business died, and the MD series has been out of production for some time. Not that there's anything wrong with an MD-79 as a geophone. Probably the natural frequency is higher than we would like, most probably in the 8 to 14 Hz range, some possibly as low as 4.5 or as high as 40 Hz. The output would be about 1/2 volt/in/second, probably a vertical. For $10, everybody should have at least one geophone laying around, even if it's more suitable as a burgular alarm than seismometer. Somebody should buy one, open it up, read the natural frequency off the inside element, and report back to the group. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: Re: Geo Phone Date: Thu, 7 May 1998 22:53:16 EDT Does anyone know the frequency of a model MD-79 Geophone like the ones being sold by Gateways Electronics? Jim Allen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: Geo Phone Date: Thu, 07 May 1998 22:32:45 -0600 Gateway has perhaps 3 outlets I think. Missouri, Colorado and California. Colorado has no geophones now. Years ago they had some foot stomp type units, but I wasn't impressed with their use, at the time. They were on the shelf forever and had about zero sales.. I got one and opened it up...simple spring coil & magnet, vertical, probably 10 hz or so. Gateway does not ship alittle of everything to all the stores, so no go here. Don't know where the California store is....or was, ? Can check with local store later, as too possible California source? No internet site or catalog known. Not much turnover over time anymore, or, new items of interest. Wonder whether they could be opened up and the period lengthened in some cases? Of course I'am not too acquainted with them. Probably would stretch the spring beyond use. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: Geo Phone Date: Thu, 07 May 1998 23:36:12 -0500 Friends, BTW, isn't it interesting how lists like this take on one topic after the other, serially, and everyone chimes in with what they know? Wonderful! On the topic of geophones, I've never seen one but will order one of these for sure. From what I can gather, the real art is in the making of a long term oscillation suspension in a small package. A one second period moving coil being fairly hard to make but just barely capable of sensing down to the twenty seconds or so movement detections needed for good teleseismic data collection. The real problem is that coils do not generate much voltage when moved very slowly through even a very strong magnet. Lehmans achieve about all that can be hoped for in a simple-easy-to-build package. But they drift, which is the price that is paid for a lack of ability to control the exact positions of the mag and coil sensing elements. Let me now suggest a use for Charles Patton's earlier proposal for using the guts of a cheap junk, surplus hard drive for something of interest to this group. Namely as a velocity detector. There are two magnets positioned so as to rotate a coil fast to move across the radius of a hard drive. This means efficient transfer of rotational energy from current to motion--or vice versa. So I suspect that these elements could be used backwards as an efficient sensor or rotary motion equally as well as head-moving element. Some while ago, I posted a piece about experiments with what I called a micro-Lehman, which was essentially an aluminum flashing cantilever extended outwards from a tiny nylon filament. If the copper coil from a junk hard drive were to be suspended horizontally from a vertical nylon filament in the same fashion, in the same garden gate configuration as my micro-Lehman, then it could be made to rotate between the poles the hard drive magnet. The virtue of this configuration is that the hard drive makers optimise the strength of the magnets and reverse the poles on each side of the coil -- so that the moving coil will interacts in the most effective way with the magnets. This might be a good cheap practical way to build a rather small Lehman, that could be easily enclosed to reduce thermal drift, etc. But the problem with coils and magnets is that coils loose sensitivity pretty rapidly as the velocity of motion is decreased, so they are only marginally effective for teleseismic events. Thus we are inclined to turn toward the so-called displacement sensors that see a tiny static change no matter how slow it may be. Differential transformers, capacitance micrometers, and optical displacement transducers are all in this class, and each of the forgoing is able to detect sub-nanometer displacements. Right now my interest lies in my high-Q magnetic suspension instrument using an optical displacement detector made from an infrared LED and phototransistor combination designed to intercept the most possible infrared photons with the least possible movement of the knife edge beam; generally along the lines of what was posted earlier. My recent improvements were to add a mag shield from an old scope and a thermal feedback oven enclosure made of an inch of styrofoam to keep it regulated to about .1 degree Celsius. It looks like the trick, circuitwise, is to have the daily drift due to thermal and earth tide changes in gravity (it is a gravimeter too at this point!) attenuated so that the phototransistor resistance shift does not quite cause its signal to swing too far in voltage, when placed in series with about a 10K resisrtor. I then drop out the high freq with a simple pi filter and drop out the lows with a big-capacitance coupled AC amp so it doesn't drop the really slow teleseismic swings of twenty seconds or more (2200 MFD). The bottom line is that I am sitting here watching microseisms of about three second duration fading in and out due to some kind of interference effect, I think, and waiting for a quake so I can see if this thing works. If I can see microseisms pretty clear, am I liable to see teleseisms? Somebody pick up this thread. --Yours, Roger At 07:51 PM 5/7/98 -0700, you wrote: >The MD-79 is a geophone, specifically a velocity transducer of the >moving coil and magnet variety. Geosource was a pretty big company in >1980. They made geophones in Texas and also owned Sensor in The >Netherlands. Geosource was merged with Texas Instruments and that >equipment business sold to Halliburton Services, and then again to Input >Output. The domestic geophone business died, and the MD series has been >out of production for some time. > >Not that there's anything wrong with an MD-79 as a geophone. Probably >the natural frequency is higher than we would like, most probably in the >8 to 14 Hz range, some possibly as low as 4.5 or as high as 40 Hz. > >The output would be about 1/2 volt/in/second, probably a vertical. For >$10, everybody should have at least one geophone laying around, even if >it's more suitable as a burgular alarm than seismometer. > >Somebody should buy one, open it up, read the natural frequency off the >inside element, and report back to the group. >-- >Doug Crice web site http://www.georadar.com >GeoRadar Inc. e-mail dcrice@............ >19623 Via Escuela Drive phone 408-867-3792 >Saratoga, CA 95070 USA fax 408-867-4900 > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Questions I always wanted to ask... Date: Thu, 07 May 1998 23:10:48 -0600 1. Anybody actually used a linear Hall effect seismometer transducer in its many various possible configurations? 2. Anybody used a water well level indicator of quakes? 3. Anybody used a strainmeter device of any kind? 4. Anybody homebuilt a bubble level tiltmeter? Or fluid device? 5. Anybody have a commercial seismograph and have never mentioned it, or its results? Opinion, features etc. 6. Anybody live near a fault, and observed or used any device in relation to it? 7. Anybody built a radio, i.e., very low frequency device for earthquake indications, electromagnetic precursors etc. ~ 2 to 11 hz? (Outside of Geomonitor) 8. Anybody used a ground probes electrical resistance device near a fault zone? 9. Anybody built and using a piezo transducer on a seismometer? 10. Observed earthquake "lights" or atmospheric ball plasma lights in a known seismic area, with or without quakes? 11. Don't hear much on eddy current damping with copper plates, or aluminum. More people seem to use wire coils. Is damping adjustment really alot harder to do? Any neat designs? With all the flat neodymium magnets around now, it would seem that they would be used increasingly. 12. Anybody ever used sawed off sections of old hard drives for capacitive plates in seismometers? Their flatness maybe more desireable for linearity and closer spacing? 13. Anybody ever tried that Sean-Thomas reference to the polaroid film pack spring as a short period vertical seismo out of curiosity? 14. Anybody into a new type of sensor, that is basically unheard of or very little known or tried? Like? Questions I've always wanted to ask...but haven't till now. guarantee they are not the last...of course. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Geo Phone Date: Thu, 07 May 1998 22:55:21 -0700 The model number of a geophone doesn't specify the frequency. Normally, a particular model will come in a range of frequencies. To buy a new one, you specify the model number, the natural frequency, the coil resistance and the orientation. So, we don't know what frequency those particular MD-79's are. Probably they are all the same though, seismic crews buy these a few thousand at a time. The real miracle of geophones is that they are small, meet the specs within about 3% for natural frequency and output, and sell for $25 or so new. Don't anybody plan on taking one apart and making it different. The parts are pretty small and specialized. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Live PSN Status: Back as "Event" PSN Date: Fri, 08 May 1998 19:11:13 +0800 Hi, The "Live" PSN station is now been reprogramed as a very near "Live" PSN station. Instead of looking at a continuos trace being updated every 6 minutes, the image is a 10 minute snapshot of an event. Every time a new seismic event occurs, a hardware trigger is activated. After an exact delay of 600 seconds a digital snapshot is taken and an image is placed into the "Event" web page. Also the last three events can be retrieved. If a quake triggers an event then a picture is taken. This means you can be the first on the block to see the activity from this station. Hopefully all the problems are now solved, but I'm sure something will surface so if you detect a problem, send an email. It will be most, appreciated. Generally this station gets some sort of an event every day. It may be a mine blast from 154km away or something real. If you find the camera taking pictures of the ceiling then a really big quake has occurred, now that's a strong motion detector. Have fun and hopefully more good things are on the way. Regards Arie. Ps: SDR settings X = 60 Four Channels at 25. Trigger AU1 = 225 East-West, High Frequency AU2 = 400 East-west, Low Frequency AU3 = 225 North-South, High Frequency AU4 = 400 North-South, Low Frequency _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Bob Lewis Subject: fwd: Geophones Date: Fri, 8 May 1998 07:00:52 -0700 ------------------ Original text From: Bob Lewis , on 05-08-98 6:53 AM: To: dcrice@............ Hi Doug...I was given an "unknown" geophone a couple of years ago, a heavy metal can about the size of a soup can with a cable coming out the top. No natural frequency was marked. I connected it to my function generator through an 18K resistor, and connected my "scope across the 'phone. Simply adjusting the generator for max on the 'scope gave me the natural frequency, 10 Hz. I was thinking that this might be easier than opening one up. Bob Lewis WB5FDF Amateur Radio Operator Precision Time&Frequency Nut Clock Collector PSN Station #39 From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Thu, 07 May 1998 13:06:07 This project is getting biger and biger.... Maybe will have things up by 2010. I could hope for an early asteroid.... The amplifiers wind up >looking more like RF power amplifiers in partitioned boxes with lids than >they do normal low-frequency amplifiers. There are shields within shields. > And they cost thousands per channel. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JHammes@......................... Subject: Re: Geo Phone Date: Fri, 8 May 1998 07:55:02 -0700 Gateway Electronics has the following toll-free number: 1-800-669-5810, and accepts plastic. ______________________________ Reply Separator _________________________________ Subject: Geo Phone Author: PSN-L Mailing List at CCSMTP Date: 5/7/98 9:12 PM Gateway Electronics is selling a Geosource geophone model MD-79 for $9.95. They call it a Geo sensor and include some parts for a simple amp/indicator. Gateway can be reached at 314-427-6116 or 8123-25 Page Blvd, st louis missouri 63130. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: fwd: Geophones Date: Fri, 08 May 1998 08:29:10 -0700 Testing for geophone natural frequency. Golly, that seems awfully sensible. The only odd thing is that 10 Hz geophones haven't been as big as soup cans for about 60 years, but maybe it was an industrial product instead of petroleum exploration gear. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Geo Phone Date: Fri, 08 May 1998 10:08:47 -0700 A friend of mine and I bought the last two $10 geophone kits from the San Diego Gateway Electronics store about two weeks ago. The guy there didn't know if they were going to get any more, and he said they came from their St. Louis store. The case is marked: GEOSOURCE INC. E.P.D C.S.O. MODEL MD-105 MADE IN USA LOT NO. 649 8 HZ 872 OHMS DATE 3 27 86 They are in cylindrical cases, 1.05" dia and 1.3" long. They're pretty sturdy. Mine survived an accidental fall to the pavement as I got out of my car and still works fine. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Geo Phone Date: Fri, 08 May 1998 10:55:33 -0700 rayv wrote: > > Gateway Electronics is selling a Geosource geophone model MD-79 for $9.95. > They call it a Geo sensor and include some parts for a simple > amp/indicator. Gateway can be reached at 314-427-6116 or 8123-25 Page Blvd, > st louis missouri 63130. Hi, I'm new on the list. My Lehman is not yet done. I'm saving money and time to buy a nice thick piece of Aluminum for the base and some other parts I need. Anyway I just found what this thread was talking about and thought you all might want to look at it. I may order one. The credit card isn't quite full yet ;) Home page: http://www.gatewayelex.com/ Geophone page (it's a little bit down the page): http://www.gatewayelex.com/gadgets.htm Also I found a toll free number (probably US only) 1-800-669-5810 ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: geophones Date: Fri, 8 May 1998 13:42:44 -0500 (CDT) Meredith and co. I will try to check the Gateway Electronics here; I can pass it on the way to the U. For them, what you see is what they have, so if one finds something to solve a problem, it is best to buy all that one might need asap. I have opened many of the exploration geophones; I have not succeeded in doing so without destroying them though. Inside, the magnet is at the core, with a double wound (hum bucking) coil suspended by etched diaphram leaf springs that also connect the coil output to the terminals. Surrounding this is another steel cylinder for the magnetic return path. Some are then press fitted into a brass case, and everything is epoxied together. Most current phones are press fitted into a larger aluminum cylinder with about 1/4 " walls. THey are not designed to be repaired or adjusted. New 4.5 hz phones cost about $50 the last time I asked. To determine the natural frequency with an oscilloscope and function generator, a bridge is used to drive the phone, and a peak in the (undamped) output is at Tn. Some phones have a calibration coil wound over main coil; it is ususlly 5 to 10 ohms, so connecting a 1.5 volt battery will burn it out immediately. THis can be used with the scope in x-y input to generate lissajous (spell?) patterns to read the natural period to about 1%. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: More Arenal volcano Date: Fri, 08 May 1998 13:07:58 -0700 -- ---/---- Charles P. Watson Seismo-Watch ---------------------------- SAN JOSE (Reuters) - Costa Rica's Arenal volcano was quiet Wednesday in the aftermath of a major eruption that forced the evacuation of 450 people, including about 70 tourists, from nearby resorts, officials said. Costa Rica's National Emergency Commission lifted the state of maximum alert it declared after the eruption Tuesday, but said people would still not be allowed to climb the volcano. Arenal, which killed 80 people in a massive 1968 eruption, was now quiet and had not registered any significant activity overnight, said commission spokesman Jorge Rojas. Some tourists watched in awe while others fled in panic when the volcano erupted, spewing out lava, flaming rock and a deadly cloud of ash and smoke, eyewitnesses said. They said lava had spewed from what looked like a fissure in the side of the 5,373-foot mountain about 100 miles northwest of the capital San Jose. "It was an unforgettable day," said geologist Fernando Alvarado of Costa Rica's state-run ICE electricity company, who was near the volcano when it erupted. "It was an unforgettable fright," added his assistant Lorenzo Murillo. Tourists evacuated from the area told local media the experience of seeing a volcano blow its top was unique. "It was beautiful, extraordinary," said 22-year-old Israeli Yubal Blankstein. The Tabacon resort at the foot of the volcano, which boasts thermal pools and streams heated by underground lava flows, was empty Wednesday after all its guests were evacuated. San Francisco travel agent Marta Tapiero, who had been staying at Tabacon, managed to take pictures of the erupting volcano that were published in local newspapers. Her friend Martha Brown said she panicked as a thick cloud of poisonous fumes spewed down the side of the volcano toward the resort and had to drag Tapiero away to safety. Geologists say the greatest danger is posed by the suffocating cloud of gases that accompanies eruptions. The cloud can reach 5,432 degrees Fahrenheit, instantly turning everything in its path to ash. Arenal is one of Central America's most active volcanoes. Since 1997 it has averaged 10 minor eruptions a day, often providing night time fireworks for tourists bathing in the bubbling pools at its feet. But the volcano has spewed lava down its sides only 10 times since 1968. One of Costa Rica's largest dams sits on a lake near the southern part of the volcano, providing the capital with most of its electricity. Officials said it was unaffected. REUTERS _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Sesimology Bibilography Date: Fri, 08 May 1998 18:20:00 -0500 Larry, Here is another reference to add to your Bibliography. I had a copy of the article for some time but I didn't have the date of the issue. I finally found the date at http://www.softcopy.co.uk/electron.htm. Anyway the article is on the construction of a mercury tiltmeter. It has some equations to let you calcuate the period, damping factor etc. "Tiltmeter" Electronics and Wireless World March 1988 PP 264-265. by A Refsum -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Geo Phone Date: Fri, 08 May 1998 16:09:40 -0700 I ordered one today and the person taking the order didn't say boo about availability.????? Hopefully the right hand knows what the left is doing. Barry Karl Cunningham wrote: > > A friend of mine and I bought the last two $10 geophone kits from the San > Diego Gateway Electronics store about two weeks ago. The guy there didn't > know if they were going to get any more, and he said they came from their > St. Louis store. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Lehman sensitivity Date: Fri, 8 May 1998 19:21:32 -0500 (CDT) Greg, I think you nicely addressed the question of what is a "good" seismometer for the amateur. The first answer that has to be determined is what is expected of the instrument. I prefer verticals, for the reasons I listed yesterday, but a long-period vertical requires squabbling with either or both a "zero-length" spring and/or broadband feedback electronics. A long-period horizontal is theoretically a cinch: just tilt it back to reduce the gravitational restoring force to get up to infinite (= unstable) periods. The Lehman is a "poor-boys'" version of the Columbia-Sprengnether S5000 long-period, of which there are over 1000 in use. Maybe the next time I play with the web site I will scan a photo of it, so the home builder can get some ideas. (although I doubt if anyone can come up with the massive aluminum castings it is made from). The stability question for a horizontal seismometer depends mostly on the mechanical period and the working range of the velocity coil; ie how far it can drift before touching. The old S5000s that I operate at 15 seconds in vaults rarely need to be recentered. (the working range is +,- 5mm for these horizontals). How are the ones doing that Meredith is operating on his crawlspace pier? Probably pretty stable. Years ago we ran them at 30 seconds, and had to center them about every other month. I understand that most Lehmans operate at 10 seconds give or take, but that some can be workable at 20 seconds with more frequent adjustment. My specific hope for someone making a new Lehman would be to to make it as rugged and massive as possible so that longer periods are easily attainable, (which provides a significantly more interesting response to teleseisms), but without the problem of needing frequent recentering. A 20 second instrument would be nice, but would need 4 times the tilt stability of a 10 second sensor. I don't have any information on the actual sensitivity of the Lehman designs that are in use. But for comparison to the S5000s I am operating at 15 seconds, which have a 32 tpi (turns per inch) leveling screw, about 1/100th turn (the leveling knob happens to have about a 100 mm circumference) is about 16 microradians, and moves the mass about 1mm. One can calculate how much the mass should move when tilted at a given period. Some formulae of interest for the horizontal pendulum: (assuming that the restoring force by the hinges and/or pivot are minimal): The natural period: Tn = 2*pi*sqrt(l/(g*sine i)) where l is the boom length in cm, g=980cm/sec^2, i is the angle that the boom makes wrt the horizontal, measured in radians, (where sine i = i). For example, a 40 cm boom hanging vertically as a simple pendulum ( an angle of 90 degrees) has a period of 1.3 seconds. (a one second clock pendulum is 24.8 cm). When tilted horizontally to about 4 degrees, the period is 5 seconds. At about a 1 degree angle, it is 10 seconds, and at about 0.23 deg. it is 20 seconds. So the period is changing with inverse of the square root of the angle, which is why long periods are so unstable. Another useful calculationis the tilt sensitivity of the horizontal pendulum (which can be used to calibrate the displacement detector) z = (g * Tn^2 / 4 * pi^2) * phi where z is the horizontal displacement of the mass, Tn is the natural period, and phi is the tilt of the base at right angles to the boom, again measured in radians. From my example above about the S5100: the base is 500 mm, so the tilt from 1/100 turn of the screw ( which is 0.008 mm) is 0.008/500 = 0.000016 radian. If Tn = 15 seconds, the mass will move 0.88 mm, which is close to my approximation. Evaluating this on my STM-8 horizontal, with l = 40 cm, and Tn = 10 seconds, 1/12 turn of the 28 tpi leveling screw is 0.9mm/12 = 0.075mm; the base width is 130mm, so the tilt is 0.075/130 = 0.00058 radians. This calculates to an offset of the mass of 1.43 cm, which is about what I measure. At 20 seconds, the offset is about 4 times, or 5.7 cm. Two points are clear: the stabilty is inversely proportional to the square of the period. And if we want to calibrate a VBB system with displacements within the reange of the feedback system, which is 100 to 500 microns, we will need to produce tilts with 1/1000 the resolution of the above method. This also has to be achieved by any remote centering system. This is why I think that we need some more robust designs. But I have to keep my ideas to myself unless I have something specific to offer; so I should probably whip together a "Lehman" some weekend, using a speaker coil and magnet as both the velocity sensor and the electromagnetic damping coil (which is how all modern velocity output seismometers are damped). I think the frame can be Al channel, with the taught-wire suspension of the boom end at the mast, and the forked wire suspension for the mass end of the boom. I need to scare up a baseplate; maybe Meredith's patio paver? Or a piece of that fine Colorado red sandstone from Ft. Collins? And maybe one of those meteorites for the mass! I am currently trying to shrink the VBB horizontal STM-8 (that has the Press-Ewing vertical hinges) to 16" long by 10" high by 8" wide so that it will fit inside a 10 gallon aquarium for draft protection. With the displacement transducer, the operating range is only about +,- 0.5 mm, so motor controlled zeroing with microradian resolution is needed . Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: rayv Subject: Re: Geo Phone Date: Fri, 08 May 1998 20:44:59 -0400 The three MD-79 units i bought were all 8 hz units, 335 ohm coil. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "d.sevold" Subject: Earthquake alarms Date: Sun, 10 May 1998 19:11:25 List: A local paper to the British Columbia Gulf Islands carries an advertisment for "quakealert" , from Innovative Technologies in Victoria, purported to be a "remarkable Canadian invention....gives you up to a one minute warning of a '5' or greater quake." See their story at: http://www.dsupernet/~innotech Years ago I found a small earthquake alarm somewhat like a smoke detector, from California. It worked, after a fashion, if you jumped up and down on the floor. Dean Sevold _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ACole65464 Subject: Re: geophones Date: Fri, 8 May 1998 23:20:53 EDT Sean-Thomas (or anyone else who can answer the question}, How is a hum bucking coil configured? I have read about other seismometer designs that have included them, to make the instruments less senstive to ambient 60 Hz noise. Are they two concentric coils? Could someone please explain. Thanks. Regards, Allan Coleman Edmonds, Washington _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: More GeoPhone Date: Fri, 8 May 1998 20:28:23 +0000 Hello All, Today, (98.05.08) I purchased two "GeoSensor Kits" -- $9.95 each, from Gateway Electronics in Missouri. Ms."L..." managed my order. I was informed their stock of geophones included different models, with MD-105 one of the models; the model I would receive. She affirmed there were additional stock available. Delivery UPS --ground, one week. Walt Williams, 98.05.08 dfheli@.............. http://www.pacificnet.net/~dfheli Woodland Hills, (suburb of Los Angeles) California, USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: "humbuck" coils Date: Fri, 8 May 1998 23:38:44 -0500 (CDT) Allen, The hum bucking configuration has two coils wound on opposite ends of the bobbin (which is part of the moving mass), but they are wound in opposite directions. Both halves are exactly identical, and usually the output ends of the windings are in the center of the bobbin, between the coils. There is a wire that connects the opposite outer ends together. The output is usually conducted to the terminals via the etched diaphram style leaf spring suspension that supports each end of the moving coils. Since the coils are moving over opposite poles of the central fixed magnet, the movement produces voltages that sum in series. But any external voltage induced is of opposite polarity, and cancels. Most geophone structures use the configuration, even the larger seismometers such as the L4C and the HS-10, which has one of the highest outputs for a 1hz, 1kgm sensor (the Air Force loved it for the nuclear test detection arrays) If someone decides to dismantle a exploration geophone, the setup is pretty obvious. Speaking of which, I am wondering about the recent flurry of interest in 8-hz phones. They may be fine for VERY local events; they were designed to pick up waves from borehole explosions or air gun sources. But for general seismic monitoring, (like Mb 3 to 4 events greater than 100 km away) they aren't very sensitive. THe seismic wave energy has usually dispersed to the 1 to 3 hz range over that distance. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: Lehman Sensitivity Date: Fri, 08 May 1998 22:43:35 -0600 Sean-Thomas, Hope that if you scan in an S5000, you can zoom in on the gimble boom pivot design; I think alot of people would be interested in that part. Earlier last year, I tried to replicate it, with another homebrew "duplicate", and although it rests unfinished as a whole, I think it will work OK...sometime. Actually it seems to be a no problem pivot, compared to the home brew standards which are different of course...and troublesome. I'am guessing here...but the pivot probably adds alot to the stability and longegivity or lack of adjustment of the S5000 horizontal. Yes, the S5000, is proving to be very stable here. You're right with regard to the adjustment screw tweaking...I move it a hair to recenter. You're also right in regard to the massive base pier, they add a degree of stability way beyond my previous ones....I was recentering alot then. Took along time to redo the vault, but the results so far, have made it worth the effort, with what I've seen so far. Even the vertical seems to be stablizing very well as of late...of course it had to wait some 25 years to get stretched out. Just finished Larry Cochranes preamp box container and the vertical is currently being displayed on the chart recorder...no problem with pre-amp drift at all, but I did tweak it afew thousanth of a volt. So....thanks for all yours and others suggestions...good stuff! In regard to the horizontal "choice" of the suspension; which of the two (Lehman v/s STM-horizontal), which is a better approach? I would think that your horizontal would be easier to make and adjust, perhaps, by a far measure. Perhaps the hardest thing to do is make the mast as precisely upright as possible; with as little tilt in any direction as possible. OK...I'am going to throw this possible 3rd suspension in here. Remember those old frail Wood-Andersons...taunt wire with the mass attached? How about a thick piano wire (pi-anna in Missouri), and a light weight boom and reasonable weight mass type deal? P.S. Betcha you are really mentally rumbling around with that concrete paver base and brick idea for a massive seismo....now aren't you? Maybe I'll even beat you to making one first...huh? Sean....Sean, are you there Sean-Thomas? Ha. Colorado secret meteorite mass recipe: Malleable iron and a blow torch, when you've exhausted the local supply of natural stuff. OOPS! Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Live PSN: first Event. Date: Sat, 09 May 1998 13:22:03 +0800 Hi, The First "Live" PSN event capture has been taken. The AU3 channel (red), max/min is 380/339. It appears to be a local event of ~ Ml 2.0 at ~ 180km. This should give some idea of scale (Y). Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael S. Healy" Subject: Re: RFI radio interferance geting into dc amp. Date: Sat, 09 May 1998 02:24:45 -0800 Doug Crice wrote Norman Davis: These days we operate with floating differential inputs, with small caps between the inputs and also to ground from each input. Also some resistors leading to the outside world so the caps have impedance to work with... Suggest using opto isolators, else capping never gets it all, and eventually adds even more problems; alluminized mylar shield works too. _____________________________________________________________________ -- Michael S.Healy internet: sunmanh@............ 1-503-355-3177 (voice) http://www.pacifier.com/~sunmanh/ 1-503-355-3367 (fax) (below RIP-aware as well) 1-503-355-8738 (bbs SysOp; 8N1 FULL DOS terminal program ANSI) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: RFI radio interferance geting into dc amp. Date: Sat, 09 May 1998 07:41:11 >These days we operate with floating differential inputs, with small >caps between the inputs and also to ground from each input. Also some >resistors leading to the outside world so the caps have impedance to >work with... I noticed that larrys amp circuit uses that type of input. Also did not think of optoisolators. Will have to give that a shot. The problem is if you use an opamp before the optoisolator it will still pull the dc level. Suggest using opto isolators, else capping never gets it all, and >eventually adds even more problems; alluminized mylar shield works too. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dick Webb Subject: JB Tables Date: Sat, 09 May 1998 10:58:09 -0400 The recent earthquake southeast of Taiwan was about 12,000 kM from my location and outside the JB teleseimic tables in Winquake. Is there a set of tables available for Winquake that goes beyond the 105 degrees? Can the Pdiff or PP and Sdiff or SS tables in the JB paper be used in some way to calculate the origin time and distance? Seems to me that aside from the difficulty in making the picks, it should be possible. Dick _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: RFI radio interferance geting into dc amp. Date: Sat, 09 May 1998 08:42:51 -0700 Michael S. Healy wrote: > > Doug Crice wrote Norman Davis: > > These days we operate with floating differential inputs, with small > caps between the inputs and also to ground from each input. Also some > resistors leading to the outside world so the caps have impedance to > work with... > > Suggest using opto isolators, else capping never gets it all, and > eventually adds even more problems; alluminized mylar shield works too. > _____________________________________________________________________ > Unless I'm getting too obsolete to participate, normal opto-isolators are digital devices and extremely non-linear when you try to use them as analog things. Here we are talking about the high-gain preamp, the first thing the signal sees when it gets to the seismograph. Its job is to turn differential microvolts into millivolts and common mode voltage into microvolts. There are instrumentation amplifiers that have opto-isolators or transformers built in, and the purpose is to completely separate the grounds and power supply between the input and the output to eliminate ground loops. The last time I looked, they were too expensive and also more noisy for seismic, but I haven't looked in a long time. If you construct a differential amplifier with an op amp and four resistors in the classic design, the common mode rejection is VERY dependent on the matching of the resistors. 1% isn't good enough. The easiest solution is to put a little trimpot in the circuit and adjust it manually. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Lehman sensitivity Date: Sat, 09 May 1998 08:56:24 -0700 All I have had pretty good luck with monitoring the displacement and running it thru a very low pass filter and thru a second smaller rezeroing coil. I think others have also mentioned this possible alternative to a screw adjustment. It's drawback is it requires more parts (K.I.S.S.). Sometimes when I have to keep recentering my Lehman the extra circuitry doesn't seem so bad. Barry S-T Morrissey wrote: >...... > With the displacement transducer, the operating > range is only about +,- 0.5 mm, so motor controlled zeroing with > microradian resolution is needed . > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Live PSN: first Event. Date: Sat, 09 May 1998 17:10:43 -0600 Arie- When I click on Seismograph Live ( Click ) of this webpage Http://iinet.net.au/~ajbv/ I get the message Starting Java and then my version of Netscape hangs up and I have to "End Task" to shut it down. Maybe it will work with Internet Explorer but I haven't tried that yet. How are you? Do you have a videotape copy of the your astronomony/geology program? -Edward Arie Verveer wrote: > Hi, The First "Live" PSN event capture has been taken. > The AU3 channel (red), max/min is 380/339. > It appears to be a local event of ~ Ml 2.0 at ~ 180km. > This should give some idea of scale (Y). > > Arie. > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: RADIOTEL Subject: Re: LEVELING A LEHMAN (Kinda catchy title dont you think) Date: Sat, 9 May 1998 19:28:45 EDT I am assembling a Lehman seismograph primary using heavy gauge aluminum for most parts. I have been attempting to locate fine thread bolts and taps to level the unit with. Thus far the finest thread 1/4 inch bolts and tap for making the threads have been 1/4 X 28. Does anyone know of a source for taps and bolts with a finer thread than this in the greater Los Angeles, Calif. area. What are most of you using for leveling - and do you find that it is sufficient? Perhaps 1/4 X 28 is fine enough. Jim Allen Cerritos, California U.S.A. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: damping, electromagnetic Date: Sat, 9 May 1998 20:16:39 -0500 (CDT) Re electromagnetic damping Meredith, One of your list of questions was about damping. For older displacement seismometers dash-pot (air or oil) damping was widely used, as were eddy currrent techniques. The problem with these methods is that the amount of damping could only be determined experimentally. With the advent of electromagnetic (velocity) transducers in the 40's, resistive damping became widely used, particularly because it used the signal coil itself, and the amouint of damping could be precisely calculated. It can be applied to any seismometer with a suitable coil and magnet. The drawback of resistive damping, other than the loss of part of the signal from the coil (made up for with less attenuation in the recording circuitry) is that it is dissipative, and makes noise. This is the reason it is not used in the VBB configuration, where the damping is a dynamic process in the feedback loop. The noise from the damping resistor is primarily Johnson or thermal noise, which can be estimated, as well as 1/f noise. To calculate the value of the damping resistor to be used, one first has to know or determine the open circuit damping, called Bo. It is the mechanical air-dashpot function of the coil movement, and is often listed in the specifications for the seismometer. For most seismometers, it ranges from 0.2 to 0.4, where a value of 0.8 is for critical damping. It can also be determined from the logrithmic decrement of the free oscillations of the undamped seismometer. Then the motor constant and resistance of the main coil have to be determined or found in the specifications. The electromagnetic damping Bem needed is determined by subtracting the Bo from the required total Bt. Bem = Bt - Bo Then the damping resistor is calculated by: Bem = G^2 / (2*omega*M*(Rs + Rd), or Rd = [G^2 / (Bem*2*omega*m)] - Rs Where Bem is the electromagnetic damping, G is the main coil constant, omega is the angular frequency, equivalent to 2*pi/Tn, where Tn is the natural period, and M is the mass. For an L4-C, with a 5500 ohm coil, with G = 270 V/m/sec, Bo = 0.27, we want Bt to be 0.77, so Bem = 0.5, M = 1 kgm, omega = 2*pi, we calculate a damping resistor Rd of 6102 ohms for critcal damping. For an S5000 Long Period Seis, with a 500 ohm coil, G = 100 V/m/sec, Bo = 0.1, we want a flatter response with Bt = 1, so Bem = 0.9, omega = 2*pi/15 (seconds), M = 11 kg, we calculate a resistor of 705 ohms for Bt = 1. For an HS-1 4.5 hz geophone with a 1250 ohm coil, G = 41 V/m/sec, and Bo = 0.28; we want critical damping with Bt = 0.8, so Bem = 0.52, omega = 2*pi*4.5 (hz), M = 0.022kg, we calculate Rd = 1348 ohms. This method of damping is the only method currently being used on velocity sensors. The method is so exact that often the resistor for Rd is installed inside the smaller geophones at the factory. Metal-film resistors are used for lower noise. When one is connecting a seismometer to an amplifier with a low input impedance Ra, that value is in parallel with the seismometer, so must be taken into account. So if Ra = 10k ohms, and Rd is to be 5k ohms, the actual resistor to be used is Rs = Rd*Ra/(Ra-Rd), or in this case Rs = 10k ohms. Generally very high input impedance amplifiers are not used because of noise considerations, so this detail is often overlooked. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: LEVELING A LEHMAN (Kinda catchy title dont you think) Date: Sat, 09 May 1998 20:49:15 -0500 RADIOTEL wrote: > > I am assembling a Lehman seismograph primary using heavy gauge aluminum for > most parts. I have been attempting to locate fine thread bolts and taps to > level the unit with. Thus far the finest thread 1/4 inch bolts and tap for > making the threads have been 1/4 X 28. Does anyone know of a source for taps > and bolts with a finer thread than this in the greater Los Angeles, Calif. > area. > What are most of you using for leveling - and do you find that it is > sufficient? Perhaps 1/4 X 28 is fine enough. > Jim Allen Jim, I don't think you will find anything much finer than 28 TPI in a 1/4 inch bolt. I have a 1/4 32 tap and die I got for a project once and that was the finest in the machine tool catalog. My Lehman has 1/2 16 bolts and I use a long handled wrench to adjust them. This gives you fine control of the movement. It seems to work ok. If you want a finer adjustment I would look into using the differential thread approach discussed on this list a while back. You can get studs from an auto parts store with 1/4 24 threads on one end and 1/4 28 on the other end. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: LEVELING A LEHMAN (Kinda catchy title dont you think) Date: Sat, 09 May 1998 18:46:36 -0700 Jim I was going to setup my Lehman with a micrometer barrel for a leveling screw. One type of installation would be to put it thru an appropriate diametet hole in the base and use a set screw. It would have a 40 turn per inch resolution and you would know how much you had to adjust. For displacement sensors one could use it to calabriate with. I found one in a cheap tool outlet for $9. Barry RADIOTEL wrote: > > I am assembling a Lehman seismograph primary using heavy gauge aluminum for > most parts. I have been attempting to locate fine thread bolts and taps to > level the unit with. Thus far the finest thread 1/4 inch bolts and tap for > making the threads have been 1/4 X 28. Does anyone know of a source for taps > and bolts with a finer thread than this in the greater Los Angeles, Calif. > area. > What are most of you using for leveling - and do you find that it is > sufficient? Perhaps 1/4 X 28 is fine enough. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Magnetics Date: Sat, 09 May 1998 18:48:26 -0700 For those with magnet personalities The june 1998 Electronics Now has a nice article by Joe Carr on experimenting with magnetic sensors. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Re: Re: Live PSN: Date: Sun, 10 May 1998 17:49:06 +0800 Hi Edward, I'm not for sure about the Netscape hanging on the Java Applet? I have tried it with Netscape communicator 4.04 and Internet Explorer. It should go something like, starting Java , followed by a small waiting period to do the applet, Then go into the Web page and then wait some more while it loads the picture. Maybe its a problem with the amount of users using the Java applet or a problem with my internet provider. I'll look into it. At one time the system did have a problem with the "FTP" data packet size. It use to hang on exactly 1024 bytes. Someone, somewhere at the works head office reset something, and it worked. General question : has anyone else had the same or similar problem with the Java Applet hanging ? Life is never easy, and especially when computers are involved. http://iinet.net.au/~ajbv/ By the way two more events have arrived. Arie. >Arie- >When I click on > Seismograph Live ( Click ) >of this webpage > Http://iinet.net.au/~ajbv/ > I get the message > Starting Java >and then my version of Netscape hangs up and I have to "End Task" to shut >it down. Maybe it will work with Internet Explorer but I haven't tried >that yet. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Dick Webb Subject: Re: Re: Live PSN: Date: Sun, 10 May 1998 09:44:03 -0400 I just tried http://iinet.net.au/~ajbv/ and the live screens with Netscape Communicator 4.05 and things worked well. By the way Arie has a great site for those who haven't visited it yet. Dick _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Dewayne (n0ssy) & Linda (n0uqf) Hill" Subject: Waveform Date: Sun, 10 May 1998 13:45:48 +0100 I notice on my Lehman that when I receive any event it does not have a sharp starting point. It builds then peaks and drops off. I am using an oil damping setup. Could it be I have to much oil and I'm over damping? Any ideas? Dewayne (n0ssy) & Linda (n0uqf) Hill Westminster, Colorado USA 39.83569n 105.0627w Elev. 5660ft. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: LEVELING A LEHMAN (Kinda catchy title dont you think) Date: Sun, 10 May 1998 08:07:17 >What are most of you using for leveling - and do you find that it is >sufficient? Perhaps 1/4 X 28 is fine enough. I used a plate made of aluminum for the base and gouged out pits around the bottom of the three holes the leveling bolts pass through I think they are 1/2 x 28 and they seem to do the job. The nuts are epoxied into the pits to provide the threads for the bolts. My problem is that a lizard has taken up residence in the box with the lehman and likes to bathe in the mineral oil. Don't know what I am going to do about that. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: win 95 and serial ports. Date: Sun, 10 May 1998 08:01:38 I got this from one of the lists I subscribe to. Thought you hacker types could use it. >Hi there. Well, I finally remembered to get this information to you. > >In a regular windows95 setup, the system boots into Win 95. > >You can change the setting in a single system file, to do a couple of things: > >One - skip the sky logo. >two - boot into dos - not a "shell to dos" which is really what WIN95 >does, when you >exit or "reboot to dos mode" If you dont believe it, type EXIT, and you >pop back into WIN95!. > >Here is how you disable WIN95. When you do so, it doesnt kill anything. It >just >allows you to boot into DOS, so if you want to run a dos program, you >dont have to >worry about WIN95 stealing the comm ports. > >In win95, hit the start button in the bottom left corner. >Select PROGRAMS, then MSDOS prompt. > >At the C: get into the root directory, if not already with CD\ > >At C: type attrib -s -h -r msdos.sys [this unhides it so you can edit it.] > >then type EDIT msdos.sys > >Look for the word [options] in square brackets. >See that BootGUI = 1... change the 1 to 0 and this prevents WIN95 booting. >If you dont want to see the clouds logo, add this statement under [options] > >logo=0 > >When done, do an ALT F, S to save the edited MSDOS.SYS file. >then do: > >attrib +s +h +r msdos.sys to make it a system file, hide it from a DIR, and >make it a read only file. > >Once you have done this, EXIT back to WIN95. > >The next time win 95 boots, you will get a dos prompt, instead of WIN95. > >Dont worry. to fire up WIN95, type WIN, just like it was in WIN 3.1 days. > >Enjoy. > > > >Byron Smith >wa6ylb@............ - Webpage: http://www.theworks.com/~wa6ylb >wa6ylb@....................... > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Waveform Date: Sun, 10 May 1998 12:44:53 -0500 (CDT) Dewayne, I would suggest trying electromagnetic damping with the main coil. Such damping is velocity sensitive: ie there is none unless the coil is moving and generating a voltage to produce a current in the damping resistor to dissipate the energy. Theoretically, oil damping should be the same, but the initial drag due to viscosity is not zero, which is why air-dashpots were used. Unfortunately I have no idea what the constants for a Lehman might be. I note that the coil is 1/4 pound of # 34 wire which has 8310 feet per pound and 2168 ohms per pound at 20 deg.C. So assuming the coil is about 500 ohms, I would try a damping resistor of about 1000 ohms, unless you already know the constant G of the main coil and can calculate the value. With this type of damping, the response should be flat to velocity from roughly the natural period to whatever low-pass filter you have in your amplifier. (BTW another place to check to see if the shorter p-wave phases are being filtered out). Also, in case you were expecting a definitive P-phase from last weeks' near Taiwan event, it did not have one stateside. P was a long period phase; this is probably because the mechanism was strike-slip, which is unusual in a subduction zone area. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: rick@.................. (Rick Hewett) Subject: Re: New WinQuake beta release. Date: 10 May 1998 19:02:30 GMT At 00:13:49 UTC on Fri 08 May, cochrane@.............. (Larry Cochrane) wrote: > At 05:52 AM 5/7/98 -0700, Warner Lindholm wrote: >>Do you think WinQuake will ever be ported to Linux? > Don't hold your breath... I am not a UNIX / Linux fan, and > I don't have the knowledge, development tools and time need to port > it over. Sorry... I guess a couple of follow-up questions might be asked: 1) Is there any source-code available should anyone feel enthusiastic enough to consider writing a unix equivalent of WinQuake? 2) Has anybody considered writing something in Java for viewing PSN format seismometer records? -- ...Rick Hewett http://www.chocky.demon.co.uk/ There seemed nowhere in it for him, but this wasn't a problem. There was always room at the top. -- (Terry Pratchett, Moving Pictures) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Re: Live PSN: Date: Sun, 10 May 1998 13:01:54 -0700 (MST) On Sun, 10 May 1998, Arie Verveer wrote: > General question : has anyone else had the same or similar problem > with the Java Applet hanging ? Arie, I have had problems with applets as well, even simple ones. I never use internet explorer because it can't even seem to handle HTML correctly, so I don't know what happens there with Java applets. I don't think all the snags have been ironed out with Netscape's use of these applets, and I know they have not focused effort on applications like yours. Mostly they have catered to interfacing with databases and simple banners and animations... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "It is easier to excuse an ignorant person who claims that theory is unnecessary and dispensable in his supposed practice, than to excuse a Sophist who concedes its value to the schools (as, perhaps, only a mental exercise) but who at the same time maintains that matters are quite different in practice- that as one leaves school to enter the world, one will realize one has been pursuing empty ideals and philosophical dreams- and, in a word, that what sounds good in theory is of no practical use." -Immanuel Kant, On the Proverb: That May be True in Theory, But Is of No Practical Use ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: Waveform Date: Sun, 10 May 1998 16:37:33 -0700 (PDT) " P was a long period1 phase; this is probably because the mechanism was strike-slip, which is unusual in a subduction zone area." Sean-Thomas, I understood tha last part (about strike-slip being unusual in a subduction zone area) but can you explain what you meant by "P was a long period phase" and why this would result in not seeing the P wave here in the states? I recorded this event but it happened while I was working in the garage on the sensor. In fact I got it running stably about 10 minutes before the first waves rolled in but because I was walking around for the next 20 minutes I thought I had ruined the recording. (My son actually pointed out to me that the signal on the PC had disappeared. At first I thought it was broken, then we noticed it was just spending most of its time off scale.) Looking back on the recording, the P arrival is certainly not distinct, but I thought I had convinced myself that I saw it at about the right time. But I've been wrong about that lots... Thanks, Ted _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Gary Lindgren" Subject: Anybody Using DSP to Enhance Seismometer Readings Date: Sun, 10 May 1998 18:38:47 -0700 There has been a lot of advances in using DSP to work with signals in various engineering and scientific areas. Is anybody with an amateur seismometer operating use DSP to enhance or work with the raw seismometer signal. What does DSP do to make it better. Gary Lindgren Palo Alto CA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Gary Lindgren" Subject: Lehman or Shackleford-Gundersen Seismometer Date: Sun, 10 May 1998 18:37:58 -0700 I'm finally going to get serious on building a seismometer. A design by Barry Shackleford and Jim Gundersen was described in the Sept. 1975, Scientific American. Also, the Lehman design was described in the July 1979 issue of Scientific American. The Lehman design has also been improved recently with articles in the PSN web page. http://psn.quake.net/ So, is there a consensus on which style works better, or what are the tradeoffs between the 2 design concepts. Gary Lindgren Palo Alto CA gel@................. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Anybody Using DSP to Enhance Seismometer Readings Date: Sun, 10 May 1998 20:18:15 -0700 Hi Gary I have used a digital filter(IIR & FIR) off and on in my data acquisition program. It helps somewhat. My trigger routine also runs a 512 FFT moving window and looks for changes in frequency indicative of an event. It also helps to eliminate constant frequency background noise. If one runs a continuous record it wouldn't help to much. What I was hopeing to include in the future is a digital filter which could change with time (recalculate coefficients on a specific time frequency). I have an Analog Devices & TI DSP board but haven't got into them yet. Barry Gary Lindgren wrote: > > There has been a lot of advances in using DSP to work with > signals in various engineering and scientific areas. Is anybody > with an amateur seismometer operating use DSP to enhance or work > with the raw seismometer signal. What does DSP do to make it better. > Gary Lindgren > Palo Alto CA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: Damping, electromagnetic Date: Sun, 10 May 1998 23:49:57 -0600 Sean-Thomas, Today, I changed the damping resistance of my S5000 seis's to 705 ohms per your determination of it. Think I'am seeing a overdamping effect with a prolonged chart recorder zero centering of its nominal "center" while recording. Specifically, when a person walks overhead on the floor above and induces tilt to the horizontal, there is a initial offset and about halfway back to the "center", there is a step dropoff back down to center. Being as I have no experience along this line, with your equation or your experience...is this normal? Of course the S5000 uses 2 coils and one specifically for damping, and therefore there is no damping noise on the other signal coil. The signal coil output does run thru a 2K gain preamp and the chart recorder circuitry which likely has an effect I'am sure. I'am presuming that your damping article would nevertheless apply to this 2 coil model also. The damping resistance is a 1K potentiometer, so its no problem to adjust/change. I ran up the resistance to about 840 ohms, and the tilt response changed to more of a general 1/2 sine wave effect, and the "step" of earlier mention has disappeared, and the signal shows no "overshoot". Is this more of an appropriate critical damping? I realize this is the experimental approach,...but whats your opinion, in light of the added or followup circuitry? I suppose when I get into computer A/D card circuitry, there will be a further change to contend with. Most of the coils resistances measures about 475 ohms average instead of 500 ohms. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Live Java, HTML, PSN: Date: Mon, 11 May 1998 19:33:27 +0800 Hi, The "Live" PSN page now has a "Java" page and a "HTML" page. This should alleviate the problem that can occur with "Java". If the choice is the "HTML" page, the browser's "reload" of "Refresh" button must be activated to load in a new image. If the reload button isn't activated then an old cached image will appear. By the way, check out the long period waves in one of the saved images. Assuming it hasn't been pushed into the bin by more new images. Thank for everyone's help in sorting out the problems. Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: WinQuake on Win98 Date: Mon, 11 May 1998 16:36:57 -0700 Hi Everyone, Has anyone tried WinQuake, hopefully the new beta release, on Windows 98? If you have access to Win98 could you try it and let me know if you run into any problems? Thanks, -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Waveform Date: Mon, 11 May 1998 19:38:13 -0500 (CDT) Ted, I may have over simplified the situation of the Mb 7.3 SE of Taiwan quake on May 03. I have posted my record on the web page at: http://www.eas.slu.edu/People/STMorrissey/index.html under the "recent quakes,data" page. What I meant by a long period P phase was that what I recorded had periods of 7 to 18 seconds, rather than the usual p periods of 1 to 3 seconds. I am far enough away that I probably got conversion phases (that passed through the core); the record does show some very emergent phase about 70 seconds before the dominant phases, but no one here has an explanation for them. It turns out that the quake was not in the subduction zone, but out in the convergent area of the plate, which in that area is quite complex. The mechanism was a strike slip oriented mostly north-south, so very little compressive energy would radiate to the east or toward the states to give a definitive p phase. Regards, Sean-thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Anybody Using DSP to Enhance Seismometer Readings Date: Mon, 11 May 1998 20:02:34 -0500 (CDT) Gary, We have been using DSP in our broadband stations for about 12 years. The basic idea is to oversample the seismic signal, like at 56k samples/second, at 16 bits, then use DSP to run an EDME (Enhanced Delta Modulation Encoding) or similar process to derive 24-bit data in real time, and come up with 80 sps data. Then the data is successively decimated to lower sample rates and cleaned up at each stage with FIR (Finite Impulse Response) filters running in real time. The output sample rates are 40, 20, 1, 0.1, and 0.01, all from the same broadband seismometer. Then the station processor runs real time event detecting on most of the data streams, storing the data in both continuous and event format circular buffers that are accessed for storage or transmission. All this takes lots of computer "horsepower": each sensor has its own EDME, decimation, and FIR filter processor, a 68020, and the station processor is also a 68030 running OS-9 on a VME buss. My staion at CCM in the Ozark cave has 9 data channels and split processing (with a 3km fiber link between), so there are 11 CPUs running simultaneously, not counting what is running the GPS engines and the satellite DPU. I don't know how or when DSP will be used by the amateur seismologist. We should eventually be able to handle the decimation/FIR filtering of VBB data with a home processor. Most likely the 24-bit dynamic range is unrealistic. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: WinQuake on Win98 Date: Mon, 11 May 1998 21:17:52 -0500 Larry Cochrane wrote: > > Hi Everyone, > > Has anyone tried WinQuake, hopefully the new beta release, on Windows 98? If > you have access to Win98 could you try it and let me know if you run into > any problems? > > Thanks, > > -Larry Cochrane > Redwood City, PSN > Larry, I have the latest version of Win 98 at work and will give WinQuake a try tomorrow if I have the time. Is there anything special you want me to test or look for? -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Anybody Using DSP to Enhance Seismometer Readings Date: Mon, 11 May 1998 21:36:26 -0500 S-T Morrissey wrote: > > I don't know how or when DSP will be used by the amateur > seismologist. We should eventually be able to handle the > decimation/FIR filtering of VBB data with a home processor. > Most likely the 24-bit dynamic range is unrealistic. > > Regards, > Sean-Thomas > Here is some idea of what can be done with DSP in a PC. At work I am busy replacing a $10000 FFT card with some software that runs in a Notebook computer. In a 266 MHz Pentium MMX processor we can do 1000 1024 point FFTs a second and have processor time left over to display the data, control a radio and save the data to disk. The FFT function is a specially hand coded assembly language routine that makes use of the MMX instructions (Multi Media eXtensions) of the Pentium processor. If anyone is interested in doing some DSP work in a PC, Intel has a software product called Vtune (<$200) it's primary function is to analyze software for speed improvments. But included with the CD is a set of libraries that can be accessed as DLLs and provide most any DSP function you can think of. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: Waveform Date: Mon, 11 May 1998 19:59:14 -0700 (PDT) Thanks for the update. I'll take a look at your recording. I hadn't realized that P wave energy was radiated preferentially in the direction of slip, but I guess that makes sense. I am thinking of adding a "distance estimation" routine to EMON so that an event pager message can include an estimate of the distance. Are there phase picker algorithms out there which would be easy to implement in QuickBasic 4.5, and could identify both P and S arrivals with some reasonable accuracy? I did an AltaVista search and did get several hits, including one with source code in FORTRAN! (My native computer language for many years) But this code seemed designed to identify *every* phase arrival, not just P and S, and no attempt to identify the phases was obvious. On Mon, 11 May 1998, S-T Morrissey wrote: > Ted, > I may have over simplified the situation of the Mb 7.3 SE of > Taiwan quake on May 03. I have posted my record on the web page at: > > http://www.eas.slu.edu/People/STMorrissey/index.html > under the "recent quakes,data" page. > > What I meant by a long period P phase was that what I recorded > had periods of 7 to 18 seconds, rather than the usual p periods > of 1 to 3 seconds. I am far enough away that I probably got > conversion phases (that passed through the core); the record > does show some very emergent phase about 70 seconds before the > dominant phases, but no one here has an explanation for them. > > It turns out that the quake was not in the subduction zone, but > out in the convergent area of the plate, which in that area is > quite complex. The mechanism was a strike slip oriented mostly > north-south, so very little compressive energy would radiate > to the east or toward the states to give a definitive p phase. > > Regards, > Sean-thomas > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: Re: WinQuake on Win98 Date: Mon, 11 May 1998 20:56:46 -0700 Subject: WinQuake on Win98 Larry, I am running WIN98 and have had no trouble as yet. I have tried the new version and it seems ok also. I will be trying it more this evening and will let you know if anything is amiss. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Lehman or Shackleford-Gundersen Seismometer Date: Mon, 11 May 1998 23:46:32 -0700 At 06:37 PM 5/10/98 -0700, Gary Lindgren wrote: > I'm finally going to get serious on building a seismometer. A > design by Barry Shackleford and Jim Gundersen was described in > the Sept. 1975, Scientific American. Also, the Lehman design was > described in the July 1979 issue of Scientific American. The > Lehman design has also been improved recently with articles in > the PSN web page. http://psn.quake.net/ > > So, is there a consensus on which style works better, or what are > the tradeoffs between the 2 design concepts. Gary, Both have there advantages and disadvantages... Lehman Advantages: Maybe easier to build, but I'm not sure about that. Less electronics. All the Lehman needs is a simple Amp / Filter. Better at receiving local events do to its velocity output. Lehman Disadvantages: Larger footprint. May need more monitoring and adjustment do to the boom wondering around. How stable your sensor is depends on the period you run it at, how well you built it, type of materials used, and where its located. SG Advantages: Smaller footprint then the Lehman. Does a little better job at receiving teleseismic events do to its lower frequency response. SG Disadvantages: More electronics. If one is into building electronics I don't really think this is a problem. Do to it lower frequency response, it needs better thermal isolation. This is need to prevent air currents from developing inside the enclosure. Hope this helps. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Indian Nuclear test. Date: Tue, 12 May 1998 16:30:59 +0800 Hi, I've just posted an event file, that contains, I believe, the traces of the three nuclear events from india. The placement is about right. Sorry about the length of the file. Also just visible in the data is the "P" and "S" waves of an event on the Indian-Pakistan Boarder region. P = 10:25:16.9 UTC S = 10:34:37.4 UTC At = 10:13:52.0 Utc 27.1276N 71.6884East 56.6Km mb 4.7 Any experts on identifying nuclear explosions.? Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 07:55:50 -0700 Hi All -- I have a rather technical question about differential capacitive displacement transducers... I've been driving the two differential capacitors with a solid-state multiplexer (DG-529) with a differential amplitude 60 volts peak-to-peak (square wave) and am getting about 40,000:1 signal-to-noise ratio (SNR). I would like to do better -- hopefully 20:1 better or more. This element is the heart of the seismometer and I would like to do the best I can since the rest of the electronics only subtracts from this figure. I am looking toward incorporating this into a VBB-feedback design, although it should have application elsewhere too. I have isolated most of the noise to the multiplexer stage and will be trying a transformer drive. This has a secondary with a grounded center tap that drives each of the two capacitors from each half of the winding. To try out, I wound a transformer with a 1:10 ratio. This will increase sensitivity by 10:1 over a 1:1 transformer, and of course increase any noise in the drive voltage by 10:1 also. But if the noise is from any other source, the SNR should be better. Does anyone have any experience with the tradeoffs of using high-ratio drive transformers like this? Or would anyone care to hazard a guess? It probably will work, but maybe there is an optimum ratio that I don't know about. Some of the disadvantages of high-ratio transformers I've considered are: 1. Corona discharge due to high voltage would undoubtedly introduce noise. 2. Attraction of dust due to high voltage could be a problem. 3. A high-ratio transformer might be more sensitive to core-induced noise (I don't know anything about it, but there is undoubtedly some) 4. There would be more electrostatic force on the plates of the cap, but hopefully this is relatively constant. 5. Effects due to changes in temperature of the transformer may be worse. Comments ? Thanks, Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Indian Nuclear test. Date: Tue, 12 May 1998 08:04:40 -0700 Arie, Thanks for reminding me to look for the tests. I had see the report on the ABC evening news and wondered how large a magnitude the blasts might have produced. I went to the International Data Center's (IDC) web site and looked for the event at or near the time you mentioned and found this line: 1998/05/11 10:13:52.0 27.12N 71.68E 44 56.6 mb 4.7 India-Pakistan Border Reg. The IDC web address for recent earthquakes is: http://140.162.3.250:65120/web-bin/recentevents As the line says, it was darn close to the Paki border. Funny place to set off a nuke. Does anyone know where the nuclear testing site is in India? The mb 4.7 is slightly smaller than the French's tests last year. -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Indian Nuclear test. Date: Tue, 12 May 1998 08:24:23 -0700 Here are the traces from the Swiss Seismic Network: http://seismo.ethz.ch/networks/telemetry_net/signals/KP199805111022.html -- ---/---- Chrales P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 08:34:37 -0700 (PDT) Karl, Is the Linear Technology LTC1043 Dual Precision Instrumentation Switched-Capacitor Building Block not suitable for your application? I used one in a modified SG and I thought it worked good, but I have no idea what the SNR was. If you'd give some pointers on how I'd measure this I'd appreciate it. I'll be using this circuit on the STM-8 that I've put together. Thanks --Warner _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Werner Wesling Subject: Re: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 17:37:37 +0200 At 16:55 12.05.98 +0200, you wrote: >I have a rather technical question about differential capacitive >displacement transducers... > >I've been driving the two differential capacitors with a solid-state >multiplexer (DG-529) with a differential amplitude 60 volts peak-to-peak >(square wave) and am getting about 40,000:1 signal-to-noise ratio (SNR). I >would like to do better -- hopefully 20:1 better or more. This element is [..] >Karl Cunningham >La Mesa, CA. >PSN Station #40 >karlc@....... > Hi, Karl, have you thought about using a lock-in amplifier? It works like this: You drive a bridge with a sine or a square wave, get a small output voltage frome the bridge buried in noise and drift. Then you amplify the signal with an ac-coupled amplifier. (No problem with dc drift, but adding noise). Now you have a signal with high amplitude, say some volts. You rectify the signal with a switch driven by your original drive signal and integrate over the result. Another way to look at it might be as a demodulation. All unwanted signal components having a different frequency and phase cancel out -- the noise, the hum and the drift. Even some amount of RFI should be eliminated. A circuit like this typically gives the improvement of 10:1 or 20:1 in signal-to-noise-ratio you need. Another advantage would be the lower drive voltage -- think of nonlinearities of components at higher voltages. I designed a precision temperature sensor circuit for an experiment for the 2. german spacelab mission giving 1/10,000 degree celsius accuracy using a digital lock-in amplifier -- same driving method, same amplifier, but followed by a voltage-to-frequency convertor and a microprocessor counting up and down in sync with the drive signal. After integrating over some periods the result was a 16-bit value. Hope this is of some interest for you Werner Wesling ---------------------------------------------- Dipl.Ing. Werner Wesling DASA Raumfahrt-Infrastruktur Abtlg. RIO52 Postfach 28 61 56 Phone +49 421 539-5218 28361 Bremen Fax +49 421 539-5127 Deutschland werner.wesling@.......... ---------------------------------------------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 11:10:57 -0500 Karl, I suspect that if you change to a sine wave rather than a square wave a lot of your noise will go away. Jim Hannon Karl Cunningham on 05/12/98 09:55:50 AM Please respond to PSN-L Mailing List To: psn-l@............. cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: Differential Cap Displacement Xducer Hi All -- I have a rather technical question about differential capacitive displacement transducers... I've been driving the two differential capacitors with a solid-state multiplexer (DG-529) with a differential amplitude 60 volts peak-to-peak (square wave) and am getting about 40,000:1 signal-to-noise ratio (SNR). I would like to do better -- hopefully 20:1 better or more. This element is the heart of the seismometer and I would like to do the best I can since the rest of the electronics only subtracts from this figure. I am looking toward incorporating this into a VBB-feedback design, although it should have application elsewhere too. Comments ? Thanks, Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: Indian Nuclear test. Date: Tue, 12 May 1998 11:13:49 -0500 I heard on the news this morning that the tests were near the Pakistan border. Jim Hannon watson@................ (Charles Watson) on 05/12/98 10:04:40 AM Please respond to PSN-L Mailing List To: PSN-L Mailing List cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: Re: Indian Nuclear test. Arie, Thanks for reminding me to look for the tests. I had see the report on the ABC evening news and wondered how large a magnitude the blasts might have produced. I went to the International Data Center's (IDC) web site and looked for the event at or near the time you mentioned and found this line: 1998/05/11 10:13:52.0 27.12N 71.68E 44 56.6 mb 4.7 India-Pakistan Border Reg. The IDC web address for recent earthquakes is: http://140.162.3.250:65120/web-bin/recentevents As the line says, it was darn close to the Paki border. Funny place to set off a nuke. Does anyone know where the nuclear testing site is in India? The mb 4.7 is slightly smaller than the French's tests last year. -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 13:00:27 -0700 Karl, My two cents worth. In the book I mentioned earlier,: Capacitive Sensors, Design and Applications by Larry K. Baxter ISBN 0-7803-1130-2 IEEE Press 445 Hoes Lane, P.O. Box 1331 Piscataway, NJ 08855-1331 http://www.ieee.org The author specifically recommends the use of sine wave drive as the use of square wave drive has problems because it contains harmonic series which are hard to balance out. That falls in line with Jim Hannon's comment. To that point I would add my own comments: a) Sine wave drive is especially easy when you resonate the secondary of a loosely coupled transformer. b) A fair amount of noise could be due to the use of a high voltage multiplexer. The switch times are loose and noisy, in particular a high voltage mux will have slower switch times. Also any noise in the high voltage supply will be part of the noise figure. Any uncertainty in the switch time will show up as noise in the output. This is also why sine wave can improve your noise floor. By filtering the drive waveform through resonance you effectively narrow the bandwidth of the available noise. Then by synchronously demodulating, you can narrow the effective bandwidth even more, essentially the width of the lo-pass section of the demodulator filter. Charles R. Patton patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 12:11:57 -0700 Karl Another idea: I use a sign wave from a phase shift oscillator(~2vts P-P). It goes into a capacitive bridge with two active arms. It then goes thru a matched diode arrangement which was in the "connectime" portion of Circuit Cellar magazine August 1995(reportedly from a NASA Tech brief). The differential output goes into a Burr Brown instrumentation amp (INA102). I have yet to check the signal to noise ratio. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Anybody Using DSP to Enhance Seismometer Readings Date: Tue, 12 May 1998 13:23:41 -0700 Sean-Thomas, The number crunching approach of FFT's is certainly a flexible way to obtain 24 bit resolution and I'm envious of the hardware. But I wonder if the current availability of 24 bit (below 60 Hz) delta-sigma A/D's from both Burr/Brown (ADS 1210, 1211) and Analog Devices (AD7710,7712, and 7714) for the $10 to $15 range and a very nice oversampled unit of 24 bits which basically doesn't need anti-aliasing filters aimed at the geophysical community from Crystal semiconductor (CS5322 and CS5323 chip combination) for around $70 wouldn't be more cost effective. Approximately what do your costs break down to in terms of cost per channel ? And since some of the units above have built-in muxes, the cost is even less per channel. Although I will be quick to admit with considerably reduced throughput (sample rate) which is typically the inverse of 3 times the number of channels used. So if using 3 channels of seismometers, and the single channel sample rate was 45 Hz, the sample rate would be divided by 9 to yield a sample rate per channel of 5 Hz. Charles R. Patton patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Anybody Using DSP to Enhance Seismometer Readings Date: Tue, 12 May 1998 17:31:33 -0500 (CDT) Charles, You must bear in mind that the designs we are operating were devised in the early 80s, when they were the only way to get high sample rates at 24 bits. The original EDME I used at the CCM station was the second prototype from Gould Ocean Systems built specifically for a broadband data acquisition system. We replaced it in 1994 with the 68020/30 based system from Quanterra, which is the standard for the new global digital seismic network. A plus of the network is that all the 100+ stations ARE using the same processor. I am quite aware of the available 24-bit converter options for seismic use, and the relative costs, which don't include the needed processor/interfaces to make them work. Even at the higher price of a few units (you quoted costs per 100) they are widely used in current new designs. Some broadband sensors include them inside the seismometer package. There are about a dozen companies providing 24-bit acquisition packages. However, most do not provide the mutiply decimated/ FIR filtered streams that a modern broadband station needs. Using 68020 CPUs for the DSP processing also allows the FIR filter coefficients, sample rates, conversion gains, etc., to be modified and loaded from the multitasking host processor. Regarding multiplexing: at most throughput rates, it skews the timing from channel to channel, which is a no-no for seismic data, so it is only used in the highly oversampled designs, like at 50k/second. Some systems attempt to correct the time skew in the DSP. Otherwise a 24-bit A/D chip is used for each channel, just as the systems we are operating use one DSP processor per channel with a maximum sample rate of 100 sps, which is used for high gain accelerometers. Obviously we are concerned about the costs involved, but we have quite exacting expectations of the digital systems and the station processor, and are generally at the mercy of the instrumentation companies that build the hardware when it comes to pricing. Fortunately there is enough competition to keep some costs down. There are also a number of affordable (less than $2k) 24-bit systems that might be OK for school or personal use; they just don't do all the things we need to be done. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Re: Indian Nuclear test. Date: Wed, 13 May 1998 19:36:03 +0800 Hi Charles Thanks for the info, It makes me a little more confident that these recordings are the real "S" waves from the event. The "P" waves are lost in the noise. Arie. Charles Watson wrote: > Here are the traces from the Swiss Seismic Network: > > http://seismo.ethz.ch/networks/telemetry_net/signals/KP199805111022.html > > -- > ---/---- > Chrales P. Watson > Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Differential Cap Displacement Xducer Date: Tue, 12 May 1998 22:31:18 -0700 Thanks to all who have written back on this subject. To Warner Lindholm -- I tried one of Linear Technology's switched capacitor devices (I don't remember if it was the LTC1043 or not) a couple of years ago and found it to work about as well as the DG529. As far as measuring SNR, it's output noise divided by the full-scale voltage. In my case full scale is 20 volts peak-to-peak (p-p). To measure noise of the circuity without the mechanical stuff attached, I have used two equal-value precision film resistors in place of the two differential capacitors. I've also tried fixed-value capacitors too, but they are less stable. Another method I've used is to remove the differential capacitor arrangement from the seismometer and have it laying on the bench, not subject to any movement. This is a rather inconvenient approach, though. To narrow down the search for noise, I've tried shorting the input to the amplifier that follows the capacitors, and measured that noise. The SNR in that configuration is about 300,000:1. I measure the p-p output noise using an oscilloscope and divide it by 20 volts to get SNR. To Werner Wesling -- I've been using a full-wave synchronous demodulator. The drive for the capacitors comes from a 32768Hz crystal (local surplus store) counted down 4:1 by a ripple counter. The output of the capacitors is amplified, then fed to a dc blocking capacitor. The output of this amplifier is also fed to an inverting (gain of -1) stage, then another blocking capacitor. The outputs of these two blocking capacitors are fed to what is like the inputs to a bridge rectifier but using solid-state switches instead of diodes. These switch synchronously with the capacitor drive, but there is a 10-microsecond period after each transition when all switches are off to allow settling. The ideas about lower drive voltages are what I'm wondering about. Using a transformer drive, the only components subject to the high voltage are the differential capacitors themselves. And they are an air dielectric, so I don't think anything particularly cares about high voltage, except for corona. To James Hannon -- I've thought about sine wave drive. It's a little more complicated to build, but probably worth a try. Sean-Thomas mentioned a couple of weeks ago that sine-wave drive is used in the better instruments. To Charles Patton -- Your comments about sine-wave drive make lots of sense. Although I planned to use a low-voltage square-wave drive and step it up with the transformer, the stability requirements of the drive increase by the transformer ratio. I suppose phase noise in the demodulator switching when using a sine wave could be a source of noise, but hopefully there is a way to keep it to a minimum. Do you have any suggestions about how to get the sine wave. I like using a crystal oscillator for frequency and phase stability, and I suppose one of the classic oscillator circuits could be coerced into oscillating synchronously with the divided crystal. To Barry Lotz -- The consensus seems to be that the sine wave is the way to go (see above). If the transducer is always at null (which hopefully it is), then the amplitude stability of the drive circuit isn't very important. (Assuming that the frequency of its drift is well below the drive frequency). This is probably a reason to keep all the circuitry well-zeroed so that the transducer winds up operating very near null (zero output). Thanks again to all who have responded. I don't mean to close this thread -- if anyone has any more comments, let 'em fly. Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 09:46:02 -0500 Karl, One thing that I see from your description here is that you are using about 8KHz for the frequency. I would be real tempted to use a higher frequency. This would get the impedance of your bridge down to something more reasonable. Also another comment about the square wave drive. The impedance of the bridge is progressivly lower for the the harmonics of the square wave and this can mess up the way the bridge will balance. Read that: cause noise. Jim Hannon Karl Cunningham on 05/13/98 12:31:18 AM Please respond to PSN-L Mailing List To: PSN-L Mailing List cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: Re: Differential Cap Displacement Xducer Thanks to all who have written back on this subject. To Werner Wesling -- I've been using a full-wave synchronous demodulator. The drive for the capacitors comes from a 32768Hz crystal (local surplus store) counted down 4:1 by a ripple counter. The output of the capacitors is amplified, then fed to a dc blocking capacitor. The output of this amplifier is also fed to an inverting (gain of -1) stage, then another blocking capacitor. The outputs of these two blocking capacitors are fed to what is like the inputs to a bridge rectifier but using solid-state switches instead of diodes. These switch synchronously with the capacitor drive, but there is a 10-microsecond period after each transition when all switches are off to allow settling. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Lake Becharof seismic swarm Date: Wed, 13 May 1998 10:07:13 -0600 (MDT) > Date: Tue, 12 May 1998 19:49:21 -0800 > To: AVO_UPDATE@.................. > From: Alaska Volcano Observatory > Subject: Becharof Info Release 5/12/98 > > ALASKA EARTHQUAKE INFORMATION CENTER > ALASKA VOLCANO OBSERVATORY > > LAKE BECHAROF SEISMIC SWARM > General Lat 57o50'N, Long 156o30'W > > A seismic swarm of tectonic earthquakes shook the mid-Peninsula region > Friday and Saturday, May 8, 9, 1998, including the towns of King Salmon, > Dillingham, Egegik, and Pilot Point. The swarm began with five earthquakes > of M5.2 to M4.7 between 4:30pm and 10:59pm ADT. Many dozens of earthquakes > in the M2.5 to M3.5 range also occurred and were felt locally. The > earthquakes continued through Saturday, May 9. By Sunday morning the number > of earthquakes was decreasing notably, though felt earthquakes are still > occurring at a rate of 1 or 2 per day as of Tuesday afternoon, 12 May. > > The earthquake locations are clustered on the SW shore of Lake Becharof, > several miles NW of the 1977 Ukinrek Maars volcanoes and the southern end of > the Bruin Bay fault. The earthquakes are all very shallow, locating less > than about 7 km depth. The area has few seismic stations so only earthquakes > greater that about M4 have been located in this general region in the past. > The recent expansion of AVO volcano seismic monitoring to volcanoes in > Katmai National Park, NE of Lake Becharof, and Aniakchak Volcano, to the SW, > has allowed better detection and location of Becharof earthquakes. > > The current swarm is the most energetic one to date. There was no major > seismic activity detected in association with the March 30 to April 10, 1977 > Ukinrek Maar eruptions except for a flurry of small events detected by a > portable seismic net that was deployed by UAF and USGS for several months > following the eruptions. > > AVO scientists traveled to King Salmon on Saturday morning for an overflight > of the swarm location and vicinity. Their Fish and Wildlife Service pilot > had overflown the area Friday evening after the first earthquakes. Nothing > indicating any volcanic activity was seen on either flight. Saturday > afternoon some small slumping was noticed along the southwest shoreline of > Lake Becharof and some local discoloration by sediments was seen - both > likely resulting from so much ground shaking. Similarly, a slight change in > the green coloration of the small crater lake in Ukinrek Maar is likely a > result of disturbed sediments in the lake. No evidence of any disturbance > or unusual activity was seen at Peulik Volcano. Peulik is heavily > snow-covered and showed no sign of discoloration, deformation, or slumping. > The scientists scouted the area for possible instrument locations to > establish a short-term temporary seismic net. The purpose of the net would > be to determine whether or not there is a volcanic component to the > earthquake swarm and any potential volcanic hazard. > > The current interpretation is that the swarm is of tectonic origin, although > the occurrence of five M4.7 to 5.2 earthquakes in such a short time period > with no clear mainshock may suggest a volcanic component. Considering the > formation of the Ukinrek Maars in 1977, where no volcano existed previously, > intrusion of magma associated with tectonic movement is possible. > > The National Park Service and Fish and Wildlife Service in King Salmon have > been very helpful with our investigation of this seismic swarm. Also, the > citizens of Egegik, Meshik, and Pilot Point have provided important > information regarding felt earthquakes. > > > > For more information contact: (http://www.avo.alaska.edu/) > > > > Roger Hansen Terry Keith > State Seismologist Scientist in Charge > Geophysical Institute Alaska Volcano Observatory > 907-474-5533 907-786-7443 > roger@............................................. > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Indian Nuclear test. Date: Wed, 13 May 1998 09:47:15 -0700 Well supposedly there were two more tests this morning. I doubt anyone outside India would have picked them up. According to the press release on CNN http://www.cnn.com/WORLD/asiapcf/9805/13/nuclear.india.text.reut/index.html they were sub-kiloton. Which basically means they would look like small mining explosions. It would probably translate in to <2.0 Richter. "1221 hours (0651 GMT) on the 13th of May 1998." ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: sine wave excitation Date: Wed, 13 May 1998 12:58:45 -0500 (CDT) Karl, The first thing we changed in the commercial tiltmeter electronics was the square wave excitation. THe square wave is rich in high frequencies, which make even moving a wire a capacitive reactance subject to thermal effects etc. We originally used a wein-bridge oscillator, but it had poor frequency stability. The oscillator I use is on my web page; you can use either the CD4047 or a crystal osc. chip, like the Exar. The oscillator runs at 8x the output frequency, and the MC14018b turns it into an 8-step sine wave weighted by the resistor values, so it is easy to filter with the output amp, since the first harmonic is the 9th. THe output is transformer coupled to prevent any DC from reaching the sensor as well as for scaling the drive amplitude and impedance to the bridge.. We continue to use low frequencies, (up to 50khz,) to minimize thermal/capacitive reactance noise. We had the best thermal stability for the tiltmeters at 600 hz. Commercial capacitive bridges use 20 to 50 khz. For demodulation, look at the bridge amp/demodulator/amp schematic also. If you drive the 4066 switches real hard, as is done there, phase errors are minimized. Regards, Sean-thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 13:18:48 -0500 Friends, A few comments on capacitance transducers. There is little doubt in my mind that these things are the most sensitive to small displacements of anything that amateurs can easily build. My version -- which was a hack of R.V. Jones's article in the Journal of Physics, series E, vol 6, p589-600, 1973 -- appeared in the Society for Amateur Scientist's Bulletin, Vol 4, #4 (fall 1997). Their drawback is perhaps that their measurement range is very limited, but this doesn't matter much with force feedback setups. I used a square wave from a 4046 phase lock loop oscillator, its sharp edges removed with a resistor and capacitor before current amplification with a JFET transistor and then run through an impedance matching transformer. By the time the signal came out of the latter transformer at about 10 kHz, it was pretty much of a sine wave. Then it went into the capacitance bridge mounted in a metal box. The bridge was three symmetrical brass plates with the center one movable as the sensor and thence into a JFET input op amp and a synchronous detector made from a 324 op amp and 4046 quad switch and slow pass filter. I think stray capicitance gets troublesome if you raise the frequency too high -- and as it is you have to shield everything pretty well and use coax connections. Essentially everything was very sensitive but buildable with easy to get Radio Shack and standard CMOS parts. I feel sure that there are easier if less educational ways to do the job using off the shelf chips. But my next question is why bother if you can see microseisms pretty well with my LED/flag/phototransistor optical displacement transducer which is far easier to build? So far as I understand things, if you can see a constant background level of slow microseisms and these are well-resolved, any additional displacement sensitivity is superfluous unless you are studying the microseisms themselves or something like that, as opposed to looking for quakes. Does it really matter how well you can resolve microseisms? My latest seismo is waiting for a quake now, to verify its overall performance, but the transducer is only one part of the design. Since an optical transducer is so easy to build for about $5, from an infrared LED and phototransistor from Radio Shack, I invite anyone to see for themselves. I recently use an infrared LED rather than a superbright red one because you can drive it a little harder and because the sensitivity of the phototransistor is a little better in the infrared than for red light. I agree that in theory a red light might be able to resolve a smaller displacement than infrared, something like 50% better, if the practical performance is diffraction limited rather than shot noise limited. But I don't think in practice that this is probably the case. The key is to get the most possible light passing between the emitting area and the detecting area, which means grinding off the integral lenses, mounting them as close together as possible, screening off all light that isn't to be intercepted by the flag, and driving the LED hard so that the shot noise will be low. I operate the system in such a way that the moving flag intercepts enough light so that the phototransistor has a resistance of 10 k. This phototransistor is in series with a 10 k metal film resistor, and the midpoint voltage fluctuation is buffered with a voltage follower, and this signal then goes onto the force feedback circuit, the low pass filter, etc. I think the shot noise, which is the statistical variation in the photons seen by the photodiode incorporated in the phototransistor, is the limiting factor in determining displacement sensitivity. The basic arrangement was posted by Larry a week or so ago on the PSN page in graphic form. --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 11:31:35 -0700 Jim -- Thanks for the comments. I wonder what frequency (sine wave) would be optimum. Would charge injection noise and switching delay jitter in the demodulator become a problem at say 50KHz? I guess I'll play with it. -- Karl At 09:46 AM 5/13/98 -0500, you wrote: > >Karl, >One thing that I see from your description here is that you are using about >8KHz for the frequency. I would be real tempted to use a higher frequency. >This would get the impedance of your bridge down to something more >reasonable. Also another comment about the square wave drive. The >impedance of the bridge is progressivly lower for the the harmonics of the >square wave and this can mess up the way the bridge will balance. Read >that: cause noise. > >Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 13:27:03 -0700 Roger -- Thanks for your comments. I'm hoping to build an instrument that is quite a bit more sensitive than the average amplitude of microseisms, then filter the output so as to resolve lower amplitude signals at the high-frequency end and especially the low-frequency end. Also, since the displacement transducer is one of the crucial components of the instrument, I'd like to do as well as I can here. Then I can make compromises in other components later . -- Karl At 01:18 PM 5/13/98 -0500, you wrote: >But my next question is why bother if you can see microseisms pretty well >with my LED/flag/phototransistor optical displacement transducer which is >far easier to build? So far as I understand things, if you can see a >constant background level of slow microseisms and these are well-resolved, >any additional displacement sensitivity is superfluous unless you are >studying the microseisms >themselves or something like that, as opposed to looking for quakes. Does >it really matter how well you can resolve microseisms? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: BIG WESTRN PACIFIC QUAKE Date: Thu, 14 May 1998 11:49:36 +1200 IN ACTION NOW!!!! MAY 13 23:30 UTC May 14 11:30 NZST DAve Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tom Frey Subject: Re: BIG WESTRN PACIFIC QUAKE Date: Wed, 13 May 1998 16:52:08 -0700 Arrival here in Tacoma Wash. at 23:14:59.1 @ 47.159N/122.473W At 11:49 AM 5/14/98 +1200, you wrote: >IN ACTION NOW!!!! > > MAY 13 23:30 UTC > > May 14 11:30 NZST > > >DAve > >Co-ordinator: >New Zealand >Public Seismic Network > Dave A. Nelson ZL4TBN > 24 Jensen St., > Green Is., Dunedin, > South Is.. New Zealand. > >http://psn.quake.net/dave/home.htm > >IF there indeed are other parallel universes... I can now rest in the >knowledge, that in at least one of them, I am filthy rich and drive a red >Ferrari > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: BIG WESTRN PACIFIC QUAKE Date: Thu, 14 May 1998 12:16:07 +1200 At 04:52 PM 5/13/98 -0700, you wrote: >Arrival here in Tacoma Wash. at 23:14:59.1 @ 47.159N/122.473W great tom thanks for fast reply tony in hawaii getting it too shortly after i did i have horrific sea noise but quake signal is still showing up Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 19:56:11 -0500 Karl Cunningham wrote: > > Jim -- > > Thanks for the comments. I wonder what frequency (sine wave) would be > optimum. Would charge injection noise and switching delay jitter in the > demodulator become a problem at say 50KHz? I guess I'll play with it. > > -- Karl > Karl, It is hard to tell what would be "optimum" without a lot of analysis. Since Sean says that the commercial units run between 20 to 50 KHz I would stay in that range. This same type of demodulator is used in SSB receivers at at least 500 KHz so 50 KHz shouldn't be too much of a problem. A lot of the charge injection noise will be way out of the demodulated pass band of interest so the output lowpass filter will remove it. I was going to post my sine wave excitation circuit on my web page tonight but I forgot to bring the disk home with me. Maybe tomorrow. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Big quake: Live Psn Date: Thu, 14 May 1998 09:14:06 +0800 Hi, Check out the "New Britain, PNG" quake. Live PSN http://iinet.net.au/ At the moment the "P" wave is at "event -1" the "LR" waves are in the principal view. Remember as a new event comes in the data is moved through the "event -x" until its sent to the bin. Its a big one. Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: microseisms Date: Wed, 13 May 1998 20:57:27 -0500 (CDT) Karl and Roger, While the 6-second microseisms are a good indicator of a working seismometer, they are relatively energetic compared to the data we can expect to see. Lately here in the mid- continent they have been runing about 0.5 microns p-p. At the time of the May 10 event, they were about -120 db on the PSD (Power spectral density) plot. But we can record data in the 20 to 100 second range as low as -160 db for an average site, which is 10 000 times lower than the microseisms. Very quiet sites go as low as -180 db. Because of this, we use a twin-T notch filter for broadband data recording on drums to reduce the microseisms by 40 db(v). It is a very sharp notch, using 6 passive components. In the days of photo-galvanometric recording, the two separate SP (short period) and LP (long) systems of the worldwide network had a combined minimum of sensitivity at the 6-second period. regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Kees Verbeek Subject: Re: Big quake: Live Psn Date: Thu, 14 May 1998 03:59:29 +0200 (CEST) At 09:14 14-05-98 +0800, you wrote: >Hi, Check out the "New Britain, PNG" quake. > >Live PSN http://iinet.net.au/ _____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > Hi Arie, I,ve looked up your page now a few times, it's realy great (strange to look "live" to the earth at the other side of the world. Got the quake very poor over here( temp. here got up in 3 days from 12 to 32 degrees c. so time for some adjusting work to do !!!) Good luck with your good work, greetings Kees Verbeek, Netherlands _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen Caruso Subject: Re: win 95 and serial ports. Date: Wed, 13 May 1998 22:29:29 -0400 (EDT) STEPHEN CARUSO CET KB8UGH "Coincidence is a shortsighted mental delusion" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: microseisms Date: Wed, 13 May 1998 20:19:37 -0700 Sean Thomas et al $0.02 The problem I see is the events (on my system) coming in have a substantial frequency component in this frequency range so I can't reduce the signal to much . I have sucessfully used 101+ tap FIR filters to try to reduce microseisms and ended up reducing event levels. Barry S-T Morrissey wrote: > > Karl and Roger, > While the 6-second microseisms are a good indicator of a > working seismometer, they are relatively energetic compared > to the data we can expect to see. Lately here in the mid- > continent they have been runing about 0.5 microns p-p. > At the time of the May 10 event, they were about -120 db > on the PSD (Power spectral density) plot. But we can > record data in the 20 to 100 second range as low as -160 > db for an average site, which is 10 000 times lower than > the microseisms. Very quiet sites go as low as -180 db. > > Because of this, we use a twin-T notch filter for broadband > data recording on drums to reduce the microseisms by 40 db(v). > It is a very sharp notch, using 6 passive components. > In the days of photo-galvanometric recording, the two > separate SP (short period) and LP (long) systems of the > worldwide network had a combined minimum of sensitivity > at the 6-second period. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 20:24:58 -0700 Karl I use a freq around 30k and have tried to increase the air cap area to get a lower bridge impedance (~170 pf each). Barry Karl Cunningham wrote: > > Jim -- > > Thanks for the comments. I wonder what frequency (sine wave) would be > optimum. Would charge injection noise and switching delay jitter in the > demodulator become a problem at say 50KHz? I guess I'll play with it. > > -- Karl > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Differential Cap Displacement Xducer Date: Wed, 13 May 1998 21:08:09 -0700 Karl I just had a thought. What about multiple sampling? Doesn't this improve the signal to noise ratio? Say 90-100 samples and average for one reading. Barry Karl Cunningham wrote: > > Thanks to all who have written back on this subject. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: Differential Cap Displacement Xducer Date: Thu, 14 May 1998 08:02:51 -0700 (PDT) The approach I took for a detector was charge pumps. The LTC1043 has an internal clock which can be driven up to 5MHz but I let mine freerun at 160KHz (nominal is 180KHz). The differential capacitors are made from two-sided pc board with the active plate area of 16 sq. in. The backs of the plates are driven with a duplicate signal from other switches in the 1043 making the capacitors Kelvin capacitors and thereby isolating them from distributed capacity and fringe effects. Capacitor plate spacing is 0.125". The calculated output is 2.9 picoamps/nanometer. The output of the differential capacitor charge pump is fed to an LTC1049 chopper stabilized opamp which is capable of picoamp performance but which I haven't achieved because of noise. --Warner _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Re: Big quake: Live Psn Date: Thu, 14 May 1998 10:27:04 -0600 (MDT) Hi Arie, Great web site! This really shows the power of the global internet and the contribution that an energetic individual can make. One minor suggestion: On or under the screen shot of the seismic data, you might want to indicate that the time shown is universal time (UT). JCLahr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Brian Chesire Subject: Re: Differential Cap Displacement Xducer Date: Thu, 14 May 1998 20:49:23 -0700 Hi All, I've been using a diffcap transducer processor that I designed several years ago for the Yaw damping channel of a light aircraft autopilot. It works with a wide range of capacitance (2pf to 500pf)and is ratiometric, responding only to the change in the differential. Uses 3 IC's, 6 resistors and few bypass and filter caps. It works with homebrew swinging vane accelerometers (oil damped), and liquid filled bubble type tiltometers (I never did get the damping constant for the bubble tube to the point where it would work in the autopilot). It might, with some refinement, be usable as a seismic pickoff. If anyone's interested, I can send them the schematic and a discription of how it works. The schematic is in HP-GL format, I have no way to convert to a GIF or JPG, at least not yet. Brian Tucson, AZ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Differential Cap Displacement Xducer Date: Thu, 14 May 1998 22:11:48 -0700 Brian Chesire wrote: > I've been using a diffcap transducer processor that I designed several... If anyone's interested, > I can send them the schematic and a discription of how it works. The schematic is in HP-GL format, > I have no way to convert to a GIF or JPG, at least not yet. Brian, 1) I would appreciate a copy. Thank you. 2) With regard to converting HPGL to GIF: I used to be able to import HPGL files into Word, but I had to do a special install to be sure the translator was in place. I just looked at my current Word 97 at home and it is not present. Once it was in Word, you could Copy&Paste it into a GIF editor such as Paint and save as a GIF. I also did a quick scan of the Simtel CD from Sept '94, and although there are several viewers, and plotter to printer translators, but no HPGL to GIF translators there. Maybe a search on the current Simtel site would find something. When I get to work tomorrow, I check and see if the translator is still on that system. (I've had to re-create the disk several times, and it may have "fallen off" into the bit bucket. Charles R. Patton, Editor, Geo-Monitor _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Differential Cap Displacement Xducer Date: Thu, 14 May 1998 22:28:12 -0700 Brian -- I'd like a copy too. Please don't send a copy to the list, but to me directly. I can convert it to a gif, and if anyone is interested I'll post the gif on my web site. -- Karl At 08:49 PM 5/14/98 -0700, you wrote: >Hi All, > I've been using a diffcap transducer processor that I designed several >years ago for the Yaw damping channel of a light aircraft autopilot. It >works with a wide range of capacitance (2pf to 500pf)and is ratiometric, >responding only to the change in the differential. Uses 3 IC's, 6 >resistors and few bypass and filter caps. It works with homebrew >swinging vane accelerometers (oil damped), and liquid filled bubble type >tiltometers (I never did get the damping constant for the bubble tube to >the point where it would work in the autopilot). _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Differential Cap Displacement Xducer Date: Thu, 14 May 1998 22:39:42 -0700 To Jim Hannon -- I experimented a bit today with the demod frequency. Using just the amplifier and demodulator, the noise decreased with higher freqeuncy, but above about 50KHz, the offset started to take off. I guess 50KHz is about optimum for the demodulator, and with just those two stages, the SNR is about 120db or so. It's getting there. Jim Hannon wrote >It is hard to tell what would be "optimum" without a lot of analysis. >Since Sean says that the commercial units run between 20 to 50 KHz I >would stay in that range. This same type of demodulator is used in SSB >receivers at at least 500 KHz so 50 KHz shouldn't be too much of a >problem. A lot of the charge injection noise will be way out of the >demodulated pass band of interest so the output lowpass filter will >remove it. I was going to post my sine wave excitation circuit on my web >page tonight but I forgot to bring the disk home with me. Maybe >tomorrow. To Barry Lotz -- I think this is what the demodulator does, since it it followed by a low-pass filter. It samples 100 or more carrier cycles for even the highest demodulated output frequency. With the coaxial capacitors I am using, the capacitance is around 27pf each, so the amplifier sees 54pf. >I just had a thought. What about multiple sampling? Doesn't this >improve the signal to noise ratio? Say 90-100 samples and average for >one reading. To Warner Lindholm -- Do you know what kind of signal-to-noise ratio you were getting? >The approach I took for a detector was charge pumps. The LTC1043 has an >internal clock which can be driven up to 5MHz but I let mine freerun at >160KHz (nominal is 180KHz). The differential capacitors are made from >two-sided pc board with the active plate area of 16 sq. in. The backs of >the plates are driven with a duplicate signal from other switches in the >1043 making the capacitors Kelvin capacitors and thereby isolating them >from distributed capacity and fringe effects. Capacitor plate spacing is >0.125". The calculated output is 2.9 picoamps/nanometer. The output of the >differential capacitor charge pump is fed to an LTC1049 chopper stabilized >opamp which is capable of picoamp performance but which I haven't achieved >because of noise. Karl Cunningham La Mesa, CA. PSN Station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Differential Cap Displacement Xducer Date: Thu, 14 May 1998 22:56:54 -0700 Brian Chesire wrote: >The schematic is in HP-GL format, I have no way to convert > to a GIF or JPG, at least not yet. I did a little searching. I went to: http://castor.acs.oakland.edu/cgi-bin/vsl-front and found the following description by searching on " hpgl or hp-gl ": wpm16.zip file size: 288 K (295288 bytes) file date: Sep 21,1997 path: misc/ Viewer for HP-GL/2 plotfiles, export to wmf and bmp So with a conversion to wmf and bmp it is easy to use any number of viewers to convert to gif in windows by Copy&Paste. Hope this helps. Charles R. Patton, Editor, Geo-Monitor _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: 2nd Nuclear test in India Date: Fri, 15 May 1998 14:46:50 +0800 Hi, I believe my recent posting to Larry's event file list, is the second run of nuclear tests conducted by India. Given the latitude, longitude and the blasts time, it appears the "P" wave arrival is right on position. The signal is really poor but for completeness, it has been posted. The general consensus is that, it is the event.? Lets hope that's the last of it. Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: coil constants Date: Fri, 15 May 1998 12:12:25 -0500 (CDT) Barry, There is no need to know the spring constant of the VBB vertical in order to evaluate its response with the transfer function. which only needs the coil constant in Newtons/Ampere. The flat portion of the response plot is the output in volts/meter/second. But first you need to know the constant of the feedback coil. THis is measured with the coil installed on the seismometer, using the displacement detector as a null indicator; first the boom is balanced with the trim weights for a zero reading. Then 1 and/or and 2 gram weights are applied at the center of the coil, and then a current controlled by a variable resistor is applied through the main coil to balance the weights to the same null position. Then the weight in Kgrams is multiplied by g (9.806m/sec^2) and divided by the current in Amperes to get Newtons/Ampere. (actually grams*g/milliamperes gives the same result). When I determine the constant by force balance, 1 gram is balanced by 0.755ma, for a constant of 12.988 N/A, Another way to estimate the the constant of a coil is to count the turns and determine the strength B of the magnetic field in gauss. Estimate the length L of the winding IN CM by multiplying the # of turns by the mean circumference. Then G = B * L *10 **-6 N/A. For the 8-ohm stereo speaker I use, there are 162 turns at a mean diameter of 3.95cm, and the flyer says the field is 7500 gauss, so the constant is 15.08 N/A. When I determine the constant by force balance, I get a constant of 12.988 N/A, which probably means that not all the winding is within the magnetic field, which is the case. (The length L can also be determined by knowing the wire size and the resistance and looking it up in a table of wire parameters). This second method can be applied to the Lehman coil if the strength of the magnetic field can be determined. There is some variation from one speaker to another: My original speaker #40-1349 has a constant of 12.988 N/A. The Beta instrument (also a 40-1349) is 11.815 +,-0.02 N/A. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: grc@............ (Gary Chantler) Subject: png quake Date: Sun, 3 Jan 1904 22:23:30 -0800 HI all, I've been looking at my graph from the png quake on the 13th (6.5mb). I've been trying to match the data to what the arrival time calculator states should be happening. Things seem to math pretty well. However, I can't seem to find a P wave. I can math several others but not a P. Strange enough I'm sure I see an S wave but I think I should be in a shadow region. Is there someone else in washington state that picked up the quake as well (Tom?).I'm In Pullman Wa. the most distinct waves I have are 23:26:16 - S? 23:45:40 - 23:53:40 - *********************************************************** ***************************************** Gary R. Chantler Instructional Tech. II Washington State University (509) 335-5353 Webster Rm 922 gchantler@....... *#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#*#* _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: coil constants Date: Fri, 15 May 1998 16:05:08 -0700 Sean Thomas My real intent with determining the response to a give weight was I was trying an experiment to put a small secondary coil on the boom to assist me in the mass position zeroing. I have a second coil/magnet which I applied a voltage and measured the force generated.(1.5 vts=0.07 gms). I then matched the secondary coil force to the force required to return the boom back to zero. I goes thru a very low pass filter before the coil to only correct long period position shifts. I'll see what happens this weekend. You previously mentioned zero options A thru ..... Maybe this was one of the posibilities. Barry S-T Morrissey wrote: > > Barry, > > There is no need to know the spring constant of the VBB > vertical in order to evaluate its response with the > transfer function. which only needs the coil constant in > Newtons/Ampere. The flat portion of the response > plot is the output in volts/meter/second. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: $40 Million to Help Los Angeles Maintain Electric Power After Major Earthq Date: Fri, 15 May 1998 17:24:56 -0700 An excellent project that reduce the risks associated with earthquake and other natural or ma-made hazards. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration/Seismo-Watch P.O. Box 18012, Reno, Nevada 89511 Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com FEMA APPROVES $40 MILLION TO HELP LOS ANGELES MAINTAIN ELECTRIC POWER AFTER A MAJOR EARTHQUAKE WASHINGTON May 15, 1998 -The Federal Emergency Management Agency (FEMA) has approved a $40.5 million grant that will help the City of Los Angeles avoid a citywide power failure like the one that crippled the community following the January 1994 Northridge earthquake, Vice President Al Gore announced today. "President Clinton and I are committed to minimizing the impact that disasters have on the lives of Americans," Vice President Gore said. "In the event of disaster, these funds will help Los Angeles residents focus on rebuilding their lives rather than having to endure the hardship and sacrifice of being without power for days." The hazard mitigation grant to the Los Angeles Department of Water and Power provides funds for seismic retrofitting of receiving, switching and generating stations throughout the Los Angeles basin. When completed, this major mitigation project will ensure against a citywide power failure. The FEMA funds are part of the Hazard Mitigation Grant Program which is designed to help break the cycle of damage, repair and repeated damage that has characterized past disasters. The Department of Water and Power will use the grant to implement mitigation measures throughout the Los Angeles basin to retrofit key power transfer stations and strengthen facilities which serve essential lifeline services to the area. The mitigation grant program assists local governments with 75 percent of the cost of retrofitting structures to withstand or minimize the impact of future earthquakes. The state or local entity must provide the remaining 25 percent match. The current project totals $54,064,044 with FEMA providing $40,548,033. The January 1994 Northridge earthquake caused damages projected to be in excess of $30 billion. To date, FEMA assistance to individuals, state and local governments, and other eligible entities has been approximately $6 billion. Federal Emergency Management Agency (FEMA) Office of Emergency Information & Media Affairs --- Washington, D.C. Information Available 24 hours a day . . . ... on the World Wide Web: http://www.fema.gov ... FEMA is also co-sponsor of Storm98: http://www.storm98.com ... via fax-on-demand: phone in the U.S.A. (202) 646-FEMA (646-3362) ... via digital audio for broadcasters & print: contact eipa@........ and listen to the FEMA Radio Network on the FEMA Website using RealAudio From: S-T Morrissey Subject: electromagnetic zeroing Date: Fri, 15 May 1998 19:47:00 -0500 (CDT) Barry, I tried this back in March, using the mass position output voltage and a passive low pass filter (I had a pair of 160 000 uf capacitors) to avoid another amplifier. I used one of my auxillary 25-turn coils wound above the main speaker coils. It does work, but I couldn't damp the secondary feedback, and the step response looked like the Bo or intrinsic mechanical damping of the sensor. This was before I rigged up the remote zeroing motor, which works very well, and could be automatically operated by a meter-relay or a bipolar comparator. I guess the main problem I had with secondary feedback was that I couldn't model it in the response, and being a &*@*#! purist, did not want to compromise the response I have. I have another mechanical compensation scheme to try this weekend, now that the steamy heat has arrived, and the air conditioning cycles show up in the data. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Teleseismic event rolling in... Date: Fri, 15 May 1998 19:47:04 -0700 Hi Everyone, P hit here 5/16 2:33:17 UTC S at 2:43:00. -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Tornado Detection Date: Fri, 15 May 1998 21:48:04 -0500 A while back someone mentioned that there was a conference on tornado detection using existing seismic networks. That and the tornado that chewed up a town about 30 miles south of her tonight got me to wondering about detecting tornados with a microbarograph (infrasonics). I did a web search and only turned up one item that mentioned they were able to detect tornados with an infrasonic microphone. Does anyone have any other information, links or thoughts on this? My searching did turn up one site that I haden't found before http://www.geology.smu.edu/~hayward/ he has a lot of large papers on various seismic and infrasonic subjects in .pdf format. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tom Frey Subject: Re: Teleseismic event rolling in... Date: Fri, 15 May 1998 19:55:28 -0700 P here @ 5/16 02:33:44 UTC (Lakewood,WA) At 07:47 PM 5/15/98 -0700, you wrote: >Hi Everyone, > >P hit here 5/16 2:33:17 UTC S at 2:43:00. > >-Larry > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Big Quake: Live Date: Sat, 16 May 1998 03:03:44 +0800 Hi, A big quake has just appeared on the Live PSN. Sorry about missing the "P" wave but I was downloading the event files. Just a few minutes of download ever other day and it had to happen then. Go figure the odds. Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Joan Chesleigh-Blaine Subject: Re: Teleseismic event rolling in... Date: Fri, 15 May 1998 20:18:37 -0700 EARTHQUAKE INFORMATION MESSAGE QUAKE OF MAY 16 VNDA P023049.4 ADK P023239.6 SMY P023245.4 MSOM P023254.4 DOL P023304.5 SDN P023307.0 SAO P023316.4 HOPS P023318.4 CMB P023322.4 WDC P023323.7 PFO P023324.5 KDAK P023327.7 KDC P023327.8 SVW P023339.5 PMS P023345.8 PMR P023347.2 TTA P023347.8 SIT P023350.0 TOA P023354.0 PV10 P023359.9 COLA P023401.2 IMA P023402.5 CCM P023459.5 LPAZ P023504.5 ORIGIN TIME=0221 PRELIMINARY LOCATION: LAT=21.8S LON=179.7W, GENERAL AREA: SOUTH OF FIJI IS. Mw = 6.4; 8 STATION AVERAGE. THE LOCATION, MAGNITUDE, AND TYPE OF MAGNITUDE (MB, MS, ML, MW) MAY CHANGE AS MORE DATA BECOMES AVAILABLE. THE LOCATION AND MAGNITUDE ARE BASED ON PRELIMINARY INFORMATION. FURTHER INFORMATION WILL BE ISSUED BY THE USGS, GOLDEN, CO. Larry Cochrane wrote: > Hi Everyone, > > P hit here 5/16 2:33:17 UTC S at 2:43:00. > > -Larry > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Tornado Detection Date: Fri, 15 May 1998 20:57:04 +0000 Hello Jim, Some time back, I posted (PSN-L) something about tornado detection using arrayed seismic instruments (and AI?) software analysis. I searched my e-mail archives to see if I saved that info, and apparently did not. Does PSN-L save list archives? Perhaps another PSN-L member also posted something? Microbarographs and geophones (infrasonic sensors) are also of interest. Thanks for the link. Walt Williams, 98.05.15 dfheli@.............. http://www.pacificnet.net/~dfheli ============================================ ------- Forwarded Message Follows ------- Date: Fri, 15 May 1998 21:48:04 -0500 From: Jim Hannon Reply-to: PSN-L Mailing List To: PSN-L Mailing List Subject: Tornado Detection A while back someone mentioned that there was a conference on tornado detection using existing seismic networks. That and the tornado that chewed up a town about 30 miles south of here tonight got me to wondering about detecting tornados with a microbarograph (infrasonics). I did a web search and only turned up one item that mentioned they were able to detect tornados with an infrasonic microphone. Does anyone have any other information, links or thoughts on this? My searching did turn up one site that I haden't found before http://www.geology.smu.edu/~hayward/ he has a lot of large papers on various seismic and infrasonic subjects in .pdf format. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: old test equipment Date: Fri, 15 May 1998 23:21:06 -0500 (CDT) Jim, and the other ham radio operators, and everyone else; I have a collection of older test equipment that was functional the last time it was used but is no longer needed for our programs as we pursue newer technology with radically reduced funding with no one to help out. . The people here don't appreciate the possibilities of the old stuff in the right hands, so they want to throw it away. I see it as a possibllity to provide someone with a real bargain while gathering a few dollars for our independent research fund, which might help forward the development of the hardware store seismometer, which so far has used entirely private funds.. So I have posted a a list of the equipment on my web site under the "Seismic Network, Test Equipment Sale" page to see if anyone is interested in buying it for a nominal sum. Since I really have no idea what these items might be worth to someone, I will set a price of $200 or the best offer, with a condition of something like $1 per pound for packaging it for shipment, which probably will be UPS. Maybe we should have a silent email auction, and I could post the most recent best offer. Suggestions are welcome. http://www.eas.slu.edu/People/STMorrissey/index.html go to the "Seismic Network; Test Equipment Sale" page. Let me know if you are interested in this by direct mail to sean@............ so we don't clutter up the psn list. One option that might be useful would be to scan some photos of the equipment. BTW, I even have some full size helical drum recorders to clear out. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Redwood City PSN System Upgrade Date: Fri, 15 May 1998 22:23:49 -0700 Hi Everyone, I will be upgrading my PSN system (psn.quake.net) to Windows NT Server 4.0 later tonight (its now 05/15 22:05 PST or 5/16 05:05 UTC). It was running NT 3.51 server. Since upgrading from 3.51 to 4.0 requires that you start from scratch, you can't upgrade and preserve all of the old settings, I needed to put together another PC system and load all of the software and event files on the new system. I think I have everything ready to go. After the changeover there may be some problems... If you run into anything that doesn't look right, please let me know. I will send out an email letting everyone know when the new system is up, and to test the email server. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: RE the fiji region quake Date: Sat, 16 May 1998 18:06:54 +1200 there seens to be something really wrong with the location that the NEIC have released it jst does not match any of the P and S arrivals AT ALL.! they are trying to tell me that the S arrival was almost 1 minute later that it really was even taking into account the depth. using the arrival time calc. on John Lahr's pages with the NEIC figures. and that the quake is some 400KM ++ further north of me.! It jst does not compute Tony in hawaii has noticed that there is a very poor match as well. Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Canie Brooks Subject: Re: RE the fiji region quake Date: Fri, 15 May 1998 23:07:30 -0700 At 06:06 PM 5/16/98 +1200, you wrote: > >there seens to be something really wrong with the location that the NEIC > have released it jst does not match any of the P and S arrivals AT ALL.! > > they are trying to tell me that the S arrival was almost 1 minute later >that it really was even taking into account the depth. using the arrival >time calc. on John Lahr's pages with the NEIC figures. and that the quake >is some 400KM ++ further north of me.! > > It jst does not compute > >Tony in hawaii has noticed that there is a very poor match as well. > > > Dave > This is listed on IDC page - earlier they also had listed one about the same time as being in queensland, but its off the list now... a 1998/05/16 02:23:18.6 21.99S 178.21W 21 mb 6.0 Fiji Islands Region a 1998/05/16 02:22:07.2 22.1S 179.57W 34 610.9 mb 5.6 South of Fiji Islands could there have been more than one? CDIDC has links to station info... > > > >Co-ordinator: >New Zealand >Public Seismic Network > Dave A. Nelson ZL4TBN > 24 Jensen St., > Green Is., Dunedin, > South Is.. New Zealand. > >http://psn.quake.net/dave/home.htm > >IF there indeed are other parallel universes... I can now rest in the >knowledge, that in at least one of them, I am filthy rich and drive a red >Ferrari > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: RE the fiji region quake Date: Sat, 16 May 1998 18:41:57 +1200 >This is listed on IDC page - earlier they also had listed one about the >same time as being in queensland, but its off the list now... >a 1998/05/16 02:23:18.6 21.99S 178.21W 21 mb 6.0 Fiji Islands >Region >a 1998/05/16 02:22:07.2 22.1S 179.57W 34 610.9 mb 5.6 South of Fiji >Islands could there have been more than one? CDIDC has links to station info... No there was only one event NEVER take the cdidc reports with any accuracy they are virtually ALWAYS way out and often have multiple reports for the same event. their magnitudes are usually at least 1 whole magnitude low. this site is useful to see if there has been an event and will give a rough indication of the location cheers dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: System Upgrade: No posts please! Date: Fri, 15 May 1998 23:39:03 -0700 Hi Everyone, I want to do the switch over to the new system now, so please don't post any new message or event files to my system until further notice. Thanks, -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: System Upgrade: OK to post again. Date: Sat, 16 May 1998 01:22:00 -0700 Hi again, Well the upgrade didn't go very well. I had some problems with the web server and the email server on the new system so I had to move back to the old system until I can work out the bugs. I will try again tomorrow night. Until then it's ok to post to this list and send event files in to the event@............. address. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: RE the fiji region quake Date: Sat, 16 May 1998 03:05:03 -0700 At 06:06 PM 5/16/98 +1200, Dave N. wrote: > >there seens to be something really wrong with the location that the NEIC > have released it jst does not match any of the P and S arrivals AT ALL.! > > they are trying to tell me that the S arrival was almost 1 minute later >that it really was even taking into account the depth. using the arrival >time calc. on John Lahr's pages with the NEIC figures. and that the quake >is some 400KM ++ further north of me.! > > It jst does not compute > >Tony in hawaii has noticed that there is a very poor match as well. The current numbers on the NEIC finger service work for me...When I use the LOC feature in WinQuake, it places the P and S markers almost exactly where they should be. The event was almost 600Km deep. Some of the older versions of WQ may have had a problem with calculating what depth table too use, when the LOC feature is first activated, so make sure that the correct depth is selected by using the Tables menu item. The P wave arrive time on the high gain USGS sensors, they pick up the P wave of teleseismic events just fine but not the S and other lower frequence waves, I monitor are within 4 seconds of the calculated location using the LOC feature and the 603km depth table. Using the 603 km depth table, WQ places the P marker a little before the actual P wave arrive time. If you change the depth table to the next closest depth table of 540km, WQ places the P marker about 1.5 seconds after the actual P wave arrive time. If WQ interpolated the depth, like it should do, it would place the P marker within 1 or 2 seconds of the actual arrival time. The travel time of the P wave was over 11 minutes, so an error of even 4 seconds is less then 0.6%. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Liberio Rossi" Subject: QUAKE| Date: Sat, 16 May 1998 11:45:22 +0200 Hello People! Received quake at h 10,57,11 UTC Data in progress. ByBy Liberio Rossi Lat. 43=B054' 79 Long. 10,31,56 From: "David A. Nelson" Subject: Re: RE the fiji region quake Date: Sun, 17 May 1998 02:38:54 +1200 >The current numbers on the NEIC finger service work for me...When I use the LOC feature in WinQuake, it places the P and S markers almost exactly where they should be. The event was almost 600Km deep. Some of the older versions of WQ may have had a problem with calculating what depth table too use, when the LOC feature is first activated, so make sure that the correct depth is selected by using the Tables menu item. Larry well larry thats strange ( I did look at ur file) as it didnt work for others even frank cooper is another station whe the P and S auto locates were wayyyyyyyyyyyy off base his S arrival is VERY obv. well b4 the S marker and tony found the same as soon as he did the auto locate and i dont even need to try the auto locate jst doing the placement to get their (NEIC) times and distance is jst Wrong! i have a ver strong S arrival that its mark cannot be disputed the S marker has to go there. it has to be noted that i see this from time to time but often it does work the other way as in the New Britian M6.5 event of a couple of days ago the match was almost perfect to with in a second or so. so im at a loss to explain it there are times when 15 yrs of reading seismograms still isnt enuf to cover all the bases one of those mysteries of seismology :) Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Frank Cooper" Subject: Re: RE the fiji region quake Date: Sat, 16 May 1998 12:31:39 -0500 ---------- It is interesting to note that Bob Lewis' (Plano, Texas) auto locate S marker was right on the money with a depth setting of 540km while mine in Friendswood, Texas, was way off. When I set the teleseismic depth to 793km (deepest possible in my set of tables) the auto S marker was closer to being correct. Frank Cooper, Friendswood, Texas. USA > From: David A. Nelson > To: PSN-L Mailing List > Subject: Re: RE the fiji region quake > Date: Saturday, May 16, 1998 9:38 AM > > >The current numbers on the NEIC finger service work for me...When I use the > LOC feature in WinQuake, it places the P and S markers almost exactly where > they should be. The event was almost 600Km deep. Some of the older versions > of WQ may have had a problem with calculating what depth table too use, when > the LOC feature is first activated, so make sure that the correct depth is > selected by using the Tables menu item. > > > Larry > > well larry thats strange ( I did look at ur file) as it didnt work for others > even frank cooper is another station whe the P and S auto locates were > wayyyyyyyyyyyy off base his S arrival is VERY obv. well b4 the S marker > and tony found the same as soon as he did the auto locate > and i dont even need to try the auto locate jst doing the placement to > get their (NEIC) times and distance is jst Wrong! > > i have a ver strong S arrival that its mark cannot be disputed the S > marker has to go there. > snip> > Dave > > > > > Co-ordinator: > New Zealand > Public Seismic Network > Dave A. Nelson ZL4TBN > 24 Jensen St., > Green Is., Dunedin, > South Is.. New Zealand. > > http://psn.quake.net/dave/home.htm > > IF there indeed are other parallel universes... I can now rest in the > knowledge, that in at least one of them, I am filthy rich and drive a red > Ferrari > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: System Upgrade Status Date: Mon, 18 May 1998 00:39:16 -0700 Hi Everyone, Well after almost three days of installing, and then reinstalling (god damn Microsoft!!!) software, I think the new system is ready. Its now online... I am sending this message using it. If anyone sees any problems with my web site (missing links etc) please let me know. One problem I need to work out is the event archiving. Event files sent to event@............. are getting archived but the NewFile list (the list that sends out a notification of a new event file but without the attached file does not seem to be working. I'm not sure about the NewEvent list. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: System Upgrade Status Date: Mon, 18 May 1998 07:09:23 -0700 (PDT) On Mon, 18 May 1998, Larry Cochrane wrote: > Hi Everyone, > > Well after almost three days of installing, and then reinstalling (god > damn Microsoft!!!) software, I think the new system is ready. Its now ^^^^^^^^^^^^^^ Gee, Larry, I dunno. You might rethink your position on linux as an option. You wouldn't have to deal with the Borg of Redmond. :-) --Warner Puget Sound Country _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: old equipment status Date: Mon, 18 May 1998 19:25:37 -0500 (CDT) Here is the status of the used test equipment sale: The current response is that there are specific inquires or offers for items 8, 13, 17, 19, 23, 24, 26, 31, 32. Most offers are about $100 plus shipping. There are some more generally interested, but not naming items yet. If you need more info about any item, ask. I have found another dual-beam Tektronix Oscilloscope (model 502A) that will be item #36. I think I have 4 Geotech Helicorders; they have vacuum tube amplifiers, and I think I have 2 amplifiers for each, and tubes to contribute. I will include manuals. There are at least 6 people interested in them so far. I will check my storage vault this week; I'm not sure how many I shipped down from Alaska. They weigh 110lbs. Thanks for your interest in the "mature" test equipment. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: National Geographic Magazine Date: Mon, 18 May 1998 19:46:38 -0600 Has an article on the North American Cascadia area, earthquakes, volcanoes etc. Pg 6-37. Also an article on Unlocking the (earths) Climate Puzzle. Pg 38-71. Also a article on Gray Wolves. Pg 72-99. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: National Geographic Magazine Date: Mon, 18 May 1998 19:53:39 -0600 Thats the May 1998 issue. Sorry. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Diffcap transducer schematic Date: Tue, 19 May 1998 09:18:37 -0700 On May 14, Brian Chesire offered a schematic of a differential capacitance transudcer conditioner, but it was in HPGL format. Brian and I have since gotten the exchange and conversion process squared away, and I have put a gif file (of the schematic) and accompanying text file on my web page. They can be accessed at: http://www.jps.net/karlc/psn/diffcap.gif http://www.jps.net/karlc/psn/diffcap.txt The gif image is large (although the file is only 64kb), and will need to be printed with software that can scale the image to a printed page. Let me know if anyone has any problem with the files. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Geo Phone Date: Tue, 19 May 1998 09:38:50 -0700 Replying to myself. I ordered two geophone kits from Gateway and I got them yesterday. I wasn't sure if anyone was still curious about them. Both of mine are Geosource model MD-81 10Hz. The case looks/feels like machined aluminum and is very small. I didn't put the little indicator circuit together yet. I'm still looking for my aluminum plate for my Lehman base. I'm going to poke around a bit more today and two other nice people are helping my look. So far the best price has been $180 for 1/2" x 18" x 36" and $350 for 1" x 18" x 36". Unless you count the guy that told me $1.20/pound if I can find it on his lot. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: FW: Phone Scam (fwd) Date: Tue, 19 May 1998 12:04:00 -0700 (MST) See Below, ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "It is easier to excuse an ignorant person who claims that theory is unnecessary and dispensable in his supposed practice, than to excuse a Sophist who concedes its value to the schools (as, perhaps, only a mental exercise) but who at the same time maintains that matters are quite different in practice- that as one leaves school to enter the world, one will realize one has been pursuing empty ideals and philosophical dreams- and, in a word, that what sounds good in theory is of no practical use." -Immanuel Kant, On the Proverb: That May be True in Theory, But Is of No Practical Use ****************************************************************************** >FYI! (Really valuable information.) > >Doug Cornell >Assistant Dean, College of Liberal Arts & Sciences >Arizona State University > >> SUBJECT PHONE SCAM >> I received a telephone call from an individual identifying himself as >> an >> AT&T Service Technician who was conducting a test on our telephone >> lines. He stated that to complete the test we should touch nine (9), >> zero (0), the pound sign (#) and then hang up. >> >> Luckily, we were suspicious and refused. >> >> Upon contacting the telephone Company we were informed that by >> pushing >> 90# you give the requesting individual full access to your telephone >> line, which allows them to place a long distance telephone calls >> billed >> to your home phone number. >> >> We were further informed that this scam has been originating from >> many >> of the local jails and prisons. I have also verified this information >> >> with UCB Telecomm. >> >> Please beware. >> This sounds like an Urban Legend - IT IS NOT!!! >> I further called GTE Security this morning and verified that this is >> definitely possible. >> DO NOT press 90# for ANYONE. >> >> The GTE Security department requested that I share this information >> with >> EVERYONE I KNOW!!! >> >> Could you PLEASE pass this on. If you have mailing lists and/or >> newsletters from organizations you are connected with, I encourage you >> to >> pass on this information. >> _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Brian Chesire Subject: Re: Diffcap transducer schematic Date: Tue, 19 May 1998 17:59:23 -0700 Thanks Karl, Looks really nice. The original drawing was an 'A' size in Orcad and output in HPGL. I sent it to myself at work and a copy from floppy back here. I still can't seem to get it right. Anyway nice job, I did find out that I could generate a .PCX file with my HPGL software but it's about 50K long. Thanks again Brian _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Rex Klopfenstein Jr Subject: Dielectric Constant-Capacitor Date: Fri, 15 May 1998 21:19:29 -0400 Does anybody have the dielectric constant for glass-epoxy used in printed circuit board? Also, what is the nominal foil thickness used in standard pc board? Thanks in advance Rex Klopfenstein, Jr Bowling Green, OH _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian Subject: Re: Geo Phone Date: Tue, 19 May 1998 21:38:43 -0700 I was able to get a good slab of aluminum through a friend in the aircraft industry. Apparently some of the plates in millitary aircraft are rather substantial. If you live near an airbase or where the maintain commercial aircraft, you might want to give that a try. Their scrap pile may be just what you need. Bob Greg wrote: > > Replying to myself. > > I ordered two geophone kits from Gateway and I got them yesterday. I > wasn't sure if anyone was still curious about them. > > Both of mine are Geosource model MD-81 10Hz. The case looks/feels like > machined aluminum and is very small. I didn't put the little indicator > circuit together yet. > > I'm still looking for my aluminum plate for my Lehman base. I'm going to > poke around a bit more today and two other nice people are helping my > look. So far the best price has been $180 for 1/2" x 18" x 36" and $350 > for 1" x 18" x 36". Unless you count the guy that told me $1.20/pound if > I can find it on his lot. > > ,Greg > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Dielectric Constant-Capacitor Date: Tue, 19 May 1998 18:55:46 -0700 Hi If this is of any help: The original SG article in SA 09/1975 said that a double sided board has a capacance of 19 pf. I seem to recall verifying this on a 2"x2" board being 76pf. Barry Rex Klopfenstein Jr wrote: > > Does anybody have the dielectric constant for glass-epoxy used in printed > circuit board? Also, what is the nominal foil thickness used in standard > pc board? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Geo Phone Date: Tue, 19 May 1998 19:07:41 -0700 Hi I have been buying it for around $1.40/lb in Sacramento Ca. at a used metals distributor. I think it should be available elsewhere for a similar price. Barry Robert Avakian wrote: > > I was able to get a good slab of aluminum through a friend in the > aircraft industry. Apparently some of the plates in millitary aircraft > are rather substantial. If you live near an airbase or where the > maintain commercial aircraft, you might want to give that a try. Their > scrap pile may be just what you need. > > Bob _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Geo Phone Date: Tue, 19 May 1998 20:07:47 -0700 Robert Avakian wrote: > are rather substantial. If you live near an airbase or where the > maintain commercial aircraft, you might want to give that a try. Their There's a thought. I now have a lead on a 3/4" piece. Hopefully it won't be too long (time). If it doesn't work out I will drive down there and ask them if I can have a titanium bathtub from an A-10 Warthog ;) There are a lot of A-10s at the local Air Force base. Unfortunately there is also a air museum of some sort there as well. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Mark Robinson Subject: Re: Dielectric Constant-Capacitor Date: Wed, 20 May 1998 16:51:18 +1200 Rex, The dielectric constant is about 4.8. The thickness is usually 0.0625 inches (1/16). The cladding is specified as either 1 ounce or 2 ounce which I assume to be per square foot. I have a value for this which I don't trust as 0.035mm, which I assume to be for 1 ounce. I have a value for the Mass Density of copper as 9.0 grams per cubic centimeter. regards Mark Robinson Rex Klopfenstein Jr wrote: > > Does anybody have the dielectric constant for glass-epoxy used in printed > circuit board? Also, what is the nominal foil thickness used in standard > pc board? > > Thanks in advance > > Rex Klopfenstein, Jr > Bowling Green, OH _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Marnie Gannon Subject: http://www.tampabayonline.net/news/news101f.htm Date: Tue, 19 May 1998 23:19:55 -0600 Don't know if many of you rely on pagers, but FWIW: > [Image] > -------------------------------------------------------------- > > 5/19/98 -- 9:58 PM > > Satellite outage interrupts pager service > nationwide > ------------------------- > > LOS ANGELES (AP) - A communications satellite spun > out of control Tuesday afternoon, interrupting > service to millions of pager users and disrupting > behind-the-scenes television transmissions across > the country. > > Galaxy 4, which is operated by PanAmSat, started > having problems about 3:30 p.m. EDT, said a > company technician who asked not to be named. The > company was still able to communicate with the > satellite, and technicians hoped to restore its > correct orbit. > > Scott Baradell, a spokesman for PageNet, one of > several paging companies whose services were > interrupted, estimated that 80 to 90 percent of > the 40 million to 45 million U.S. pager users lost > service. > > The only customers not affected were those whose > connections are through ground-based radio > transmitters, he said. > > Baradell said it would take about a day for his > company to switch service to another satellite. > ``You have to make adjustments to your system,'' > he said. ``If it's at all possible to get Galaxy 4 > back in service, that's much preferred.'' > > A woman who answered the phone at Greenwich, > Conn.-based PanAmSat refused to comment. > > If Galaxy 4 can't be fixed, traffic would have to > be redirected to other satellites, said Russ > Colby, a vice president at Digicom Services, a Los > Angeles-based pager company that has 40,000 > subscribers. He estimated up to 20,000 of its > customers were out of service. > > ``It's important that word gets out. People don't > know it's not working,'' Colby said. > > Television stations use Galaxy 4 to transmit feeds > of advance shows, said Marguerite Sullivan, > satellite coordinator for KCAL-TV in Los Angeles. > > It was not clear what television programming might > be affected. > > ``Hopefully, TV stations will be able to work > around it,'' she said. ``It's just satellite space > is going to be very tight. It's going to be a > problem for syndication. ... Thank God most stuff > is done two days in advance. We're not too bad > off.'' > > In addition to the syndicated programs, CBS radio > and television, the Chinese Television Network and > the CNN Airport Channel send feeds through Galaxy > 4. CBS apparently switched to the Galaxy 7 > satellite, Ms. Sullivan said. > > Galaxy 4 was launched in June 1993 aboard an > Ariane rocket. Its coverage area is primarily the > United States and Caribbean, according to > PanAmSat's World Wide Web sites. > > PanAmSat is 81 percent owned by Los Angeles-based > Hughes Communications Inc. > > Copyright 1998 Associated Press. All rights > reserved. This material may not be published, > broadcast, rewritten, or redistributed. > > [Image] http://www.tampabayonline.net/news/news101f.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Erich F. Kern" Subject: Re: Dielectric Constant-Capacitor Date: Tue, 19 May 1998 23:07:51 -0700 Howdy, In answer to your question, I cut a 2 by 5 inch piece of double sided epoxy-fiberglass board and measured the capacity between the 2 foil surfaces. It measured 220 pf, or 22 pf per square inch. The thickness of the board includuding the foil surface is 0.060 inches, so the dielectric is probably on the order of 0.050 inches. The foil thickness has no effect on the capcitance per area, and the dielectric constant is irrelevant if you know the capacity per square inch. OR am I missing something here? Regards, Erich Kern ---------- > From: Rex Klopfenstein Jr > To: 'psn-l@.............. > Subject: Dielectric Constant-Capacitor > Date: Friday, May 15, 1998 18:19 > > Does anybody have the dielectric constant for glass-epoxy used in printed > circuit board? Also, what is the nominal foil thickness used in standard > pc board? > > Thanks in advance > > Rex Klopfenstein, Jr > Bowling Green, OH > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: Re: Dielectric Constant-Capacitor Date: Tue, 19 May 1998 23:19:56 -0700 Hi Group, I wonder how losses in the dielectric would affect the accuracy of this device. Low loss board materials like teflon and PPO (Polyphenol Oxide) and others are available if it is a problem. Al _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: IRIS software seminar and WinQuake classroom exercises. Date: Wed, 20 May 1998 01:27:53 -0700 Hi Everyone, As some of you may know there will be a software seminar put on by IRIS (Incorporated Research Institutions for Seismology) in Santa Cruz California on July 8-12. See http://www.iris.washington.edu/HTM/other.htm#workshops for more info. I have been asked to present WinQuake at one of the workshops. Michelle Hall-Wallace, who is putting on the workshop, has asked me to supply the following: 1.Short description of the software and its features. 2.User manual. 3.Example classroom exercises that uses the software. I can come up with 1 and 2 with the WinQuake help documents I am working on, but I'm not sure about 3. I'm not sure what something like this should look like. Does anyone have an suggestions on this? Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: SOUTHERN ITALY EVENT Date: Wed, 20 May 1998 13:34:08 +0200 09.56.18 UTC =20 MB 4.3 SOUTHERN ITALY (Southern Tyrrenian Sea) =20 Depth 200 km I.ES.N. - PSN ITALY
09.56.18  UTC   
MB  4.3
SOUTHERN ITALY  (Southern Tyrrenian Sea) =20
Depth  200 km
 
I.ES.N. - PSN ITALY
From: Arie Verveer Subject: Event Files, april 98 West Australia Date: Wed, 20 May 1998 20:22:13 +0800 Hi, Over the month of April the "Kalamunda" PSN in Western Australia recorded some 20 low level local events. (ML 1.5 - 2.9) The data has been placed in a file called "april98.zip" and can be download from Larry's FTP site. Its in the incoming folder. I hope this is the way to distribute this sort of info? Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bob@................. (Bob Hammond (USGS-AVO Geophysicist)) Subject: Re: IRIS software seminar and WinQuake classroom exercises. Date: Wed, 20 May 1998 06:21:06 -0800 Larry, I use Winquake as part of my elementary school seismograph project. In general, the goal is to have the kids: 1. copy data from the data collection PC (running EMON) to the data analysis PC (running WinQuake). 2. Analyze triggered events: noise or earthquake? (this is the most challenging aspect by far). 3. Pick P and S phases and determine magnitudes. (After the students have "graduated" from the Virtual Earthquake "course" and received their "Virtual Seismologist" certificates!). 4. Plot earthquake epicenters on a map of Alaska. 5. Compare their earthquake epicenter determinations with "professional" epicenters determined at the Alaska Earthquake Information Center. 6. Understand the relationship between earthquakes, tectonics, and geology in Alaska. The project goals have been fully achieved at one school, are being worked on at two others, and the project has failed at one school. I have learned a TREMENDOUS amount about working with elementary school kids, their parents, teachers, and administrators. Hope this is of use. regards, Bob ====================================================== Bob Hammond, Geophysicist US Geological Survey Alaska Volcano Observatory, Fairbanks ph: 907-474-5333 fax: 907-474-5618 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Dielectric Constant-Capacitor Date: Wed, 20 May 1998 09:14:31 -0700 One ounce copper means on ounce per square foot and is about .0014" thick. Most *finished* PC boards are 2-ounce copper on each side, but many I've found at surplus outlets come from an intermediate step in the manufacturing process and have one-ounce copper. The second ounce gets put on when the vias (holes connecting traces on one side to the other) are plated through. The dielectric constant is around 5 but is not linear with voltage and produces what's known as the "hook effect," named after the non-linear shape of the graph of capacitance vs voltage. This should not be a problem unless you try to use it for signals where low distortion is important. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Johnston, Michael K" Subject: RE: Dielectric Constant-Capacitor Date: Wed, 20 May 1998 09:56:14 -0700 The dielectric constant for FR-4 is 4.7 +/- 20% at low frequencies, declining to 4.5 at high frequencies. It varies positively with temperature by about 20% over 0-70 C. 1oz. Cu = 0.00135 inches thick All the above from "High-speed Digital Design, A Handbook of Black Magic," Howard W. Johnson & Martin Graham Personally, 4.5 is what I've always used, but I'm interested in controlling the impedance of relatively high frequency traces on the PCB. Thicknesses of PCB's I have see: 0.0625", 0.093", 0.100", 0.125", including Cu on both sides. Usually, it is 2 oz Cu and 0.0625" thick, with 0.093" being the second most common. Mike Johnston _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: No. Calif Area Date: Wed, 20 May 1998 11:15:21 -0700 OK what's the story????? Nev USGS and NEIC report a 3.4 quake on the Calif, Nev border about 20 miles north of Lake Tahoe at 16:19:43 UTC today but there is no info on the Calif recent quake net. The S wave just started to saturate my station (about 77 miles away). Do they not detect them? (ha ha) or what?????? They didn't post the one on May 4th either(a 2.9 a little farther north and west)!!! ?????? Stephen Pilot Hill Calif. USA lat / long 38.828 N / 120.978 W PSN station #55 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: No. Calif Area Date: Wed, 20 May 1998 13:23:03 -0700 I just got back from the University of Nevada, Reno, where I talked with Diane de Polo who is in charge of the analysis of seismic events for the Western Basin and Range Seismic Network. She said the temblor registered M2.8 and was felt at Cold Springs and Border Town, two small communities about 11 miles north-northeast of Reno. They usually are a little low in their analyses, so the M3.1 from NEIC may not be too far off. Her lab received a dozen or so calls reporting the earthquake. A M4.6 triggered not far from this epicenter in November 1996. That one I felt at my office and I'm about 12 miles south of Reno. BTW: you can see the USGS/UCB Northern California network information here: http://quake.wr.usgs.gov/recenteqs/Quakes/quakes.big.html Their M3.3 is probably way off, but then notice the nearest station is 59 km away! Cheers!! -- ---/---- Charles P. Watson Seismo-Watch Stephen & Kathy wrote: > > OK what's the story????? > Nev USGS and NEIC report a 3.4 quake on the Calif, Nev border about > 20 miles north of Lake Tahoe at 16:19:43 UTC today but there is no > info on the Calif recent quake net. The S wave just started to > saturate my station (about 77 miles away). > Do they not detect them? (ha ha) or what?????? They didn't post the > one on May 4th either(a 2.9 a little farther north and west)!!! ?????? > Stephen > Pilot Hill Calif. USA > lat / long 38.828 N / 120.978 W > PSN station #55 > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: IRIS software seminar and WinQuake classroom exercises. Date: Wed, 20 May 1998 17:14:05 -0700 (MST) On Wed, 20 May 1998, Larry Cochrane wrote: > 3.Example classroom exercises that uses the software. > > on, but I'm not sure about 3. I'm not sure what something like this should > look like. Does anyone have an suggestions on this? It probably depends on what level the class exercises will be used. Maybe you could include simpler exercises for students in intro geology and then move to more complex types of exercises for seismology students... For example: - With a couple of the quake files included in the software have them determine the distance to the source... Maybe get a few files for the same quake so that the data could be plotted on a map to find the epicenter... - Find some good files with examples of arrival times not in agreement with the J-B tables and get into measurements of slower and faster velocities... - Find some files with SV splitting (PKP, PKIKP). Chop out these arrivals and look at the frequency domain of the two arrivals to show they are the same... - Have examples of raw files that have a strong amount of background noise removable by filtering the spectrum... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "It is easier to excuse an ignorant person who claims that theory is unnecessary and dispensable in his supposed practice, than to excuse a Sophist who concedes its value to the schools (as, perhaps, only a mental exercise) but who at the same time maintains that matters are quite different in practice- that as one leaves school to enter the world, one will realize one has been pursuing empty ideals and philosophical dreams- and, in a word, that what sounds good in theory is of no practical use." -Immanuel Kant, On the Proverb: That May be True in Theory, But Is of No Practical Use ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: No. Calif Area Date: Wed, 20 May 1998 19:36:52 -0700 Hi The S wave clipped on my hi gain channel in Grass Valley. Barry Stephen & Kathy wrote: > > OK what's the story????? > Nev USGS and NEIC report a 3.4 quake on the Calif, Nev border about > 20 miles north of Lake Tahoe at 16:19:43 UTC today but there is no > info on the Calif recent quake net. The S wave just started to > saturate my station (about 77 miles away). > Do they not detect them? (ha ha) or what?????? They didn't post the > one on May 4th either(a 2.9 a little farther north and west)!!! ?????? > Stephen > Pilot Hill Calif. USA > lat / long 38.828 N / 120.978 W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Geo Phone Date: Wed, 20 May 1998 19:43:36 -0700 Hi I have(just received) a similar geophone from Gateway. I plugged it into an instrumentation amp and output driver etc. It looks pretty sensitive. I'll plug it in adjacent to my Lehman and get some ambient vibration to up load so we can see the frequency spectrum. I realize one is horizontal and one is vertical. Oh well... Barry Greg wrote: > > Replying to myself. > > I ordered two geophone kits from Gateway and I got them yesterday. I > wasn't sure if anyone was still curious about them. > > Both of mine are Geosource model MD-81 10Hz. The case looks/feels like > machined aluminum and is very small. I didn't put the little indicator > circuit together yet. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Three Happy GeoPhone Experimenters Date: Wed, 20 May 1998 21:27:59 +0000 Hello All, My two geophones arrived on Tuesday, from Gateway Electronics in Missouri. Incidentally when I called to check on my order, 'they' informed me; Gateway had received 1000 more sensors to cover the orders they were receiving from seismic groups. -------- My devices are: 1.61" height x 1.25" diameter There are two very short, (0.150" long) by 0.060" diameter leads protruding from an insulator on 0.35" centers. Geophone is marked in black ink: GEOSOURCE INC. E.P.D. C.S.O. Model MD-81 10 Hz GEO-MAX/GEMININ, Lot Number 612, 05-20-85 (13 years old today) Before I can experiment with these, I must finish the electronics for my Lehman. They will just have to wait in the drawer for the time being. Best Regards, Walt Williams, 98.05.20 dfheli@.............. ================================================== ------- Forwarded Message Follows ------- Date: Wed, 20 May 1998 19:43:36 -0700 From: barry lotz Reply-to: PSN-L Mailing List Organization: cel To: PSN-L Mailing List Subject: Re: Geo Phone Hi I have(just received) a similar geophone from Gateway. I plugged it into an instrumentation amp and output driver etc. It looks pretty sensitive. I'll plug it in adjacent to my Lehman and get some ambient vibration to up load so we can see the frequency spectrum. I realize one is horizontal and one is vertical. Oh well... Barry Greg wrote: > > Replying to myself. > > I ordered two geophone kits from Gateway and I got them yesterday. I > wasn't sure if anyone was still curious about them. > > Both of mine are Geosource model MD-81 10Hz. The case looks/feels like > machined aluminum and is very small. I didn't put the little indicator > circuit together yet. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Alan & Jocelyn Munro Subject: Re: IRIS software seminar and WinQuake classroom exercises. Date: Thu, 21 May 1998 19:18:17 +1200 Hi Larry Some suggestions with point 3. I am a teacher here in New Zealand and this year I have set up a seismograph and use Winquake with my senior students. I use the above with my Yr 11,12,13 students. (15,16,17 yr olds) 1.We are monitoring the Alpine fault in the Fiordland Area. 2. the students have been plotting the earthquakes on a map of the area. 3. With 3 location sites including Dave Nelson in Dunedin we plot the location of the quakes and compare with the NZ Seismological data. We can differ with the experts. My students also collect witness reports. 4. it has been a novel way to teach the transfer of energy by waves. Con textural teaching. 5. has generated a community interest and newspapers contact me about quakes. 6. Students are looking for patterns and discussing there significance. eg: Fiordland quakes from depth of about 90km have P-waves bigger than S-waves. As the moderator in NZ for Earth Sciences I will be at NZ Scicon (conference for science teachers) to introduce NZ teachers to seismographs and Winquake in particular in July. So any further help would be useful Alan Munro Invercargill New Zealand _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: USGS Cal Net event lists Date: Thu, 21 May 1998 08:46:34 -0600 (MDT) > > From: Stephen & Kathy > > OK what's the story????? > > Nev USGS and NEIC report a 3.4 quake on the Calif, Nev border about > > 20 miles north of Lake Tahoe at 16:19:43 UTC today but there is no > > info on the Calif recent quake net. I asked Rick Lester, who is in charge of earthquake processing in Menlo Park, about this event. He explained that most events are automatically picked and go onto the web page right away. However, if there are indications that the solution is very poor, which often happens if the event is well outside the network or if there are some bad automatic phase picks, then the event must be corrected by hand. This event had some incorrect automatic phase picks that delayed its appearance on the web listings. JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### Geologic Hazards Team, MS966 ############################## PO Box 25046 #############################/############################## ############################/############################### Denver, Colorado 80225-0046 ################################ Phone: (303) 273-8596 ################################## Fax: (303) 273-8600 ################################### lahr@........ ##################################### http://giseis.alaska.edu/lahr http://lahr.org/john-jan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: "Live" Psn: Trigger level Date: Thu, 21 May 1998 22:53:15 +0800 Hi, After a long dry summer the first real heavy winter rains have arrived. I was told that the background noise level could rise up to 4 times the summer level. I nodded my head and thought that seems a bit high. But its true! So I have reset the trigger level on the "live event PSN" . This should reduce the false triggers. By the way, the East-West seismometer points to the ocean. http://www.iinet.net.au/~ajbv/ Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: RE: "Live" Psn: Trigger level Date: Thu, 21 May 1998 13:16:23 -0700 and you didn't believe me... I have 5 or 6 years of data sets showing = the local lightrail train that runs at the end of my block taken just = before the first rain and just after it. This would make a good = classroom project for a science class with a seismograph and a constant = seismic noise source. In the summer, an FFT sample of the lightrail train present scattered = random frequencies. But, as soon as the first rain hits, the dominate = frequency spectrum of the train passing at an average speed of 45MPH = shifts to 11Hz. I have made the assumption that the coupling action of = the fluid on the surface changes the background noise by tightly = coupling the receiver and source relationship. Knowing that the fluid = has not had a chance to penetrated more than a few feet, I can then make = an assumption that loose surface alluvium, without the presents of = fluid, is much less effective at transmitting seismic waves then fluid = filled alluvium. Could this be an explanation for spermatic damage = patterns in an earthquake?=20 I really don't have enough information to make that kind of judgement. = But, I can conclude that the amount of damage in an earthquake could be = different based on the weather conditions during the year. An example of = the type of energy transfer I write about can be demonstrated in the = explosion of a depth charge. Consider the difference of a depth charge = spent in water and one spent in free air. If my assumption is true, then = the amount of damage in an earthquake, could be increased considerably = from summer to winter in areas such as the SF Bay area, because of the = coupling or "hydraulic" action of the fluid. I my argument is correct, = one might even be able to state that El Nino has increased the = earthquake risk in many parts of the world by increasing the sender / = receiver relationship between surface structures and a seismic source by = increasing the coupling effect of the soil/fluid mixture which would = normally not contain as much fluid. Regards,=20 Steve Hammond -- PSN San Jose, California -----Original Message----- From: Arie Verveer [SMTP:ajbv@............. Sent: Thursday, May 21, 1998 7:53 AM To: PSN-L@.............. Subject: "Live" Psn: Trigger level Hi, After a long dry summer the first real heavy winter rains have arrived. I was told that the background noise level could rise up to 4 times the summer level. I nodded my head and thought that seems a bit high. But its true! So I have reset the trigger level on the "live event PSN" . This should reduce the false triggers. By the way, the East-West seismometer points to the ocean. http://www.iinet.net.au/~ajbv/ Arie _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: RE: "Live" Psn: Trigger level Date: Thu, 21 May 1998 16:09:45 -0500 (CDT) Please do not send bitmaps, HTML code, etc, as attachments to PSN email. Some of us do not read mail with a browser or anything that can handle a bitmap or whatever, and it just ties up the process of reading email while all the junk goes by. Images, etc, should be pointed to so that those who can decode them can do so if they want to, and those of us who have enough trouble keeping up with just text email don't get slammed with 200 lines of bitmaps. Thanks, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre Subject: Re: IRIS software seminar and WinQuake classroom exercises. Date: Thu, 21 May 1998 16:09:49 -0700 (PDT) On Wed, 20 May 1998, Larry Cochrane wrote: (snip) > 1.Short description of the software and its features. > 2.User manual. > 3.Example classroom exercises that uses the software. > > I can come up with 1 and 2 with the WinQuake help documents I am working > on, but I'm not sure about 3. I'm not sure what something like this should > look like. Does anyone have an suggestions on this? Larry, one example could be to tile the screen and show a comparison for the same event from different sensors using the same compression rates. You could show how the waveform from one location might differ from another that was lying on a different soil bed. See if there was amplification due to soil issues... Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: "Live" Psn: Trigger level Date: Thu, 21 May 1998 18:18:04 -0500 S-T Morrissey wrote: > > Please do not send bitmaps, HTML code, etc, as attachments to PSN > email. Some of us do not read mail with a browser or anything that > can handle a bitmap or whatever, and it just ties up the process of > reading email while all the junk goes by. > > Images, etc, should be pointed to so that those who can decode them > can do so if they want to, and those of us who have enough trouble > keeping up with just text email don't get slammed with 200 lines > of bitmaps. > > Thanks, > Sean-Thomas Interesting: Even my Netscape email could not figure out what to do with the attachment from Steve. It looks to me to be an accident. I look at my home email at work by telnetting to a unix server and using "Pine" as the email program. This is a text only email program but at least it is "mime aware" and the attachment shows up as a note indicating it cannot be displayed and asks if you want it saved to a file. This eliminates the problem of having to view a chunk of encoded junk. It also doesn't send the attachment so you don't have to wait for the data on a slow link. Using Pine or a similar email program might help eliminate the hastle of attachments. I agree that odd attachments should not be sent on this list. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Frank Cooper" Subject: Re: IRIS software seminar and WinQuake classroom exercises. Date: Thu, 21 May 1998 20:49:26 -0500 ---------- > To: PSN-L Mailing List > Subject: Re: IRIS software seminar and WinQuake classroom exercises. > Date: Thursday, May 21, 1998 6:09 PM > > On Wed, 20 May 1998, Larry Cochrane wrote: > > (snip) > > 1.Short description of the software and its features. > > 2.User manual. > > 3.Example classroom exercises that uses the software. > > > > I can come up with 1 and 2 with the WinQuake help documents I am working > > on, but I'm not sure about 3. I'm not sure what something like this should > > look like. Does anyone have an suggestions on this? > > > Larry, one example could be to tile the screen and show a comparison for > the same event from different sensors using the same compression rates. > You could show how the waveform from one location might differ from > another that was lying on a different soil bed. See if there was > amplification due to soil issues... > > Ken > Larry, A number of times over a period of many years I demonstrated "live" geophones in Earth Science public school classes. I used an amplifier and galvanometer and a few times a chart recorder to show wave forms that were generated by changing classes, sway of building when the demonstration was done on an upper floor, would have someone tap a foot in the back of the class, have the class sway back and forth in unison, traffic noise outside the building, etc. Perhaps that could be done with sdr showing wave forms on a computer screen and then transfer it to winquake to print, show comparison frequencies with FFT, etc. --- possibly use a geophone on some kind of shake table where frequency could be shown while demonstrating and then with Winquake and FFT. Just a thought. Frank Cooper, Friendswood, Texas, USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: "Live" Psn: Trigger level Date: Thu, 21 May 1998 18:46:09 -0700 Sean Thomas et al Pardon my stupidity but can you explain about pointing. I don't have a web page yet to post bitmaps etc for others to review. Barry > Images, etc, should be pointed to so that those who can decode them > can do so if they want to, and those of us who have enough trouble > keeping up with just text email don't get slammed with 200 lines > of bitmaps. > > Thanks, > Sean-Thomas > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: "Live" Psn: Trigger level Date: Thu, 21 May 1998 18:50:50 -0700 Hi My Netscape mailer worked fine. I saved it "as a file" and it accepted it. I have had this alternate way to save files occasionally happen with certain events posted. I can't remember who though. Barry Jim Hannon wrote: > Interesting: Even my Netscape email could not figure out what to do > with the attachment from Steve. It looks to me to be an accident. > > I look at my home email at work by telnetting to a unix server and using > "Pine" as the email program. This is a text only email program but at > least it is "mime aware" and the attachment shows up as a note > indicating it cannot be displayed and asks if you want it saved to a > file. This eliminates the problem of having to view a chunk of encoded > junk. It also doesn't send the attachment so you don't have to wait for > the data on a slow link. Using Pine or a similar email program might > help eliminate the hastle of attachments. > > I agree that odd attachments should not be sent on this list. > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Chris Nicassio" Subject: {EarthWaves} SUB-SEAFLOOR MAGMA FORMATION Date: Thu, 21 May 1998 23:13:05 -0500 (CDT) EarthWaves ---- A Forum for the Discussion of Earth Changes ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^ To POST a message, send to earthwaves@........... ^^^^ Media contact: May 21, 1998 Cheryl Dybas NSF PR 98-29 (703) 306-1070/cdybas@.............. contact:Dave Epp(703) = 306-1586/depp@....... NEW, SURPRISING PICTURE EMERGES OF SUB-SEAFLOOR MAGMA FORMATION For the first time, seismologists have captured detailed images of the deep underground processes that give birth to most of the planet's new surface, along mid-ocean ridges where the seafloor pulls apart. Some of the underground patterns confirm predictions. Others are a surprise. The new data represent a major step forward in understanding the formation of the crust, convection in the planet's interior, and the source of the most abundant volcanic activity on Earth. Funded by the National Science Foundation, the $7 million project is called the Mantle Electromagnetic and Tomography Experiment, also known as MELT. One of the largest marine geophysical experiments ever conducted, its main goal is to find where melted rock, also known as magma or "melt," is formed and how it moves to the ridge crest to form new oceanic crust. "The experiment has set a new standard for the type and scale of experiments to be done in the oceans," says Dave Epp, program director in NSF's marine geology and geophysics program, which funded the research. "We expect this line of research to continue for the next decade or more." In this week's issue of Science, geophysicists from Brown University and six other institutions report that melting rock flows up in a broad zone in the Earth's upper mantle, rather than in the narrower plume that some researchers had predicted. Under the separating seafloor, magma starts forming nearly twice as deep as scientists had expected and, surprisingly, wells up slightly-off center, not directly beneath the ridge where most of the magma eventually erupts and cools to form new oceanic crust. "The seafloor spreading process is like a conveyor belt carrying away crust from mid-ocean ridges," says Donald Forsyth, a geologist at Brown University and coordinator of the imaging project. "We're seeing a suggestion that the upper mantle beneath the oceans is stirred up by small-scale convection, such that melting would be pretty much the same no matter where aridge opened = up." The early findings are reported in a special section in this week's Science. An overview article and seven research papers present direct observations of the mantle from seafloor seismic recorders and from other geophysical observations. More details will be added Friday, May 29, at the American Geophysical Union meeting in Boston, when results from the second part of the experiment, using electromagnetic imaging techniques, will be reported for the first time. The results show that melt is generated over a much larger region than many scientists had expected. Some of the surprising observations will likely lead to the development of a new generation of models of mantle flow and magma generation beneath mid-ocean ridges. Scientists had debated about mantle activity, and it turns out that their predictions were at least partly wrong. One model described a broad, shallow region of passive upwelling and a second model predicted a narrow, shallow and active upwelling zone. Neither model predicted the asymmetry of the upwelling magma or the depth at which melting occurs. Other institutions involved in MELT are: the Carnegie Institution of Washington, the Scripps Institution of Oceanography in San Diego, the University of Colorado, the University of Oregon, the University of Washington in Seattle, and the Woods Hole Oceanographic Institution in Massachusetts. -NSF- chrisqk@....... ^^ To UNSUBSCRIBE: Send "unsubscribe earthwaves" to majordomo@........... ^^ To SUBSCRIBE: Send "subscribe earthwaves" to majordomo@........... ^^ To SUBSCRIBE ANOTHER: Type "subscribe earthwaves name@........." ^^ All commands should be placed in body of message, with no quotes ^^ Auto-approval occurs when confirmation email is returned by subscriber ^^ Check current EQ reports: http://www.earthwaves.com/current.html _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Shackleford-Gunderson Seismometer Date: Thu, 21 May 1998 22:57:41 -0600 Hi guys, The S-G seismo, is creating more curiosity on my part lately. The basic design too me, seems to be more of a tiltmeter at first glance...but I suppose the function is the same as a horizontal. Am guessing that the adjustment feet may not need ultra-precision threads? The hanging down mass I would expect would greatly reduce the amount of tilt offset, and the drift would not seem to be very great compared to other seismometers. The mechanics of the unit also seems to be alot simplier than other seismometers. The hinges themselves are a curiosity. I would think for the directional characteristics, that a stiffer flat spring would be more desireable to alleviate side/mass signals. Am not aware of any commercial equivalent... Actually I would like to hear more on the S-G...if anyone would care to dare to comment-ha. Satisfaction, limitations, maintenance comparisons, tilt comparisons, temperature effects and about the whole ball of wax? Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tom Frey Subject: Quake Date: Thu, 21 May 1998 22:19:26 -0700 Hi Currently receiving low frequency moderate size waves: May 22 05:01:02 UTC Tacoma , WA 47.159n/122.473W tom _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: UP about comments -- Re: "Live" Psn: Trigger level Date: Fri, 22 May 1998 05:57:26 -0700 I'm at home now and on a netscape system... Gee guys, what you are talking about is Bill's mail system. We are required at work to use MS Outlook as "the only" mail system. Here at home, netscape is able to decode the mail pack without error. So, that's what's going on-- Jim Hannon, I don't know what to tell you. There is notheing attached to the mail message I sent. I assume you are still using a UUCP account. As I still have netscape installed at work, I'll try to remember to switch back to it if I post from work again. But guys, the bad news is, your problems are going to get worst as time goes on and MS Outlook gets installed around the world. Regards, Steve Hammond PSN San Jose barry lotz wrote: > > Hi > My Netscape mailer worked fine. I saved it "as a file" and it > accepted it. I have had this alternate way to save files occasionally > happen with certain events posted. I can't remember who though. > Barry > > Jim Hannon wrote: > > > Interesting: Even my Netscape email could not figure out what to do > > with the attachment from Steve. It looks to me to be an accident. > > > > I look at my home email at work by telnetting to a unix server and using > > "Pine" as the email program. This is a text only email program but at > > least it is "mime aware" and the attachment shows up as a note > > indicating it cannot be displayed and asks if you want it saved to a > > file. This eliminates the problem of having to view a chunk of encoded > > junk. It also doesn't send the attachment so you don't have to wait for > > the data on a slow link. Using Pine or a similar email program might > > help eliminate the hastle of attachments. > > > > I agree that odd attachments should not be sent on this list. > > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: LARGE STH AMERICAN QUAKE Date: Fri, 22 May 1998 19:02:18 +1200 its in progress 0500 utc ........ onwards jst recorded in New zealand cheers DAve Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Re:Re: "Live" Psn Trigger level Date: Fri, 22 May 1998 20:40:45 +0800 Hi Steve, (Steve Hammond -- PSN San Jose, California) I read your message about the transmission of seismic waves in a fluid and I found it very interesting. In my situation, the seismometers are buried about 2.5 meters below the ground and surrounded by a few kilometres of trees to the west and 20 kilometres of trees to the east and south. In summer when the wind blows there is a distinct peak in the frequency spectrum, other than the 6 second micro seisms level. In the case of the heavy winter rains the whole background was lifted between 0.1 - 1 Hertz. As you suggest the coupling between the ground and the sensor may be better.. Maybe by checking with an insurance company and plotting the claims cost against month, would be a good proof for the solid/fluid risk damage. You would have to compensate for the population growth. If the results are true? Would this indicate the quake magnitudes in the water soaked soils are overestimated? Interesting stuff. Regards Arie. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: UP about comments -- Re: "Live" Psn: Trigger level Date: Fri, 22 May 1998 05:56:49 -0700 (PDT) On Fri, 22 May 1998 shammon1@............. wrote: > back to it if I post from work again. But guys, the bad news is, your > problems are going to get worst as time goes on and MS Outlook gets > installed around the world. > Don't bet on it. Linux is catching on fast. And for the very reason you're talking about here: M$ stuff often doesn't work and has a host of other annoyances. ob PSN-L: I also prefer to see plain text files here on the list because I too use pine. --Warner Puget Sound Country _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: New event Date: Fri, 22 May 1998 05:15:56 -0700 Hi all It appears to be Bolivia @ approx M6.7 17.3s 65.0w 04:48:52 UTC I was holding up my file until I get more firm parameters Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: UP about comments -- Re: "Live" Psn: Trigger level Date: Fri, 22 May 1998 12:48:59 -0700 (MST) On Fri, 22 May 1998, Warner Lindholm wrote: > On Fri, 22 May 1998 shammon1@............. wrote: > > back to it if I post from work again. But guys, the bad news is, your > > problems are going to get worst as time goes on and MS Outlook gets > > installed around the world. > Don't bet on it. Linux is catching on fast. And for the very reason you're > talking about here: M$ stuff often doesn't work and has a host of other > annoyances. A look at the practical side of computing is what will allow Linux to triumph over Windows. I personally would love to use Linux over Windows. But here are the issues, and they are what made the PC compatible computer so popular in the first place: 1) $$$ Less expensive than mac. 2) More software in the store than mac. 3) Easier for programming (leads to the above) than mac (This is a myth too). Just ask yourself: How many people you know are aware of the name of a good mac compiler? What would make Linux more popular of a platform are the same exact things. Just replace the word "mac" in the above list with "MS Windows." In other words, the people that can make this happen are the major software producers. But one problem here is that the major software usage comes from word processing, and too many people have been doped into almost believing that there is no better program than MS Word, when there are many that put it to shame and also use 10% of the disk space (For example, Claris Works fits all the criteria). In fact, the only decent software ever made by microsoft is excel, in terms of comparing it with other spreadsheet apps out there. Another danger for Linux is Windows NT, because people have been doped (again) into thinking it is a big improvement over Windows 9X (they think it has less problems; LAUGH) and which people also think is better for networking than the Linux platform. I am stuck with an old mac for now at home (starving student here). The computers at school are still on Windows 95. This really sucks, because I have some cool software for Linux that I have been itching to use. A while back I met with Jonathan Lees (Yale seismologist) who had developed some great stuff (or his students had) for Linux and showed me the system and how well it worked for many applications (Some others here may have heard his sales pitch as well). Also, Linux has become the platform for using the IRIS software and event files downloadable from their "Spyder" site. If anyone could post the following information to this list, it may help convince myself and others of the practical side of Linux: 1) How much does it cost to install Linux? 2) How much does it take to get other essential apps like word processing going? I am not talking about a text editor like pico, but something you can do page layouts, change fonts, and other things people will want. 3) Does it crash often? 4) Can a computer idiot use it? ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: [Fwd: Re: finger quake broken?] Date: Fri, 22 May 1998 13:55:36 -0700 FYI: In case you were wondering why the NEIC finger quake links were not updating. -- ---/---- Charles P. Watson Seismo-Watch From: lahr@.................. Subject: A great opportunity Date: Fri, 22 May 1998 15:11:22 -0600 (MDT) This sounds like a very interesting project that is coming up in the Bay Area and that some PSN members may be able to help with by providing a site for one of the recorders. Contact Allan Lindh if you're interested. Cheers, JCLahr > From lindh@................... Wed May 20 18:51 MDT 1998 > Date: Wed, 20 May 1998 17:54:02 -0700 (PDT) > From: Al Lindh > Subject: A great opportunity > > JOIN THE URBAN SEISMOLOGY REVOLUTION > In conjunction with a number of my colleagues here at the USGS, > and faculty members at Berkeley and Hayward State, we are > undertaking a relatively large scale seismic recording effort in > the Santa Clara Valley this summer. This will involve deploying > 40 REFTEK recorders which we are borrowing from IRIS, an NSF > funded consortium of universities. This instruments will be > installed from about 15 June to 15 September, and for this we > need about 40 sites in the Santa Clara Valley. > > The area to be instrumented will include essentially all of San > Jose, Santa Clara, Milpitas, Fremont (south of the Irvington > District), Campbell, Los Gatos, Saratoga, Cupertino, Sunnyvale, > and Los Altos/Mountain View (south of El Monte / Shoreline). > While most of the stations will be on the valley floor, we will > need a few along the edge of the hills as well. > > So, this is your opportunity to adopt a seismic instrument for > the summer. We would love to put an instrument in your back > yard. The only requirement is that you have a few square feet > where we could set the instrument enclosure, and a nearby place > to dig a small hole and bury the seismometers. The site would > need to be reasonably secure; a fenced back yard would be great. > We will need access to the stations about once a week to pick up > the data. Since we will be driving around all day picking up > data, we would not be able to schedule a specific time when you > would be home, so the only possible inconvenience would be giving > us permission to go into your back yard when you were not at > home. If you could provide an A/C outlet to plug in the battery > charger, that would be ideal, since it would save us the trouble > and expense of hauling around fresh batteries. > > There is no known hazard of any kind associated with these > instruments; they will just sit there quietly all summer and > record whatever the earth has to say. We will be happy to tuck > them in behind a bush, put them against the garage wall, or do > anything else to make them unobtrusive. And while we hope to > find as quiet sites as possible, this is urban seismology, and > there is no need to tip-toe around the instrument, avoid running > the roto-tiller or the like; whatever you do around your back > yard is fine, that's just part of the experiment. > > The data from this experiment will be used for many purposes, > including building a better model of the Santa Clara Valley for > modeling strong ground motion, estimating the site-amplification > effects, and getting better locations for earthquakes on the > faults bounding the valley. By participating in this experiment, > you will be contributing in an essential way to these efforts. > At the end of the experiment, you will be given copies of the > best seismograms recorded at your home. > > If you think you might be interested in participating, please > email me your street address (please include town and > cross-street). > > Thank you very much, and hoping to hear from you soon > Allan Lindh > 650 329 4778 or lindh@................... > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Oops -- Schematic Error Date: Fri, 22 May 1998 15:00:54 -0700 Hi all -- I discovered (after more than a year) an error on one of the schematics on my web page. It is a schematic of the LVDT excitation oscillator, and a capacitor on the left side was connected wrong. If anyone tried to build the circuit according to my schematic, it wouldn't have worked. I've corrected the schematic on my web page. My appologies to anyone who might have had a problem due to the error. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: A great opportunity Date: Fri, 22 May 1998 23:58:23 -0700 Hi Al, sign me up-- 37.14' 43.44N 121 48 54.52W San Jose 101/Blossom Hill Rd area. I have a seismic house to put the gear in and can provide, power and phone line if needed. Send me a note if you want one installed in my area and I'll send you the street address. Regards, Steve Hammond PSN San Jose lahr@.................. wrote: > > This sounds like a very interesting project that is coming up > in the Bay Area and that some PSN members may be able to > help with by providing a site for one of the recorders. > Contact Allan Lindh if you're interested. > > Cheers, > > JCLahr > > > From lindh@................... Wed May 20 18:51 MDT 1998 > > Date: Wed, 20 May 1998 17:54:02 -0700 (PDT) > > From: Al Lindh > > Subject: A great opportunity > > > > JOIN THE URBAN SEISMOLOGY REVOLUTION > > In conjunction with a number of my colleagues here at the USGS, > > and faculty members at Berkeley and Hayward State, we are > > undertaking a relatively large scale seismic recording effort in > > the Santa Clara Valley this summer. This will involve deploying > > 40 REFTEK recorders which we are borrowing from IRIS, an NSF > > funded consortium of universities. This instruments will be > > installed from about 15 June to 15 September, and for this we > > need about 40 sites in the Santa Clara Valley. > > > > The area to be instrumented will include essentially all of San _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Seismo-party in the Santa Clara Valley and the 13th fairie Date: Fri, 22 May 1998 19:07:45 -0600 Al- In no case is the double positive construed as the negative: Yeah, Yeah ... As Branch Chief, you were the one who suggested that the PSN start a BBS as a means of communicating about and sharing seismic data. Consequently, Steve Hammond put the first PSN PC-based BBS together, and you operated the USGS/PSN PC-based BBS in your office. The BBSs evolved to the PSN websites that Larry Cochrane was the first to establish ... check it out! Anyway, John Lahr was the first one, USGS member at least, in this post-sixties zeitgeist to suggest that professional seismologists should enlist the assistance of the public in the "witchcraft" (Frankel, 1996) involved in determining the seismological characteristics of the Earth. I have said enough, probably too much as usual. Good Luck! -Edward Al Lindh wrote: > > but you know I was thinking of you > and you're the one who started us down theis twisted > path > I don't think its impossible that so many o fthe people > will like having their own REFTEK > that they will incist on buying it so we can't take it away. > > If only they were smart units with a phone line connection > and cost more like $5K > but that will be the units our kids will deploy > I really did think of you this morning, but > couldn't find your email address > we're up to about 60 respondents already > and it hasn't even gone out to the entire USGS campus yet > > In effect its become a chain letter, and people are just passing it on. > > Does the PSN have a WEB site? > The data is going straight to the IRIS data center > where it can be retreived as individual events > if they had a WEB site, everybody's seismograms could > be on-line for them to look at within a few days. > > Take care > allan -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: (Linux) UP about comments Date: Fri, 22 May 1998 21:16:26 -0700 I tried to trim this down a bit, becuase I'm sure someone isn't going to care much. > If anyone could post the following information to this list, it may help > convince myself and others of the practical side of Linux: > 1) How much does it cost to install Linux? The most popular distribution set is Redhat. Redhat is about $35 from Cheap Bytes (http://www.cheapbytes.com/). Since you mentioned the Mac, you can also get MkLinux or PPC Linux. If you have a T-1 or maybe ISDN you could download the whole thing for free and burn a CD. You can get Debian for about $8 or an unofficial (legal but unsupported) RedHat for about $3. SUSE is also becomming popular. SUSE is a German company with some advantages over RedHat. I have RedHat 4.2 and I'm waiting for RedHat 5.1's public approval (due out soon) to upgrade. > 2) How much does it take to get other essential apps like word processing > going? I am not talking about a text editor like pico, but something you > can do page layouts, change fonts, and other things people will want. Corel has recently announced it will write WordPerfect 8 for Linux (probably Intel only). WordPerfect 7 is out right now. There is also StarOffice and Applixware Suite (about $100 with RedHat Linux). I think Corel also said that there will be a complete suite available sometime in the future. If you know how to use LaTeX or TeX or whatever, they come with the operating system usually. Some people are working on free word processors. I don't use them on either platform much myself. A new program that's on the verge of 1.0 release is GIMP. It's sort of a free Photoshop clone. It's completely open and tweakable if you're into that. > 3) Does it crash often? It doesn't crash on it's own however I have occasionaly locked it up with some software. Just recently I locked it up trying to cancel Netscape 4.05 from getting all of the newgroup headers. Of course, I've also locked Win95 a lot as well. It's really pretty stable on my computer. There is always the problem of hardware. A lot of manufacturers won't release the neccessay information to write a driver for Linux, let alone write it themselves. For example my parallel port tape drive only works in Win95. There are a few (growing) vendors that sell computers with Linux already set up and installed. VA Research is one. > 4) Can a computer idiot use it? I'd say no. I'm not too smart, but I managed to get into some things that other people think take intelligence. Configuring the kernel and installing it isn't anything like plug and play. If you don't like DOS, you're probably not going to like Linux. It also helps to know C programming at least a little. Some things in Linux are better than DOS. Some of the programs don't come as installable programs; you have to compile and install them manually or through a script. Sometimes it doesn't work and sometimes it does and your amazed. Linux Journal is a new magazine that has a lot of usefull information about how to use Linux. Running Linux is a book that's supposed to be very good for begginers. You may notice that I'm using Win95 right now (in message headers) because sometimes you just want to do something and your not interested in logging in and doing all kinds of fancy stuff with X Windows, window managers, xterms, ppp, root, etc... email me directly if you want any further information, Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: UP about comments -- Re: "Live" Psn: Trigger level Date: Fri, 22 May 1998 21:42:58 -0700 Taking about operating systems (OS) is kinda like taking about politics or religion, and a little off topic...Anyway a few comments below. At 12:48 PM 5/22/98 -0700, John Hernlund wrote: > > A look at the practical side of computing is what will allow Linux to >triumph over Windows. I personally would love to use Linux over Windows. But >here are the issues, and they are what made the PC compatible computer so >popular in the first place: > 1) $$$ Less expensive than mac. > 2) More software in the store than mac. > 3) Easier for programming (leads to the above) than mac (This is a myth > too). Just ask yourself: How many people you know are aware of the name > of a good mac compiler? > > What would make Linux more popular of a platform are the same exact things. >Just replace the word "mac" in the above list with "MS Windows." But the problem is Linux/UNIX is in the same position as the mac. If you go into a computer store there is very little, if any, software for it. And I just don't see that changing anytime in the near future. There is a lot of free software for it on the Internet, but most of it is written by students and individuals. This is great, but you get what you pay for.... What I don't like about UNIX/Linux is the inconstancy between how the programs behave, like command line options etc. You can tell it's written by many different people, unlike VMS, Windows and the mac. To make it worse, UNIX has different flavors, Linux being one of them, and the same commands, between the different versions, can do different things. This is from what I understand from UNIX type people I have talk to. And then theres the different shells....I just don't see it being used by the average person who want's too do word processing and surf the net. >In other >words, the people that can make this happen are the major software producers. >But one problem here is that the major software usage comes from word >processing, and too many people have been doped into almost believing that >there is no better program than MS Word, when there are many that put it to >shame and also use 10% of the disk space (For example, Claris Works fits all >the criteria). In fact, the only decent software ever made by microsoft is >excel, in terms of comparing it with other spreadsheet apps out there. I do agree that Microsoft's products are disk space, ram memory and CPU hogs. It seems that all they want to do is ship something without spending time to optimize anything. I try to stay away from MS products as much as possible, but that's hard to do sometimes.... >Another >danger for Linux is Windows NT, because people have been doped (again) into >thinking it is a big improvement over Windows 9X (they think it has less >problems; LAUGH) and which people also think is better for networking than the >Linux platform. This statement I disagree with. NT is a stable OS system, once you get it up and running. May companies use it in critical applications. I just went to a seminar about voice over the Internet. The company is using NT for its voice server and the other things like billing costumers etc. They said they would port the code over to a UNIX system if any they get enough requests. Windows NT is more stable because its was designed from the ground up. From what I understand, one of the designers of DEC's VMS (I worked on VMS systems for almost 8 year, that was about 5 years ago, but I still us it as a standard for OSs) was the main person behind the design of NT. Win3.1 and 95 all evolved around DOS and needed to be compatible with it, unlike NT. As far as networking, my guess is that they are about the same. One thing about UNIX is the open architecture. Since all of the software code for the OS is available, it makes it easier for hackers to find holes in it. > > I am stuck with an old mac for now at home (starving student here). The >computers at school are still on Windows 95. This really sucks, because I >have some cool software for Linux that I have been itching to use. A while >back I met with Jonathan Lees (Yale seismologist) who had developed some great >stuff (or his students had) for Linux and showed me the system and how well it >worked for many applications (Some others here may have heard his sales pitch >as well). Also, Linux has become the platform for using the IRIS software and >event files downloadable from their "Spyder" site. WinQuake can read the SAC, and now the SEED volumes, from the Spyder system.... About a year and 1/2 ago I asked them if they would like to place a copy of WinQuake on their system. They never got back to me. I will ask someone about it at the IRIS meeting in July. > > If anyone could post the following information to this list, it may help >convince myself and others of the practical side of Linux: > 1) How much does it cost to install Linux? From what I understand Linux is free. You can probably download it on the Internet. I'm sure its very big, so people buy a CDRom that costs between $35 and $100. > 2) How much does it take to get other essential apps like word processing > going? I am not talking about a text editor like pico, but something you > can do page layouts, change fonts, and other things people will want. Don't know... > 3) Does it crash often? All operating systems crash... Its a matter of how often, and that can depend on what applications are running and the hardware, not just the OS. DOS, since it was doing only one thing at a time, and if the app was stable, worked fine. Then Windows came along and tried to made a single app OS run more then one program, that's when things started going downhill... Since NT was written to be a multiple process OS like the mac (not multiple user like UNIX/Linux and VMS) it is inherently more stable. > 4) Can a computer idiot use it? > Depends, if a user only has to turn on the system, logon, and run a few apps, almost anyone can do that. The problem is when you need to install new hardware/ software or when things go wrong. Any OS can be a pain in the you know what when you need to do these things. Just my .02cents... -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: UP about comments -- Re: "Live" Psn: Trigger level Date: Fri, 22 May 1998 21:48:03 -0700 (PDT) With some trepidation, I'll try to answer these questions. Experts please come to my aid. On Fri, 22 May 1998, John Hernlund wrote: > > If anyone could post the following information to this list, it may help > convince myself and others of the practical side of Linux: > 1) How much does it cost to install Linux? It can be free. ftp installs are possible. Network file system installs can be done. Cheapbytes sells cdroms that are less than $10. Somebody suggested I try RedHat linux and it turned out to be something I, a novice, was able to do fairly easily. RedHat 5.0 sells for $50. Here in the Seattle area there are boot fests. People pack up their computers, meet somewhere, and the experts help them install. So it doesn't cost a lot. > 2) How much does it take to get other essential apps like word processing > going? I am not talking about a text editor like pico, but something you > can do page layouts, change fonts, and other things people will want. This is something I can't answer because it's not something I do but I'm certain the capability is there. I don't think the Linux Journal is put together using Microsoft Word. There are office applications like Applixware or Starwave. One is free and the other is < $100. And, you know, this isn't an either/or proposition. You can have M$ stuff on another drive partition if you want. Just reboot and select. > 3) Does it crash often? Linux is quite stable. It's a point of pride and you hear of uptimes of hundreds of days. My system is quite stable until I load Netscape 4.05 Then I can hang it if I don't watch it. I've only got 16 megs of memory and it's my understanding the new browsers want a lot more - like 32 megs. I don't know how true this is but I've read that Netscape will happily swap everything out of ram including portions of itself when it runs out of memory. > 4) Can a computer idiot use it? I gotta say that the learning curve was pretty steep for me. I must have blown away the linux installation 5 times in the beginning I got so frustrated. The darned unix commands seemed so arcane, but after one or two days of the M$ stuff I'd reinstall linux and it'd be like a breath of fresh air. There are plenty of books out there and *lots* of help in comp.os.linux.* usenet groups plus the linux-list@........ I suggest you try it. It's likely you'll never look back. --Warner Puget Sound Country _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Linux, Unix-- a Rose By Any Name Date: Fri, 22 May 1998 22:08:35 +0000 Hello John and All, My reason for selecting Linux as one of my platforms of choice, is based on two ideas: 1- Linux or FreeBSD are not easily influenced (regulated?) by the whims of a market plan. Operating Systems come and go. 2- Linux is beginning to be used as a science platform. In theory, as long as Linux is an 'open' platform and is used as a science platform, science source code will be available to students and researchers alike, in theory. This is good. Keep the intellectual processes open. There are many worth while products available for Windows platforms, but how these products are manifest are highly guarded secrets. Linux supports 'openness', and connotes intellectual freedom in that sense. A basic tenet of science is sharing and the nature of the Linux movement supports that notion. See below: >>JH : John Hernlund >>WW : Walt Williams ------- Forwarded Message Follows ------- Date: Fri, 22 May 1998 12:48:59 -0700 (MST) From: John Hernlund Subject: Re: UP about comments -- Re: "Live" Psn: Trigger level To: PSN-L Mailing List Reply-to: PSN-L Mailing List >>? On Fri, 22 May 1998, Warner Lindholm wrote: > On Fri, 22 May 1998 shammon1@............. wrote: > > back to it if I post from work again. But guys, the bad news is, your > > problems are going to get worst as time goes on and MS Outlook gets > > installed around the world. > Don't bet on it. Linux is catching on fast. And for the very reason you're > talking about here: M$ stuff often doesn't work and has a host of other > annoyances. >>JH A look at the practical side of computing is what will allow Linux to triumph over Windows. I personally would love to use Linux over Windows. But here are the issues, and they are what made the PC... -------- >>JH If anyone could post the following information to this list, it may help convince myself and others of the practical side of Linux: 1) How much does it cost to install Linux? >>WW This text is Intel biased, i.e., for PC. Most Linux source and binaries are 'freely' available on the InterNet via anonymous ftp. It is daunting to mentally collate all of the attendant modules which are needed to construct a working Linux platform, regardless whether one is already quite familiar with Linux, its distributions and Unix. This approach is not 'newbie' friendly. Although if one is patient, can read, and reads many of the LDP FAQs, the task can be accomplished. Using one of the Value Added Distributers (VAD)s, such as SlackWare, InfoMagic, SUSE (Europe?), Debian, Red Hat, Caldera, or others, sorted in no particular order, the installation process can be much eased. These Linux distributions also come with a price tag; with Caldera being the most expensive. Last time I checked around $250, and is, I have heard, the easiest to install and to configure. I received a RedHat 5.0 CD set as a gift so I use that distribution, @....... These VADs make general cosmetic modifications to the OS environment and/or some of its parts. They write 'freindly' user install scripts or install widgets. But, to answer your question simply, typically $3....$75 for a VAD CD set can get you running Linux. Then the fun starts! >>JH 2) How much does it take to get other essential apps like word processing going? I am not talking about a text editor like pico, but something you can do page layouts, change fonts, and other things people will want. >>WW I am not sure how to answer the question, There was a version of Word Perfect which runs on Unix. I do not know if there are any other 'windows-like' GUI programs available. There must be some, but I use JStar (available via InterNet) which implements my favorite user interface, i.e., similar to the old WordStar command set. I am a simple guy. When I need to 'pretty-up' a document, I use a 'prettier' program such as WordPerfect in Win95 to do so. >>JH 3) Does it crash often? >>WW Not in my experience. I think this depends entirely on what is being done and used. Oh, it is full of bugs, but bugs can be user fixed, assuming one can program in 'C'. >>JH 4) Can a computer idiot use it? >>WW Some will not like this answer: Nope. If the user is truely computer illiterate, they should be using a Mac. Actually, I think the Mac GUI is fairly elegant. I have been surprised to see the breadth of users with varying computer usage skills who successfully use and favor Linux. Best Regards, Walt Williams, 98.05.22 dfheli@.............. http://www.pacificnet.net/~dfheli ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) ============================================= >>JH A look at the practical side of computing is what will allow Linux to triumph over Windows. I personally would love to use Linux over Windows. But here are the issues, and they are what made the PC compatible computer so popular in the first place: 1) $$$ Less expensive than mac. 2) More software in the store than mac. 3) Easier for programming (leads to the above) than mac (This is a myth too). Just ask yourself: How many people you know are aware of the name of a good mac compiler? What would make Linux more popular of a platform are the same exact things. Just replace the word "mac" in the above list with "MS Windows." In other words, the people that can make this happen are the major software producers. But one problem here is that the major software usage comes from word processing, and too many people have been doped into almost believing that there is no better program than MS Word, when there are many that put it to shame and also use 10% of the disk space (For example, Claris Works fits all the criteria). In fact, the only decent software ever made by microsoft is excel, in terms of comparing it with other spreadsheet apps out there. Another danger for Linux is Windows NT, because people have been doped (again) into thinking it is a big improvement over Windows 9X (they think it has less problems; LAUGH) and which people also think is better for networking than the Linux platform. I am stuck with an old mac for now at home (starving student here). The computers at school are still on Windows 95. This really sucks, because I have some cool software for Linux that I have been itching to use. A while back I met with Jonathan Lees (Yale seismologist) who had developed some great stuff (or his students had) for Linux and showed me the system and how well it worked for many applications (Some others here may have heard his sales pitch as well). Also, Linux has become the platform for using the IRIS software and event files downloadable from their "Spyder" site. If anyone could post the following information to this list, it may help convince myself and others of the practical side of Linux: 1) How much does it cost to install Linux? 2) How much does it take to get other essential apps like word processing going? I am not talking about a text editor like pico, but something you can do page layouts, change fonts, and other things people will want. 3) Does it crash often? 4) Can a computer idiot use it? ********************************************************************** ******** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ********************************************************************** ******** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: rick@.................. (Rick Hewett) Subject: Re: "Live" Psn: Trigger level Date: 22 May 1998 20:29:20 GMT At 23:18:49 UTC on Thu 21 May Jim Hannon wrote: > Interesting: Even my Netscape email could not figure out what to do > with the attachment from Steve. It looks to me to be an accident. It identified itself thus "Content-Type: application/ms-tnef" so presumably it's something that the Micro$oft application Steve was using figured would be useful for the recipient. Maybe it has something to do with formatting? Whatever, I'm sure that somewhere there's an option that says something like "Send mail as plain text only" which, if selected, would save the list the burden of transmitting un-necessary binary data. Unfortunately many applications seem to be distributed with the most cumbersome options set by default. -- ...Rick Hewett http://www.chocky.demon.co.uk/ No one was avoiding him, it was just that an apparent random Brownian motion was gently moving everyone away. -- (Terry Pratchett, Reaper Man) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: iliad@.................. (ISAT) Subject: Re: iliad query SEN12266 doc 3 Date: Sat, 23 May 1998 10:53:48 -0500 (CDT) Dear ILIAD User: This document qualified as a response to the question you sent to ILIAD. The items in [brackets] such as IMAGE or a NUMBER indicate a hyperlink in the orginating Web document. Your question was: "Elementary Seismology" Output Type: documents ILIAD Session ID: SEN12266 ------------------- Results begin here -------------------- Document Reference URL: http://www.gsrg.nmh.ac.uk/~phoh/faq2.htm [IMAGE] EARTHQUAKE REFERENCES _________________________________________________________________ GENERAL SEISMOLOGY, WORLD EARTHQUAKES AND SEISMICITY Bolt, B.A., (1993), "Earthquakes: Newly Revised and Expanded ", WH Freeman & Company, New York. ISBN 0-7167-2236-4. Gutenberg, B. and Richter, C.F., (1954), "Seismicity of the Earth and Related Phenomena", 2nd, Revised Edition - Reprinted Hafner 1965. Richter, C.F., (1958), "Elementary Seismology", WH Freeman & Company, New York. Van Rose, S. and Musson, R.M.W, (1997), "Earthquakes Our Trembling Planet",The British Geological Survey, Keyworth, Nottingham, UK. Related GSGG pages. [1]Earthquake questions and answers (FAQ's) [2]Recent earthquakes (UK and significant world earthquakes) [3]Earthquake monitoring [4]World seismicity map _________________________________________________________________ UK SEISMOLOGY, EARTHQUAKES AND SEISMICITY Musson, R.M.W., (1994), "A Catalogue of British Earthquakes", Technical Report No. WL/94/04. Available from GSRG (address below) The annual "Bulletin of British Earthquakes" provides detailed information on UK earthquakes recorded by GSGG. This is supplemented by more detailed reports on individual, larger earthquakes. Available from GSGG (address below) Marrow, P.C., (1992), "Seismic Monitoring of the North Sea", Health and Safety Executive/HMSO, London. ISBN 0-11-885999-4 Musson, R.M.W., (1996), "The Seismicity of the British Isles", Annali Di Geofisica, Vol. XXXIX, pp. 463-469. Related GSGG pages. [5]Earthquake questions and answers (FAQ's) [6]Recent earthquakes [7]UK earthquake monitoring [8]Historical earthquakes [9]UK historical seismology overview [10]The UK National Seismological Archive [11]The UK macroseismology home page (felt effects and intensity) _________________________________________________________________ SEISMIC HAZARD Reiter, L., (1990),"Earthquake Hazard Analysis: Issues and Insights", Columbia University Press, New York. ISBN 0-231-06534-5 Tiedemann, H. (1992). " Earthquakes and Volcanic Eruptions: A Handbook on Risk Assessment", Swiss Reinsurance Company, Mythenquai 50/60, P.O. Box, CH-8022 Zurich, Switzerland. Musson, R.M.W., Et al (1997), "UK Continental Shelf Seismic Hazard", Health and Safety Executive/HMSO, Norwich. ISBN 0-7176-1319-4 Related GSGG pages. [12]GSGG seismic hazard services [13]A short guide to seismic hazard [14]Seismic hazard in the UK _________________________________________________________________ EARTHQUAKE EFFECTS; BUILDING CODES AND INTENSITY Katayama, T., (Ed.), (1992), "Earthquake Resistant Regulations: A World List - 1992", Compiled by; International Association for Earthquake Engineering, Tokyo. Distributed by; Gakujutsu Bunken Fukyu-Kai (Association for Science Documents Information), Oh-Okayama, 2-12-1, Meguro-ku, Tokyo, 152, Japan. Related GSGG pages. [15]UK macroseismology home page (felt effects and intensity) [16]Synopsis of the European Macroseismic Scale (EMS) _________________________________________________________________ Go back to the [17]Earthquake Information Page Go back to the [18]GSGG Earthquakes Home Page This document is http://www.gsrg.nmh.ac.uk/~phoh/faq2.htm Last Updated Monday, January 12, 1998 Page Maintained by [19]P.Henni@......... Global Seismology and Geomagnetism Group, British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA, UK. Tel: +44 (0)131 667 1000, Fax: +44 (0)131 667 1877. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: iliad@.................. (ISAT) Subject: Re: iliad query SEN12266 doc 2 Date: Sat, 23 May 1998 10:53:35 -0500 (CDT) Dear ILIAD User: This document qualified as a response to the question you sent to ILIAD. The items in [brackets] such as IMAGE or a NUMBER indicate a hyperlink in the orginating Web document. Your question was: "Elementary Seismology" Output Type: documents ILIAD Session ID: SEN12266 ------------------- Results begin here -------------------- Document Reference URL: http://www.tinaja.com/amlink01.html [1][LINK] [2] [LINK] [3] [LINK] Book Access Links [4] [LINK] [INLINE] "Amazon.com is pleased to have Don Lancaster's GURU'S LAIR in the family of Amazon.com associates. 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[206][LINK] View recommended [207]books. [208][LINK] Visit the [209]Synergetics library. [210][LINK] Return to [211]home page. [IMAGE] _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Al Lindh Subject: Santa Clara Valley Seismic Experiment (SCVSE) Date: Sat, 23 May 1998 11:34:34 -0700 (PDT) Dear Steve and PSNer's Sorry I'm so slow on the uptake but of course you guys should have been involved in this from the get-go events have gotten out ahead of me, and I just haven't been thinking of anything Of course we would love to put stations at any of your houses that are interested, logistics and other siting permitting and of course we would love to have any of your help. In addition, if any of you have stations that you have been running for a while what have good timing (to 0.02 more or less) I would love to talk to you about any EQs you have recorded I am currently writing a paper on the seismicity along the edge of the valley, and if you have arrivals that can help I invite your collaboration And the data from the SCVSE will be available w/in 1-2 weeks of when recorded. If you have a WEB site, and would like to put the seismograms online, we would love it. So, I'm sorry I forgot you guys have been the vanguard for some time and if there are any ways we can collaborate, I'd love it thanks allan lindh _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: Santa Clara Valley Seismic Experiment (SCVSE) Date: Sat, 23 May 1998 22:02:02 -0700 Al Lindh wrote: > > Dear Steve and PSNer's > Sorry I'm so slow on the uptake > but of course you guys should have been involved in this > from the get-go > events have gotten out ahead of me, and I just haven't been >snip sip > allan lindh > day two-- Hi Al, I talked to Bruce Kenny this morning. He wants to signed up to host one of your devices. I will send the address in another note not addressed to the public list. Bruce is in San Jose about 2.5 miles west of me. Major cross street N/E of Bruce is Snell and Blossom Hill Rd. Counting just the PSN people down at the south end of San Jose, we might be able to setup 4 sites within a 5Km area. I expect they will check email during the next week and comment. Are you interested in the Gilroy area? Jan has been working with some schools in that area. Bruce had a couple of tech questions. He wanted to know if he would be able to get a data feed from the unit? He also asked if you were going to use a radio link to telemeter? Can you kind of outline the hardware involved for the group. Regards, Steve Hammond _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Hot Spring turns into Geyser Date: Sun, 24 May 1998 08:15:55 -0700 (PDT) Hello All: I wonder what is going on (seismically) in the mountains north of San Bernardino, CA? Here is all of the information that I currently have about this "geyser." Received from another source: ----------------------------------------------------------------------------- The anomalous geyser is located about 1/8 mile north of the entrance to the Arrowhead Springs Christian Conference Center on Waterman Canyon Road. And that is just about a quarter mile north of the intersection of Highway 18 (Rim of The World Highway) and Waterman Canyon Road. There are some surveyors markings there for a tunnel the Metropolitan Water folks are digging in the area that conveniently mark the spot where the geyser can be seen. It is about 300 feet east of the road at the base of the hill. Easy to find because it really is doing a wonderful job of making its presence known with nice plumes of steam and lots of water squirting up in the air! Some days it is just steam coming out of a hole but normally you can see numerous jets of water shooting up as high as 15-20 feet or more! From the performance of the water, I'd guess the temperature was 250+ degrees! And that is *hot* for a hot spring in that area! I'll be hiking up to it soon to measure the temperature and gather some samples of the water for testing. (I am interested in the helium 3 and sulphur content) -------------------------------------------------------------------- Please let me know what in your opinion is currently causing the increase in temperature and pressure at the hot springs. Thanks, Frank Condon Email to: "frankcnd@.........." "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Arie Verveer Subject: Mb6.0 MINDANAO Live event PSN Date: Sun, 24 May 1998 02:53:31 +0800 Hi there is a good view of the Mindanao quake on the "Live event PSN " screen. Note the background noise compared with "event-3", dry to raining day. http://www.iinet.net.au/~ajbv/ "Mb6.0, 4514km from West Australia, MINDANAO " _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Central Bolivia Earthquake Date: Sun, 24 May 1998 23:50:43 -0600 Meredith- Congratulations for getting the first three-component PSN system up and running, and on the air!! I don't know what I have been doing with my life, because I am very busy, but I haven't done anything. However, I did check out your record of the Bolivian Earthquake, the first one of that event I have looked at so far (despite the others that have been posted on the PSN in the last few days). I also FFT'd it to the frequency domain, high-pass filtered it at 0.01 Hz with 6 poles, inverse FFT'd back to the time domain, and integrated it. I repeated this process to .LZ1 and .LN1, and all the waveforms looked suspisciously similar. Anyway, the .LE1 result can be seen in this .GIF-file: ftp://groundmotion.cr.usgs.gov/PSN/lamb/980522a_le1_int.GIF which highlights the existence of some phases such as SS (but also emphasizes some other phases that I, in my ignorance of teleseismology, cannot identify). I am still confused about the depth and magnitude of this event. I am also confused as to whether your seismometer is an E-W, i.e., .LE1, or W-E? Thank you for your note last week. -Edward meredith lamb wrote: > > Sprengnethers -10X coil signal attenuation. > On line...have a long way to go yet...am > learning. > > --------------------------------------------------------------- > > Name: 980522a.le1 > Part 1.2 Type: unspecified type (application/octet-stream) > Encoding: base64 > > Name: 980522a.ln1 > Part 1.3 Type: unspecified type (application/octet-stream) > Encoding: base64 > > Name: 980522a.lz1 > Part 1.4 Type: unspecified type (application/octet-stream) > Encoding: base64 -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: Central Bolivia Earthquake Date: Mon, 25 May 1998 12:53:21 -0600 Edward Cranswick wrote: > Meredith- > Congratulations for getting the first three-component PSN system up and > running, and on the air!! > I don't know what I have been doing with my life, because I am very > busy, but I haven't done anything. However, I did check out your record > of the Bolivian Earthquake, the first one of that event I have looked at > so far (despite the others that have been posted on the PSN in the last > few days). I also FFT'd it to the frequency domain, high-pass filtered > it at 0.01 Hz with 6 poles, inverse FFT'd back to the time domain, and > integrated it. I repeated this process to .LZ1 and .LN1, and all the > waveforms looked suspisciously similar. Anyway, the .LE1 result can be > seen in this .GIF-file: > > ftp://groundmotion.cr.usgs.gov/PSN/lamb/980522a_le1_int.GIF > > which highlights the existence of some phases such as SS (but also > emphasizes some other phases that I, in my ignorance of teleseismology, > cannot identify). I am still confused about the depth and magnitude of > this event. I am also confused as to whether your seismometer is an > E-W, i.e., .LE1, or W-E? > Thank you for your note last week. > -Edward > Edward and Larry, thanks for the response to the seismograms. Will be the first to say I don't know what I'am really doing here-ha. I think that... yes...all 3 components are being electronically integrated, and I think it lies at the 3 common ground pre-amp board. Have a huge clue though, pulled the junction plugs on the N-S and E-W, and observed the vertical response to floor walking tilt...there was about zero response if any, and then ran the e-w and the response was different and dramatic. Same with only running the N-S. The gain seemed to jump 3X on every component when ran alone. Am using Larry Cochranes triple amplifier pre-amp, at minimum gain (~1600), but, I do have presently a 50K attenuation resistor into the input of each amplifier....which is a good candidate for the problem of possibly integrating all the signals on the common board somehow. After jerking the 50K, and running them all in the board, I see the same integration problem. Reckon, I can try adjusting the gain further in the common board, and/or, use separate boards for each seismometer. Nothing wrong with the pre-amp, but it may not work for this specific seismometer generator/impedance of ~475 ohms, with more than 1 per amplfier board/seismo/common ground (?), which when paraelled X 3= 152 ohms. No expert here, but it seems logical, until...I get shot down-ha. I went out of my way to avoid shorts in the circuits everywhere. Regardless...I can still run one, and that will be the vertical, with its about zero tilt response to overhead traffic, and which I will use as the trigger anyway for all (when they work right). Shucks...in regard to the designations...they do get confusing with them all, and especially unless one has a reference to all the stations and designations, it is kind of perhaps without merit, to address them with anything except like a n-s or e-w or v/z alone; as the station location is prominently displayed in the gram anyway, for most of us. (telemetry aside) Can also see the ready reference need for the various designations, and from that I don't see any ready solutions, unless their was space for more than 3 characters in SDR or etc. Hence I used L=Lamb, N=north-south, 1= first horizontal...with likely more circuits/seismos to try...2,3 etc. I suppose the best would be like MLN, or MLE, or MLV if one is only wanting a set limit of seismometers over the long run. Appreciate the response...it all helps. Eventually everything will be made right, and I will gain experience/knowledge with it all. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: ascii data to psn? Date: Mon, 25 May 1998 13:59:00 -0500 (CDT) RE. ascii data to psn: I am wondering if there is an interest in the data from the 90 second VBB vertical I am running here in St. Louis: ie: should I make an effort to post it to the psn? I generally don't have a need for the data, since I support a number of broadband stations that send their data to NEIS in real time (and show up in the stations listing in the "bigquake" email from NEIS). But there might be an interest in what this VBB homemade seis will do. I sometimes post a MATHCAD plot of the waveform that is scanned and converted to a gif image of the seismogram on my web site, often to compare it with regional Streckeisen STS-1 sensors. But this doesn't make the numbers available for anyone to work with. Since I am just running the Radio Shack multimeter digitizer, rather than SDR or winquake, etc, all I have is strings of numbers (microns/second) at 1 sample/ second. The format is the same as I generate when retrieving data from an IRIS station, without any header. The approximate time of the first sample is known. Maybe Larry or someone knows a simple method to use to post the data to the psn site. I can use C to reformat the data, as long as it remains ascii. This actually might be of interest to anyone running alternate digitizers. Beware that I am not super PC saavy: I use LYNX here at home as a text only web browser. I can also kermit the data to the Univ. and use Netscape, if that is needed. I appreciate any suggestions. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: ascii data to psn? Date: Mon, 25 May 1998 18:04:38 -0700 Sean Thomas I would be interested. If we know a few of the parameters we could convert it to the psn format. Psn format has a 100 byte header with the data. We would need to know the start/stop time (for conversion rate) ,count range& ascii data . Optional: station coordinates. I think a *.dat or *.zip would work for me. Barry S-T Morrissey wrote: > > RE. ascii data to psn: > > I am wondering if there is an interest in the data from the > 90 second VBB vertical I am running here in St. Louis: ie: > should I make an effort to post it to the psn? > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: ascii data to psn? Date: Mon, 25 May 1998 22:36:16 -0700 Sean-Thomas & Barry -- Before I started using SDR with Larry's A/D board, I was recording events with a borrowed laptop running Labview with a PCMCIA A/D. I got ascii data out of Labview and wrote a program in C to convert to WinQuake format. I would be happy to send anyone the C source code for the converter program. It has my location, station info, etc hard coded into the program, so you'd have to get in and change a few things -- should all be in #defines at the top. If anyone wants it, let me know and I'll put the source on my web page and post the URL here. -- Karl At 01:59 PM 5/25/98 -0500, you wrote: >Maybe Larry or someone knows a simple method to use to post the >data to the psn site. I can use C to reformat the data, as long >as it remains ascii. This actually might be of interest to anyone >running alternate digitizers. Beware that I am not super PC saavy: >I use LYNX here at home as a text only web browser. I can also >kermit the data to the Univ. and use Netscape, if that is needed. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: ascii data to psn? Date: Mon, 25 May 1998 23:07:18 -0700 (MST) I would also be interested, even if it is in text it could easily be fed into some other programs. ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Adjustment Screws Date: Tue, 26 May 1998 19:48:42 -0600 Just received some 1/4-80 thread adjustment screws from http://www.lasersur.com/laseraccessories.htm which although narrow in diameter look to be fairly well done. Aluminum Knob, stainless steel bolt (non-magnetic), with the tip slightly rounded and very smooth. They (should) come with a 3/4" long brass bushing of a diameter of .400". However, the ones I got, did not have all the bushings. The bushings (nuts) I did get, did have alittle wobble, but were smooth in action. More nuts would likely have to be made to lock in position when the adjustment is done. Never tried that fine a thread, but I see that there are taps available for that size for around ~$12.00. Would think a drill press & vise would work with the power off and hand twisting the drill head (X fingers) with the drive belt off. Would suggest brass for the nuts, aluminum for the base tapping. On the same web page, are micrometer heads with 1" travel, .001" increments and mount through any 9/16" hole, but are expensive at $39.00 each. They do have a catalog which you can request via the web site. Catalog delivery might be over a month. This is not the first notice of this site. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Sorensen Subject: Re: Hot Spring turns into Geyser Date: Tue, 26 May 1998 19:34:39 -0700 Hello all. I just talked to my dad who is retired and lives up in these mountains. He said that the two local lakes (Arrowhead and Grass Valley) are both running over their spillways. He had heard that they had 70" of moisture this winter. If I remember correctly, that's a lot more than usual. There is a spring near his cabin that flows from a 2" pipe. Last year when I saw it, there was little water coming from it. (maybe a trickle 1/4" dia.) He said that the pipe in now running 100% capacity. He did not estimate the pressure. It sounds to me like it might just be El Nino runoff. Maybe some of our mentors can fill us in on how ground water levels effect fault activities (if in fact they do). Roger Sorensen - Chatsworth CA USA 34.27116N 118.59386W Frank Condon wrote: > > Hello All: > I wonder what is going on (seismically) in the mountains north of San > Bernardino, CA? Here is all of the information that I currently have about > this "geyser." Received from another source: > ----------------------------------------------------------------------------- > The anomalous geyser is located about 1/8 mile north of the entrance to the > Arrowhead Springs Christian Conference Center on Waterman Canyon Road. > And that is just about a quarter mile north of the intersection of Highway 18 > (Rim of The World Highway) and Waterman Canyon Road. > snip _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: ascii data to psn? Date: Tue, 26 May 1998 19:17:41 -0700 Hi Karl I would be interested. I runmost of my programs in Quickbasic 4.5 but I have a working knowledge in C. Let us know. Barry > If anyone wants it, let me know and I'll put the source on my web page and > post the URL here. > > -- Karl > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: bschafer@......... Subject: Roger.Sorensen@................ Date: Wed, 27 May 1998 00:06:11 -0500 (CDT) Hot Spring turns into Geyser Hi, Is there any discoloration in the lakes? I had heard that this hot spring had actually turned into a gizer--with water shooting up about ft20. I have also heard that this is very close to the San Andreas fault. Could someone fill me in on this? Thanks. Bonnie the crafty crafter _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Trudy Harlow Subject: USGS: Map of Western Hemisphere Indicates Location of Potential Date: Wed, 27 May 1998 00:06:03 -0500 (CDT) News Release U.S. Department of the Interior U.S. Geological Survey Office of Outreach Central Region PO Box 25046, MS 150 Denver, CO 80225-0046 ReleaseContact Phone E-mail May 29, 1998Heidi Koehler 303.236.5900 x302 hkoehler@........ Map of Western Hemisphere Indicates Location of Potential Earthquake Damage BOSTON -- A new ground shaking hazard map of the Western Hemisphere will show regions of potential earthquake damage, providing a useful global seismic hazard tool for government, industry and the general public. As a part of the 1998 American Geophysical Union Spring Meeting, Kaye Shedlock, a geophysicist with the U.S. Geological Survey in Golden, Colo., and James Tanner, a geophysicist with the University of Western Ontario, Ottawa, Ontario, will present Preliminary Seismic Hazard Map of the Western Hemisphere (Poster S51B-01), Friday, May 29 at 10 a.m. in Exhibit Hall C of the Hynes Convention Center. "This map represents the first systematic attempt to produce a global seismic hazard map, and is the culmination of nearly a decade of cooperative work by scientists, engineers, and technical personnel from all over the world," said Shedlock, who has been working with colleagues on this effort since 1992. "The public will care about this map because it will ultimately contribute to their personal safety." The final version of the Global Seismic Hazard Map, and all associated documentation, is scheduled to become available via the WWW, on CD-ROMs, and in various publications in late 1998 or early 1999. The U.S. National Map is currently available at http://gldage.cr.usgs.gov/eq/ or through contacting the USGS map sales office at 303/202-4700. Seismic hazard maps are useful to National, state and local governments, decision makers, engineers, planners, emergency response organizations, builders, universities and the general public. They assist planners and engineers in building codes to set a level of design criteria for seismic safety; in some cases, to determine whether or not anything can be built. Additionally, these maps help set insurance rates. Primarily, maps such as this serve as the foundation for public safety and damage mitigation strategies in earthquake-prone regions, and informing the public about whether or not they live in earthquake-prone regions. National or regional agencies can also benefit from this map as a basis for further detailed studies applicable to their needs. Catastrophic earthquakes account for 60 percent of worldwide casualties associated with natural disasters. Economic damage from earthquakes is increasing, even in technologically advanced countries with some level of seismic zonation, as illustrated by the earthquakes hitting Loma Prieta, Calif., in 1989, Northridge, Calif., in 1994 Kobe, Japan in 1995. In addition to the USGS, organizations that contributed to this international effort include: Geological Suvey of Canada, Universidad Nacional Autonoma De Mexico, International Association of Seismology and Physics of the Earth's Interior, International Lithosphere Program, PanAmerican Institute of Geography and History, and the Global Seismic Hazard Assessment Program. As the Nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation, economic and physical development of the Nation's natural resources, and enhance the quality of life by monitoring water, biological, energy and mineral resources. To receive the latest USGS news releases automatically by e-mail, please send a request to listproc@.................... Please specify the listserver(s) of interest from the following list of names: water-pr; geologic-hazards-pr; biological-pr; mapping-pr; products-pr; lecture-pr. In the body of the message say subscribe (name of listserver)(your name). Example: subscribe water-pr joe smith. NOTE TO EDITORS: Interviews during the AGU meeting with Kaye Shedlock can be arranged by contacting Marion Fisher in AGU newsroom 105 at 617-954-3867. ***USGS*** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Microseisms Date: Wed, 27 May 1998 00:42:15 -0500 Friends, I had somehow thought that earthquakes would be a little bit more common than they actually seem to be. This has led me to contemplate the appearance of vertical microseisms, since they apparently constitute about 99.9%, or more, of all that is to be seen. While small earthquakes may be reasonably common, these unwanted but always present microseisms get in the way and set a minimum background noise level in the frequency from about one to four seconds (at the moment, I would judge). There appear to be combinations of various overlapping sine waves, which I believe from my reading elsewhere are due to ocean waves interacting with the continental shelf and various waveguide effects. This causes microseisms to have the appearance of trains of rather irregular and angular waves that slowly shift their shape over ten or more seconds, while fairly being predictable in their shape and frequency over the shorter run. In other words these microseisms appear to be Fourier transform waves generated by the addition of other fairly constant and predictable trains of other lesser sine waves that grow and fade in magnitude. If so, I would imagine that these could could be used to correct the amplitude of a teleseismic by predicting and subtracting the anticipated microseismic component from the total output. Maybe this is commonly done already? What is the spectral analysis of seismic noise going down to very low frequencies? Are there three-dimensional plots of the spectral components of microseisms that look interesting, say with time frequency and amplitude plotted on three axes? --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Hot Spring turns into Geyser Date: Wed, 27 May 1998 01:18:07 -0700 (MST) On Tue, 26 May 1998, Roger Sorensen wrote: > I just talked to my dad who is retired and lives up in these mountains. > He said that the two local lakes (Arrowhead and Grass Valley) are both > running over their spillways. He had heard that they had 70" of moisture > this winter. If I remember correctly, that's a lot more than usual. > There is a spring near his cabin that flows from a 2" pipe. Last year > when I saw it, there was little water coming from it. (maybe a trickle > 1/4" dia.) He said that the pipe in now running 100% capacity. He did > not estimate the pressure. > It sounds to me like it might just be El Nino runoff. Maybe some of our > mentors can fill us in on how ground water levels effect fault > activities (if in fact they do). There has been a correlation in some areas with high water tables and increased seismicity, but it depends on many different factors. The first is that there may be a lot of water, but is the ground permeable enough to allow it to spread out into the surrounding sediment and rock? The number of cracks (fractures) in the rocks increases the overall permeability, and is usually associated with highly strained rock which is present in many areas of faulting. The kind of rock through which the fault cuts, and the conditions of the slip along the fault create different kinds of fault rock. Many times the rock is brecciated (broken into angular fragments) and the size of the peices in the breccia will regulate the permeability of water in the fault itself (larger peices=more permeability). Sometimes the rocks are smooth and display smooth surfaces, which is generally lower permeability. So if the water gets into the fault and saturates the openings in the fault rock it reduces the overall friction on the fault because of the fluid pressure exerted by the water on the rocks surrounding it. The friction (friction is the force that resists slip) in a simple case is proportional to the normal force or normal stress in this case. The normal stress is the force per unit area directed onto the fault plane at a 90 degree (right) angle. This is usually simply expressed as follows: Normal Stress = coefficient of friction * frictional force When fluid pressure becomes a factor, the equation is modified as follows: Normal Stress - fluid pressure = coefficient of friction * frictional force As you can see, this takes away from the normal stress, which takes away from the frictional force. The reason slip will then take place easier is that the "traction" acting across the fault (this is the stress or force that makes the fault slip) remains constant. At any fault, there is a fight between this traction and the frictional force (like a tug of war, except really this would be a "push of war"), and when traction becomes stronger than the reduced friction then it wins, and the fault slips.... I am no mentor, but I hope this helps... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Microseisms Date: Wed, 27 May 1998 01:27:53 -0700 (MST) On Wed, 27 May 1998, Roger Baker wrote: > There appear to be combinations of various overlapping sine waves, which I > believe from my reading elsewhere are due to ocean waves interacting with > the continental shelf and various waveguide effects. This causes > microseisms to have the appearance of trains of rather irregular and > angular waves that slowly shift their shape over ten or more seconds, while > fairly being predictable in their shape and frequency over the shorter run. > In other words these microseisms appear to be Fourier transform waves > generated by the addition of other fairly constant and predictable trains > of other lesser > sine waves that grow and fade in magnitude. If so, I would imagine that > these could could be used to correct the amplitude of a teleseismic by > predicting and subtracting the anticipated microseismic component from the > total output. > Maybe this is commonly done already? What is the spectral analysis of > seismic noise going down to very low frequencies? Are there > three-dimensional plots of the spectral components of microseisms that look > interesting, say with time frequency and amplitude plotted on three axes? Roger, these could definitely be modeled as a fourier series (really anything can according to mathematicians), just the same way earthquakes could. If I am not mistaken, most microseismic noise has waveforms similar to Love and Rayleigh waves, and accordingly, the deeper you go the less noticable the microseismic noise becomes. You can always "chop out" certain frequencies of a fourier series using numerical techniques (Winquake does this for me). But the problem is that you can only do the correcting after the quake, because the background is always irregular and cannot be accurately taken care of beforehand... So if your quake has waveforms of the same frequencies choping out the microseismic noise removes some of the seismic arrivals from your seismogram... such is life... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: And More Geophones! Date: Wed, 27 May 1998 06:15:36 +0000 All, This is for those list-members who live in the Los Angeles County -- 'Valley' area, may be interested to know that 'All Electronics' surplus store in Van Nuys California, USA, are selling the same Geophone kit which Gateway Electronics is selling. I saw them today for $10.00 each. Several 'kits' all contained MD-81, 10 Hz geophones. Walt Williams, 98.05.27 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Sorensen Subject: Re: Geyser / Lake Discoloration Date: Wed, 27 May 1998 07:54:47 -0700 I have not been told of any lake discoloration. The geyser is at the base of Arrowhead Mountain. I believe that the San Andreas fault runs along the base of the mountains at that point. I can't seem to find my fault map, but I think the fault is within a couple of miles. Roger bschafer@......... wrote: > > Hot Spring turns into Geyser > > Hi, Is there any discoloration in the lakes? I had heard that this hot > spring had actually turned into a gizer--with water shooting up about > ft20. I have also heard that this is very close to the San Andreas > fault. Could someone fill me in on this? Thanks. > > Bonnie > the crafty crafter > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: IRIS software seminar and WinQuake classroom exercises. Date: Wed, 27 May 1998 08:44:21 -0700 (PDT) Larry, I don't think you can do much better than to try and replicate the classroom example that the "Virtual Earthquake" web site takes you through. Here's one approach: - divide the room into 3-4 teams. Each team gets a globe and three recordings of the same quake from different widely-spaced locations. They also have a copy of Winquake and a PC. They use the PC and Winquake to calculate the distance from each recording site, draw the circles on the globes (with water-soluble marker) and then do their best to identify the epicentral location. The team which gets closest gets a prize - perhaps a Beany Baby? Or a 500 lb horizontal sensor weight? :-) On Wed, 20 May 1998, Larry Cochrane wrote: > Hi Everyone, > > As some of you may know there will be a software seminar put on by IRIS > (Incorporated Research Institutions for Seismology) in Santa Cruz > California on July 8-12. See > http://www.iris.washington.edu/HTM/other.htm#workshops for more info. I > have been asked to present WinQuake at one of the workshops. Michelle > Hall-Wallace, who is putting on the workshop, has asked me to supply the > following: > > 1.Short description of the software and its features. > 2.User manual. > 3.Example classroom exercises that uses the software. > > I can come up with 1 and 2 with the WinQuake help documents I am working > on, but I'm not sure about 3. I'm not sure what something like this should > look like. Does anyone have an suggestions on this? > > Regards, > Larry Cochrane > Redwood City, PSN > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: water and earthquakes Date: Wed, 27 May 1998 09:56:03 -0600 (MDT) I don't think that there is a clear relationship between rain fall and earthquakes, as there is between rain fall and landslides. My guess is that, in most regions, rain fall fluxuations do not effect the conditions at the depths of several km where earthquakes nucleate. However, there are some counter examples. Deep reservoirs often induce seismicity when they are filled. Clearly, rain fall was required to fill the reservior. Pumping fluids deep into the ground, as was done near Denver, induced earthquake activity. This did require high pressures and man-made drill holes. In a "natural" setting, seasonal variations in the rate of activity within a cluster of earthquakes located about 50-km southeast of Juneau, Alaska, have been attributed to hydrological effects. For more details on this, see: http://www.ees.nmt.edu/~char/html/mt_ogden.html with excerpts from a recent Bulletin of the Seismological Society of America (BSSA) paper. JCLahr ################################## John C. Lahr ################################# Seismologist ################################ U.S. Geological Survey ############################### Geologic Hazards Team, MS966 ############################## PO Box 25046 #############################/############################## ############################/############################### Denver, Colorado 80225-0046 ################################ Phone: (303) 273-8596 ################################## Fax: (303) 273-8600 ################################### lahr@........ ##################################### http://giseis.alaska.edu/lahr http://lahr.org/john-jan _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: Microseisms Date: Wed, 27 May 1998 11:07:14 -0500 John, et al, Actually, what I was trying to say is that the constant background noise I see has a very regular periodic structure of some kind, extending for tens of seconds sometimes, that should allow actual short range prediction rather than just filtering. Its not sine waves, but rather has the look of several predominent sine waves riding on top of each other to give slowly shifting distorted waveforms. I would think spectral analysis would easily tell the underlying frequencies. So you could tell your computer to look at this in terms of the amplitude of the several sine waves which predominate. Anyhow, with a little number crunching it looks to me like that could predict with much better than random accuracy the predicted waves on a seismographic chart five or ten seconds from now, particularly in the one second or longer seismic band. Obviously computer power has gotten cheap fast, at least a lot faster than seismographs have gotten cheap (with the notable exception of this group) so it makes good sense to augment your instrument with a bunch of computer power nowadays. Which is one reason why we're lucky to have guys like Larry C. around. But anyhow, if the microseisms are largely surface waves, then wouldn't a much better way to null out this background noise be to have several seismographs recording along the axes that can best discriminate by the typical vectors of motion, i.e., horizontal versus vertical? So an interesting question I have now is how much useful additional information we could gather if we had a three axis instrument along along with lots of cheap computing power. In other words if we could look at motion at any point in time as a constantly shifting vector with both direction and magnitude components. Would this give us a lot more useful information to analyze compared to having three separate stations wired closely together? One would think that some multiaxis technique along these lines might allow us to subtract out microseismic noise exceptionally well, and that there must be lots of discussion of the value and potential of such number crunching in the teleseismic literature. I also imagine that advanced number crunching techniques to work out three-dimensional subterranean structures have been worked out much better for local geophone-based seismic exploration where a big economic payoff is involved, as opposed to the teleseismic stations where the instrumentation more typically involves a few old and expensive instruments at fixed locations. --Yours, Roger At 01:27 AM 5/27/98 -0700, you wrote: >On Wed, 27 May 1998, Roger Baker wrote: >> There appear to be combinations of various overlapping sine waves, which I >> believe from my reading elsewhere are due to ocean waves interacting with >> the continental shelf and various waveguide effects. This causes >> microseisms to have the appearance of trains of rather irregular and >> angular waves that slowly shift their shape over ten or more seconds, while >> fairly being predictable in their shape and frequency over the shorter run. >> In other words these microseisms appear to be Fourier transform waves >> generated by the addition of other fairly constant and predictable trains >> of other lesser >> sine waves that grow and fade in magnitude. If so, I would imagine that >> these could could be used to correct the amplitude of a teleseismic by >> predicting and subtracting the anticipated microseismic component from the >> total output. >> Maybe this is commonly done already? What is the spectral analysis of >> seismic noise going down to very low frequencies? Are there >> three-dimensional plots of the spectral components of microseisms that look >> interesting, say with time frequency and amplitude plotted on three axes? > > Roger, these could definitely be modeled as a fourier series (really >anything can according to mathematicians), just the same way earthquakes >could. If I am not mistaken, most microseismic noise has waveforms similar to >Love and Rayleigh waves, and accordingly, the deeper you go the less noticable >the microseismic noise becomes. You can always "chop out" certain frequencies >of a fourier series using numerical techniques (Winquake does this for me). >But the problem is that you can only do the correcting after the quake, >because the background is always irregular and cannot be accurately taken care >of beforehand... So if your quake has waveforms of the same frequencies >choping out the microseismic noise removes some of the seismic arrivals from >your seismogram... such is life... > >*************************************************************************** *** > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ > http://www.public.asu.edu/~hernlund/ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Hot Spring turns into Geyser Date: Wed, 27 May 1998 10:49:11 -0700 John Hernlund wrote: > So if the water gets into the fault and saturates the openings in the fault > rock it reduces the overall friction on the fault because of the fluid > pressure exerted by the water on the rocks surrounding it. The friction There was an incident in Denver (1980s I think) where the military was pumping liquid waste of some kind into the ground under pressure. I heard that it was toxic waste from Rocky Flats, but I'm not sure. Anyway the liquid acted like a lubricant of sorts and a lot of small earthquakes happened as a result. Rocky Flats was being cleaned the last time I visited. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- New Lehman Construction Date: Wed, 27 May 1998 11:20:40 +0000 Hello All, Some points and some questions. Regarding my new PSN style, modified Lehman seismometer: Please see: http://www.pacificnet.net/~dfheli/seismo.html Last nine seismometer pictures near bottom of html text. The new base plate is about 10" wide, 35" long, 5/16" Al. I located and tapped five 1/4" x 20 holes for 6" long machine bolts for leveling. I plan to shorten these to 3", each. My boom is ~30" long, 5/16" threaded stock slotted and with razor blade inserted. Scientific American -- 1/2" black gas nipples and union cross member construction. A 12 VAC contactor from a heater/AC unit failure, and ball-pein revealed a nice bobbin coil, which escaped its surrounding with a little application of drill-press! As Meridith says, "Ha". Two steel 5/16" nuts and a 1/8" x 1/8" x 1" long rectangular rare metal magnet epoxied together, is threaded onto end of boom. A drop of 'blue' Loctite on threads of boom fix magnet orientation parallel with base plate. Coil is mounted on AL right angle, is attached to base plate and is aligned with magnet assembly on boom swing axis. All coil support parts are non-magnetic -- Al, and plastic. Any problem with attaching magnet end to steel nuts threaded on boom? Boom support are two lengths/segments of high 'G' guitar string bound in middle by small turn-buckle, top end string segment is attached to eye-loop on top cross-member of black gas nipple support structure. The bottom string segment is attached through a drilled 'wing' of a wing-nut which is threaded onto the boom and is located 'above' 5 Lb fishing weight which is Tyewrapped to boom. Boom is forced balanced through edge of vertical razor blade captive in small vertical groove ground on surface of pipe union. Changing wing-nut position on the boom, by threading/unthreading affects the period of the instrument. Is this adjustment useful in some manner? Aside from leveling the Lehman, are there any other mechanical adjustments of which I should be aware? I purchased software to make electronic PCB artwork but the programs are very buggy and I am stuck. I would buy Larry Cochrane's great three channel amplifier/filter assembly, but I really need the ability to make my own PCBs for several instruments I am building. Anybody have any suggestions? I really do not need the features of a $500+ PCB artwork CAD program. Any comments or hints will be appreciated. Walt Williams, 98.05.25 dfheli@.............. http://www.pacificnet.net/~dfheli _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: water and earthquakes Date: Wed, 27 May 1998 13:01:17 -0600 (MDT) Charlotte Rowe, one of the authors of the BSSA paper, send me this message based on her research into the subject. JCLahr > From: Charlotte Rowe > Date: Wed, 27 May 1998 10:01:44 -0600 > To: lahr@.................. > Subject: Re: water and earthquakes > > > FYI there has been a high correlation between seismicity and seasonal rainfall > observed in an area of Turkey (poster on the subject at the Dec 97 AGU), and > larger "climatalogical" changes in the American South (S.C. for one) have shown > high correlation in terms of long-term water table fluctuation and seismicity > levels. Additionally there was a very convincing study done in Albania that > showed strong seasonal seismic cyclicity in the high rainfall regions, AFTER > potentially reservoir-induced events had been eliminated from the catalog. > Although mainstream seismologists consider the whole thing to be pretty "fringe' > if not outright crackpot, alot of evidence has recently begun to point to > rainfall triggering if the conditions are right. > > c _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: water and earthquakes Date: Wed, 27 May 1998 12:26:47 -0700 Here is a web site with a biblio for induced earthquake activity: http://www.nyx.net/~dcypser/induceq/induceq.bib.html -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: PSN- New Lehman Construction Date: Wed, 27 May 1998 13:49:17 -0600 Walt Williams wrote: > Hello All, > > Some points and some questions. > > Regarding my new PSN style, modified Lehman seismometer: > > Please see: > http://www.pacificnet.net/~dfheli/seismo.html > > Last nine seismometer pictures near bottom of html text. > Wow! neat pictures. Congratulations on the web page and wish you much success with the seismometers and computer combo. Real nice to see someone elses instruments. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Microseisms Date: Wed, 27 May 1998 17:08:38 -0700 Roger & John I agree with Roger. I still believe( I think John and I had this conversation before) the background can be removed from the event. Especially with knowing the background just before and after the event. One could reduce the amplitude of each frequency component due to the background noise. The only problem which I haven't resolved is , at a particular frequency, the possible phase shift from the signal to background component. I am currently sucessfully running a trigger routine which runs a overlaping FFT window continously. It keeps track of the spectral amplitudes of the background noise. When an event exceeds an predetermined spectral treshhold, based on the difference to the background FFT it triggers an event. Basically the program looks for changes in frequency and amplitude from a continuously adjusted background signal. The beauty in the program is one can block or reduce certain known frequencies if desired and they would not be looked at or viewed with the same importance ( like trains etc.) in the trigger routine. The routine was based on an earlier paper by Goforth & Herrin in BSSA 8/91. With Larry's continuous recording program, the trigger aspect may not be important to others but the frequency content from before to during an event is very instructive to me as to how a wave train passes. I wrote a primitive DOS based program which runs thru an event and plots frequency content with time . It is interesting to see the P then S then surface waves as the event passes ones station. Barry Roger Baker wrote: > > John, et al, > Actually, what I was trying to say is that the constant > background noise I see has a very regular periodic structure of some kind, > extending for tens of seconds sometimes, that should allow actual short > range prediction rather than just filtering. Its not sine waves, but rather > has the look of several predominent sine waves riding on top of each other > to give slowly shifting distorted waveforms. > > I would think spectral analysis would easily tell the underlying > frequencies. So you could tell your computer to look at this in terms of > the amplitude of the several sine waves which predominate. Anyhow, with a > little number crunching it looks to me like that could predict with much > better than random accuracy the predicted waves on a seismographic chart > five or ten seconds from now, particularly in the one second or longer > seismic band. > > Obviously computer power has gotten cheap fast, at least a lot faster than > seismographs have gotten cheap (with the notable exception of this group) > so it makes good sense to augment your instrument with a bunch of computer > power nowadays. Which is one reason why we're lucky to have guys like Larry > C. around. > > But anyhow, if the microseisms are largely surface waves, then wouldn't a > much better way to null out this background noise be to have several > seismographs recording along the axes that can best discriminate by the > typical vectors of motion, i.e., horizontal versus vertical? > > So an interesting question I have now is how much useful additional > information we could gather if we had a three axis instrument along along > with lots of cheap computing power. In other words if we could look at > motion at any point in time as a constantly shifting vector with both > direction and magnitude components. Would this give us a lot more useful > information to analyze compared to having three separate stations wired > closely together? > > One would think that some multiaxis technique along these lines might allow > us to subtract out microseismic noise exceptionally well, and that there > must be lots of discussion of the value and potential of such number > crunching in the teleseismic literature. > > I also imagine that advanced number crunching techniques to work out > three-dimensional subterranean structures have been worked out much better > for local geophone-based seismic exploration where a big economic payoff is > involved, as opposed to the teleseismic stations where the instrumentation > more typically involves a few old and expensive instruments at fixed > locations. > > --Yours, Roger > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Lehman Construction Date: Wed, 27 May 1998 20:20:51 -0500 A couple of comments. Resent list postings about finding a chunk of Al for the base plate got me to questioning the need for a nonmagnetic material for the baseplate. Since the Lehman usually has a great big magnet attached to the boom, magnetic susceptiability problems are going to center around this magnet rather than the baseplate. For the most part intereactions between the baseplate and the magnet are going to constant. Seems to me a big chunk of steel would be less expensive, more rigid and have a lower tempco than Al. Rearanging things and putting the coil on the boom seems to me to be the best way to reduce magnetic effects. One could then have a completely nonmagnetic boom assy. I was trying to repair my garden tiller this evening and the though struck me that a small engine magneto coil might make an excellent Lehman coil. Lots of turns. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Warner Lindholm Subject: Re: PSN- New Lehman Construction Date: Wed, 27 May 1998 18:27:21 -0700 (PDT) On Wed, 27 May 1998, Walt Williams wrote: [ ... ] > > I purchased software to make electronic PCB artwork but the programs > are very buggy and I am stuck. I would buy Larry Cochrane's great > three channel amplifier/filter assembly, but I really need the > ability to make my own PCBs for several instruments I am building. > Anybody have any suggestions? I really do not need the features of a > $500+ PCB artwork CAD program. > > Any comments or hints will be appreciated. > There's always Protel's freeware Eztrax which I think can be found on Simtelnet. Runs on DOS and is serviceable but is limited to single layer boards. If you're running linux you can use 'pcb' which can do up to eight layers. It's free of course. --Warner Puget Sound Country _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: And More Geophones! Date: Wed, 27 May 1998 22:44:36 EDT TO: ALL LIST MEMBERS Has anyone actually hooked up their geophone kits from Gateways Electronics to detect actual earthquakes? If so I, as well as others I am sure, would like to hear of your experience. Will a 10 Hz geophone really detect earthquakes and if so what types and what special amp/filter would be required? Jim Allen Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: And More Geophones! Date: Thu, 28 May 1998 17:23:31 +1200 >Has anyone actually hooked up their geophone kits from Gateways Electronics to >detect actual earthquakes? If so I, as well as others I am sure, would like >to hear of your experience. Will a 10 Hz geophone really detect earthquakes >and if so what types and what special amp/filter would be required? >Jim Allen >Cerritos, Calif. > Jim a 10 Hz phone will record local / regional events very easily !! i have even experimented with 20 Hz phones and they will easily detect a M6 at 800 km (500miles) so go and play Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shammon1@............. Subject: Re: PSN- New Lehman Construction Date: Thu, 28 May 1998 06:33:19 -0700 Hi Walt-- It looks like you are well on your way already. You asked a couple of questions. These are my thoughts. Regards, Steve Hammond PSN San Jose Walt Williams wrote: >=20 > attaching magnet end to steel nuts threaded on boom? I assume you mean the magnet on the boom for the coil. No I don't think the nuts will be a problem. Be aware that if there is rebar in the cement floor, which I suspect there is, the boom magnet might be attracted to it. I remember one of the guys telling a story about the boom going to the stop overnight... It took several night to figure out that it was the steel in the floor.=20 Boom is forced balanced > through edge of vertical razor blade captive in small vertical > groove ground on surface of pipe union. Keep an eye on the location of the blade, it can work itself down over long periods of time because of gravity. >=20 > Changing wing-nut position on the boom, by threading/unthreading > affects the period of the instrument. Is this adjustment useful in > some manner? Aside from leveling the Lehman, are there any other > mechanical adjustments of which I should be aware?=20 Yep-- Let's just talk about the objective first. Remember your about to have some fun so take your time, because it never works right the first time you try this. Now Look at your seismograph from the side so the pipe upright and boom form an "L". You want to end up with the boom level, the pipe upright vertical, and the upper wire's pivot point on the upper eye bolt within a nat=92s backside of being almost exactly over the sharp edge of that razor blade. So it's time to play. Don't fling the thing across the room... But first, tell me where is the wire bending on the upper G string? I'm looking at your photo. I see you have wound the wire back around the string at the eye bolt. I'm assuming the pivot point is now 1/2-inch down the wire from the eye bolt. This could make the adjustment more difficult. Just so you understand, Let's think about the original 1950's design that had a gas burner jet with a wire going through it. The reason they did this was to form a fixed upper pivot point. This is the point at which the wire comes into contact with the jet. If you can't get the period to come in, then you might want to look at this area. But for now, let's go on and see if the way you have it setup will work. Terminology-- =20 There are two critical timings. The un-dampened period and the dampened period. Un-dampened period - a measurement made without damping magnets in place. Dampened period - a measurement made with damping magnets in place.=20 Period-- A measurement made of the time it takes for the boom to swing through center to the far extreme point, return back through center to the near extreme point, and swing back to center again. This is general done by pulling the boom back and releasing it from the left or right stop. The center point is the point at which the boom naturally comes to rest. Comment-- You might want to add some stops on that base to contain the boom swing. You only need a couple of free inches of travel on each side of center. The stops help keep it from damaging itself if it get slammed, which it will in an earthquake or if it get kicked. =20 So lets start out with a period that is easy to setup, an un-dampened period of 10 seconds. Pull the damping magnets off and use a plum-bob to align the upper pivot point so that it has a 1/4-inch of tilt to the damping magnets side. Once that is done, take a few turns on the upper eyebolt, level the boom and check the un-dampened period. As you get closer and closer to the vertical center line of the upper and lower pivots, the period will lengthen. When you get to an un-dampened period of 10 seconds, look the device over and see if you can find the exact vertical point. Once you think you got it, I suggest you go past center so the eye bolt is to the rear of center. Now swing the boom and notice how it is reacting. It will almost work but you have trouble keeping the boom centered to the base plate. Notice that it is not nearly as sensitive as it was in front of center. I had you do this because this is where you "don=92t" want to setup your device. Learn to recognize when you are past center. It's important because it's easy to accidentally tweak something and end up past center.=20 Set the device back to an un-dampened period of 10 seconds with the boom level and the pipe uprights vertical. Center the boom so it is in the middle of the base plate. Check the period by pulling the boom back an inch and releasing it on it's own power. Check it from both left and right side. Now take another turn on the upper eye blot. Use the turn buckle on the wire to level the boom. The period should be getting longer and longer each time you repeat these steps. Remember that the upper eye bolt should always tilt slightly to the damping magnets side regardless of how long the period gets. Once you get a natural un-dampened period of 18 - 20 seconds, you can reinstall the damping magnets.=20 Setting the dampened period. =20 The goal hers is to pull the boom back about an inch and release it. The damping should reduce the swing 80% on each swing. The boom should come to rest in 3 1/2 swings. You achieve this adjustment by moving the damping magnets in and out. You have some huge magnets. I'm concerned that they are too powerful... See if you can adjust it to stop in 3 1/2 swings. The dampened period is then taken after the damping is set to coming to rest after 3 1/2 swings. The timed period can be as high as 30 or 40 seconds depending on the adjustment of the magnets and the strength of the magnets. Once you get this setup, you'r ready to record an earthquake. One other observations. It's not uncommon for the unit to require adjustment several time within the first few months. The wires lengthen and the pipe will bend... =20 Regards-- Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Microseisms Date: Thu, 28 May 1998 00:10:04 -0700 (MST) On Wed, 27 May 1998, barry lotz wrote: > Roger & John > I agree with Roger. I still believe( I think John and I had this > conversation before) the background can be removed from the event. > Especially with knowing the background just before and after the event. > One could reduce the amplitude of each frequency component due to the > background noise. The only problem which I haven't resolved is , at a > particular frequency, the possible phase shift from the signal to > background component. I am currently sucessfully running a trigger > routine which runs a overlaping FFT window continously. It keeps track > of the spectral amplitudes of the background noise. When an event > exceeds Sounds like a neat program. I misunderstood the original question and thought it to mean predicting background noise before it arrives. I commonly use the background spectrum after an event to see which frequencies need to be chopped from the seismogram. Because I am in Arizona, with few local quakes, most of the time the background noise is at a higher frequency than any event that I receive (a few exceptions with quakes in Northern AZ). ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Cristiano Subject: Re: pc boards Date: Thu, 28 May 1998 06:54:34 -0700 Warner Lindholm wrote: > > On Wed, 27 May 1998, Walt Williams wrote: > > [ ... ] > > > > > I purchased software to make electronic PCB artwork but the programs > > are very buggy and I am stuck. I would buy Larry Cochrane's great > > three channel amplifier/filter assembly, but I really need the > > ability to make my own PCBs for several instruments I am building. > > Anybody have any suggestions? I really do not need the features of a > > $500+ PCB artwork CAD program. > > > > Any comments or hints will be appreciated. > > > > There's always Protel's freeware Eztrax which I think can be found on > Simtelnet. Runs on DOS and is serviceable but is limited to single layer > boards. If you're running linux you can use 'pcb' which can do up to eight > layers. It's free of course. > > --Warner > Puget Sound Country > Hi all, I use Easytrax here at work and really like it. It DOES do multi-layer pcb's, prints and Gerber plot files for thru-hole boards. If you want surface mount then use Autotrax from the same company. Fabing the circuit board is the hard part. If you can design the circuit as a thru-hole, single-sided layout then you can make your own pcb's in the kitchen. Get some Press-n-Peel transfer film from Techniks, Inc. (chelsea.ios.com/~techniks). Use a laser printer to print your circuit side layout onto the Press-n-Peel then iron on the image to the copper side of the single copper sided board material. Getting a good transfer is essential. Get some copper etchant (Radio Shack or Mouser) and etch the board in a glass pan. Use some Acetone to dissolve the resist after etching. Use a 25mil pad center hole for a drilling guide. Jim cristiano@........... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: ascii data to psn? Date: Thu, 28 May 1998 08:19:44 -0700 Barry, John, Peter -- My ftp server is down and I have been unable to upload the source code I promised to my web site. The support people assure me it will be up sometime today. Anyway, once the server is up, I will upload the source code to http://www.jps.net/karlc/lv2wq.zip Sorry for the delay. Look for it tonight or tomorrow, crossing one's fingers. The zip file contains two source-code files and a readme that briefly describes them. Please email me if anyone has any questions. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Lehman Fun & JPL Date: Thu, 28 May 1998 08:24:25 +0000 All, First, thanks to: Jim Hannon, (things are still hovering around) Meredith Lamb, Warner Lindholm, Roger Sorensen, and Steve Hammond, for comments, encouragement, solutions and adjustment information. Second, for those who are in the Los Angeles area of California, USA, the Jet Propulsion Laboratory in Pasadena California is hosting a Lab 'Open House' this Saturday, Sunday and the public are invited. Many interesting booths, gadgets, displays and very nice people. I highly recommend this adventure to science folk. Walt, 98.05.28 dfheli@...................... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- HST Image Date: Thu, 28 May 1998 08:34:22 +0000 All, Off topic, but interesting NASA announcement: http://www.flatoday.com/space/today/e98035.htm Walt, 98.05.28 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: PSN- New Lehman Construction Date: Thu, 28 May 1998 08:42:55 -0700 (PDT) We all struggled to make our home-built Lehman's work reliably, which was a big part of the fun, so don't get discouraged even if it takes a few adjustments over some weeks to get things to settle down. Remember, the miracle is that it works so well! Just a couple of additions to Steve's comments. Since I did not have a gas burner nozzle, I simply drilled a hole in the black pipe cross-piece, pushed the suspension wire throught the hole and wound it around a cotter pin. This worked reliably for years. Be careful to make the hole exactly the size of the wire diameter. You want to avoid any "clicking" as the boom moves back and forth. Also, try to avoid putting the turnbuckle in the middle of the suspension wire. It has a lot of mass compared to the wire and will oscillate for a long time, giving a small sinusoidal wave. Put the turnbuckle a few inches from the upright support. In my original Lehman I used a steel boom (3/8" rod) ground flat at one end where your razor blade is, and threaded at the other end. I found that the damping magnets attracted the steel boom, so I ended up putting an 8" dowel as an extension on the end of the boom, and mounting the copper damping plate on the end of the dowel. This would not be necessary if you used an aluminum boom. No matter whether you mount the magnet or the coil on the boom, the slightest off-center mounting will put an enourmous amount of torque on that razor blade suspension. You will need to provide some sort of adjustment to offset the torque. A small weight on a threaded rod mounted across the boom would probably work, just screw the weight in or out to balance the weight of the magnet or coil. Finally, I never could get the knife-edge adjusted properly when it touched the base all across its edge. I finally ground away the middle part of the knife edge so it consisted of two tiny knife edges, one at the top and one at the bottom of the boom. Now it was easy to adjust the turnbuckle until I felt both knife edges grip equally (by twisting the boom with my fingers). Once I had that adjustement made, all further balancing adjustements were made with the screws in the base and I never touched the turnbuckle again, unless the wire stretched a bit. This is the disadvantage of the knife-edge support design, not mentioned in the article. Best regards, Ted _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Pakistan Date: Thu, 28 May 1998 09:37:27 -0700 Anyone see the Pakistan tests? NEIC has this 10:16:15 28.96N 64.73E but I don't know how correct that is. Supposedly there were 5 tests to match India's. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: pc boards Date: Thu, 28 May 1998 09:50:19 -0700 In my web/Usenet wanderings I found this company for prototype circuit boards: http://www.cl.ais.net/farcir/ FAR CIRCUITS 18N640 Field Court Dundee, Illinois 60118 847) 836-9148 Voice/Fax email: farcir@....... In part they say: "Note: Do NOT order via email; see order info" "All boards are made of G-10, FR-4 material, 1 oz. copper, solder coated, and drilled. Double sided boards DO NOT have plated through holes. Custom boards may be made for $.50 square inch or $4.00 minimum per board for single sided, etched, drilled and solder coated. Custom double sided non-plated through holes, etched, drilled and solder coated boards may be made for $.75 per square inch or $6.00 minimum per board. A clear film negative is required for custom boards. Film from camera ready artwork is $8.00 per shot based on 8" x 10" film per shot. Quantity pricing available. Far Circuits reserves the right to change the pricing based on the complexity of the board." This is an extremely good price for one off boards for the experimenter. A more standard price is about $250 to $300 minimum for maybe 10 - 15 4in^2 boards. Although I haven't used them yet, you will see by the site and the things I've read that they have been around for awhile (I found out about them Oct/97). The important thing to note is they don't plate thru-holes. This is easily circumvented by placing vias in the open and use full component size pads rather than via hole sized pads so you can place wire thru them and solder both sides to complete front-to-back via connections. Takes a little extra time, but is quite satisfactory for prototype boards. The other technique is to plan ahead and use component leads for the vias and just solder top and bottom. The problem with that technique is you often want to change components in the prototype stage, and having soldered top and bottom makes that more of a problem. Neater, but more hassle. To make up for the silkscreening I just print off the silkscreen layer on paper or transparentcy on a printer at 1:1, cut it out, and glue it to the circuit board, and install the components through it. Quite neat looking actually. I've used the Eztrax software for a two layer board with silk screen (a third layer) and it works just fine. If anybody is interested you can email me directly and I'll send you my collection of about 30+ Usenet postings over the years on PCB layout, etching and software for do-it-yourself techniques that I thought were particulary interesting. A lot of anecdotal experience in this area! Charles R. Patton charles.r.patton@.......................... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: A clearer picture of seisms? Date: Thu, 28 May 1998 14:02:56 -0500 Friends, I am now looking at the world through my vertical and trying to get my bearings by tweaking the response in different ways. From what I currently understand the typical seismic situation is somewhat as follows. High Frequency urban noise is pretty unpredictable and often sufficient to mask all else if not filtered out. Once that is filtered out, there is sort of another layer of somewhat lower frequency regional noise typified by microseisms. The latter, being largely the result of the predictable and periodic interaction of ocean waves with the earth, tends to generate pretty regular patterns, potentially allowing short term prediction in this frequency band if it were considered to be very important to do this, which is usually not the case. But if we filter the microseisms out, with a still lower pass filter, we see things get much less predictable in the slow typically teleseismic region of seconds per wave, going all the way down to DC response where you see earth tides, which get very predictable again. It is in the seconds per wave region that we look for the teleseisms, and to what degree we filter out the microseisms, which can often mask teleseisms (although micros are typically higher frequency), is somewhat a matter of taste. I assume this picture is generally accurate? *************************************************************************** To tie up a couple of loose ends, it is possible to detect down to as little as one thousandth Angstrom static displacement with a laser and optical lever and position sensitive detector, and this arrangement is often used for atomic force microscopes. But a more practical detection limit is .03 Angstrom, or three thousandths of a nanometer, and this is not too hard to homebrew, if such sensitivity is really needed for seismometry. In other words you can, or could if you want to, merely rest the tip of an atomic force microscope's little reflective cantilever on your seismo beam and take the seismic data with the scanning circuit turned off. Otherwise, there are various other optical arrangements, like the optical lever, also limited by shot noise and diffraction, which factors limit the optical lever as well in its theoretical resolution. In fact, it turns out that the Michelson interferometer and the 'optical beam deflection method' have the same physics when you analyze them deeply, and thus have the same displacement detection sensitivity of about .001 Angstrom (Journal of Applied Physics, vol 72, July 1992, page 6+). By far the best review article/comparison I found in the literature on various modes of measuring static displacement is in 'Sensors and Actuators', series A, Vol 48, page 87-100 (1995). Such general comparisons of the most sensitive microdisplacement sensors are unexpectedly hard to find. Incidently, electron tunneling could also be used for .001 Angstrom displacement sensitivity except that the tunneling tip tends to get covered with organic junk absorbed from the air, and thus drifts a lot, plus it is only linear over a very small distance. It is true this review cited above does not discuss the very simple LED beam occultation configuration I am using, but that does not mean that that the physics of my configuration are not limited by shot noise and diffraction too. The most revealing article with relevance to my displacement sensing configuration that I have found is in the 'Instrument Society of America' or ISA Transactions, vol 19, #4, 1980, page 73+. This latter sensor arrangement was able to detect 25 nanometers of displacement by just moving a mirror toward or away from a simple off the shelf LED optoelectronic reflection transducer. But this was using an unmodified off the shelf part from 20 years ago. I think that my optimised arrangement with its much brighter LED beam probably does a lot better because of its correspondingly lower shot noise, allowing more amplification of the photransistor signal before you hit the shot noise background level. (my optics is also in an isothermal enclosure which helps slow drift, which could cause different problems). --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Moderate event in N. California Date: Thu, 28 May 1998 14:42:51 -0700 Hi Everyone, Well the seismicity here in N. Cal just picked up. We had a 4.5Md event about 100km south of me. Heres the info from the Berkeley finger system: 98/05/28 20:31:32 36.81N 121.55W 8.4 4.5Md A* 5 km S of San Juan Bautista, CA The event saturated my S-G sensor. My Lehman's boom was hitting one of the stops, do to the ran we are having and me not adjusting it in a few days, so it was offline at the time of the event. My strong motion FBA-23 sensor (*.LC5 and *.lc7 files) did pick up the event, but only a few counts above the noise level. My ADX05 sensor continued to pick up noise only.... -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: EASTERN MEDITERRANEAN SEA EVENT Date: Thu, 28 May 1998 23:52:09 +0200 18.33 utc MB 5.5 Loc.: EGYPT =20 I.E.S.N. PsnItaly
18.33  utc
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I.E.S.N. PsnItaly
From: Ted Blank Subject: Virtual Earthquake Assessment Date: Thu, 28 May 1998 17:21:21 -0700 (PDT) If any of you have used the Virtual Earthquake, Gary Novak is inviting you to complete a survey on the effectiveness of the site as a teaching tool. Please see the URL below: --- begin included note --- Dear Colleague, ;Virtual Earthquake has been on-line for nearly two years. Support from the National Science Foundation to develop and maintain VEQ and other Geology Labs On-line activities depends upon dissemination and project assessment. ;Please help us find out how you are using VEQ. We have engaged CUDA, the Center for Usability in Design and Assessment, of Cal State University Long Beach to conduct this survey in our behalf. Take a couple of minutes and use your Web browser to link to the on-line survey page. You can complete the survey in a very short time. Your input will make a difference! I only have the email address of people who have contacted me during the past year or so. Please pass this URL on to other instructors at your institution who might be using VEQ. The survey is located at http://130.157.14.140:591/edp_surveys/ Thank you very much for using VEQ and for your time. Gary Novak Department of Geology Cal State LA gnovak@.............. --- end included note --- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Richard Walker" Subject: DI-150RS Date: Tue, 26 May 98 01:21:25 PDT Hello everybody, This is the first time that I've contributed anything to the forum, = but I would like to say that I have throughly enjoyed the discussions, = comments, and information I've been privy to over the last several months= .. Thank you all! I have built a Golitsyn-type seismometer and am now in the process = of choosing an economical and effective method of A/D conversion and rec= ording. Has anyone had any experience using Dataq Instruments' DI-150RS, = and furthermore, can this converter be operated in an MS/DOS environment?= Any, and all, comments would be highly appreciated. Sincerely, Dick Walker Erie, PA rwalker@........ > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the = > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "D. POPE" Subject: Re: {EarthWaves} Re: Hot Spring turns into Geyser Date: Thu, 28 May 1998 19:26:25 -0700 Yup, just what I've been saying; God delaying EQs with His rain. You explained it very well in nature. Thanks. Diane John Hernlund wrote: > > EarthWaves ---- A Forum for the Discussion of Earth Changes > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > ^^^^ To POST a message, send to earthwaves@........... ^^^^ > > On Tue, 26 May 1998, Roger Sorensen wrote: > > I just talked to my dad who is retired and lives up in these mountains. > > He said that the two local lakes (Arrowhead and Grass Valley) are both > > running over their spillways. He had heard that they had 70" of moisture > > this winter. If I remember correctly, that's a lot more than usual. > > There is a spring near his cabin that flows from a 2" pipe. Last year > > when I saw it, there was little water coming from it. (maybe a trickle > > 1/4" dia.) He said that the pipe in now running 100% capacity. He did > > not estimate the pressure. > > It sounds to me like it might just be El Nino runoff. Maybe some of our > > mentors can fill us in on how ground water levels effect fault > > activities (if in fact they do). > > There has been a correlation in some areas with high water tables and > increased seismicity, but it depends on many different factors. The first is > that there may be a lot of water, but is the ground permeable enough to allow > it to spread out into the surrounding sediment and rock? The number of cracks > (fractures) in the rocks increases the overall permeability, and is usually > associated with highly strained rock which is present in many areas of > faulting. The kind of rock through which the fault cuts, and the conditions > of the slip along the fault create different kinds of fault rock. Many times > the rock is brecciated (broken into angular fragments) and the size of the > peices in the breccia will regulate the permeability of water in the fault > itself (larger peices=more permeability). Sometimes the rocks are smooth and > display smooth surfaces, which is generally lower permeability. > > So if the water gets into the fault and saturates the openings in the fault > rock it reduces the overall friction on the fault because of the fluid > pressure exerted by the water on the rocks surrounding it. The friction > (friction is the force that resists slip) in a simple case is proportional to > the normal force or normal stress in this case. The normal stress is the > force per unit area directed onto the fault plane at a 90 degree (right) > angle. This is usually simply expressed as follows: > > Normal Stress = coefficient of friction * frictional force > > When fluid pressure becomes a factor, the equation is modified as follows: > > Normal Stress - fluid pressure = coefficient of friction * frictional force > > As you can see, this takes away from the normal stress, which takes away > from the frictional force. The reason slip will then take place easier is > that the "traction" acting across the fault (this is the stress or force that > makes the fault slip) remains constant. At any fault, there is a fight > between this traction and the frictional force (like a tug of war, except > really this would be a "push of war"), and when traction becomes stronger than > the reduced friction then it wins, and the fault slips.... > > I am no mentor, but I hope this helps... > > ****************************************************************************** > > John Hernlund > E-mail: hernlund@....... > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karen Renee Wood Subject: Alaskan Glaciers Yield Massive Floods Date: Thu, 28 May 1998 23:28:09 -0500 (CDT) News Release U.S. Department of the Interior U.S. Geological Survey Office of the Eastern Regional Geologist 953 National Center Reston, VA 20192 Release: Upon Receipt (May 27, 1998) Contact: Diane Noserale 703-648-4333 dnoseral@........ Glaciers, Outbursts, and the Environment... Alaskan Glaciers Yield Massive Floods Note to Editors: Interviews with Dr. Molnia on Fri., May 29 can be arranged by contacting Marion Fisher in the AGU Newsroom, Convention Center Room 105; phone 617-954-3867. Video footage of Bering Glacier, including the 1994 flood locations and the eastern 1994 flood in progress is available from William R. Reckert, 202-646-2763. Torrents of meltwater are unleashed suddenly from the margins of the great moving sheets of snow and ice, known as glaciers. In Alaska, these pulses of activity, called "outburst floods," are usually caused by the failure of ice dams that restrain the meltwater of glacial margin lakes. Although the effects of outburst floods are mostly local, they are stunning. Bruce F. Molnia, a USGS scientist who has studied the glaciers of Alaska for 30 years, will describe two recent outburst floods during a special session at the American Geophysical Union meeting in Boston, MA, that will gather experts from around the world to discuss the effects of these events on regional environments in Alaska and other sites. "One of my field parties was working about two kilometers away from the origin of the eastern 1994 flood. Suddenly, they heard very loud noises and the ground began to violently shake. Unable to see that a flood had begun, the field party thought they were experiencing a large magnitude earthquake. The ground shaking continued for many minutes and the noises for many hours. Only when they were able to climb to the top of a nearby hill, did they realize that they had experienced the onset of a major flood. We continued to monitor this flood for more than a year, and its history was just as dramatic as its origin," said Molnia. Molnia's presentation will focus on southern Alaska's Bering Glacier, the largest temperate glacier in the world. In 1994, two outburst floods significantly impacted local plant and animal life, and modified adjacent land surfaces. One flood lowered the surface level of Berg Lake by more than 100 meters in only 72 hours, when an estimated 5.5 billion cubic meters of water escaped and drained through the Bering River, inundating the river valley. "The Berg Lake flood occurred in May, a time of moose calving and significant nesting of Dusky Canada Geese, Trumpeter Swans, and many other species of birds," said Molnia. "Thousands of nests were destroyed and many mammals were drowned. If this flood event happened in the fall during hunting season, we may have had human casualties as well," Molnia said. The second flood, about 45 kilometers east of the first, started in late July and cut a kilometer-long gorge in the glacier within the first few days. It produced peak discharges exceeding one thousand cubic meters per second. These floods are not unique to Bering Glacier or confined to uninhabited wilderness. The city of Yakutat is near the flood-hazard zone of Russell Lake, at the margin of Hubbard Glacier. Significant outburst flooding has occurred several times this century at other Alaskan sites and, most recently, at Vatnajokull in Iceland when a subglacial volcano erupted, producing huge quantities of meltwater. The session, titled "Catastrophic Outburst Floods" starts at 1:30 on Friday, May 29 in Convention Center Room 311. As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the conservation and the sound economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources. ### USGS ### This press release and in-depth information about USGS programs may be found on the USGS home page: http://www.usgs.gov. To receive the latest USGS news releases automatically by email, send a request to . Specify the listserver(s) of interest from the following names: water-pr; geologic-hazards-pr; biological-pr; mapping-pr; products-pr; lecture-pr. In the body of the message write: subscribe (name of listserver) (your name). Example: subscribe water-pr joe smith. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: And More Geophones! Date: Thu, 28 May 1998 20:41:14 -0700 Hi I hooked the two leads up to an instrument amp(differential input). No power to leads. The two wires out seem like a coil output. I got pretty good background noise which were comparable to my Lehman in amplitude except the frequency range of the background noise ranged from about 1-8 hz with the geophone. I think, as others have said before, that it would work fine for events to maybe 300km. I uploaded the lehman and geophone background noise to psn events a few days ago. Barry RADIOTEL@....... wrote: > > TO: ALL LIST MEMBERS > > Has anyone actually hooked up their geophone kits from Gateways Electronics to > detect actual earthquakes? If so I, as well as others I am sure, would like > to hear of your experience. Will a 10 Hz geophone really detect earthquakes > and if so what types and what special amp/filter would be required? > Jim Allen > Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Microseisms Date: Thu, 28 May 1998 20:48:11 -0700 John I could send you the source code(Quickbasic 4.5) but it's uncommented and set up for a JDR computer board. It would be better to try to describe it in text first. It has some problems with wind gusts since they are longer sporatic movements in the frequency range of an event. I am still working on the program recognizing them. Barry John Hernlund wrote: > > On Wed, 27 May 1998, barry lotz wrote: > > Roger & John > > I agree with Roger. I still believe( I think John and I had this > > conversation before) the background can be removed from the event. > > Especially with knowing the background just before and after the event. > > One could reduce the amplitude of each frequency component due to the > > background noise. The only problem which I haven't resolved is , at a > > particular frequency, the possible phase shift from the signal to > > background component. I am currently sucessfully running a trigger > > routine which runs a overlaping FFT window continously. It keeps track > > of the spectral amplitudes of the background noise. When an event > > exceeds > > Sounds like a neat program. I misunderstood the original question and > thought it to mean predicting background noise before it arrives. I commonly > use the background spectrum after an event to see which frequencies need to be > chopped from the seismogram. Because I am in Arizona, with few local quakes, > most of the time the background noise is at a higher frequency than any event > that I receive (a few exceptions with quakes in Northern AZ). > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: And More Geophones! Date: Thu, 28 May 1998 22:14:12 -0700 (PDT) Hello Barry: I tested the geophone using a digital spectrum analyzer and its response peaked at 8.8 Hz! Frank Condon "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" >Hi > I hooked the two leads up to an instrument amp(differential input). >No power to leads. The two wires out seem like a coil output. I got >pretty good background noise which were comparable to my Lehman in >amplitude except the frequency range of the background noise ranged from >about 1-8 hz with the geophone. I think, as others have said before, >that it would work fine for events to maybe 300km. I uploaded the lehman >and geophone background noise to psn events a few days ago. > Barry > > >RADIOTEL@....... wrote: >> >> TO: ALL LIST MEMBERS >> >> Has anyone actually hooked up their geophone kits from Gateways Electronics to >> detect actual earthquakes? If so I, as well as others I am sure, would like >> to hear of your experience. Will a 10 Hz geophone really detect earthquakes >> and if so what types and what special amp/filter would be required? >> Jim Allen >> Cerritos, Calif. > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: DI-150RS Date: Fri, 29 May 1998 06:34:00 -0700 (PDT) Dick, If the Dataq converter is a card for the PC I can probably add support for it to the EMON package which supports 14 different A/D cards, but not any from Dataq. EMON runs under DOS. Send me a note offline and we can discuss. Ted Blank San Jose, California On Tue, 26 May 1998, Richard Walker wrote: > > Hello everybody, > > This is the first time that I've contributed anything to the forum, but I would like to say that I have throughly enjoye d the discussions, comments, and information I've been privy to over the last several months. Thank you all! > > I have built a Golitsyn-type seismometer and am now in the process of choosing an economical and effective method of A/ D conversion and recording. Has anyone had any experience using Dataq Instruments' DI-150RS, and furthermore, can this converte r be operated in an MS/DOS environment? Any, and all, comments would be highly appreciated. > > Sincerely, > > Dick Walker > Erie, PA > rwalker@........ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email listserver@............. with the body of the > > message: leave PSN-L > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: DI-150RS Date: Fri, 29 May 1998 06:49:46 At 06:34 AM 5/29/98 -0700, you wrote: >Dick, >If the Dataq converter is a card for the PC I can probably add support >for it to the EMON package which supports 14 different A/D cards, but not >any from Dataq. EMON runs under DOS. Send me a note offline and we can >discuss. > Ted It is a RS232 device... We do need some support for this kind of a/d converter so we can get notebooks into this stuff.... Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Plyler Subject: Pakistan Tests Date: Fri, 29 May 1998 10:08:12 +0000 Hello All, I successfully detected and recorded the Pakistan nuclear tests early thursday morning. There are three distinct pulses, however Pakistan states that five explosions were conducted. The distance from the receive site to the test site is 11987.34 calculated kilometers or 107.822 degrees. The azimuth to the site is 151.0 degrees. These recordings were made with equipment designed to detect electromagnetic transients and pulses traveling through the earth rather than the atmosphere. If anyone should desire a copy of these photos in .gif format get in touch by private email and I would be glad to send them along with further details. Charlie Plyler ELFRAD GROUP _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: Pakistan Tests Date: Fri, 29 May 1998 07:31:15 -0700 Nice catch, Charlie! Other seismic netowrks recorded only two events as well. -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "d.sevold" Subject: Re: And More Geophones! Date: Fri, 01 May 1998 09:01:30 At 10:44 PM 5/27/98 EDT, you wrote: >TO: ALL LIST MEMBERS > >Has anyone actually hooked up their geophone kits from Gateways Electronics to >detect actual earthquakes? If so I, as well as others I am sure, would like >to hear of your experience. Will a 10 Hz geophone really detect earthquakes >and if so what types and what special amp/filter would be required? >Jim Allen >Cerritos, Calif. > I have a 10 hz exploration geophone installed in a 2kg lead ring inside a stainless steel 35mm film developing tank, sealed with butyl rubber tape. The amplification is a simple caz max420 amplifier with a gain of about 1000. This feeds into a cio-das08/jr board,with a 386sx running eamon. The geophone has a 4k resistor across the coil. Sensitivity is 20V/(m/s).I am told that this geophone was designed to work with an input impedance of 10k or more, so I'm using a 10M/10K resistor pair on the amp.I have not detected any local events, perhaps a more sophisticated amplifier with a higher gain would be necessary. At this time I have a lehman under construction. The coil was wound from a couple of auto ignition spark coils, #40 magnet wire, about .003" dia., 12.6K internal resistance,perhaps 12000 turns. What would be the optimal coil for this application, does anyone have any ideas? Dean Sevold _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: And More Geophones! Date: Fri, 29 May 1998 12:43:12 EDT Hello All, At 10:44 PM 5/27/98 EDT, you wrote: >TO: ALL LIST MEMBERS > >Has anyone actually hooked up their geophone kits from Gateways Electronics to >detect actual earthquakes? If so I, as well as others I am sure, would like >to hear of your experience. Will a 10 Hz geophone really detect earthquakes >and if so what types and what special amp/filter would be required? >Jim Allen >Cerritos, Calif. > >I have a 10 hz exploration geophone installed in a 2kg lead ring inside a >stainless steel 35mm film developing tank, sealed with butyl rubber tape. >The amplification is a simple caz max420 amplifier with a gain of about >1000. This feeds into a cio-das08/jr board,with a 386sx running eamon. The >geophone has a 4k resistor across the coil. Sensitivity is 20V/(m/s).I am >told that this geophone was designed to work with an input impedance of 10k >or more, so I'm using a 10M/10K resistor pair on the amp.I have not >detected any local events, perhaps a more sophisticated amplifier with a >higher gain would be necessary. >Dean Sevold I have worked with these geophones for many years. I believe all that lead is a mistake as you are making an audio mismatch between the earth and your geophone. You want the geophone to have nearly the same mass as the earth around it. George Erich _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: Re: DI-150RS Date: Fri, 29 May 1998 09:41:32 -0700 Richard Walker wrote: > > Hello everybody, > > This is the first time that I've contributed anything to the forum, but I would like to say that I have throughly enjoye d the discussions, comments, and information I've been privy to over the last several months. Thank you all! > > I have built a Golitsyn-type seismometer and am now in the process of choosing an economical and effective method of A/ D conversion and recording. Has anyone had any experience using Dataq Instruments' DI-150RS, and furthermore, can this converte r be operated in an MS/DOS environment? Any, and all, comments would be highly appreciated. > > Sincerely, > > Dick Walker > Erie, PA > rwalker@........ > I,m using a DI-150RS on my system! It has several options for different conversions but I haven't figured them out yet. It will handle signals to +/- 10 volts. It is a seperate little module that plugs into a serial port. If I had known about Larrys board I probably would have bought his so that I could be compatable with PSN! On the other hand, if they add it to their software ????????? Don't even bother to run the software that comes in the box -- download it from the Dataq site!! I ran it on win3.1 before my upgrade and now run it on win95!!! Your welcome to email me directly if you like,, I'll be gone for a couple of days but will be back next week. In the mean time if you would like to see a trace from my system, I send them to Robert Shannon and he posts them on his site under GIF-NOW!! http://www.televar.com/~earth/alert.html The gif there is a screen capture of the latest event that I send him, in this case it should be the San Juan Bautista event. They have been having floods where Shannon is so hopefully they aren't down!!! OOPs, I just checked and he has an older gif on there, his alert page says it is on there so with the floods maybe something went ?????? Anyway keep checking back he might get it updated eventually!! Stephen Pilot Hill Ca. USA lat /lon 38.828N /120.978 PSN Station # 55 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: JHammes@......................... Subject: Re[2]: And More Geophones! Date: Fri, 29 May 1998 10:05:07 -0700 George wrote.... I have worked with these geophones for many years. I believe all that lead is a mistake as you are making an audio mismatch between the earth and your geophone. You want the geophone to have nearly the same mass as the earth around it. I assume you mean same density; if so does that make it preferable to bury it in the ground with a minimum of added material? Will a thin plastic cover membrane work? Jerry Hammes Palo Alto _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Fwd[2]: New Lehman Construction Date: Fri, 29 May 1998 11:38:59 +0000 Steve, Thank you. Regarding the magnets, they are too big. Everything in the lab is attracted to those magnets.....I wanted to use them for something. Maybe Roger Baker would have an idea? There are several items which need attention which you identified for me. I pushed the boom and watched where the string bends, surprise, 1/2" down from the eye-loop! Ted Blank has made a suggestion to use a cotter pin attachment arrangement, which I think I also noted in one of the PSN archive texts. The eye-loop is not aligned over the 'interface' edge of the razor blade and pipe union surface, nor is it currently adjustable. Walt, 98.05.29 dfheli@.............. ================================================= ------- Forwarded Message Follows ------- From: shammon1@............. Date: Thu, 28 May 1998 06:33:19 -0700 To: PSN-L Mailing List Subject: Re: PSN- New Lehman Construction Reply-to: PSN-L Mailing List Hi Walt-- It looks like you are well on your way already. You asked a couple of questions. These are my thoughts. Regards, Steve Hammond PSN San Jose Walt Williams wrote: > > attaching magnet end to steel nuts threaded on boom? I assume you mean the magnet on the boom for the coil. No I don't think the nuts will be a problem. Be aware that if there is rebar in the cement floor, which I suspect there is, the boom magnet might be attracted to it. I remember one of the guys telling a story about the boom going to the stop overnight... It took several night to figure out that it was the steel in the floor. > Boom is forced balanced > through edge of vertical razor blade captive in small vertical > groove ground on surface of pipe union. Keep an eye on the location of the blade, it can work itself down over long periods of time because of gravity. > > Changing wing-nut position on the boom, by threading/unthreading > affects the period of the instrument. Is this adjustment useful in > some manner? Aside from leveling the Lehman, are there any other > mechanical adjustments of which I should be aware? Yep-- Let's just talk about the objective first. Remember your about to have some fun so take your time, because it never works right the first time you try this. Now Look at your seismograph from the side so the pipe upright and boom form an "L". You want to end up with the boom level, the pipe upright vertical, and the upper wire's pivot point on the upper eye bolt within a nat's backside of being almost exactly over the sharp edge of that razor blade. So it's time to play. Don't fling the thing across the room... But first, tell me where is the wire bending on the upper G string? I'm looking at your photo. I see you have wound the wire back around the string at the eye bolt. I'm assuming the pivot point is now 1/2-inch down the wire from the eye bolt. This could make the adjustment more difficult. Just so you understand, Let's think about the original 1950's design that had a gas burner jet with a wire going through it. The reason they did this was to form a fixed upper pivot point. This is the point at which the wire comes into contact with the jet. If you can't get the period to come in, then you might want to look at this area. But for now, let's go on and see if the way you have it setup will work. Terminology-- There are two critical timings. The un-dampened period and the dampened period. Un-dampened period - a measurement made without damping magnets in place. Dampened period - a measurement made with damping magnets in place. Period-- A measurement made of the time it takes for the boom to swing through center to the far extreme point, return back through center to the near extreme point, and swing back to center again. This is general done by pulling the boom back and releasing it from the left or right stop. The center point is the point at which the boom naturally comes to rest. Comment-- You might want to add some stops on that base to contain the boom swing. You only need a couple of free inches of travel on each side of center. The stops help keep it from damaging itself if it get slammed, which it will in an earthquake or if it get kicked. So lets start out with a period that is easy to setup, an un-dampened period of 10 seconds. Pull the damping magnets off and use a plum-bob to align the upper pivot point so that it has a 1/4-inch of tilt to the damping magnets side. Once that is done, take a few turns on the upper eyebolt, level the boom and check the un-dampened period. As you get closer and closer to the vertical center line of the upper and lower pivots, the period will lengthen. When you get to an un-dampened period of 10 seconds, look the device over and see if you can find the exact vertical point. Once you think you got it, I suggest you go past center so the eye bolt is to the rear of center. Now swing the boom and notice how it is reacting. It will almost work but you have trouble keeping the boom centered to the base plate. Notice that it is not nearly as sensitive as it was in front of center. I had you do this because this is where you "don't" want to setup your device. Learn to recognize when you are past center. It's important because it's easy to accidentally tweak something and end up past center. Set the device back to an un-dampened period of 10 seconds with the boom level and the pipe uprights vertical. Center the boom so it is in the middle of the base plate. Check the period by pulling the boom back an inch and releasing it on it's own power. Check it from both left and right side. Now take another turn on the upper eye blot. Use the turn buckle on the wire to level the boom. The period should be getting longer and longer each time you repeat these steps. Remember that the upper eye bolt should always tilt slightly to the damping magnets side regardless of how long the period gets. Once you get a natural un-dampened period of 18 - 20 seconds, you can reinstall the damping magnets. Setting the dampened period. The goal hers is to pull the boom back about an inch and release it. The damping should reduce the swing 80% on each swing. The boom should come to rest in 3 1/2 swings. You achieve this adjustment by moving the damping magnets in and out. You have some huge magnets. I'm concerned that they are too powerful... See if you can adjust it to stop in 3 1/2 swings. The dampened period is then taken after the damping is set to coming to rest after 3 1/2 swings. The timed period can be as high as 30 or 40 seconds depending on the adjustment of the magnets and the strength of the magnets. Once you get this setup, you'r ready to record an earthquake. One other observations. It's not uncommon for the unit to require adjustment several time within the first few months. The wires lengthen and the pipe will bend... Regards-- Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Fwd[3]: New Lehman Construction Date: Fri, 29 May 1998 11:43:47 +0000 Ted, This project has been interesting, challenging and just plain fun. The turnbuckle is very nearly directly in the middle of the string segments. It does oscillate for (seems to me) a prolonged time. I will move it as you say. As for the upper string to nipple attachment, I have to do some work there as well. I also plan to use the wood dowel method when I resolve the other issues. As you have identified, my 'magnet-on-the-boom' is causing rotational torque on the razor/edge. An adjustable counter-balance eh? Thank you for the suggestions and encouragement. Walt, 98.05.29 dfheli@.............. ====================================== ------- Forwarded Message Follows ------- Date: Thu, 28 May 1998 08:42:55 -0700 (PDT) From: Ted Blank Subject: Re: PSN- New Lehman Construction To: PSN-L Mailing List Reply-to: PSN-L Mailing List We all struggled to make our home-built Lehman's work reliably, which was a big part of the fun, so don't get discouraged even if it takes a few adjustments over some weeks to get things to settle down. Remember, the miracle is that it works so well! Just a couple of additions to Steve's comments. Since I did not have a gas burner nozzle, I simply drilled a hole in the black pipe cross-piece, pushed the suspension wire throught the hole and wound it around a cotter pin. This worked reliably for years. Be careful to make the hole exactly the size of the wire diameter. You want to avoid any "clicking" as the boom moves back and forth. Also, try to avoid putting the turnbuckle in the middle of the suspension wire. It has a lot of mass compared to the wire and will oscillate for a long time, giving a small sinusoidal wave. Put the turnbuckle a few inches from the upright support. In my original Lehman I used a steel boom (3/8" rod) ground flat at one end where your razor blade is, and threaded at the other end. I found that the damping magnets attracted the steel boom, so I ended up putting an 8" dowel as an extension on the end of the boom, and mounting the copper damping plate on the end of the dowel. This would not be necessary if you used an aluminum boom. No matter whether you mount the magnet or the coil on the boom, the slightest off-center mounting will put an enourmous amount of torque on that razor blade suspension. You will need to provide some sort of adjustment to offset the torque. A small weight on a threaded rod mounted across the boom would probably work, just screw the weight in or out to balance the weight of the magnet or coil. Finally, I never could get the knife-edge adjusted properly when it touched the base all across its edge. I finally ground away the middle part of the knife edge so it consisted of two tiny knife edges, one at the top and one at the bottom of the boom. Now it was easy to adjust the turnbuckle until I felt both knife edges grip equally (by twisting the boom with my fingers). Once I had that adjustement made, all further balancing adjustements were made with the screws in the base and I never touched the turnbuckle again, unless the wire stretched a bit. This is the disadvantage of the knife-edge support design, not mentioned in the article. Best regards, Ted _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- New Lehman Constr'n & PCB Date: Fri, 29 May 1998 11:47:22 +0000 Warner, Thanks. Walt, 98.05.29 ============================= ------- Forwarded Message Follows ------- Date: Wed, 27 May 1998 18:27:21 -0700 (PDT) From: Warner Lindholm To: PSN-L Mailing List Subject: Re: PSN- New Lehman Construction Reply-to: PSN-L Mailing List On Wed, 27 May 1998, Walt Williams wrote: [ ... ] > > I purchased software to make electronic PCB artwork but the programs > are very buggy and I am stuck. I would buy Larry Cochrane's great > three channel amplifier/filter assembly, but I really need the > ability to make my own PCBs for several instruments I am building. > Anybody have any suggestions? I really do not need the features of a > $500+ PCB artwork CAD program. > > Any comments or hints will be appreciated. > There's always Protel's freeware Eztrax which I think can be found on Simtelnet. Runs on DOS and is serviceable but is limited to single layer boards. If you're running linux you can use 'pcb' which can do up to eight layers. It's free of course. --Warner Puget Sound Country _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Microseisms Date: Fri, 29 May 1998 12:38:48 -0700 (MST) Barry, It would be interesting to see the source. If you want you cam mail it to me directly... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Pakistan Tests Date: Fri, 29 May 1998 12:41:33 -0700 (MST) On Fri, 29 May 1998, Charlie Plyler wrote: > I successfully detected and recorded the Pakistan nuclear tests > early thursday morning. There are three distinct pulses, however > Pakistan states that five explosions were conducted. > The distance from the receive site to the test site is 11987.34 > calculated kilometers or 107.822 degrees. The azimuth to the > site is 151.0 degrees. > These recordings were made with equipment designed to detect > electromagnetic transients and pulses traveling through the > earth rather than the atmosphere. > If anyone should desire a copy of these photos in .gif format > get in touch by private email and I would be glad to send them > along with further details. > Charlie Plyler Charlie, send me a copy at hernlund@....... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: And More Geophones! Date: Fri, 29 May 1998 17:11:08 -0700 Hi Frank I think it's a useful sensor for reasonably close events (5-10hz). My problem now is I have more sensor permutations than computers. Though my A/D cards will take 16 channels, the software doesn't take more than 3 each. EMON uses 3 and my other board takes only one now. If I had a VGA monitor I would run Larry SDR, but is it also 3 max? What I need to do now is modify my software to monitor 16 channels but only record those triggered. More future projects. Barry Frank Condon wrote: > > Hello Barry: > I tested the geophone using a digital spectrum analyzer and its response > peaked at 8.8 Hz! > > Frank Condon > "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Pakistan event Date: Fri, 29 May 1998 20:22:52 -0500 (CDT) Answering some queries: In case you want to scan your records for the event, NEIS lists it on 98/05/29: origin time: 10:16:15 28.96N 64.73E 0.0km (deep) Mb 4.8. Allow for travel time to your station (14 to 18 minutes stateside). We did not see anything here at St. Louis U. on the high gain monitor records. The noise levels were low, but we wouldn't expect to see such a small event at that distance. Dispersion would make it a relatively long period (3 to 5 seconds) arrival. regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: VRDT Drive Circuit Date: Fri, 29 May 1998 22:43:14 -0500 I have put the almost complete schematic of my design for a VRDT drive circuit at http://soli.inav.net/~jmhannon/driver.html It has a couple of unique features. It only uses three IC's and has very low power consumption, crystal controlled frequency and a stable drive level. The drive signal for the demodulator is a ttl level signal. The phase of the demodulator drive can be adjusted to compensate for phase shifts in other parts of the circuit. Over the next few months I hope to turn this start into a complete description of my 3 axis seismograph design. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: And More Geophones! Date: Fri, 29 May 1998 21:55:31 -0700 At 05:11 PM 5/29/98 -0700, barry lotz wrote: >Hi Frank >EMON uses 3 and my other board takes only one now. If I had a VGA >monitor I would run Larry SDR, but is it also 3 max? What I need to do >now is modify my software to monitor 16 channels but only record those >triggered. More future projects. SDR will record up to 6 channels at 5, 10, 25, 50 or 100 samples per seconds. Currently all channels need to be sampled at the same sample rate. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Procedures in Experimental Physics Date: Fri, 29 May 1998 22:01:11 -0700 Back on April 27, 1997 Roger Baker mentioned a couple of classic instrument construction books. One he mentioned was "Procedures in Experimental Physics" by John Strong. You may remember that C.L Strong ran the Scientific American "Amateur Scientist" column for many years and put out at least one book titled "The Amateur Scientist". I don't know if there is a connection or not, but the wonderful ink line drawings for both were done by Roger Hayward. So I decided to get a copy and put out a request for a book search per the store in Santa Clara mentioned in an earlier PSN post (which I cannot find at the moment since I did it from work -- boy keeping the bookmark files synchronized between home and work is a b****! Anybody have some good software that can keep Netscape bookmark files synchronized? Anyway back to the book...) I did find a copy and ordered it. When I got it, I find that it had been reprinted by Lindsay Publications Inc. Their URL is: http://www.lindsaybks.com/ Not only do they have this book for $24.95 in paperback, all 642 pages of it, they also have many wondrous books that I think would be of interest to this crowd. Many classic machining books, Sterling engine construction books, esoteric science books -- Embalming for Fun and Profit! -- go to the site and enjoy. Charles R. Patton, Editor, Geo-Monitor patton@......... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Pakistan Tests Date: Fri, 29 May 1998 23:56:44 -0600 Charlie- WOW! That is a pretty impulsive spike on the waveform, 980528z.ahe, that you posted. I would like to have some .GIF files and PSN-format files of the other events and some more information about how you recorded them. -Edward Charlie Plyler wrote: > Hello All, > > I successfully detected and recorded the Pakistan nuclear tests > early thursday morning. There are three distinct pulses, however > Pakistan states that five explosions were conducted. > > The distance from the receive site to the test site is 11987.34 > calculated kilometers or 107.822 degrees. The azimuth to the > site is 151.0 degrees. > > These recordings were made with equipment designed to detect > electromagnetic transients and pulses traveling through the > earth rather than the atmosphere. > > If anyone should desire a copy of these photos in .gif format > get in touch by private email and I would be glad to send them > along with further details. > > Charlie Plyler > ELFRAD GROUP > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: Procedures in Experimental Physics Date: Sat, 30 May 1998 01:28:43 -0500 At 10:01 PM 5/29/98 -0700, you wrote: >Back on April 27, 1997 Roger Baker mentioned a couple of classic >instrument construction books. One he mentioned was "Procedures in >Experimental Physics" by John Strong. You may remember that C.L Strong >ran the Scientific American "Amateur Scientist" column for many years >and put out at least one book titled "The Amateur Scientist". Charles, et al, Actually Strong and Stong were two different guys. John Strong wrote this fantastic book on homebrew physics in the 1930's. Roger Hayward, who was not only a scientific illustrator but a very good amateur scientist too, and organized amateurs to make tank prisms during WWII, and continued to work illustrating the Amateur scientist column in Scientific American with C.L. Stong, until he got cataracts. Notice that Stong's name is an uncommon surname. C.L. 'Red' Stong was the patron saint of amateur science for many years; a good example for all amateur scientists to follow. He answered all his mail from all the Scientific American readers, and was always wonderfully encouraging to myself and everyone else who wrote or submitted projects. He was an interesting fellow who sometimes wrote nearly a hundred letters in one day, he announced in one he wrote to me one time. His letters were typically covered with typing mistakes and whiteout but full of good advice. He was also an airplane barnstormer in the 1930's, who ended up working for Western Bell, then retired and who duplicated most of the science projects in his basement on Staten island to make sure they would work, and was loved and missed by all the staff at Scientific American. --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: East of Kamchatka Date: Sat, 30 May 1998 02:24:56 -0600 Meredith- It looks really good! particularly after integration (and it integrates very nicely, without need of high-pass filtering: how did you do that?)! Give me a couple of days, and I hope to put it into one of our three-component format files and check it out. -Edward meredith lamb wrote: > > Better this time. Thanks Edward and Larry for corrections. > Easy to tell the quake direction on this one with e-w component. > Figured out more on program. With time.... > > --------------------------------------------------------------- > > Name: 980527a.le1 > Part 1.2 Type: unspecified type (application/octet-stream) > Encoding: base64 > > Name: 980527a.ln1 > Part 1.3 Type: unspecified type (application/octet-stream) > Encoding: base64 > > Name: 980527a.lz1 > Part 1.4 Type: unspecified type (application/octet-stream) > Encoding: base64 -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Pakistan Date: Sat, 30 May 1998 09:11:17 -0400 Hi gang, There is something fishy about the bomb tests, esp. the Indian ones:The= only seismic data I have seen in the papers was a single seismic event fo= r the first Indian test and none for the 2nd day. There was supposed to be= three tests on the 1st day and 2 on the 2nd day. The published suppositi= on was that the 3 bombs on the 1st day were detonated simultaneously and hen= ce gave only 1 seismic record. These three (per Science mag.) "involved a thermonuclear warhead, a large fission bomb and a low-yield device". The= thermonuclear was 43 k tons. Paul Richards of Lamont (who knows a very great deal about seismic detection of tests) gave an estimate of the lowest yield which should hav= e been detectable at the Pakistan station. This was a very small yield (I have forgotten the actual number). How come no seismic event for the 2nd day? Are the Indians lying? or we= re both duds? = I haven't seen enough discussion of the Pakistan tests to decide if the= y are also messing with the truth. Bob Barns = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: PSN- New Lehman Construction Date: Sat, 30 May 1998 09:11:12 -0400 Hi gang, About razor blades for the pivot on a Lehman boom: I tried this and hat= ed it. A long (say 1") line contact makes alignment very difficult and a razor blade is too flimsy for this use. = I have used for several years (with complete satisfaction) a steel dis= k about 1 1/4" dia. and 1/16" thick clamped in a slot in the end of the boo= m so that the plane of the disk is parallel to the boom and the disk is approx. vertical. The edge of the disk is rounded and simply presses against a brass bar (steel would be OK) which is bolted to the 1/2" pipe= vertical supports (supports for the top end of the suspension wire). Thi= s gives a lot of latitude for boom rotation so that accurate balancing of weights at the end of the boom is not necessary. It is easy to move the disk around on the bar so that the boom is rough= ly parallel to the base in both the vertical and horizontal planes. As far = as I can tell, the contact point of the disk and the bar is perfectly stable= , at least until a 'quake sufficient to knock the house down comes along. If the contact between the disk was too broad, I think that flat region= s of the Lehman output would be apparent in records of lowest noise. I see= no such flats so I think that just rounding the edge of the disk makes a sharp enough pivot. I think that a steel ball (e.g., a bearing ball) of almost any diameter= (say 1/8" to 1/2") would be just as good. Bob Barns = = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: PSN- New Lehman Construction Date: Sat, 30 May 1998 08:52:16 -0500 Some more notes on Lehman pivots. I used a broken carbide printed circuit board drill which I ground to a rounded point. This rests in a samll hardened steel cup made from a piece of 1/4" oil hardening drill rod. The difficulty I have seen with this single point pivot is that the mass tends to want to rotate or oscilate about the axis of the boom. An edge or two points would eliminate this problem. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: ICL8038 Date: Sat, 30 May 1998 07:36:19 -0700 For those who are not familiar with it, Harris/Intersil makes a neat Precision waveform generator ICL8038 which produces square,sign and sawtooth waves from an impresive 0.001hz-300khz. It uses a little power, around 4-5ma @ 5vts. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Afghan M6.9 quake Date: Sat, 30 May 1998 08:49:27 -0700 An earthquake registering a preliminary magnitude of Ms 6.9 (NEIC), Mw = 6.5 (Caltech), occurred at 06:22 UTC, May 30, in northeastern = Afghanistan. The focal depth was fixed at 33 km deep for quick = processing and the Moment magnitude is from the Caltech Automatic = Processor and has not been reviewed by humans as of yet. The quake was = centered about 45 miles west Feyzbad in a remote mountainous region near = Rostaq. Preliminary reports are sketchy and reveal more than 124 people = have been killed and 1,000=B9s of homes destroyed. Most of the damage = appears to have occurred in Chiab in northern Takhar province near the = Taijkistan border. The quake occurred in roughly the same area as a M6.1 = earthquake in February that killed over 2,500 people and destroyed = nearly 10,000 homes. -- = ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: PSN- New Lehman Construction Date: Sat, 30 May 1998 16:51:15 -0700 I use this same idea and had the same rotate about the boom which prompted the crossbow design. http://pw2.netcom.com/~shammon1/equip.htm presents a picture of it on the bench. The Y shape upper wire eliminated the unwanted rotation. I bought a 100 test high current test points that are an 1/8" x 2" and drilled a mounting hole in the end of the boom. I just put in a new one when needed (2 times a year). I used the same idea that Ted did by just drilling a small hole in the upper cross pipe to feed the upper wire through. I wrap the end of the wire around a wood block. The vertical alignment is coarsely set with the three anchor bolts used to bolt the base plate to the block set in concert. The fine adjustment is made on the =93cup screw=94 which is treaded through the lo= wer cross bare bolted to the pipe uprights. The 10-32 machine screw allows for the period adjustment to be made easily without disturbing the other components at all. I should pint out one other feature. I=92ve seen a lot of comments about leveling screws. Think about this solution. There are three machine lags set in the mounting block out in the seismic shed. I bolt the base plate to blot using 9/16 nuts and large flat washers. Once I level the base plate I never change these bolts again. I make all the leveling adjustments by tweaking or bending the base plate with two 10-32 allen headed machine screws threaded right through the base in the corner. The photo on the web sight is not the great but, if you look at the base plate you can see one of the screws sticking up through the plate in the front right corner to the right of the closest pipe upright. I place a small AL block between the screw tip and the cement to for a small pad. A 1/2 turn on the base machine screws results in 2 inches of boom centering. A 1/16 inch turn on the machine screw at the rear of the boom equals about a second of period change.=20 These are my thoughts. Regards,=20 Steve Hammond PSN San Jose =20 Jim Hannon wrote: >=20 > Some more notes on Lehman pivots. I used a broken carbide printed > circuit board drill which I ground to a rounded point. This rests in a > samll hardened steel cup made from a piece of 1/4" oil hardening drill > rod. The difficulty I have seen with this single point pivot is that > the mass tends to want to rotate or oscilate about the axis of the boom. > An edge or two points would eliminate this problem. > -- > Jim Hannon > http://soli.inav.net/~jmhannon/ > 42,11.90N 91,39.26W > WB0TXL >=20 > _____________________________________________________________________ >=20 > Public Seismic Network Mailing List (PSN-L) >=20 > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Laser instrument interface Date: Sat, 30 May 1998 13:25:53 -0700 I was looking as someone's web site with a picture of an laser instrument and I was thinking about how the computer would get the data. I thought a CCD from an old video camera might work, but I got something even better. A nice high resolution CCD from a flatbed scanner. I know someone that has broken scanner in the garage right now if anyone is interested in it. It's a 300 dpi optical UMAX flatbed SCSI. I have very little idea how the computer interface would work. You might have better luck with a modified fully functional scanner and a custom computer driver. I also don't know if a low power laser would burn out the CCD. Just a thought, Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: PSN- New Lehman Construction Date: Sat, 30 May 1998 17:57:29 EDT Steve Hammond Jim Hannon Other List Participants Steve and Jim, I understand are using a pointed pivot arrangement on their Lehmans. I am presently building one with a simular arrangement using a hardened pointed drill bit that was previously used for printed circuit board fabrication. You both indicated that you had experienced boom rotation with this arrangement. However, Steve indicated that the problem had been solved by using a Y suspension arrangement. I attempted to view the Y arrangement on Steve's web page but my eyes are not as good as they use to be and I could not make it out in the photograph. PLease explain the details such as 1). What type suspension wire are you using? 2) how wide apart are the two end wires as they enter the small holes in the top frame and how many inches from the top frame do the two top end wire join the one wire going to the boom? Are there other ways to solve this problem and still use the pointed pivot arrangment? Is this the reason I see pictures of some Lehmans with a solid rod joined by wire on each end? I have been looking for oil burner nozzles like the one in Scientific American. However, all I have been able to find thus far are ones with 1/16 inch diameter holes which are much larger than G string guitar strings. Do you think it would be suitable to use two of these nozzels in Steve's "Y" configuration or must I continue the search for smaller hole oil burnner nozzles? Any help appreciated. Jim Allen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Pakistan Nuke Test on the 28th Date: Sat, 30 May 1998 19:03:28 -0700 Hi Everyone, I download a seed volume from the DMC (dmc.iris.washington.edu) system containing seismograms from the Pakistan nuke test on the 28th. The closest station in the volume is in Tibet, China about 2500km from the event. I created a PSN formatted event file that is now on my system. The file name is 980528A.LSAZ. It can be accessed using the New Event or Archive links on the Redwood City PSN Web site (http://psn.quake.net). I also created a GIF image of the event file that can be viewed at http://psn.quake.net/nuketest.gif. As you can see from the event file, there is very little amplitude information recorded from the "small" event at 2500km. The seed volume contains event files from many stations, but only the ones under 3000km had anything in them other than background noise. Luckily the DMC system had a SEED volume that could be used by WinQuake and downloaded using a 28k modem. The India event had a SEED volume over 150 megabytes! The SEED volume for this event was a little over 2 megs. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Tom Frey" Subject: 05/31/98 01:58:40 Event(??) Date: Sat, 30 May 1998 19:24:35 -0700 'lo received an event at 01:58:40.1 in Tacoma, but it appears very strange.. also received it on two monitored Univ Washington sites 45 miles apart and average of 50 miles from me it saturated my system but it was very short duration..orientation doesn't allow for even good line of bearing anyone else getting anything? tom _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Pakistan Date: Sat, 30 May 1998 20:37:06 -0700 (MST) On Sat, 30 May 1998, robert barns wrote: > Hi gang, > There is something fishy about the bomb tests, esp. the Indian ones:The > How come no seismic event for the 2nd day? Are the Indians lying? or were > both duds? > I haven't seen enough discussion of the Pakistan tests to decide if they > are also messing with the truth. Of course the success rate of the nuclear tests will be top secret! No government will let us know that they know the Pakistanis only had a 3/5 success rate! ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Icebergs from Earthquakes Date: Sat, 30 May 1998 21:24:58 -0700 (PDT) Hello all: What comments can you all contribute to the theory that glacial thaws are related to earthquakes and not global warming. See the story at the listed link: http://cnn.com/EARTH/9805/22/icebergs/index.html Thanks, Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Pakistan Date: Sat, 30 May 1998 23:19:46 -0600 Robert- I agree with your suspicions about the Indian & Pakistan tests. A decade ago, I was a little involved for awhile in some of the research on using seismic methods to detect small nuclear explosions in order to assure compliance with a comprehensive test ban treaty (CTBT). In the last few days, I was thinking that all that research assumed that the bomb detonator would try to conceal the test, not flaunt it. So it is a very interesting technical and policy question that is addressed to the monitoring agencies; they must reconcile the issue of The Emperor's New Bomb. If they say they did not detect it, then they must admit in public that they may be unable to perform the mission for which they were funded. So maybe it is easier to say they recorded everything regardless of what the records say; this is what the US did with the USSR with respect to overestimating yield and continues on occasion with the Russians, i.e., the Nova Zemlya earthquake last year. The monitoring agencies are not accustomed to having their work exposed to public scrutiny because, in addition to CIA or KGB obsessions with secrecy, etc., there are only a relative few members of the public who have independent sources of seismic data and/or the knowledge to interpret those data. Hence, the PSN. Robert, good topic! I was thinking about posting something after the Indian event, but I never got a chance to find the relevant data and work them up -- then I got distracted. So I am grateful for Arie Verveers seismograms, Charlie Plyler's electromagnetic records (which I don't understand yet), your comments, and the contributions of the many other PSN people I have overlooked as usual (and to whom I apologize): I never imagined in 1990 when I was concerned with strong ground motions produced by earthquakes in San Francisco and nuclear bomb detection in the Soviet Union -- and running back and forth between those two places -- that it would all be combined in some way in the PSN. Thank you. -Edward robert barns wrote: > Hi gang, > There is something fishy about the bomb tests, esp. the Indian ones:The > only seismic data I have seen in the papers was a single seismic event for > the first Indian test and none for the 2nd day. There was supposed to be > three tests on the 1st day and 2 on the 2nd day. The published supposition > was that the 3 bombs on the 1st day were detonated simultaneously and hence > gave only 1 seismic record. These three (per Science mag.) "involved a > thermonuclear warhead, a large fission bomb and a low-yield device". The > thermonuclear was 43 k tons. > Paul Richards of Lamont (who knows a very great deal about seismic > detection of tests) gave an estimate of the lowest yield which should have > been detectable at the Pakistan station. This was a very small yield (I > have forgotten the actual number). > How come no seismic event for the 2nd day? Are the Indians lying? or were > both duds? > I haven't seen enough discussion of the Pakistan tests to decide if they > are also messing with the truth. > Bob Barns > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Pakistan Nuke Test on the 28th Date: Sat, 30 May 1998 23:35:58 -0600 Larry- Thank you for getting us that Pakistan data from the IRIS DMC. -Edward Larry Cochrane wrote: > Hi Everyone, > > I download a seed volume from the DMC (dmc.iris.washington.edu) system > containing seismograms from the Pakistan nuke test on the 28th. The closest > station in the volume is in Tibet, China about 2500km from the event. I > created a PSN formatted event file that is now on my system. The file name > is 980528A.LSAZ. It can be accessed using the New Event or Archive links on > the Redwood City PSN Web site (http://psn.quake.net). I also created a GIF > image of the event file that can be viewed at > http://psn.quake.net/nuketest.gif. > > As you can see from the event file, there is very little amplitude > information recorded from the "small" event at 2500km. The seed volume > contains event files from many stations, but only the ones under 3000km had > anything in them other than background noise. > > Luckily the DMC system had a SEED volume that could be used by WinQuake and > downloaded using a 28k modem. The India event had a SEED volume over 150 > megabytes! The SEED volume for this event was a little over 2 megs. > > -Larry Cochrane > Redwood City, PSN > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: Pakistan Date: Sat, 30 May 1998 23:01:33 -0700 (PDT) Hello Edward: Where can I view the ELF data recorded by Charlie Plyler? Thanks, Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" >Robert- > I agree with your suspicions about the Indian & Pakistan tests. A decade >ago, I was a little involved for awhile in some of the research on using >seismic methods to detect small nuclear explosions in order to assure >compliance with a comprehensive test ban treaty (CTBT). In the last few days, >I was thinking that all that research assumed that the bomb detonator would try >to conceal the test, not flaunt it. So it is a very interesting technical and >policy question that is addressed to the monitoring agencies; they must >reconcile the issue of The Emperor's New Bomb. If they say they did not >detect it, then they must admit in public that they may be unable to perform >the mission for which they were funded. So maybe it is easier to say they >recorded everything regardless of what the records say; this is what the US did >with the USSR with respect to overestimating yield and continues on occasion >with the Russians, i.e., the Nova Zemlya earthquake last year. The monitoring >agencies are not accustomed to having their work exposed to public scrutiny >because, in addition to CIA or KGB obsessions with secrecy, etc., there are >only a relative few members of the public who have independent sources of >seismic data and/or the knowledge to interpret those data. Hence, the PSN. > Robert, good topic! I was thinking about posting something after the Indian >event, but I never got a chance to find the relevant data and work them up -- >then I got distracted. So I am grateful for Arie Verveers seismograms, Charlie >Plyler's electromagnetic records (which I don't understand yet), your comments, >and the contributions of the many other PSN people I have overlooked as usual >(and to whom I apologize): I never imagined in 1990 when I was concerned with >strong ground motions produced by earthquakes in San Francisco and nuclear bomb >detection in the Soviet Union -- and running back and forth between those two >places -- that it would all be combined in some way in the PSN. Thank you. >-Edward > >robert barns wrote: > >> Hi gang, >> There is something fishy about the bomb tests, esp. the Indian ones:The >> only seismic data I have seen in the papers was a single seismic event for >> the first Indian test and none for the 2nd day. There was supposed to be >> three tests on the 1st day and 2 on the 2nd day. The published supposition >> was that the 3 bombs on the 1st day were detonated simultaneously and hence >> gave only 1 seismic record. These three (per Science mag.) "involved a >> thermonuclear warhead, a large fission bomb and a low-yield device". The >> thermonuclear was 43 k tons. >> Paul Richards of Lamont (who knows a very great deal about seismic >> detection of tests) gave an estimate of the lowest yield which should have >> been detectable at the Pakistan station. This was a very small yield (I >> have forgotten the actual number). >> How come no seismic event for the 2nd day? Are the Indians lying? or were >> both duds? >> I haven't seen enough discussion of the Pakistan tests to decide if they >> are also messing with the truth. >> Bob Barns >> >> >> >> _____________________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email listserver@............. with the body of the >> message: leave PSN-L > > > >-- >Edward Cranswick Tel: 303-273-8609 >US Geological Survey, MS 966 Fax: 303-273-8600 >PO Box 25046, Federal Center cranswick@........ >Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Procedures in Experimental Physics Date: Sat, 30 May 1998 23:17:25 -0700 Roger, Thanks for the clarification -- for some reason (probably senility) I had the name C.L Strong, not the correct C.L. Stong, in my mind. I have to admit I went and took down "The Amateur Scientist" book to confirm it! Thanks for the interesting background information. Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- Lehman Boom Construction Ideas Date: Sun, 31 May 1998 09:37:29 +0000 Robert, The 'steel disc' idea is interesting, do you have a picture of your configuration which I could view? What did you use, a washer perhaps? I am visualizing something akin to a 2" hard disk platter from a laptop as the disc. Thank you. Walt Williams, 98.05.31 http://www.pacificnet.net/~dfheli/~seismo.html http://www.pacificnet.net/~dfheli Woodland Hills, (a Los Angeles suburb), California USA ------- Forwarded Message Follows ------- Date: Sat, 30 May 1998 09:11:12 -0400 From: robert barns <75612.2635@..............> Subject: Re: PSN- New Lehman Construction To: PSN-L Mailing List Reply-to: PSN-L Mailing List Hi gang, About razor blades for the pivot on a Lehman boom: I tried this and hated it. A long (say 1") line contact makes alignment very difficult and a razor blade is too flimsy for this use. I have used for several years (with complete satisfaction) a steel disk about 1 1/4" dia. and 1/16" thick clamped in a slot in the end of the boom so that the plane of the disk is parallel to the boom and the disk is approx. vertical. The edge of the disk is rounded and simply presses against a brass bar (steel would be OK) which is bolted to the 1/2" pipe vertical supports (supports for the top end of the suspension wire). This gives a lot of latitude for boom rotation so that accurate balancing of weights at the end of the boom is not necessary. It is easy to move the disk around on the bar so that the boom is roughly parallel to the base in both the vertical and horizontal planes. As far as I can tell, the contact point of the disk and the bar is perfectly stable, at least until a 'quake sufficient to knock the house down comes along. If the contact between the disk was too broad, I think that flat regions of the Lehman output would be apparent in records of lowest noise. I see no such flats so I think that just rounding the edge of the disk makes a sharp enough pivot. I think that a steel ball (e.g., a bearing ball) of almost any diameter (say 1/8" to 1/2") would be just as good. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Rex Klopfenstein Jr Subject: RE: Pakistan Date: Sun, 31 May 1998 14:24:04 -0400 -----Original Message----- From: Edward Cranswick [SMTP:cranswick@......... Sent: Sunday, May 31, 1998 1:20 AM To: PSN-L Mailing List Subject: Re: Pakistan Robert- I agree with your suspicions about the Indian & Pakistan tests. There is an article in today's (Sunday 5/31/98) New York Times about the lack of solid evidence of number of explosions claimed . Rex Klopfenstein, Jr From: "Gary Lindgren" Subject: RE: Laser instrument interface Date: Sun, 31 May 1998 11:30:40 -0700 Does anybody have a seismometer that uses a laser as the displacement measuring concept. The idea is good in that there would be no low frequency pickup problems. Gary Lindgren Palo Alto CA > I was looking as someone's web site with a picture of an laser > instrument and I was thinking about how the computer would get the data. > I thought a CCD from an old video camera might work, but I got something > even better. A nice high resolution CCD from a flatbed scanner. I know > someone that has broken scanner in the garage right now if anyone is > interested in it. It's a 300 dpi optical UMAX flatbed SCSI. > > I have very little idea how the computer interface would work. You might > have better luck with a modified fully functional scanner and a custom > computer driver. > > I also don't know if a low power laser would burn out the CCD. > > Just a thought, > Greg > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Long Period sensor Date: Sun, 31 May 1998 11:59:02 -0700 Hi All I was wondering if someone would send (to me) a typical vertical background (microseism) file for me to review. With the integrator I seem to be getting progressively larger amplitudes with decreasing frequency. I question the data. I don't get a predominate 0.1-0.15 hz signal as I do with my Lehman. Thanks. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: RE: Laser instrument interface Date: Sun, 31 May 1998 19:01:27 -0500 At 11:30 AM 5/31/98 -0700, you wrote: >Does anybody have a seismometer that uses a laser as the displacement >measuring concept. The idea is good in that there would be no low frequency >pickup problems. >Gary Lindgren >Palo Alto CA > Friends, I am currently using an LED/phototransistor combination for displacement detection for reasons I have described recently, but I am also interested in laser detection for scanning microscopy, which needs sensitive displacement detection also. In brief here is how to build such a system. First you hotwire a typical red pointer laser so it operates off of two external batteries for days, etc. The higher power pointers are better. The focus of the beam will often be within six inches of the pointer, after which it diverges slightly with distance. You can either reflect the laser off a polished piece of front surface mirror (use MEK to dissolve the protective varnish from a little piece of vanity mirror) attached to the beam, or reflect it off a little sliver of aluminized space blanket which is anchored to one side so it rests on the seismo beam and is flexed like a little cantilever by any motion of the beam. This flexing of the reflective strip greatly amplifies any relative motion. You try to make sure the reflected beam stays as well collimated as possible when it hits the detector. The laser might typically be three inches from the reflector and the position sensitive detector likewise three inches from the reflector or something on that order. The only real hands-on work in this project is to make the position sensitive detector. These can be made by filing a little chunk of aluminum so that it has a 60-90 degree angle. It does not have to be an optical mirror surface; just shiny and diffuse is good enough. This is mounted on top of some piece of glass like a microscope slide so that the edge of the filed angle is down against the glass. Then two phototransistors or photodiodes are glued with silicone rubber so that they both face the aluminum wedge as close as possible from opposite sides, the end result being that the position of a very narrow laser beam passing through the glass will hit the corner of the aluminum and be reflected into one or the other sensors facing the shiny aluminum. Obviously, you need to take care that the angles are just right and that the translucent silicone or clear epoxy that holds everything in place has no bubbles that would disturb light transmission. The end result is that a collimated pencil of light is split by the edge of the aluminum and deflected into one or the other photodetector in accord with its exact position. The goal in operation is to have the photon stream evely split so the electrical signals are equal. The two sensors are wired in series if phototransistors and in this case the mid-point voltage is led into a voltage follower op amp configuration. Or the photodiodes are wired in opposition, like I think Karl Cunningham described, and the net voltage is put across the input of an op amp and amplified to give the signal. This is fancier and undoubtedly more sensitive than just an LED and phototransistor, but I still think the latter combination will be found ample as well as cheaper and simpler and smaller when used in combination with a light-intercepting flag on the seismo beam. --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: ralvarez@........ (Raul Alvarez) Subject: RE: Laser instrument interface Date: Sun, 31 May 1998 18:54:09 -0600 (MDT) >Does anybody have a seismometer that uses a laser as the displacement >measuring concept. The idea is good in that there would be no low frequency >pickup problems. >Gary Lindgren >Palo Alto CA >snip.. > Gary, Greg and others, About two years ago I started working on a similar idea and the shelved it as other interest consumed much of my free time. I was glad to read that others had similar thoughts. Breifly, my idea was using a laser reflecting off a minute mirror on the seismo arm and reflecting on to, yes, a flatbed scanner linear sensor. To determin the position, one would have to build a circuit that would scan the array (sort of a serial register) and count the steps from the zero or index position to where the laser light is detected. For example, if the array has 2k cells, then a 2k counter would be built to count 1 thru 2k and loop back to 1, etc. if the beam is set to the rest position and the counter detects at 1k, then it is centered. Any motion of the arm would show as a lesser or greated count, depending on the direction of the movement. This count value would then be the amount of displacement. BTW, the "detect" would be the cell or cells that see the laser beam. The only problem I suspect might be that the glass over the linear sensor might cause undesireable reflections. Also the laser spot would have to be made very small, so as not to saturate the target area. I hope all this rambling makes some sense. I would be glad to hear from others that are doing similar work. Raul Alvarez La Estrellita Observatory ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ "My dreams are the seeds of my reality, ~ ~ nurtured in the womb of my soul" ~ ~ RJA, 1985 ~ ~ ~ ~ ~ ~ Raul J. Alvarez ~ ~ La Estrellita Observatory ~ ~ Bellvue, Colorado ~ ~ e-mail ralvarez@........ ~ ~ homepage www.frii.com/~ralvarez ~ ~ "The Renaissance Experimenter" ~ ~ doing research in: ~ ~ Radio and Optical Astronomy, Seismology, Weather, ~ ~ Computers, Instrumentation and Neat Stuff! ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: PSN- New Lehman Construction Date: Sun, 31 May 1998 20:20:30 -0500 RADIOTEL@....... wrote: > > rod joined by wire on each end? > I have been looking for oil burner nozzles like the one in Scientific > American. However, all I have been able to find thus far are ones with 1/16 > inch diameter holes which are much larger than G string guitar strings. Do > you think it would be suitable to use two of these nozzels in Steve's "Y" > configuration or must I continue the search for smaller hole oil burnner > nozzles? > Any help appreciated. > Jim Allen > Jim, I had a bunch of old oil burner nozzles around here but I think I recycled them when I got rid of the oil boiler. :( In my Lehman I eliminated the need for such a device by making the upper pivot a point pivot also. The only need I see for any wire in the upper support is if you are going to use a wire flexure support. Although wire keeps the mass of the support small. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Gary Lindgren" Subject: RE: Laser instrument interface Date: Sun, 31 May 1998 18:56:33 -0700 Roger, A laser pointer is an excellent low cost laser source. Have you had any problems with the laser burning out. Gary Lindgren > > > At 11:30 AM 5/31/98 -0700, you wrote: > >Does anybody have a seismometer that uses a laser as the displacement > >measuring concept. The idea is good in that there would be no > low frequency > >pickup problems. > >Gary Lindgren > >Palo Alto CA > > > > Friends, > I am currently using an LED/phototransistor combination for > displacement detection for reasons I have described recently, but > I am also > interested in laser detection for scanning microscopy, which needs > sensitive displacement detection also. > > In brief here is how to build such a system. First you hotwire a typical > red pointer laser so it operates off of two external batteries for days, > etc. The higher power pointers are better. The focus of the beam > will often > be within six inches of the pointer, after which it diverges slightly with > distance. > > You can either reflect the laser off a polished piece of front surface > mirror (use MEK to dissolve the protective varnish from a little piece of > vanity mirror) attached to the beam, or reflect it off a little sliver of > aluminized space blanket which is anchored to one side so it rests on the > seismo beam and is flexed like a little cantilever by any motion of the > beam. This flexing of the reflective strip greatly amplifies any relative > motion. You try to make sure the reflected beam stays as well > collimated as > possible when it hits the detector. The laser might typically be three > inches from the reflector and the position sensitive detector likewise > three inches from the reflector or something on that order. > > The only real hands-on work in this project is to make the position > sensitive detector. These can be made by filing a little chunk of aluminum > so that it has a 60-90 degree angle. It does not have to be an optical > mirror surface; > just shiny and diffuse is good enough. > > This is mounted on top of some piece of glass like a microscope slide so > that the edge of the filed angle is down against the glass. Then two > phototransistors or photodiodes are glued with silicone rubber so > that they > both face the aluminum wedge as close as possible from opposite sides, the > end result being that the position of a very narrow laser beam passing > through the glass will hit the corner of the aluminum and be > reflected into > one or the other sensors facing the shiny aluminum. Obviously, you need to > take care that the angles are just right and that the translucent silicone > or clear epoxy that holds everything in place has no bubbles that would > disturb light transmission. The end result is that a collimated pencil of > light is split by the edge of the aluminum and deflected into one or the > other photodetector in accord with its exact position. The goal in > operation is to have the photon stream evely split so the electrical > signals are equal. > > The two sensors are wired in series if phototransistors and in this case > the mid-point voltage is led into a voltage follower op amp configuration. > Or the photodiodes are wired in opposition, like I think Karl Cunningham > described, and the net voltage is put across the input of an op amp and > amplified to give the signal. > > This is fancier and undoubtedly more sensitive than just an LED and > phototransistor, but I still think the latter combination will be found > ample as well as cheaper and simpler and smaller when used in combination > with a light-intercepting flag on the seismo beam. > > --Yours, Roger > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: PSN- New Lehman Construction Date: Sun, 31 May 1998 22:49:43 EDT TO: JIM HANNON You indicated that in your seismometer you had made the upper pivot a point pivot. Could you explain how the upper pivot is constructed as a point pivot. Thanks Jim Allen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: RE: Laser instrument interface Date: Sun, 31 May 1998 21:48:20 -0500 At 06:56 PM 5/31/98 -0700, you wrote: >Roger, >A laser pointer is an excellent low cost laser source. Have you had any >problems with the laser burning out. >Gary Lindgren > Nope. I think they'll probably last thousands of hours and that the optical feedback circuit packaged with the laser pointers is quite well engineered to make sure they don't burn out for a very long time in most cases. Red helium neon lasers can be made very stable in frequency, but they age and the tube dies in a few years as the gain goes down. At least my tube did. --Yours, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: VRDT Drive Circuit Date: Sun, 31 May 1998 21:38:49 -0600 Jim Hannon wrote: > I have put the almost complete schematic of my design for a VRDT drive > circuit at http://soli.inav.net/~jmhannon/driver.html > It has a couple of unique features. It only uses three IC's and has very > low power consumption, crystal controlled frequency and a stable drive > level. The drive signal for the demodulator is a ttl level signal. The > phase of the demodulator drive can be adjusted to compensate for phase > shifts in other parts of the circuit. Jim, No electronic specialist here, but am wondering about your circuit. I'am guessing that they are "blocks" of circuitry roughly thrown together and the values derived thereafter? Do you envision adding more "blocks" to it over time, which encompass other necessary functions? What kind of seismometer type and pickup sensor do you anticipate using with your circuit? Really hope that the final circuit works out very well...and I appreciate your effort in that endeavor. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: New release of WinQuake Date: Sun, 31 May 1998 22:46:27 -0700 Hi Everyone, I just got finished with releasing the new version of WinQuake. This release is version 2.5. Both 32-Bit and 16-Bit versions (probably the last) are available. Links to the self-extracting setup program containing WinQuake can be found at http://psn/quake.net/software.html. Do to the size of the files, 1.3meg for the 32-Bit version and 1.1meg for the 16-Bit version, I no longer have a copy on my system. I have located the files on other systems so downloads won't slow down access to my system. For a feature list of the new release, see the new Online documentation for WinQuake at http://psn.quake.net/wqdocs/winquake.htm. One thing that's new with this version, and all new releases, is WinQuake is now Shareware instead of Freeware. I had some direct costs related to this release. That was purchasing a new Install / Setup program that is easier to use and that has more features for the end user, like uninstalling the program etc. This is the same program that most Windows programs use to install new software. The registration fee also goes too help pay for the month cost need to run this list and the PSN archive system. I used several programs as a Shareware model. This includes Allan Jone's SeisVol and Seismic Waves programs and LViewPro, a graphics program that may people use. Basically it works like this; After downloading and installing the program the user has 30 days to try it out. During that time the program is fully functional. After the 30-day trial period several features, like doing a FFT and saving an event file, are disabled. The program can still be used to view an even file. If the user want's to use all of the features of the program they can register it by paying the registration fee of $30.00 USD. After receiving the payment, I will email and/or send via snail mail, the registration information need to make the program fully functional again. The registration information is then entered into a dialog box. If the User name and registration code are correct, the program will then be registered. The registration fee will not be required for primary and secondary (K-12) schools and for people who buy $100.00 or more of equipment from me. I think this is far... I have spent A LOT of time on WinQuake over the last 4+ years. Now that it can be used to view other formats (PEPP, SAC Binary, SEED volumes) other than PSN, it can be used by other organizations who are funded better than us. There are also some individuals who are starting to sell seismic monitoring equipment that now produce PSN of SAC formatted event files, and that's fine. But they are using the fact that WinQuake is available so they do not have to spend the time creating a viewer of there own. I don't think it's unreasonable to get some compensation for the time it takes to add new features and to maintain it. Regards, Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: DI-150RS & San Juan Bautista Date: Sun, 31 May 1998 22:50:02 -0700 For those interested in the DI-150RS Data logger and the San Juan Bautista quake,, Shannon has the gif to look at!! At: http://www.televar.com/~earth/alert.html The picture is under the GIF*NOW button! Any comments that he has are under the FLASHING button! The way I have it set up now, it records 20 samples per sec. and that sets the gridmarks at 1 sec intervals for normal recording. For playback (for this picture) I have it compressed to 5,, which makes the gridmarks 5 sec. The time at the lower right is the time at the cursor which is at the center of the screen. My clock at the time of this event was approx. 2.5 sec fast! The time is PDT which is 7 hours behind UTC. (Add 7 hr to get UTC) The travel time calculator puts me at 2.06 deg (approx 142 miles). For those interested, the old GIF was of the Truckee 2.9 (later down- graded to, I think, a 2.1. It was approx. 37 miles from my station! As you can see, Larrys' set up has some definite advantages for the serious PSNer!!!! I'm using the STM-8 mechanism but with oil damping and coil, magnet sensor. Other things keep stalling the finishing of the feedback!! Stephen Pilot Hill, Ca USA lat / lon 38.828N / 120.978W PSN station # 55 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Pakistan Date: Sun, 31 May 1998 23:56:36 -0700 There was a short video clip on CNN/HN today showing one of the Pakistani tests. It apparently was in the side of a mountain. It ejected some debris. I wonder if it vented. It could have easily been faked with a conventional explosion on the video. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Steve Hammond's Lehman Date: Mon, 1 Jun 1998 06:34:46 +0000 Steve, Thanks. Walt, 98.06.01 ========================================= ------- Forwarded Message Follows ------- Date: Mon, 01 Jun 1998 05:49:41 -0700 From: Steve Hammond To: dfheli@............... RADIOTEL@....... Subject: Photos of Steve Hammond's Lehman design >Robert, Walt, >This is several pictures of my Lehman that Robert >asked about. Kind of late so I'll just post the facts. >Regards, >Steve Hammond >----- lots of snipping -----< _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: DI-150RS & San Juan Bautista Date: Mon, 01 Jun 1998 06:56:04 At 10:50 PM 5/31/98 -0700, you wrote: >For those interested in the DI-150RS Data logger and the San Juan >Bautista quake,, Shannon has the gif to look at!! At: I don't know if you saw the exchange between me and ted but he says if we can get him a di-150rs to use he will try and write a driver for emon. I am going to order one hopefully this week. So much to do. So little time. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: New release of WinQuake Date: Mon, 1 Jun 1998 10:25:26 -0400 Larry, I'm glad to see that you are making Winquake shareware. An invaluable program should be self-supporting. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: PSN- Lehman Boom Construction Ideas Date: Mon, 1 Jun 1998 10:25:28 -0400 Walt, I don't have a photo of the disk-bearing thing. The disk was indeed a large steel washer I found in my junk box. I jus= t rounded (hand-held) the edge with a grinding wheel. My boom is 1/2" dia.= aluminum and I sawed a slot about 1/2" deep in the end of it. A set-scre= w clamps the washer in the slot. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: CENTRAL ITALY Date: Mon, 1 Jun 1998 16:46:39 +0200 UTC 13.57 Md >4.1 Local.: CENTRAL ITALY 50 KM Ovest from Osimo After main event, many aftershock Francesco Nucera I.E.S.N.-PSN ITALT=20
UTC 13.57
Md  >4.1
Local.: CENTRAL ITALY 50 KM Ovest = from=20 Osimo
 
After main event, many = aftershock
 
Francesco Nucera  I.E.S.N.-PSN=20 ITALT 
From: Stephen & Kathy Subject: Re: DI-150RS & San Juan Bautista Date: Mon, 01 Jun 1998 08:16:46 -0700 Norman Davis WB6SHI wrote: > > At 10:50 PM 5/31/98 -0700, you wrote: > >For those interested in the DI-150RS Data logger and the San Juan > >Bautista quake,, Shannon has the gif to look at!! At: > > I don't know if you saw the exchange between me and ted but he says if we > can get him a di-150rs to use he will try and write a driver for emon. I am > going to order one hopefully this week. So much to do. So little time. > > Norman Davis WB6SHI > Shingle Springs, Ca > normd@............. > http://www.directcon.net/normd/index.htm > OOPS!!!! Didn't mean to ignore Ted and EMON!!!!!! I'm sure there are SERIOUS PSNers using EMON or other options and I'd be glad to use EMON or any software that could convert my files to be compatable with other PSNers!!!! Sorry Ted, or others What I had intended with the word serious was if you wanted to exchange files and it didn't even register that I might be pushing one or ignoring other options. After all, I'm a serious PSNer ????? about recording quakes -- for fun!! Of course everyone could buy a Dataq,, ha ha ha Stephen Pilot Hill Ca. USA PSN Station #55 PS As long as I'm on the line --- If the Pakistan nuke registered as a 4.8 quake, would that calculate to approx 237 tons of TNT??? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Re: Long Period sensor Date: Mon, 1 Jun 1998 11:32:38 -0500 (CDT) Barry, I'm not sure what your question is, which I assume is about your VBB vertical sensor. It WILL show much more long period (30 secs to 100+ seconds) noise than a velocity sensitive Lehman, mainly because the Lehman is a narrow band instrument, with a peak response near its natural period, which is often 10 to 20 seconds. The VBB is very sensitive to atmoshperic noise via buoyancy of the mass. It is also sensitive to thermal transients. The one I am using here currently has a 1000 second high pass filter in the output just to keep the atmospherics (especially when the wind is blowing) and thermal meanderings (like when the air conditioning turns on) out of the data. Do you have a way of running a Power Spectral Density plot on your data, or even just a FFT, to see where most of the energy is? I think you have MATHCAD? I can post the PSD worksheet for you. It needs data in a single array, one sample per component per line. Samples of PSD plots are on my web site, under the ...data.. page. The 6-second microseisms here in the mid-continent can vary considerably in amplitude, depending on the storm conditions off the east coast. Also, I can update the most recent quake file (like last nights' 6.2 near Kamchatka) if you want to make comparisons. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: DI-150RS & San Juan Bautista Date: Mon, 1 Jun 1998 10:52:42 -0700 (PDT) Wait wait! Let's get everything straight. EMON collects and saves data in just one format, what we have taken to calling PSN format files. It doesn't read or convert files from one format to another - that's function that Larry has added to WinQuake. (Actually, EMON does have an option to read its input data from an existing file instead of from a sensor. Using this you can change around your trigger settings and determine whether you would have triggered on an old data file with the new settings. But that's not what you were asking about). EMON gets its input data from an A/D converter. All of the A/D converters it supports today are internal cards that you insert into an expansion slot on the motherboard. The DI-150rs, as I understand it, uses a serial port connection. I agreed with Norman that this would open up the possibility of using laptops for demos or data collection, so I offered to try to add support to EMON for this new hardware type. In the past I've tried adding hardware support without having the hardware in my PC, but it just doesn't work. If someone can send me the hardware, disks, connecting cables and written documentation I'll give it a shot. I believe Norman will be doing this when he gets some hardware. Ted Blank San Jose, California On Mon, 1 Jun 1998, Stephen & Kathy wrote: > Norman Davis WB6SHI wrote: > > > > At 10:50 PM 5/31/98 -0700, you wrote: > > >For those interested in the DI-150RS Data logger and the San Juan > > >Bautista quake,, Shannon has the gif to look at!! At: > > > > I don't know if you saw the exchange between me and ted but he says if we > > can get him a di-150rs to use he will try and write a driver for emon. I am > > going to order one hopefully this week. So much to do. So little time. > > > > Norman Davis WB6SHI > > Shingle Springs, Ca > > normd@............. > > http://www.directcon.net/normd/index.htm > > > > OOPS!!!! Didn't mean to ignore Ted and EMON!!!!!! > I'm sure there are SERIOUS PSNers using EMON or other options and I'd > be glad to use EMON or any software that could convert my files to be > compatable with other PSNers!!!! Sorry Ted, or others > What I had intended with the word serious was if you wanted to exchange > files and it didn't even register that I might be pushing one or > ignoring other options. After all, I'm a serious PSNer ????? about > recording quakes -- for fun!! > Of course everyone could buy a Dataq,, ha ha ha > Stephen > Pilot Hill Ca. USA > PSN Station #55 > > PS As long as I'm on the line --- If the Pakistan nuke registered > as a 4.8 quake, would that calculate to approx 237 tons of TNT??? > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: lahr@.................. Subject: Northridge Earthquake Web Site Date: Mon, 1 Jun 1998 14:48:20 -0600 (MDT) > > ------------- USGS Northridge Earthquake Research Products ---------------- > > Now online is a new webpage summarizing the work of the US Geological Survey > following the 1994 Northridge earthquake. Users can download data and maps > showing many aspects of the earthquake, such as the mainshock rupture, > damage patterns, local site response effects, and landside effects. Also > available are various supporting data sets including, a fault database, > digital geologic maps, t opographic data, and reference lists to Northridge > publications. > > The site has photos from the earthquake and animations of the earthquake > rupture and aftershock sequence. > > > http://www-socal.wr.usgs.gov/north > > (note: hyphen "-" after www) > > > ---------------------------------------------------------------------------- > Lisa Wald Jim Mori > US Geological Survey US Geological Survey > Pasadena, California Pasadena California > > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: zero6600@........... Subject: 8-04 Date: Mon, 01 Jun 98 19:17:29 EST BENCHMARK PRINT SUPPLY 1091 REDSTONE LANE ATLANTA GA 30338 FOR ORDERS/PRICING ONLY PLEASE CALL (770)399-0953 CUSTOMER SERVICE/SUPPORT ISSUES PLEASE CALL (770)399-5505 FOR COMPLAINTS OR E-MAIL REMOVAL PLEASE CALL (770)399-5614 OUR LASER PRINTER/FAX/COPIER TONER CARTRIDGES, PRICES NOW AS LOW AS $39 & UP WE CARRY MOST ALL LASER PRINTER CARTRIDGES, FAX SUPPLIES AND COPIER TONERS AT WAREHOUSE PRICES INCLUDING: HEWLETT PACKARD SERIES 2/3/4/2P/4P/5P/4L/5L/3SI/4SI/5SI IBM/LEXMARK OPTRA SERIES 4019/4029/4039/4049/4059 EPSON SERIES 2/1100/1500/6000/7000/8000 NEC SERIES 90/95 CANON COPIER PC SERIES INCLUDING 3/6RE/7/11/320/720/10/20/25 ETC... HP FAX SERIES 700/720/5000/7000/FX1/FX2/FX3/FX4/FX5 CANON FAX ALL MODELS WE DO NOT CARRY : BROTHER - PANASONIC - XEROX - FUJITSU - OKIDATA - SHARP PRICES DO CHANGE PERIODICALLY. PLEASE CALL TO GET THE MOST RECENT PRICING/AVAILABILTY AND SPECIALS OF THE WEEK!!!! ORDERS/PRICING LINE ONLY CALL (770)399-0953 *****NEW,NEW,NEW $10 MAIL IN REBATE ON ALL CARTRIDGES***** ****SIMPLY ORDER YOUR NEW CARTRIDGE, WHEN IT ARRIVES MAIL BACK**** ****YOUR REBATE CERTIFICATE WITH ANY USED CARTRIDGE FOR INSTANT CREDIT**** WE ACCEPT ALL MAJOR CREDIT CARDS OR COD ORDERS CORPORATE ACCOUNTS AVAILABLE WITH APPROVED CREDIT ALL PACKAGES SHIPPED UPS GROUND UNLESS SPECIFIED OTHERWISE . PLEASE NOTE: WE ARE CURRENTLY BUYING HP-SERIES 5L - 5P - AND 4000 CARTRIDGES ALL LEXMARK OPTRA CARTRIDGES CANON PC COPIER CARTRIDGES NOTE: THESE ARE THE ONLY CARTRIDGES CURRENTLY INCLUDED IN OUR BUY BACK PROGRAM TO ARRANGE CARTRIDGE PICKUP CALL CUSTOMER SERVICE (770)399-5505 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: PSN- New Lehman Construction Date: Mon, 01 Jun 1998 19:56:11 -0500 RADIOTEL@....... wrote: > > TO: JIM HANNON > You indicated that in your seismometer you had made the upper pivot a point > pivot. Could you explain how the upper pivot is constructed as a point pivot. > Thanks > Jim Allen Jim, There are a lot of different approaches to this depending on the materials and tools you have avaliable. My design may be a little hard to reproduce as I have a reasonable collection of metal working tools. Basically you have to reverse the direction of the pivot from the lower pivot. One way to do this is to mount the pivot cup on a L shaped bracket attached to the top of the support. With the cup facing away from the mass. Then attach a yoke to the support wire with a pivot point facing towards the mass. The yoke would surround the L shaped bracket allowing the pivot point to rest in the cup. As they say a picture is worth 1K words. If you can't figure it out from my words ask and I will put a sketch on my web server. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: zero6600@........... Subject: 8-05 Date: Mon, 01 Jun 98 21:19:16 EST BENCHMARK PRINT SUPPLY 1091 REDSTONE LANE ATLANTA GA 30338 FOR ORDERS/PRICING ONLY PLEASE CALL (770)399-0953 CUSTOMER SERVICE/SUPPORT ISSUES PLEASE CALL (770)399-5505 FOR COMPLAINTS OR E-MAIL REMOVAL PLEASE CALL (770)399-5614 OUR LASER PRINTER/FAX/COPIER TONER CARTRIDGES, PRICES NOW AS LOW AS $39 & UP WE CARRY MOST ALL LASER PRINTER CARTRIDGES, FAX SUPPLIES AND COPIER TONERS AT WAREHOUSE PRICES INCLUDING: HEWLETT PACKARD SERIES 2/3/4/2P/4P/5P/4L/5L/3SI/4SI/5SI IBM/LEXMARK OPTRA SERIES 4019/4029/4039/4049/4059 EPSON SERIES 2/1100/1500/6000/7000/8000 NEC SERIES 90/95 CANON COPIER PC SERIES INCLUDING 3/6RE/7/11/320/720/10/20/25 ETC... HP FAX SERIES 700/720/5000/7000/FX1/FX2/FX3/FX4/FX5 CANON FAX ALL MODELS WE DO NOT CARRY : BROTHER - PANASONIC - XEROX - FUJITSU - OKIDATA - SHARP PRICES DO CHANGE PERIODICALLY. PLEASE CALL TO GET THE MOST RECENT PRICING/AVAILABILTY AND SPECIALS OF THE WEEK!!!! ORDERS/PRICING LINE ONLY CALL (770)399-0953 *****NEW,NEW,NEW $10 MAIL IN REBATE ON ALL CARTRIDGES***** ****SIMPLY ORDER YOUR NEW CARTRIDGE, WHEN IT ARRIVES MAIL BACK**** ****YOUR REBATE CERTIFICATE WITH ANY USED CARTRIDGE FOR INSTANT CREDIT**** WE ACCEPT ALL MAJOR CREDIT CARDS OR COD ORDERS CORPORATE ACCOUNTS AVAILABLE WITH APPROVED CREDIT ALL PACKAGES SHIPPED UPS GROUND UNLESS SPECIFIED OTHERWISE . PLEASE NOTE: WE ARE CURRENTLY BUYING HP-SERIES 5L - 5P - AND 4000 CARTRIDGES ALL LEXMARK OPTRA CARTRIDGES CANON PC COPIER CARTRIDGES NOTE: THESE ARE THE ONLY CARTRIDGES CURRENTLY INCLUDED IN OUR BUY BACK PROGRAM TO ARRANGE CARTRIDGE PICKUP CALL CUSTOMER SERVICE (770)399-5505 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: VRDT Drive Circuit Date: Mon, 01 Jun 1998 20:34:52 -0500 meredith lamb wrote: > Jim, > > No electronic specialist here, but am wondering about your circuit. > I'am guessing that they are "blocks" of circuitry roughly thrown > together and the values derived thereafter? > > Do you envision adding more "blocks" to it over time, which > encompass other necessary functions? > > What kind of seismometer type and pickup sensor do you anticipate > using with your circuit? > > Really hope that the final circuit works out very well...and I > appreciate your effort in that endeavor. > > Thanks, Meredith Lamb > Meredith, I guess I would debate the use of the words "roughly thrown together" :) But most electronic designs consists of several functional blocks strung together to produce the desired results on a signal. For the VRDT driver circuit I started with a list of requirements for the circuit. :> Low power consumption. :> Stable frequency with the ability to derive the frequency from a common source for the entire sesimograph system. :> Small number of inexpensive parts. :> Stable signal amplitude. :> Full bridge drive to the VRDT coils. :> and so on etc. For this design I only kept the requirements in my head. For a more complex design it would be necessary to write out the requirements. We then decide on an overall approach to meet the requirements. In this case I decided to use a PIC processor for generating a digital representation of the sine wave. This helps meet the "stable signal amplitude" and "stable frequency" requirements. It also lets me have a phase adjustable digital signal to drive the demodulator. For the next block using a D/A converter part would be a bit of overkill so I chose to "build" D/A converter with an op amp. The high frequency D/A steps need to be removed from the signal so I stuck in my favorite low pass filter circuit. The component values haven't been determined yet as I haven't decided on the operating frequency I want to use. The frequency may end up being determined by experiment. This is partly because I am going to wind my own VRDT coils and I don't know yet how much inducatance they will end up with. The final stage or block is the two op amps that drive the coils. This is just two unity gain inverting op amps in series. There are several more "blocks" on the web server. If you keep hitting the "return" button it will take you back up the design heriachy and you can explore some of the other parts of the design. The other parts are heavily "under construction" though. Yes I hope to finish the web page description over the next few months as the design progresses and I find the time. The seismometers (three axis) are going to be a variation on Sean-Thomas' VBB design (STM-8). The sensors are the VRDTs as in the STM-8. The web page description of the design is set up the way it is because I wanted to explore the use of hyperlinks to describe a design heriachy. You can start at http://soli.inav.net/~jmhannon/blokdia.html if you want to start at the top level. Thanks for looking at my design. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Lehman hinges Date: Mon, 1 Jun 1998 20:41:29 -0500 (CDT) to all the Lehman fans: I have seen enough frustration with the design of the hinges for the Lehman horizontal, what with razor blades and oil burner nozzles, so I am presenting a well proven option, namely the design that was used in the WWNSS (World Wide Network of Standard Seismographs) for the Long Period Horizontal. I have scanned a drawing of the details of the lower and upper hinges to my web page labeled ... PSN info... at: http://www.eas.slu.edu/People/STMorrissey/index.html Hopefully this simple taught-wire arrangement will simplify the problems with hinges. IN fact, the overall design of the seis can easily be copied. If there is some interest, I will take a photo of one of 4 that I am still operating and post it. (I do not have the exact size of the hinge wires, but I will find out and post it with the drawing. The size is not critical; use a guitar string). Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: zero6600@........... Subject: 8-05 Date: Mon, 01 Jun 98 21:54:01 EST BENCHMARK PRINT SUPPLY 1091 REDSTONE LANE ATLANTA GA 30338 FOR ORDERS/PRICING ONLY PLEASE CALL (770)399-0953 CUSTOMER SERVICE/SUPPORT ISSUES PLEASE CALL (770)399-5505 FOR COMPLAINTS OR E-MAIL REMOVAL PLEASE CALL (770)399-5614 OUR LASER PRINTER/FAX/COPIER TONER CARTRIDGES, PRICES NOW AS LOW AS $39 & UP WE CARRY MOST ALL LASER PRINTER CARTRIDGES, FAX SUPPLIES AND COPIER TONERS AT WAREHOUSE PRICES INCLUDING: HEWLETT PACKARD SERIES 2/3/4/2P/4P/5P/4L/5L/3SI/4SI/5SI IBM/LEXMARK OPTRA SERIES 4019/4029/4039/4049/4059 EPSON SERIES 2/1100/1500/6000/7000/8000 NEC SERIES 90/95 CANON COPIER PC SERIES INCLUDING 3/6RE/7/11/320/720/10/20/25 ETC... HP FAX SERIES 700/720/5000/7000/FX1/FX2/FX3/FX4/FX5 CANON FAX ALL MODELS WE DO NOT CARRY : BROTHER - PANASONIC - XEROX - FUJITSU - OKIDATA - SHARP PRICES DO CHANGE PERIODICALLY. PLEASE CALL TO GET THE MOST RECENT PRICING/AVAILABILTY AND SPECIALS OF THE WEEK!!!! ORDERS/PRICING LINE ONLY CALL (770)399-0953 *****NEW,NEW,NEW $10 MAIL IN REBATE ON ALL CARTRIDGES***** ****SIMPLY ORDER YOUR NEW CARTRIDGE, WHEN IT ARRIVES MAIL BACK**** ****YOUR REBATE CERTIFICATE WITH ANY USED CARTRIDGE FOR INSTANT CREDIT**** WE ACCEPT ALL MAJOR CREDIT CARDS OR COD ORDERS CORPORATE ACCOUNTS AVAILABLE WITH APPROVED CREDIT ALL PACKAGES SHIPPED UPS GROUND UNLESS SPECIFIED OTHERWISE . PLEASE NOTE: WE ARE CURRENTLY BUYING HP-SERIES 5L - 5P - AND 4000 CARTRIDGES ALL LEXMARK OPTRA CARTRIDGES CANON PC COPIER CARTRIDGES NOTE: THESE ARE THE ONLY CARTRIDGES CURRENTLY INCLUDED IN OUR BUY BACK PROGRAM TO ARRANGE CARTRIDGE PICKUP CALL CUSTOMER SERVICE (770)399-5505 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: New release of WinQuake Date: Mon, 01 Jun 1998 19:57:23 -0700 At 12:20 AM 6/1/98 -0700, Greg wrote: >Larry Cochrane wrote: > >> Links to the self-extracting setup program containing WinQuake can be found >> at http://psn/quake.net/software.html. Do to the size of the files, 1.3meg > >I just finished a college class on Windows programming and although I >learned very little, I was curious about how you were writing it. I seem >to remember reading that you used C++? MFC or API programming? WinQuake uses Microsoft's Visual C++ Version 4.2, with MFC (sounds like a toothpaste MFC stands for Micro$oft Foundation Classes ). This is a set of software functions used to make Windows programing easier, sometimes...). >I used to do multistation analysis a while ago and I was wondering if >this would be coming to WinQuake anytime in the future. Most PSN sites >probably wouldn't be able to see differences in arrival time, but phase >might be a little easier to see. I'm not sure what type of multi station analysis you want? The only thing I can think of that would be useful for the average user would be have it locate the event. This is something I would like to add, but don't know how. I have the code for a program called hypo that can locate events. The problem is it's written in FORTRAN, a language that I never learned ( like English ). From what I hear one of our members, Dr. John Lahr, is an expert on locating earthquakes. Maybe I could work with him sometime and add the code needed to add this feature. The output of this "function" could open the Xerox map page and display the location. >Thank you. I will be sending more money in the future. The check for my >little order is on the way. Thanks... >> I think this is far... I have spent A LOT of time on WinQuake over the last >> 4+ years. Now that it can be used to view other formats (PEPP, SAC Binary, That should be "fair", I wish I could proof read better... -Larry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: SPAM Email sent to this list. Date: Mon, 01 Jun 1998 20:26:17 -0700 Hi Everyone, Looks like we are now on a spamming list. Unfortunately that means it will spread to other lists...First, don't hit reply! The god damn spammers are not on this list, so sending messages back to this list does no good. If you don't like spam Email, like most people, contact the sender. I called them on the phone and left a VERY nasty message! The only thing I can do is set the mailing lists I run, PSN-L, SDRUSER, NEWFILE and NEWEVENT, so that only members of the list can post. For most people this will not be a problem because they only listen in or post from one system. The problem is some people like to post from more than one system. For those people they will need to subscribe to the list from the systems they will be posting from, or wait until you get to the system that is subscribed. Another way around this; The mailing server will use the "From:" address to determine where the message came from. If you post from another system, you can change this setting to use the subscribed email address for your message. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Long Period sensor Date: Mon, 01 Jun 1998 18:32:50 -0700 Sean Thomas I was concerned about my VBB. With A FFT of the background noise on a linear plot ,the response amplitude increases with lower frequency to the point of the high pass filter (currently set @ 100 sec). I have tried filling the sensor box with foam to reduce possible air currents, insulated the box to reduce thermal bouyancy. Nothing seems to reduce the low end. I plan now to fix the sensor to make sure the "problem" isn't electronic. I am then going to move the sensor from the garage slab to under the house on a small concrete pad to see if that helps. The FFT on a log amplitude plot looks alot better (constant amplitude) than a linear plot. A linear scale amplitude FFT plot of your background noise would be very helpful. Barry S-T Morrissey wrote: > > Barry, > > I'm not sure what your question is, which I assume is about > your VBB vertical sensor. It WILL show much more long period > (30 secs to 100+ seconds) noise than a velocity sensitive > Lehman, mainly because the Lehman is a narrow band instrument, > with a peak response near its natural period, which is often > 10 to 20 seconds. > The VBB is very sensitive to atmoshperic noise via buoyancy of > the mass. It is also sensitive to thermal transients. The one > I am using here currently has a 1000 second high pass filter in > the output just to keep the atmospherics (especially when the > wind is blowing) and thermal meanderings (like when the air > conditioning turns on) out of the data. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: Lehman hinges Date: Mon, 1 Jun 1998 23:34:19 EDT There is definitely interest in your posting a photo of one of your WWNSS units. Jim Allen Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: PSN- New Lehman Construction Date: Mon, 1 Jun 1998 23:36:04 EDT Appreciate the description of your yoke. Should you have the time a drawing posted to your web site would be very informative. Jim Allen Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: PSN- New Lehman Construction Date: Mon, 1 Jun 1998 23:40:47 EDT Jim Hannon As indicated in my previous post which I forgot to indicate what I was referring to which was your offer to place a drawing on your web site - such a drawing would certainly be informative. I apoligize to PSN participants for my forgetfullness. Jim Allen Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Long Period sensor Date: Mon, 01 Jun 1998 20:29:43 -0700 Well Mr STM The problem with my VBB appears(thankfully) to be electronic. The mechanical seems more difficult to troubleshoot. I fixed the sensor and got the same response out. I got the impression, within reason, that the quality of components is not too important. I am using 1% resistors and I checked capacitor impedence with a DVM. I am suspicious of my displacement sensor. It is a capacitive bridge made up of two variable air caps and two fixed caps. The air caps are made of brass plates with an overlapping area of about 1"x2". there is a lot of surface area. Also the rectifying circuit has been previously untested. The output looks ok on a DMM but maybe not with a scope. I think a way to proceed is to keep the sensor fixed and start at the front end (displacement sensor) and work my way to the end of the line. I am using dual FET op amps and the circuit is set up for +5 to -5. I will try to send you a ASCII picture of the displacement sensor. Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ken Navarre Subject: Re: New release of WinQuake Date: Mon, 1 Jun 1998 22:28:59 -0700 (PDT) On Sun, 31 May 1998, Larry Cochrane wrote: (snip) > I think this is fair... Yup. So do I. I'm glad that you put the effort to continually make the program more effective and easier to use. It's making the "hobby" easier than ever for neophytes and other obessive types (specifically me...) to get and stay involved in amateur seismology... (snip again...) > I don't think it's unreasonable to get some compensation for the time > it takes to add new features and to maintain it. Thanks for the great work, Larry. We can only say it just so long before it sounds patronizing. BUT! IF it weren't for your support and sacrifice our progress would be considerable behind the current "state of the art" for our little projects!!! Thanks! Ken _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: SPAM Email sent to this list. Date: Tue, 02 Jun 1998 00:27:35 -0700 (MST) Larry, As long as nobody else is using the service, maybe a good place to start is by excluding all hotmail.com addresses (if it can be done). I get them from all kinds of sources (not just this list) and inevitably that damned domain name is always there!!! ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: New release of WinQuake Date: Tue, 02 Jun 1998 00:32:12 -0700 (MST) On Sun, 31 May 1998, Larry Cochrane wrote: > One thing that's new with this version, and all new releases, is WinQuake > is now Shareware instead of Freeware. > The registration fee will not be required for primary and secondary (K-12) > schools and for people who buy $100.00 or more of equipment from me. Larry, do our past purchases at MCC and ASU count??? ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- SPAM is not a Sweet Meat Date: Tue, 2 Jun 1998 01:29:03 +0000 Hello Larry, John and All, I have noticed that when ever I send e-mail to anyone who has a FREE e-mail service, such as hotmail.com, the spam begins. Hotmail.com, as best as I can discern is an ISP that collects 'from and to' e-mail addresses of their users, and sells these e-mail lists to SPAMMERs. Incidentally, I have not used the Yahoo search engine(s) for several years, then recently, I used it for one search, and immediately thereafter (one day) I started receiving spam e-mail with xxxxx@......... domain. Nothing is free. A search engine which I use that does not exhibit this offensive behavior is http://www.hotbot.com but that could change. Best Regards Walt, 98.06.02 dfheli@.............. ================================================= ------- Forwarded Message Follows ------- Date: Tue, 02 Jun 1998 00:27:35 -0700 (MST) From: John Hernlund Subject: Re: SPAM Email sent to this list. To: PSN-L Mailing List Reply-to: PSN-L Mailing List Larry, As long as nobody else is using the service, maybe a good place to start is by excluding all hotmail.com addresses (if it can be done). I get them from all kinds of sources (not just this list) and inevitably that damned domain name is always there!!! ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: 05/31/98 01:58:40 Event(??) Date: Tue, 2 Jun 1998 07:44:46 -0500 "Tom Frey" on 05/30/98 09:24:35 PM Please respond to PSN-L Mailing List To: "PSN-L Mailing List" cc: (bcc: James M Hannon/CedarRapids/Collins/Rockwell) Subject: 05/31/98 01:58:40 Event(??) >'lo > received an event at 01:58:40.1 in Tacoma, but it appears very strange.. > also received it on two monitored Univ Washington sites 45 miles apart and >average of 50 miles from me >it saturated my system but it was very short duration..orientation doesn't >allow for even good line of bearing >anyone else getting anything? >tom THIS IS JUST HUMOR... REDMOND (BNN)--World leaders reacted with stunned silence as Microsoft Corp. (MSFT) conducted an underground nuclear test at a secret facility in eastern Washington state. The device, exploded at 01:58:40 today, was timed to coincide with talks between Microsoft and the US Department of Justice over possible antitrust action. "Microsoft is going to defend its right to market its products by any and all necessary means," said Microsoft CEO Bill Gates. "Not that I'm anti-government" he continued, "but there would be few tears shed in the computer industry if Washington were engulfed in a bath of nuclear fire." Scientists pegged the explosion at around 100 kilotons. "I nearly dropped my latte when I saw the seismometer" explained University of Washington geophysicist Dr. Whoops Blammover, "At first I thought it was Mt. Rainier, and I was thinking, damn, there goes the mountain bike vacation." In Washington, President Clinton announced the US Government would boycott all Microsoft products indefinitely. Minutes later, the President reversed his decision. "We've tried sanctions since lunchtime, and they don't work," said the President. Instead, the administration will initiate a policy of "constructive engagement" with Microsoft. Microsoft's Chief Technology Officer Nathan Myrhvold said the test justified Microsoft's recent acquisition of the Hanford Nuclear Reservation from the US Government. Not only did Microsoft acquire "kilograms of weapons grade plutonium" in the deal, said Myrhvold, "but we've finally found a place to dump those millions of unsold copies of Microsoft Bob." Myrhvold warned users not to replace Microsoft NT products with rival operating systems. "I can neither confirm nor deny the existence of a radioisotope thermoelectric generator inside of every Pentium II microprocessor," said Myrhvold, "but anyone who installs an OS written by a bunch of long-hairs on the Internet is going to get what they deserve." The existence of an RTG in each Pentium II microprocessor would explain why the microprocessors, made by the Intel Corporation, run so hot. The Intel chips "put out more heat than they draw in electrical power" said Prof. E. Thymes of MIT. "This should finally dispell those stories about cold fusion." Rumors suggest a second weapons development project is underway in California, headed by Microsoft rival Sun Microsystems. "They're doing all of the development work in Java," said one source close to the project. The development of a delivery system is said to be holding up progress. "Write once, bomb anywhere is still a dream at the moment." Meanwhile, in Cupertino, California, Apple interim-CEO Steve Jobs was rumored to be in discussion with Oracle CEO Larry Ellison about deploying Apple's Newton technology against Microsoft. "Newton was the biggest bomb the Valley has developed in years," said one hardware engineer. "I'd hate to be around when they drop that product a second time." Sorry about the "spam" but this was just too good to pass up. Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: 05/31/98 01:58:40 Event(??) Date: Tue, 2 Jun 1998 09:44:25 EDT Orson Welles is not dead, he is writing script for Bill Gates!!!!!!!!!!!! _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Michael J. Roseberry" Subject: Re: SPAM Email sent to this list. Date: Tue, 02 Jun 1998 10:47:13 -0500 Group: I like the "from" suggestion that Larry mentioned. Michael J Roseberry Fort Worth, Texas, uSA Larry Cochrane wrote: > > Hi Everyone, > > Looks like we are now on a spamming list. Unfortunately that means it will > spread to other lists...First, don't hit reply! The god damn spammers are > not on this list, so sending messages back to this list does no good. If > you don't like spam Email, like most people, contact the sender. I called > them on the phone and left a VERY nasty message! > > The only thing I can do is set the mailing lists I run, PSN-L, SDRUSER, > NEWFILE and NEWEVENT, so that only members of the list can post. For most > people this will not be a problem because they only listen in or post from > one system. The problem is some people like to post from more than one > system. For those people they will need to subscribe to the list from the > systems they will be posting from, or wait until you get to the system that > is subscribed. > > Another way around this; The mailing server will use the "From:" address to > determine where the message came from. If you post from another system, you > can change this setting to use the subscribed email address for your message. > > -Larry Cochrane > Redwood City, PSN > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian Subject: Re: SPAM Email sent to this list. Date: Tue, 02 Jun 1998 14:48:18 -0700 I guess the whole problem of Spam is one we have to face in the wild west of cyberspace. I'd sure like to do some guerilla retaliation, though. Is there a program out there that would a) send repeated messages to a given e-mail address and, at the same time b) shield the retun address of the sender? :> > > Larry, > As long as nobody else is using the service, maybe a good place to start is > by excluding all hotmail.com addresses (if it can be done). I get them from > all kinds of sources (not just this list) and inevitably that damned domain > name is always there!!! > > ****************************************************************************** > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ > http://www.public.asu.edu/~hernlund/ > > "Enlightenment is man's emergence from his self-imposed immaturity. > Immaturity is the inability to use one's understanding without guidance from > another. This immaturity is self-imposed when its cause lies not in lack of > understanding, but in lack of resolve and courage to use it without guidance > from another. Sapere Aude! "Have courage to use your own understanding!"- > that is the motto of enlightenment. > -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" > > ****************************************************************************** > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: ORFEUS: software ftp site Date: Tue, 02 Jun 1998 12:54:48 -0700 I found this site while looking for a specific program someone (Larry C.) mentioned. I'm going to download and try some programs right now. http://bswor6.knmi.nl/other.services/software.html ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: PSN- SPAM is not a Sweet Meat Date: Tue, 02 Jun 1998 16:26:18 -0700 (MST) On Tue, 2 Jun 1998, Walt Williams wrote: > Hotmail.com, as best as I can discern is an ISP that > collects 'from and to' e-mail addresses of their users, and sells > these e-mail lists to SPAMMERs. hotmail.com is owned and run by Microsoft Corp. ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Ditto Geophones! Date: Tue, 2 Jun 1998 17:18:26 -0700 (PDT) Hello All: I've got one of those units (MD-81) and want to know how deep I should bury it underground? I will be putting it into a sealed PVC pipe. Also, what kind of a material should I use inside of the pipe for ballast. I thought of self expanding foam, except I figured it would dampen the seismic waves too much. Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: burying geophones Date: Tue, 2 Jun 1998 20:00:26 -0500 (CDT) Frank, For years we have been using a 1 meter length of 3" schedule 40 PVC pipe with a cemented on bottom cap and a top cap sealed with self-vulcanizing rubber tape (so it can be reopened). The geophone (usually an L4-C) is in the bottom, and can be surrounded with fine dry sand. The amplifier and telemetry electronics cannister fits in the upper portion of the pipe, and the power and signal leads go through a waterproof feedthrough fitted to the top cap. (you can see a short "pipe vault" used for the telemetry for a horizontal seis in the "mug shot" on my web page). We install the pipe so that the top is about 30 cm down from the local ground surface. Then we put one of those irrigation valve boxes over it to make it easier to dig up. Alternately, we have made a cover from the bottom half of 2-liter orange soda bottles to make relocating the top of the pipe easier. I usually have to open the pipe to replace the desiccant about every two years. To install it perfectly vertical, we have an alternate top cap with a bulls-eye bubble level fitted to a machined flat surface in the center (it also keeps dirt out while the pipe is being planted). I hope these ideas help. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: PSN- New Lehman Construction Date: Tue, 02 Jun 1998 21:23:01 -0500 RADIOTEL@....... wrote: > > Jim Hannon > As indicated in my previous post which I forgot to indicate what I was > referring to which was your offer to place a drawing on your web site - such a > drawing would certainly be informative. I apoligize to PSN participants for > my forgetfullness. > Jim Allen > Cerritos, Calif. Jim, Here is a sketch of an upper pivot arrangment for a Lehman. http://soli.inav.net/~jmhannon/pivots.html The upper pivot support is a length of 1.5 inch square steel tubing with the top cut at the same angle as the wires. A piece of angle iron is welded to the top of the tubing to make the L bracket. The yoke is half of an aluminum ring with a hole drilled for the PC board drill pivot. A grove cut in the outside of the ring guides the wire around the yoke. I hope this helps. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: PSN- New Lehman Construction Date: Wed, 3 Jun 1998 01:03:43 EDT Jim Hannon The drawing that you placed on your web site makes it very clear how the suspension on your seismometer is configured. It seems to be basically simular to the professional ones that Sean-Thomas referenced and now has a diagram on his site. Much appreciation to the both of you. I will use this type configuration in the unit I am building. Jim Allen Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: CENTRAL ITALY Date: Wed, 3 Jun 1998 09:01:43 +0200 23.11 UTC MB 4.5 Local.: CENTRAL ITALY Station: OSIMO 68 km est from epicenter Francesco Nucera - I.ES.N. PSN-ITALY
23.11 UTC
MB 4.5
Local.: CENTRAL ITALY
Station: OSIMO 68 km est from=20 epicenter
 
Francesco Nucera  - I.ES.N.=20 PSN-ITALY
From: "d.sevold" Subject: optimal coil for lehman Date: Wed, 06 May 1998 09:26:28 Hello list I have wound a coil for my new lehman seismo, using the high tension windings from two auto ignition coils. The wire is easily salvaged, and was wound on a teflon tape spool. The internal resistance is about 12.5k, wire size is .003", or 40 awg. A led lights up when connected to the coil and it is dragged through the magnet field. The magnet comes from an old radar transmitter. By building up a new coil form I could easily fit twice as many turns between the poles of the magnet. Does anyone know what the optimal coil for the lehman would be ? Thanks Dean Sevold _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: L4-C 1 hz seis Date: Wed, 3 Jun 1998 12:00:45 -0500 (CDT) Greg, New L4-C 1 hz vertical seismometers cost about $1000 today from Mark Producrs. I don't know of any alternate source. We are still using them for the short period telemetered network. Maybe someone on the PSN has seen them at a better price. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Magnets Mystery Date: Wed, 03 Jun 1998 12:12:18 -0700 Meredith, I recently come into possession of a defunct microwave oven. With a bit of persuasion, I liberated a set of donut magnets almost identical to the description of your "magnet mystery." I then set out to duplicate your results. Nothing interesting with a straight piece of rebar tie wire, as you had noted. I then fabricated a pseudo- jumbo paperclip out of said same wire per dimensions you mentioned. Lo and behold, interesting results. I want to confirm that I understand your setup. I attached a joint, essentially a universal joint in action, at one end of the clip, then inserted the clip down the donut hole. When most of the way in, the clip would center its free end. The end I was holding had to be held centered with the "universal joint". If I tried to free dangle it with virtually any length of string, it was unstable and would attach itself to the sidewall. Am I correct in duplication, or were you able to get a free suspension centering action? Now, step two was the interesting variation. I took a single piece of wire as long as the clip and repeated the experiment. Unstable. Next I modified the wire in the same way a paperclip is different. That is, a paperclip has double the amount of wire in the center 1/3 of the clip. So I took another straight piece of wire about 1/3 the length of the first piece and taped it to the first piece midway. Eureka! The magic action reappears, and the wire is stable in the center. At this point I think we need a FEM package capable of solving non-linear saturation effects. My suspicion is that the iron is saturating in the high fields of this setup and that this centering effect depends on the requirement of a higher magnetizing force being necessary where the wire is doubled. This would lead to an interesting distortion of the field lines down the hole. Anyway I enjoyed the exercise. Where do we go from here? Think we can make a UFO propulsion unit next? Charles R. Patton patton@........................... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- This SPAM is definately not a Sweet Meat Date: Wed, 3 Jun 1998 17:02:25 +0000 John, Well, that explains it. Walt ------- Forwarded Message Follows ------- Date: Tue, 02 Jun 1998 16:26:18 -0700 (MST) From: John Hernlund Subject: Re: PSN- SPAM is not a Sweet Meat To: PSN-L Mailing List Reply-to: PSN-L Mailing List On Tue, 2 Jun 1998, Walt Williams wrote: > Hotmail.com, as best as I can discern is an ISP that > collects 'from and to' e-mail addresses of their users, and sells > these e-mail lists to SPAMMERs. hotmail.com is owned and run by Microsoft Corp. ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: James Lehman Date: Wed, 3 Jun 1998 20:32:25 -0400 Hi gang, The '79 Sci. Am. article on the Lehman seismograph attributed the desig= n to James D. Lehman at James Madison U. in Harrisonburg, VA. Hotbot quick= ly gave me the URL of the school (www.jmu.edu/). This site is very attracti= ve and complete. He is listed (with a photograph) in the Physics department along with h= is 'phone no. I called him to see if he is still interested in seismology. = We had a long chat and he still runs his rig with a strip chart recorder.= = He is especially interested in microseisms. = He modestly says that he never refers to the design as a Lehman but I think that he faces an impossible job if he ever tries to get us to chang= e. He sez that he monitors the PSN e-mail and has been in touch with Larry= in the past. His e-mail address is lehmanjd@........ Bob Barns Why do psychics have to ask you for your name? _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Rex Klopfenstein Jr Subject: SG Data for WinQuake32 Date: Wed, 3 Jun 1998 20:47:56 -0400 I am wondering if anyone has data that is compatible with WinQuake32 = from a SG seismometer. Specifically, I am looking for data recorded in = the Midwest from distant events. I am considering building a SG = seismometer and would like to see what others have recorded. I live in = Bowling Green just south of Toledo Ohio which is in a relative = geological quit area. We are however located on the Bowling Green Fault Zone. I believe that = this is an old and relative inactive fault. One can actually see the = fault in the bed of the Maumee River during the summer when the water = level is low. Also, it can be seen in several small creeks that have = followed the fault. Most of the fault is buried under glacial deposits. = The Bowling Green Fault Zone has made a little local press lately and = a couple of geophysicist are arguing what will happen when the New = Madrid Fault lets go. Rex Klopfenstein Jr Bowling Green, OH From: meredith lamb Subject: Re: Magnets Mystery Date: Wed, 03 Jun 1998 22:30:11 -0600 Charles R. Patton wrote: > I want to confirm that I understand your setup. I > attached a joint, essentially a universal joint in action, at one end of > the clip, then inserted the clip down the donut hole. When most of the > way in, the clip would center its free end. The end I was holding had > to be held centered with the "universal joint". If I tried to free > dangle it with virtually any length of string, it was unstable and would > attach itself to the sidewall. Am I correct in duplication, or were you > able to get a free suspension centering action? Yes, that is the configuration I had. No, I had no free suspension action. > Now, step two was the interesting variation. I took a single piece of > wire as long as the clip and repeated the experiment. Unstable. Next I > modified the wire in the same way a paperclip is different. That is, a > paperclip has double the amount of wire in the center 1/3 of the clip. > So I took another straight piece of wire about 1/3 the length of the > first piece and taped it to the first piece midway. Eureka! The magic > action reappears, and the wire is stable in the center. At this point I > think we need a FEM package capable of solving non-linear saturation > effects. My suspicion is that the iron is saturating in the high fields > of this setup and that this centering effect depends on the requirement > of a higher magnetizing force being necessary where the wire is > doubled. This would lead to an interesting distortion of the field > lines down the hole. Anyway I enjoyed the exercise. Where do we go > from here? Think we can make a UFO propulsion unit next? FEM....is that like a gaussmeter? The, where do we go from here, is somewhat of a mystery, isn't it-ha. My original idea was too perhaps use this bottom flux field, in perhaps a vertical seismo, as a free mechanical amplifiying mechanism. I.E., from a centering position the "paperclip" bottom would be zero, and any up or down movement, would be a deflection off to the side of the donut hole and perhaps more overall "amplification" than occurs naturally. Imagine that it may need a "universal joint" which only flexs in 2 directions....or maybe only one direction is necessary. Perhaps a mirror on the bottom of the "paperclip" with light and photocell or phototransistor or whatever. I suppose the mass of the seismo would have to be significant and use the strong pull as a form of "spring", some 90 degrees aside from the donut magnet pull.....kind of a balanced mechanism, with stops created for both directions of movement. It would perhaps be grossly unstable, but it sounds vaguely somewhat feasible-ha. Who knows...with good feedback, it maybe more interesting than suspected and perhaps the "free spring" will have less drift than the real metal spring. Interesting.....? Sometimes....it seems amazing that about every seismo has to have a magnet there in one form or other, in the sensor or feedback. Suspect the boom and donut feed would need a "L" shape like a carpenter square shape. The long side end could hold the mass, and the lower end of the apparatus would hold the universal joint and paper clip. I suppose it would react to everything also, earths magnetic field, barometric, and on and on-ha. The pivot for this may create horrible friction. Perhaps the "stops" could be real, small, springs attached on either side of the "L" frame near the Donut magnets, but in opposite directions. Somehow....all of this sounds very impractical.... doesn't it? Wonder if there is another form of non-contact feedback...that does NOT use a magnet? Anyway....haven't gotten back to that,... to busy with other projects for the moment...but it isn't forgotten, thanks. As for the UFO propulsion...it sounds funny, but I don't discount anything any more...some day, it may arrive. No scientist here, but I think there is alot of things left undiscovered, overlooked, or not checked out throughly. Too me, many of the things you're aware of, and doing, ...like your flux gate articles on Geo-monitor, are very interesting things that are just as important as those seen on PSN, or anywhere else. Sometimes....I wish Geo-monitor was internet accessible...somewhat like PSN in rough format....... Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Re: James Lehman Date: Thu, 04 Jun 1998 05:07:19 -0700 I think that is really interesting detail. I'll save your note for future reference. Thanks-- Regards, Steve Hammond PSN San Jose robert barns wrote: > > Hi gang, > The '79 Sci. Am. article on the Lehman seismograph attributed the design > to James D. Lehman at James Madison U. in Harrisonburg, VA. Hotbot quickly > gave me the URL of the school (www.jmu.edu/). This site is very attractive > and complete. > He is listed (with a photograph) in the Physics department along with his > 'phone no. I called him to see if he is still interested in seismology. > We had a long chat and he still runs his rig with a strip chart recorder. > He is especially interested in microseisms. > He modestly says that he never refers to the design as a Lehman but I > think that he faces an impossible job if he ever tries to get us to change. > He sez that he monitors the PSN e-mail and has been in touch with Larry > in the past. His e-mail address is lehmanjd@........ > Bob Barns > > Why do psychics have to ask you for your name? > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: burying geophones Date: Thu, 4 Jun 1998 01:13:02 -0700 (PDT) Hi Sean: Thanks for the information. That is what I'm going to do... Use the sand at the bottom. Where can I get some of the self-vulcanizing rubber tape from? The foam idea was from where I work. We build railroad grade crossing predictors and use narrow band shunts to terminate the ends and feed points for our signal. The shunts are installed inside of black sewer pipe and sealed with plastic pipe cement. For my geophone, I prefer to keep it easy to open. >Frank, >For years we have been using a 1 meter length of 3" schedule 40 >PVC pipe with a cemented on bottom cap and a top cap sealed with >self-vulcanizing rubber tape (so it can be reopened). The geophone >(usually an L4-C) is in the bottom, and can be surrounded with >fine dry sand. The amplifier and telemetry electronics cannister >fits in the upper portion of the pipe, and the power and signal >leads go through a waterproof feedthrough fitted to the top cap. >(you can see a short "pipe vault" used for the telemetry for a >horizontal seis in the "mug shot" on my web page). > >We install the pipe so that the top is about 30 cm down from the >local ground surface. Then we put one of those irrigation valve >boxes over it to make it easier to dig up. Alternately, we have >made a cover from the bottom half of 2-liter orange soda bottles >to make relocating the top of the pipe easier. I usually have >to open the pipe to replace the desiccant about every two years. > >To install it perfectly vertical, we have an alternate top cap >with a bulls-eye bubble level fitted to a machined flat surface >in the center (it also keeps dirt out while the pipe is being >planted). > >I hope these ideas help. >Regards, >Sean-Thomas > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Nuke Date: Thu, 4 Jun 1998 12:32:50 +0000 et al, Seismic Pakistani nuke info: www.envirolink.org/issues/nuketesting/hew/Pakistan/PakTest5-28-98.txt http://www.envirolink.org/issues/nuketesting/hew/ Map & seismic data: http://www-seismo.hannover.bgr.de/nucimg/aktuell.html Walt, 98.06.04 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: electrostatic force Date: Thu, 4 Jun 1998 16:06:47 -0500 (CDT) Meredith, You asked about another force feedback that does not use a magnet. The continuously recording gravimeter that I operate here uses electrostatic force applied to a capacitive plate to produce a calibration of the gravimeter. The plates are about 2 cm x 2 cm, separated by about 1 mm, A zener regulated voltage of 52 volts produces a force of 98.7 microgals. The force applied is F = K * E^2 / d^2, where K includes the plate area, E is the voltage, and d is the spacing. (I don't know what else is included in K). Electrostatic feedback is not used in VBB instruments because it is too weak to handle reasonable values of mass at short periods. It has been used for years in force-fedback gravimeters, that have natural periods of 20 seconds or more. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: coil for lehman Date: Thu, 4 Jun 1998 22:40:52 EDT I am in the process of completing a Lehman seismograph. I plan to use two identical coils (one for the signal and one for damping) and two identical magnets. Question: to make the damping coil damp the boom swing I understand all I have to do is place an appropriate resistor across the coil wire ends. Is this correct or am I missing something? Jim Allen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Lehman damping Date: Thu, 4 Jun 1998 23:55:10 -0500 (CDT) Jim, Here is what I have posted previously on the subject: Re electromagnetic damping The drawback of resistive damping, other than the loss of part of the signal from the coil (made up for with less attenuation in the recording circuitry) is that it is dissipative, and makes noise. This is the reason it is not used in the VBB configuration, where the damping is a dynamic process in the feedback loop. The noise from the damping resistor is primarily Johnson or thermal noise, which can be estimated, as well as 1/f noise. However, most moving coil seismometers do use resistive damping. To calculate the value of the damping resistor to be used, one first has to know or determine the open circuit damping, called Bo. It is the mechanical air-dashpot function of the coil movement, and is often listed in the specifications for the seismometer. For most seismometers, it ranges from 0.2 to 0.4, where a value of 0.8 is for critical damping. It can also be determined from the logrithmic decrement of the free oscillations of the undamped seismometer. Then the motor constant and resistance of the main coil have to be determined or found in the specifications. The electromagnetic damping Bem needed is determined by subtracting the Bo from the required total Bt. Bem = Bt - Bo Then the damping resistor is calculated by: Bem = G^2 / (2*omega*M*(Rs + Rd), or Rd = [G^2 / (Bem*2*omega*m)] - Rs Where Bem is the electromagnetic damping, G is the main coil constant, omega is the angular frequency, equivalent to 2*pi/Tn, where Tn is the natural period, and M is the mass. For an L4-C, with a 5500 ohm coil, with G = 270 V/m/sec, Bo = 0.27, we want Bt to be 0.77, so Bem = 0.5, M = 1 kgm, omega = 2*pi, we calculate a damping resistor Rd of 6102 ohms for critcal damping. For an S5000 Long Period Seis, with a 500 ohm coil, G = 100 V/m/sec, Bo = 0.1, we want a flatter response with Bt = 1, so Bem = 0.9, omega = 2*pi/15 (seconds), M = 11 kg, we calculate a resistor of 705 ohms for Bt = 1. For an HS-1 4.5 hz geophone with a 1250 ohm coil, G = 41 V/m/sec, and Bo = 0.28; we want critical damping with Bt = 0.8, so Bem = 0.52, omega = 2*pi*4.5 (hz), M = 0.022kg, we calculate Rd = 1348 ohms. This method of damping is the only method currently being used on velocity sensors. The method is so exact that often the resistor for Rd is installed inside the smaller geophones at the factory. Metal-film resistors are used for lower noise. When one is connecting a seismometer to an amplifier with a low input impedance Ra, that value is in parallel with the seismometer, so must be taken into account. So if Ra = 10k ohms, and Rd is to be 5k ohms, the actual resistor to be used is Rs = Rd*Ra/(Ra-Rd), or in this case Rs = 10k ohms. Generally very high input impedance amplifiers are not used because of noise considerations, so this detail is often overlooked. Unfortunately I have no idea what the constants for a Lehman might be. I note that the coil is 1/4 pound of # 34 wire which has 8310 feet per pound and 2168 ohms per pound at 20 deg.C. So assuming the coil is about 500 ohms, I would try a damping resistor of about 1000 ohms, unless you already know the constant G of the main coil and can calculate the value. With this type of damping, the response should be flat to velocity from roughly the natural period to whatever low-pass filter you have in your amplifier. (BTW another place to check to see if the shorter p-wave phases are being filtered out). Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: coil for lehman Date: Thu, 04 Jun 1998 23:02:33 -0700 (MST) On Thu, 4 Jun 1998 RADIOTEL@....... wrote: > I am in the process of completing a Lehman seismograph. I plan to use two > identical coils (one for the signal and one for damping) and two identical > magnets. Question: to make the damping coil damp the boom swing I understand > all I have to do is place an appropriate resistor across the coil wire ends. > Is this correct or am I missing something? > Jim Allen Jim, Your idea could work, however there are probably better ways. What I do with two coils is to connect the coils in series to get a higher potential output for the seismometer. What you then do with the output is to connect a resistor in parallel with your amplifier/recorder. This has the effect of creating a current path which feeds back into the seismometer. When you allow the current to flow back into the coils you create a self-inductance in the coils, which is essentially a magnetic field which can then impede the motion of the magnets on the boom of your seismometer, and thus damps it. Plus you get a larger voltage output from your seismometer cutting your amplification needs in half. I would recommend using a variable resistor (rheostat or whatever) that has a large resistance range (0 - 1 Kohm) and has many turns. This will allow you to fine tune your damping as much as possible. Good luck! ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Lehman damping Date: Thu, 04 Jun 1998 23:17:18 -0700 (MST) On Thu, 4 Jun 1998, S-T Morrissey wrote: > The drawback of resistive damping, other than the loss of part > of the signal from the coil (made up for with less attenuation > in the recording circuitry) is that it is dissipative, and makes > noise. This is the reason it is not used in the VBB configuration, > where the damping is a dynamic process in the feedback loop. The > noise from the damping resistor is primarily Johnson or thermal > noise, which can be estimated, as well as 1/f noise. Yes, I have seen the noise from some resistors, however they are generally more sensitive to higher frequencies (>1kHz) because the manifestation of the flaws in a resistor is to make it also have a residual capacitance and in some types of resistors also an inductance. Theoretically the capacitance is a result of heterogeneity setting up small electric fields in the same manner as a capacitor. The well-sortedness of the heterogeneities determines the range of capacitance values found in a resistor. These capacitance values can be found using impedance spectroscopy, but the effects can be removed only with a controlled input potential. The wire wound type resistors have few heterogeneities and thus less capacitance... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Gravity gradiometry Date: Thu, 04 Jun 1998 23:23:55 -0700 (MST) This is a little off subject, but there was an article in a recent Scientific American about gravity gradiometry. The article wasn't very descriptive, but the topic is intriguing. - Does anyone know of any good references on the theory of gravity gradiometry??? - Does anyone know much about the availability of good gradiometers??? Any help would be appreciated... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Frank Cooper" Subject: Frank Cooper's new home page Date: Fri, 5 Jun 1998 12:39:15 -0500 Hi all, I have posted eight pictures of my Lehman and associated equipment on my new home page. My home page is a very rough draft at this time with many needed improvements. The major purpose of the page is to share the pictures. It may take a few minutes to download. Frank Cooper, Friendswood, Texas, USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Frank Cooper" Subject: Home Page - forgot url Date: Fri, 5 Jun 1998 12:42:54 -0500 Hi All, Sorry I forgot to include the url. It is HTTP://freeweb.pdq.net/fxc/ Frank Cooper. Friendswood, Texas, USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: Frank Cooper's new home page Date: Fri, 05 Jun 1998 12:39:10 -0600 Frank, Hey!....thanks for the views of your stuff...nice to see someone elses equipment. You have frequent event posts so it seems to be working well. My event buzzer just went off at 18:32 UTC or so...and I may see your record of it soon....wherever it is. Think it is not a teleseism. Is your seismo on the basement floor? Any chance of a photo on the page of some of those seismograms on the wall? Thanks for the new page and photos and notes. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: coil for lehman Date: Fri, 05 Jun 1998 07:05:09 >Jim, > Your idea could work, however there are probably better ways. What I do >with two coils is to connect the coils in series to get a higher potential >output for the seismometer. I was wondering what is your type of magnet setup. Could you come up with a pix or drawing to look at. I would like to try your setup on mine. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: coil for lehman Date: Fri, 5 Jun 1998 21:52:34 EDT Norman Davis I am planning to use two magnets mounted on opposite sides of the boom. Each magnet will be attached (epoxied) to oposite sides of a large nut that will be screwed onto a 5/8 inch diam. boom that is 30 inches long. There will be two 750 ohm relay coils ( one on each side of boom that will fit into magnets. An alternative is I have found some very powerful rare-earth neodymium magnets that were I believe used in computer disk drives. Each magnet set consist of two flat metal mountings, each with a magnet facing each other with a space in between. These magnets are only $3.00 per set from "All Electronics" in Los Angeles, Calif. (USA) Toll Free Pho. # 1-800-826-5432 - They will send you a free catalog with pictures). The magnet part CAT# MAG-32. The problem is the space between the magnets in only about 1/4 inch and would have to be enlarged by removing the existing two spacers that separate the magnets and inserting wider spacers. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Magnet mounting Date: Sat, 6 Jun 1998 01:02:11 -0500 (CDT) Jim, I notice your plans about mounting magnets to the boom. I want to chime in and suggest that this creates lots of problems, making the seis a magnetometer of sorts that interacts with all ferrous materials, moving or fixed, as well as geomagnetic storms. Seismic instrument designers long ago found this out, and mounted the magnets to the frame, and the coils to the boom, even though this requires the extra effort of making fine coiled wire jumpers across the hinge or pivot to convey the signals. The fine (#44) wires do not add noise if they are loose and do not touch each other. Even the $$$$ STS-1 seises use them. I have 5 pairs at the hinge of the STM-8: one for the force coil, three for calibration coils, and one pair for the zero centering motor, which is mounted on the moving flange of the hinge. Another advantage of mounting the magnets to the frame is that you can use large magnets of wierd geometry, even the 350lb neodymium magnet Meredith suggested for his April 1 design. Look at the drawing I just posted of the S5000H. It clearly shows the large right side magnet mounted to the cast aluminum base, and the hollow coil mounted to the side of the mass. It also shows the wiring and terminal strips for the jumpers across the lower pivot. When I get a chance, I'll try to get a photo of the seis I am still operating. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: coil for lehman Date: Sat, 06 Jun 1998 07:30:54 -0500 RADIOTEL@....... wrote: > > Norman Davis > I am planning to use two magnets mounted on opposite sides of the boom. Each > magnet will be attached (epoxied) to oposite sides of a large nut that will be > screwed onto a 5/8 inch diam. boom that is 30 inches long. There will be two > 750 ohm relay coils ( one on each side of boom that will fit into magnets. An > alternative is I have found some very powerful rare-earth neodymium magnets > that were I believe used in computer disk drives. Each magnet set consist of > two flat metal mountings, each with a magnet facing each other with a space in > between. These magnets are only $3.00 per set from "All Electronics" in Los > Angeles, Calif. (USA) Toll Free Pho. # 1-800-826-5432 - They will send you a > free catalog with pictures). The magnet part CAT# MAG-32. The problem is the > space between the magnets in only about 1/4 inch and would have to be enlarged > by removing the existing two spacers that separate the magnets and inserting > wider spacers. > I have some of these same magnets. Which I plan to use for my Lehman and also for my 3 axis design. One thing to be aware of is the nature of the magnetic field associated with these magnets. Each half of the assembly has a North and South pole facing the opposite pole on the other half. The magnetic flux has a complete path that goes across the air gap through one half of the magnet, across to the other half through the backplate, across the air gap on the other side, etc. Since air has a lower permiability than the magents or backplate increasing the air gap will considerably reduce the amount of flux avaliable in the gap. Also if you separate them too far the flux lines will close back between the poles on each half and not cross the gap and intercept your coil. There is a trade off here between the avaliable flux and the amount of turns that you can cram in the field. Without doing the calculations I can't be sure but my gut feel tells me that winding a coil that will fit the existing gap and has the largest area inside the truns that is mechanically possible will get you the highest output. I know winding coils is difficult and so is finding the wire, but here I think it is worth the effort. One little tip here, I use superglue to keep the windings in place and make a solid coil. It is very liquid and soakes into the windings easily. (unless you have the gel type). I am also mounting the coils on the boom rather than the magnets. Even though these magnet assemblies have a fairly closed magnetic path extenal iron and magnetic field variations would add noise to the output. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shansen@........ (shansen) Subject: Scientific American's Microbarograph Date: Sat, 6 Jun 1998 12:52:21 -0400 (EDT) Hi all, Frank Cooper and I recently exchanged some email concerning the microbarograph that was presented in a recent Scientific American "Amateur Scientist" column. We thought the list might like to have an opportunity to comment as well. By the way, I've done a lot of refinement on my capacitance manometer based instrument and will be reporting on the changes in the near future. Steve Hansen ***************** Hi Steve, I am sure you must have seen "The Amateur Scientist" column in the May issue of Scientific American regarding the construction of a microbarograph? I am considering building it. Is the design any good? How do the atmospheric waves appear on a computer screen? Is it gradual rise and then a gradual fall --- i.e. almost a straight line? The article calls the excursions of the atmosphere "typically just a few millibars." The author refers to them as "subtle tsunamis." Thanks, Frank Cooper Hi Frank, Yes, I saw the article. I thought the design was rather ingenious but I've got a few comments. The device works by changing the temp in the reservoir to maintain a constant pressure. Since it's a variable temperature device, then there is going to be some lag in the system and it may not be responsive to shorter term events. The article didn't specify the device's response characteristics, a critical factor. Microbarographs usually operate with passbands in the range of 0.003 Hz to a few Hz. For natural events (acoustic gravity waves) the high frequency cutoff is generally around 0.1 Hz or thereabouts. (Since the bottle is sealed, there is no low end cutoff.) The test ban treaty devices operate in the higher end of the band. Thermal uniformity in the reservoir would be enhanced by filling the reservoir with copper (or stainless) scouring pads. I don't think the article mentioned this. Most microbarographs have a leaky reservoir instead of the sealed one that this design has. The leak gives the device it's low end rolloff and makes it immune to the normal long term (large) atmospheric pressure changes due to normal meteorological processes. The Scientific American device is more like a high resolution barometer in that it will record all changes. Since normal barometric variations can be of magnitudes of 10s of millibar, the smaller events may get lost. An option here would be for some additional electronic filtering and/or scaling. So, my quick summary is that this appears to be an interesting device that can probably produce some interesting results. The fact that it's pretty cheap to build would invite one to spend a pleasant day or so building it just to see what it can do. I do wish that Sci Am had included a typical output plot - that would say a lot. There are some examples of microbarograph results on the Web. A good one is from a microbarograph network in Bavaria. This is at http://www.pa.op.dlr.de/cleocd/microbar/s.htm. Also check out Chris Hayward's page at http://www.geology.smu.edu/~hayward. I think I found this one via the PSN. Best regards, Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: coil design Date: Sat, 6 Jun 1998 11:58:48 -0500 (CDT) Re. coil constants: first: the RS speakers: My original speaker #40-1349 has a constant of 12.988 N/A. The Beta instrument (also a 40-1349) is 11.815 +,-0.02 N/A. Both were measured as installed on the seismometer, using the displacement detector as a null indicator (+.- 5 microns), and 1 and 2 gram weights to balance with a current read by a 4.5 digit DMM. About 2mm of the coil is visible above the face of the magnet pole. I have also found some indication of mutual inductance (transformer coupling) between my 5-turn coils and the main coil, even though the cal coils are about 2mm above the main coil. The problem starts to show up when using sine wave calibrations above 1 hz or so. THis problem could be serious if the two coils fully overlap. Some of the mysteries of coil design are explained in the first appendix of the BSSA article "Limits of Sensitivity of Inertial Seismometers with Velocity Transducers and Electronic Amplifiers" by Riedesel, Moore, and Orcutt; BSSA, Vol 80, No. 6, pp 1725- 1752, Dec. 1980. THis article should be a must for those designing their own seismometer. Full coil design criteria can also be found in the handbook "Reference Data for Radio Engineers" from the ITT press. In general, the output voltage increases with the square root of the number of turns or the resistance, or a 8000 ohm coil has only four times the output of a 500 ohm coil. OR, if I wanted to double the generator constant of my speaker coil of 160 turns, it would need 640 turns. So attempting very high resistance or number-of-turns coils can be traded off with just doubling the amplifier gain. One approach is to just wind the best coil you can over a lightweight form that fits the magnet gap, and then determine the constant. THis is measured with the coil installed on the vertical seismometer, using the displacement detector as a null indicator; first the boom is balanced with the trim weights for a zero reading. Then 1 and/or and 2 gram weights are applied at the center of the coil, and then a current controlled by a variable resistor is applied through the main coil to balance the weights to the same null position. For a horizontal seis, a thread is arranged to pull sideways on the mass from a rod attached to the frame, with the length carefully set so that it makes a symmetrical V with the angle at the bottom exactly 45 degrees. Then the lateral force is half of the weight applied at the bottom of the V. Then the weight in Kgrams is multiplied by g (9.806m/sec^2) and divided by the current in Amperes to get Newtons/Ampere. (actually grams*g/milliamperes gives the same result). Another way to estimate the the constant of a coil is to count the turns and determine the strength B of the magnetic field in gauss. Estimate the length L of the winding IN CM by multiplying the # of turns by the mean circumference. Then G = B * L *10 **-6 N/A. For the 8-ohm stereo speaker I use, there are 162 turns at a mean diameter of 3.95cm, and the flyer says the field is 7500 gauss, so the constant is 15.08 N/A. When I determine the constant by force balance, I get a constant of 12.988 N/A, which probably means that not all the winding is within the magnetic field, which is the case. (The length L can also be determined by knowing the wire size and the resistance and looking up the ohms/foot value in a table of wire parameters). This second method can be applied to the Lehman coil if the strength of the magnetic field can be determined. Conversely, if you determine G by force balance, then B can be calculated. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: Scientific American's Microbarograph Date: Sat, 06 Jun 1998 13:41:17 -0500 Friends, About a year ago I posted some instructions to this list on how to build a microbarograph similar in some aspects to that described in the recent Scientific American article. My design was more conventional in that I used a slow leak rather than thermal feedback to keep the instrument from going off range. I used a a slightly different version of U-tube and optical occlusion detector. In essence, my method, which seemed to work quite well, (and with which I made records of nearby storms with my then new DATAQ), consisted in putting a gallon glass jug reservoir in a styrofoam cooler, attaching a two hole stopper with one leading to a slow leak made by adjusting a clamp on some cotton inside a section of aquarium tube. The other section of tube leads to a melting point capillary bent into a U-shape and filled with a drop of blue food coloring, water, detergent and sometimes glycerine. The air in the jug in the cooler stays at reasonably constant temperature, and slow changes are equalized by the slow but adjustable leak. On the other hand, the rapid but still subsonic air pressure changes that we are assumed to be mainly interested in are reflected very sensitively by a change in the meniscus level. Since the liquid was blue, this was very well adapted to absorb red light passing between an LED and photransistor, especially when the other possible light transmission paths are blocked off. The U-tube (actually bending it 90 degrees is more practical) and optical detector assembly was mounted so that it could be adjustably tilted to recenter the liquid column meniscus exactly into proper relation to the optical detector. The aquarium tubing can be softened by heating and stretching so it makes a good joint with the melting point capillary. If we think about the math, a melting point capillary has a diameter of about one millimeter, and the sensor can be made reasonably linear over about one millimeter of fluid travel. Thus one microliter change of volume in a fluid meniscus with undetectably little hysteresis and very little back pressure easily results in a full scale change in the light sensor and thus the output chart reading. Its easy to see that since the gallon reservoir holds about four million microliters, an extremely small change in air pressure gives easily detectable results. The real question is how to put this kind of instrumental data to good use. They might pick up the chacteristic signature of tornados with a little number crunching--that might be one of the best uses. They are very good for storm fronts and high level wind gusts, etc. But generally the weatherman can tell you more. I think that by putting such sensors, which aren't that much trouble to build as described, a quarter of a mile apart they could be used to triangulate the direction of disturbances. They are also used to detect stuff like nuclear blasts or even mining blasts hundreds of miles away. --Yours, Roger At 12:52 PM 6/6/98 -0400, you wrote: >Hi all, > >Frank Cooper and I recently exchanged some email concerning the >microbarograph that was presented in a recent Scientific American >"Amateur Scientist" column. We thought the list might like to have >an opportunity to comment as well. > >By the way, I've done a lot of refinement on my capacitance manometer >based instrument and will be reporting on the changes in the near future. > >Steve Hansen > >***************** > >Hi Steve, >I am sure you must have seen "The Amateur Scientist" column in the May >issue of Scientific American regarding the construction of a >microbarograph? I am considering building it. Is the design any good? >How do the atmospheric waves appear on a computer screen? Is it gradual >rise and then a gradual fall --- i.e. almost a straight line? >The article calls the excursions of the atmosphere "typically just a few >millibars." The author refers to them as "subtle tsunamis." >Thanks, >Frank Cooper > > >Hi Frank, > >Yes, I saw the article. I thought the design was rather ingenious but >I've got a few comments. > >The device works by changing the temp in the reservoir to maintain a >constant pressure. Since it's a variable temperature device, then >there is going to be some lag in the system and it may not be >responsive to shorter term events. > >The article didn't specify the device's response characteristics, a >critical factor. Microbarographs usually operate with passbands in >the range of 0.003 Hz to a few Hz. For natural events (acoustic gravity >waves) the high frequency cutoff is generally around 0.1 Hz or thereabouts. >(Since the bottle is sealed, there is no low end cutoff.) The test ban >treaty devices operate in the higher end of the band. > >Thermal uniformity in the reservoir would be enhanced by filling the >reservoir with copper (or stainless) scouring pads. I don't think the >article mentioned this. > >Most microbarographs have a leaky reservoir instead of the sealed one >that this design has. The leak gives the device it's low end rolloff >and makes it immune to the normal long term (large) atmospheric pressure changes >due to normal meteorological processes. The Scientific American device >is more like a high resolution barometer in that it will record all changes. >Since normal barometric variations can be of magnitudes of 10s of millibar, >the smaller events may get lost. An option here would be for some >additional electronic filtering and/or scaling. > >So, my quick summary is that this appears to be an interesting device that >can probably produce some interesting results. The fact that it's pretty >cheap to build would invite one to spend a pleasant day or so building it >just to see what it can do. > >I do wish that Sci Am had included a typical output plot - that would >say a lot. > >There are some examples of microbarograph results on the Web. A good one >is from a microbarograph network in Bavaria. This is at >http://www.pa.op.dlr.de/cleocd/microbar/s.htm. Also check out Chris Hayward's >page at http://www.geology.smu.edu/~hayward. I think I found this one via >the PSN. > >Best regards, > >Steve > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: Magnet mounting-Lehman design Date: Sat, 6 Jun 1998 19:19:01 EDT Sean-Thomas John Hernlund Jim Hannon Other list members I appreciate the input you provided regarding my proposed magnet mounting and coils for a Lehman seismograph. Based on your recommendations, I am changing my plans and will construct my lehman as follows: 1) 30 X 5/8 inch all-tread boom with last 5 inches of boom(which hold a bracket attached to two coils) made out of brass so it will not interact with magnet. 2) Two 780 ohm coils on bracket attached to brass end of boom that will interact with a 3 X 3.5 inch surplus (very strong but not as big as the 350 lb one proposed by Meridith) magnet with a 1 inch by 3 inch opening which the coils will partially fit in. Arrangement will be simular to setup used by Frank Cooper -"HHP://freeweb.pdq.net/fxc/ " 3) Boom support will be simular to the Seismograph drawing on Sean-Thomas's web-site with one long oval of guitar string going from one side of bracket attached to boom up to top of mast and return to bracket on other side of boom. A brass air cylinder clevis bolted to mast at a 41 degree angle will be utilized to wrap guitar string around at top of mast. 4) will use two cylindical lead ingots weighing 3 pounds each for mass. 5) Open to suggestions regarding best method to damp boom swing. 6) Boom attachment to lower mast will be by a carbide circuit board drill bit inserted in end of boom and pressing against an indentation in a large hardened aircraft steel bolt head that slipos into mast with another bolt on other side of mast that can be screwed out or end for adjustment purposes. Any other recommendations would be greatly appreciated. Jim Allen Cerritos, Calif. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Just out of curiousity Date: Sat, 06 Jun 1998 17:49:46 -0700 Is there anyone using the MAX186 12 bit parallel port ADC? I stumbled onto this link and I thought someone might have converted the output data into PSN format (possible?). It probably just records raw data and not events like SDR. http://www.win.net/~radiosky/a2dmax.html Also I uploaded a picture of my first attempt at a Lehman (now labeled a prototype for convenience). I now have magnets, a coil, a turnbuckle, $30 worth of pipe for the mast and tons of nuts and washers for clamping garbage to the boom. I expect the aluminum soon and I have to buy the and melt the lead mass yet. The current mass is a rusty machined steel casting? If I have trouble finding plumber's lead I'll melt a ton of fishing weights. I'll have to dig around and find a cat protector (box ;). Pictures at: http://www.azstarnet.com/~ghost/pics.html My main page: http://www.azstarnet.com/~ghost/ My CGI/SSI/etc test page: http://www.treefort.org/~ghost/ ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: coil for lehman Date: Sat, 06 Jun 1998 12:29:45 .. These magnets are only $3.00 per set from "All Electronics" in Los >Angeles, Calif. (USA) Toll Free Pho. # 1-800-826-5432 - They will send you a >free catalog with pictures). The magnet part CAT# MAG-32. The problem is the >space between the magnets in only about 1/4 inch and would have to be enlarged >by removing the existing two spacers that separate the magnets and inserting >wider spacers. I have delt with all before. Will Check that out. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: Just out of curiousity Date: Sat, 06 Jun 1998 18:15:44 At 05:49 PM 6/6/98 -0700, you wrote: >Is there anyone using the MAX186 12 bit parallel port ADC? I stumbled >onto this link and I thought someone might have converted the output >data into PSN format (possible?). It probably just records raw data and >not events like SDR. I have been fighting this thing for months. The software that jim sky wrote is very buggy and does not work well. I get input on dead shorted inputs. Don't know where the stuff is coming from. Unless you can write your own software for this chip, it is not worth the effort. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: PSN- A Weighty Subject Date: Sat, 6 Jun 1998 18:46:35 +0000 Hello Greg, FYI, Regarding the lead mass, I found a five pound fishing (ocean) sinker at SportMart in California for $5.00. I just tyewrapped it to my boom. Cool cat. Walter, 98.06.06 =========== edited e-letter ======================== ------- Forwarded Message Follows ------- Date: Sat, 06 Jun 1998 17:49:46 -0700 From: Greg To: psn list Subject: Just out of curiousity Reply-to: PSN-L Mailing List ------->deletia<-------- Also I uploaded a picture of my first attempt at a Lehman (now labeled a prototype for convenience). I now have magnets, a coil, a turnbuckle, $30 worth of pipe for the mast and tons of nuts and washers for clamping garbage to the boom. I expect the aluminum soon and I have to buy the and melt the lead mass yet. The current mass is a rusty machined steel casting? If I have trouble finding plumber's lead I'll melt a ton of fishing weights. I'll have to dig around and find a cat protector (box ;). Pictures at: http://www.azstarnet.com/~ghost/pics.html ----->deletia<----- ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Gravity gradiometry Date: Sat, 06 Jun 1998 18:19:06 -0700 John Maybe not as theoretical as what you are looking for but I just got the most recent Electronics Now magazine and they had an article on building practical magnetometers and gradiometers. I havent't read it yet. Barry John Hernlund wrote: > > This is a little off subject, but there was an article in a recent Scientific > American about gravity gradiometry. The article wasn't very descriptive, but > the topic is intriguing. > > - Does anyone know of any good references on the theory of gravity > gradiometry??? > > - Does anyone know much about the availability of good gradiometers??? > > Any help would be appreciated... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: Scientific American's Microbarograph Date: Sat, 06 Jun 1998 21:26:02 -0500 shansen wrote: > > Hi all, > > Frank Cooper and I recently exchanged some email concerning the > microbarograph that was presented in a recent Scientific American > "Amateur Scientist" column. We thought the list might like to have > an opportunity to comment as well. > > By the way, I've done a lot of refinement on my capacitance manometer > based instrument and will be reporting on the changes in the near future. > > Steve Hansen > Steve et all, Have you been following the discussions on this on the SAS forum? I think http://web2.thesphere.com/SAS/WebX.cgi?14@............... will get you to them, otherwise you will have to start at http://web2.thesphere.com/SAS/WebX.cgi and go to Scientific American's "The Amateur Scientist" (2 folders) then "The Amateur Scientist" column (4 folders) then for 1998 (5 discussions) then Sensing Subtle Tsunamis, May (23 messages). -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Just out of curiousity Date: Sat, 06 Jun 1998 18:37:03 -0700 Hi I don't use it for seismic applications, but I use it at work to tie my parallel port to a signal conditioning box I made which has the MAX inside. I use it to measure deflections and loads/pressures. I wrote my own software using Quickbasic though. Barry Norman Davis WB6SHI wrote: > > At 05:49 PM 6/6/98 -0700, you wrote: > >Is there anyone using the MAX186 12 bit parallel port ADC? I stumbled > >onto this link and I thought someone might have converted the output > >data into PSN format (possible?). It probably just records raw data and > >not events like SDR. > > I have been fighting this thing for months. The software that jim sky > wrote is very buggy and does not work well. I get input on dead shorted > inputs. Don't know where the stuff is coming from. Unless you can write > your own software for this chip, it is not worth the effort. > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: 4 Pole Butterfly Neo's & Relay Coil combination Date: Sat, 06 Jun 1998 22:45:53 -0600 Aaaahhhhh.....the world of amateur seismology does revolve around magnets doesn't it.....ha. Anyway....I've been messing with these 4 pole butterly or wing neos off and on for awhile trying to make them more adaptable for amateur use. Jim Hannon's, Norman Davis and Sean-Thomas recent magnet and coil emails, inspired me try another configuration which seems to work fairly well. I'am using the whole magnets, and not, breaking them in half. Basically it uses a U channel iron shape, and the width is roughly the same as the width of the neo's. The height of the U channel inside is less than half the length of the neos. The spacing between the upright portions of the U channel need to be such that with the neos attached to the inside walls vertically, there is space between for the relay coil to fit sideways without touching....and of course the closer the better on output. coil movement /\ \/ s pole /// n s /// n pole /// /// magnetic center line > /// coil /// ###/// ///### n ###/// s n ///### s ####################### ####################### /// denotes side of neo ## denotes "U" iron channel cross view s denotes south pole's n denotes north pole's The coil center hole runs parallel to the magnetic junction and seems to defy the normal conflict with neos/coils cancellation. Suspect the coil is really picking up 4 fields of flux...one between the junction of the magnets, for each magnet; and 2 fields across the gap between the upper n-s, and the lower s-n gap. The coil is centered down the length of the neo's, and is not offset, as sometimes is better, and... centered in all aspects laterally also. The coil I used was a 500 ohm relay coil. It seems to deliver twice the voltage as that of a single neo with the coil run laterally over the magnetic junction. The movement of the coil is up and down as looking at the above side view. Movement towards or away of this view is not effective. Naturally the coil would need glue or epoxy or a mechanical contriveance to attach to the boom. The neo's ends are touching the bottom of the U channel assembly. However, your unit may experience variation depending on iron sizes used. Main thing seems to be to not run the magnetic center line down to the iron channel. I'am guessing that two separate assemblys would work for both the pickup for one, and the damping (and resistor), for the other as separate units fairly well. Unless you want to try one for both functions. Anyway....thats it so far. Have to say though, that its not the best combo, I've ever seen. The best was a loop coil run around the outside of a alnico "U" magnet single pole. It delivered 3 times the voltage and it is perhaps of the speaker coil class. Over the poles is better than in between in my opinion. Perhaps some day I'll try a loop over the neo's...that might be very interesting....and very strong generator I'am positive. Anyone doing this? Surplus and various outlets usually have them in a assembly. I've disassembled mine from ~ 1/16" thick metal assemblys fairly easily, usually by a light tap to the side of the neo, which pops most of them loose. Sometimes a vise can squeeze the metal and pop them also. Freezing before tapping or distorting the metal can also assist. Not all neos will survive, and it is usually dependent on the glue they use to attach to the metal. Too strong a glue and its very hard to remove them without destroying them. Too thick a metal...like 1/4" or more, makes things more difficult. Usually, I strongly prefer neo's that are chrome plated, it makes them stronger and less susceptable to breakage. Also, look for 1/8" thickness over the thinner varietys. If the neo is painted, it might well break on removal, regardless of thickness. I used a piece of oak as the contact medium, with a light tap from a small hammer. At one time, I even tried a acid on a thick samarium assembly....bye bye magnet, and it never did work. Neo magnets usually have a gray metal appearance inside, while samarium magnets look more like a bright silver appearance inside. Samarium magnets seem to be rare now...although back in the late 70's, they were the mainstay, until superceded by Neodymium magnets with their slightly stronger field. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: Hi-res microbarometer Date: Sun, 7 Jun 1998 00:22:30 -0500 (CDT) Re Microbarometers: Another way to make a very sensitive microbarometer is to install a VRDT or LVDT in an aneroid type barometer. It is an expensive arrangement, though. For years I have been making a microbarometer with an output of 100mv/millibar before amplification by installing the Schaevitz 005MHR LVDT ($100) in the Taylor thermally compensated dial barometer ($300), using the Validyne VRDT electronics module ($100). It allows in-situ calibration by turning the altitude compensation screw and watching the dial. For high resolution, the coupling pins to the dial mechanism then have to be disconnected. A 1000 second high-pass buffer amplifier removes the ambient pressure, and provides additional gain for a signal of 10mv/microbar. We test the instrument by raising it up or down a few centimeters, which produces an output in the atmospheric gradient of about 10mv/cm. We have made about ten of these. One can avoid the cost by buying the dial aneroid device at a flea market ($25) and use a VRDT and homemade electronics. This is the instrument used for the study to remove barometric noise from horizontal VBB data as outlined in the abstracts on my web page re Barometric Studies. No data is presented there, but I will post some of the results if there is an interest. Another source of data on acoustic gravity waves IS a VBB vertical sensor that is not shielded from barometric pressure. Latelely here in St. Louis the Lows have been sliding along the cold front and producing lots of symmetric pressure waves with periods from 1 to 10 minutes. I will scan a plot of one to the web site next week. Unfortunately, this output from a VBB vertical is "noise", and is not calibrated. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Brian Chesire Subject: Re: Just out of curiousity Date: Sat, 06 Jun 1998 22:23:29 -0700 The MAX 186 and just about all CMOS multiplexers have a very nasty habit--They will transfer a charge from one input to the next unless it is driven with a source impedance somewhat lower than 10K. I use 2K and eliminated that problem. Also all unused input should be tied to the analog ground point. If your using just a couple channels, try using the odd for inputs and grounding the even channels to provide some isolation. This will let you get away with a somewhat higher input resitance. Brian WA5PPO Tucson AZ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "John Krempasky" Subject: Other EQ Lists? Date: Sun, 7 Jun 1998 03:21:24 -0400 Hi, Have been subscribed for a few months, unsubscribed once for about 8 hours right before the Balleny Is. quake, and couldn't resist re-subscribing once I heard the first inklings of it....I'm always by the various first seismogram reports that people post, discussions on the mechanisms, etc. - especially when I get that info here before ANY other site on the net. HOWEVER (and I think this has been discussed before), I don't currently, and have little interest, ever, in building my own seismometer :-). And my mailbox is really getting flooded with stuff about, well, building seismometers :-). I don't mean this in a critical way, because the problem is NOT with too many people building seismometers and talking about it here, the problem is with ME. Clearly, the PSN list was started, and is mainly comprised, of private seismometer builders, and this list is a valuable resource for them. So, my basic question is, is there another list for people like me interested in seismology, earthquake mechanisms, EQ reports, tectonics, that isn't totally comprised of on the one hand, academics, or on the other hand, whacko junk science nuts? I'm merely a highly-educated Lehman (er, Layman :-). sci.geo.earthquakes is really a disaster, like the rest of USENET, anyone intelligent doesn't seem to bother with it anymore....and is either inactive or filled with junk. John Krempasky _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: shansen@........ (shansen) Subject: Re: Scientific American's Microbarograph Date: Sun, 7 Jun 1998 08:30:53 -0400 (EDT) >Jim Hannon wrote: > >Steve et all, >Have you been following the discussions on this on the SAS forum? I >think http://web2.thesphere.com/SAS/WebX.cgi?14@............... will get >you to them, otherwise you will have to start at >http://web2.thesphere.com/SAS/WebX.cgi and go to Scientific American's >"The Amateur Scientist" (2 folders) then "The Amateur Scientist" column >(4 folders) then for 1998 (5 discussions) then Sensing Subtle >Tsunamis, May (23 messages). >-- >Jim Hannon Jim, Thanks for the pointer. I looked at the SAS site a few weeks ago but didn't find that thread. Steve _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Steve Carniglia" Subject: Fw: Magnet mounting-Lehman design Date: Sun, 7 Jun 1998 09:29:26 -0700 Hi Jim.... I have just been experimenting with different types of boom arrangements. I only have a couple of different prototypes that I have built. (I have a MIG welder and oxy/acc. setup which helps with the experiementing..) Anyway, I have tried several dampener experiments and I have found that passing a copper plate thru 2 good strong magnets is the best and easiest to adjust dampener so far. I took 2 very strong square magnets and attached them to 2 "L" shaped pieces of steel so that the magnets north and south are facing each other. I bolted the plates to the main aluminum board thereby allowing for adjustment by increasing or decreasing the gap between the 2 magnets. I have the copper plate at about 22 inches from the pivot point and the pickup coil at about 27 inches. I am a rookie at seismology but the dampener seems pretty good. Best Regards Steve Carniglia KV6A Oh one comment....doesnt having 2 wires pulling down and attached to each side of the boom slightly desensitive the unit? Wouldnt 1 be better? (guess it depends how wide the boom is) -----Original Message----- From: RADIOTEL@....... To: psn-l@............. Date: Saturday, June 06, 1998 4:24 PM Subject: Re: Magnet mounting-Lehman design >>Sean-Thomas >>John Hernlund >>Jim Hannon >>Other list members >>I appreciate the input you provided regarding my proposed magnet mounting >and >>coils for a Lehman seismograph. Based on your recommendations, I am >changing >>my plans and will construct my lehman as follows: 1) 30 X 5/8 inch >all-tread >>boom with last 5 inches of boom(which hold a bracket attached to two coils) >>made out of brass so it will not interact with magnet. 2) Two 780 ohm >coils >>on bracket attached to brass end of boom that will interact with a 3 X 3.5 >>inch surplus (very strong but not as big as the 350 lb one proposed by >>Meridith) magnet with a 1 inch by 3 inch opening which the coils will >>partially fit in. Arrangement will be simular to setup used by Frank >Cooper >>-"HHP://freeweb.pdq.net/fxc/ " 3) Boom support will be simular to the >>Seismograph drawing on Sean-Thomas's web-site with one long oval of guitar >>string going from one side of bracket attached to boom up to top of mast >and >>return to bracket on other side of boom. A brass air cylinder clevis >bolted >>to mast at a 41 degree angle will be utilized to wrap guitar string around >at >>top of mast. 4) will use two cylindical lead ingots weighing 3 pounds each >for >>mass. 5) Open to suggestions regarding best method to damp boom swing. 6) >Boom >>attachment to lower mast will be by a carbide circuit board drill bit >inserted >>in end of boom and pressing against an indentation in a large hardened >>aircraft steel bolt head that slipos into mast with another bolt on other >side >>of mast that can be screwed out or end for adjustment purposes. >>Any other recommendations would be greatly appreciated. >>Jim Allen >>Cerritos, Calif. >> > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: coil for lehman Date: Sun, 07 Jun 1998 13:59:58 -0700 (MST) On Fri, 5 Jun 1998, Norman Davis WB6SHI wrote: > > Your idea could work, however there are probably better ways. What I do > >with two coils is to connect the coils in series to get a higher potential > >output for the seismometer. > I was wondering what is your type of magnet setup. Could you come up with > a pix or drawing to look at. I would like to try your setup on mine. I use this with every kind of magnet and coil set up. We had a discussion here a while back about the best kind of magnet-coil design and the basic idea is that you want the magnetic field to be perpendicular to the walls of the coil and the wires to be perpendicular to the motion of the boom's end. This insures the maximum potential output. The best kind of design is to have two rings of magnets, one smaller than the other and that the coil can move freely between. All magnets should be oriented the same so that all the north poles point outward or all the south poles point outward. To help avoid erratic flux inside the inner ring of magnets an iron cylinder can be inserted which will return the magnetic field lines to the top and bottom of the cylinders. I can post a .gif file of this if this description is not clear... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Rex Klopfenstein Jr Subject: Leveling Screw Sources Date: Sun, 7 Jun 1998 17:04:39 -0400 I am working on building a SG seismometer. What I am looking for is a = source where I can purchase fine-thread leveling screws. I would like = something in the line of 1/2" to 3/4" diameter. It would be nice if the = source also sells the mating female thread insert. I have thought about = turning the things myself, but I hate turning very fine threads!! = Anyway it would be nice to have a precision-fit thread so that there is = a minimum free play between male and female component. I have = considered using some of those really cheap micrometer heads that are = advertised. I have a feeling that these are not quite strong enough. = If I remember right, they have about 1/4" diameter shafts. Any information would be appreciated. Rex Klopfenstein, Jr. Bowling Green, OH =20 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: Re: coil for lehman Date: Sun, 07 Jun 1998 15:22:01 -0700 John Hernlund wrote: > > I use this with every kind of magnet and coil set up. We had a discussion > here a while back about the best kind of magnet-coil design and the basic idea > is that you want the magnetic field to be perpendicular to the walls of the > coil and the wires to be perpendicular to the motion of the boom's end. This > insures the maximum potential output. The best kind of design is to have two > rings of magnets, one smaller than the other and that the coil can move freely > between. All magnets should be oriented the same so that all the north poles > point outward or all the south poles point outward. To help avoid erratic > flux inside the inner ring of magnets an iron cylinder can be inserted which > will return the magnetic field lines to the top and bottom of the cylinders. > I can post a .gif file of this if this description is not clear... > > ****************************************************************************** > > John Hernlund > E-mail: hernlund@....... > WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ > http://www.public.asu.edu/~hernlund/ Yes, I for one would like to see a picture!!!! Stephen Pilot Hill _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: coil for lehman Date: Sun, 7 Jun 1998 18:26:47 EDT John Hernlund I would like to see a picture of your magnet arrangement. Jim Allen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: coil for lehman Date: Sun, 7 Jun 1998 17:47:37 -0700 (PDT) I often found when winding coils that the tension on the wire at the periphery of the coil made the coil spread out so the sides of the coil were not co-planar any more but got wider toward the edges. If I used thicker plastic for the sides it meant fewer turns of wire. I ended up using a large-ish wooden core which was about 2/3 of the diameter of the entire coil, and only wound wire on the outer 1/3. By gluing the coil sides to the wooden core it made it stiff enough to resist the outward pressure of the wire. But if anyone has other suggestions that avoid sacrificing about half of the # of turns I'd love to hear them. Ted Blank San Jose, California _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: Fw: Magnet mounting-Lehman design Date: Sun, 7 Jun 1998 18:02:39 -0700 (PDT) I was also very happy with a 1/8" solid copper plate between two magnets oriented to attract each other. Some aluminum angles and threaded rods made a handy way to adjust the distance between the magnets and thus the restoring force. Lehman's original design shows the copper plate hanging down from the boom and passing between the two magnets below the plane of oscillation of the boom. I found that this applied a torque to the boom (bad) as well as a damping force (good). So I modified it so the magnets were out to one side and the copper was mounted in the plane of swing. No more torque and a quieter signal. PS - 5 lb plumber's lead is easy to find. I drilled mine off center by accident and then found that that was a big advantage, because by rotating it around the boom you could re-balance the boom for any one-sided mountings (like that copper plate). 1/4" offset provides a *lot* of torque when it is at 90 degrees from vertical on a 5 lb mass. (I was looking at my copy of the 1979 article and it does seem to me that the hole in the weight was drilled off center...guess I got lucky) Ted Blank San Jose, California On Sun, 7 Jun 1998, Steve Carniglia wrote: > > > Hi Jim.... > > I have just been experimenting with different types of boom arrangements. I > only have a couple of different prototypes that I have built. (I have a MIG > welder and oxy/acc. setup which helps with the experiementing..) Anyway, > I have tried several dampener experiments and I have found that passing a > copper plate thru 2 good strong magnets is the best and easiest to adjust > dampener so far. > > I took 2 very strong square magnets and attached them to 2 "L" shaped pieces > of steel so that the magnets north and south are facing each other. I > bolted the plates to the main aluminum board thereby allowing for adjustment > by increasing or decreasing the gap between the 2 magnets. I have the > copper plate at about 22 inches from the pivot point and the pickup coil at > about 27 inches. > > I am a rookie at seismology but the dampener seems pretty good. > > Best Regards > > Steve Carniglia > KV6A > > Oh one comment....doesnt having 2 wires pulling down and attached to each > side of the boom slightly desensitive the unit? Wouldnt 1 be better? > (guess it depends how wide the boom is) > > > > -----Original Message----- > From: RADIOTEL@....... > To: psn-l@............. > Date: Saturday, June 06, 1998 4:24 PM > Subject: Re: Magnet mounting-Lehman design > > > >>Sean-Thomas > >>John Hernlund > >>Jim Hannon > >>Other list members > >>I appreciate the input you provided regarding my proposed magnet mounting > >and > >>coils for a Lehman seismograph. Based on your recommendations, I am > >changing > >>my plans and will construct my lehman as follows: 1) 30 X 5/8 inch > >all-tread > >>boom with last 5 inches of boom(which hold a bracket attached to two > coils) > >>made out of brass so it will not interact with magnet. 2) Two 780 ohm > >coils > >>on bracket attached to brass end of boom that will interact with a 3 X 3.5 > >>inch surplus (very strong but not as big as the 350 lb one proposed by > >>Meridith) magnet with a 1 inch by 3 inch opening which the coils will > >>partially fit in. Arrangement will be simular to setup used by Frank > >Cooper > >>-"HHP://freeweb.pdq.net/fxc/ " 3) Boom support will be simular to the > >>Seismograph drawing on Sean-Thomas's web-site with one long oval of guitar > >>string going from one side of bracket attached to boom up to top of mast > >and > >>return to bracket on other side of boom. A brass air cylinder clevis > >bolted > >>to mast at a 41 degree angle will be utilized to wrap guitar string around > >at > >>top of mast. 4) will use two cylindical lead ingots weighing 3 pounds each > >for > >>mass. 5) Open to suggestions regarding best method to damp boom swing. 6) > >Boom > >>attachment to lower mast will be by a carbide circuit board drill bit > >inserted > >>in end of boom and pressing against an indentation in a large hardened > >>aircraft steel bolt head that slipos into mast with another bolt on other > >side > >>of mast that can be screwed out or end for adjustment purposes. > >>Any other recommendations would be greatly appreciated. > >>Jim Allen > >>Cerritos, Calif. > >> > > > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: coil for lehman Date: Sun, 07 Jun 1998 20:04:42 -0500 Ted Blank wrote: > > I often found when winding coils that the tension on the wire at the > periphery of the coil made the coil spread out so the sides of the coil > were not co-planar any more but got wider toward the edges. If I used > thicker plastic for the sides it meant fewer turns of wire. I ended up > using a large-ish wooden core which was about 2/3 of the diameter of the > entire coil, and only wound wire on the outer 1/3. By gluing the coil > sides to the wooden core it made it stiff enough to resist the outward > pressure of the wire. But if anyone has other suggestions that avoid > sacrificing about half of the # of turns I'd love to hear them. > > Ted Blank > San Jose, California > To avoid spreading of the coil I use an aluminum winding mandril which supports the sides of the coil while winding. It is thick and strong enough to prevent spreading and is held together with a bolt or screw thru the center of the coil. After winding I soak the windings with superglue which holds the windings in place after removing the mandril. With this method I can wind coils that consist of only the wire when finished. -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: coil for lehman Date: Sun, 07 Jun 1998 18:56:08 -0700 Hi Ted I had the same problem. I glued acrylic tubing to acrylic plates. The glue was strong enough to "melt" the acrylic and provide a pretty strong bond. I have also had some luck using solder or other empty spools. But everything revolves around the size of the spool. Barry Ted Blank wrote: > > I often found when winding coils that the tension on the wire at the > periphery of the coil made the coil spread out so the sides of the coil > were not co-planar any more but got wider toward the edges. If I used > thicker plastic for the sides it meant fewer turns of wire. I ended up > using a large-ish wooden core which was about 2/3 of the diameter of the > entire coil, and only wound wire on the outer 1/3. By gluing the coil > sides to the wooden core it made it stiff enough to resist the outward > pressure of the wire. But if anyone has other suggestions that avoid > sacrificing about half of the # of turns I'd love to hear them. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: coil for lehman Date: Sun, 7 Jun 1998 22:08:14 -0700 (PDT) Ah, yes. I was winding with just a 1/4" bolt through the middle of the coil form. I think such a supporting mandrel would be simple to make. Thanks! Ted Blank San Jose, California On Sun, 7 Jun 1998, Jim Hannon wrote: > Ted Blank wrote: > > > > I often found when winding coils that the tension on the wire at the > > periphery of the coil made the coil spread out so the sides of the coil > > were not co-planar any more but got wider toward the edges. If I used > > thicker plastic for the sides it meant fewer turns of wire. I ended up > > using a large-ish wooden core which was about 2/3 of the diameter of the > > entire coil, and only wound wire on the outer 1/3. By gluing the coil > > sides to the wooden core it made it stiff enough to resist the outward > > pressure of the wire. But if anyone has other suggestions that avoid > > sacrificing about half of the # of turns I'd love to hear them. > > > > Ted Blank > > San Jose, California > > > To avoid spreading of the coil I use an aluminum winding mandril which > supports the sides of the coil while winding. It is thick and strong > enough to prevent spreading and is held together with a bolt or screw > thru the center of the coil. After winding I soak the windings with > superglue which holds the windings in place after removing the mandril. > With this method I can wind coils that consist of only the wire when > finished. > > -- > Jim Hannon > http://soli.inav.net/~jmhannon/ > 42,11.90N 91,39.26W > WB0TXL > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: Just out of curiousity Date: Sun, 07 Jun 1998 08:00:21 At 06:37 PM 6/6/98 -0700, you wrote: >Hi > I don't use it for seismic applications, but I use it at work to tie >my parallel port to a signal conditioning box I made which has the MAX >inside. I use it to measure deflections and loads/pressures. I wrote my >own software using Quickbasic though. > Barry > I havn't writen any heavy duty basic but have played around the edges. I have visual basic. Could you email me the source code on that so I could take a look at it. Maybe I could use it. The guy the wrote the stuff called a2dmax uses c and I don't have that. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: PSN- A Weighty Subject Date: Sun, 07 Jun 1998 07:56:38 At 06:46 PM 6/6/98 +0000, you wrote: >Hello Greg, > >FYI, Regarding the lead mass, I found a five pound fishing (ocean) >sinker at SportMart in California for $5.00. I just tyewrapped it to >my boom. > >Cool cat. I took lead shot, put a small can and heated it on a coalman stove. Slowly added shot till all was melted. Let it cool. Cut the can off and scraped the slag off the top. Drilled a hole in the center and mounted it on the threaded shaft. Worked well but wish I had a drill press so the hole would have been a little more true. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: George Harris Subject: Re: 4 Pole Butterfly Neo's & Relay Coil combination Date: Sun, 07 Jun 1998 22:37:23 +0000 meredith lamb wrote: > > Aaaahhhhh.....the world of amateur seismology does revolve around > magnets doesn't it.....ha. > Some years ago, a printer company , Data Products, spent a lot of money optimizing a magnet-coil combination. It was used to drive the hammers on a drum printer while printing on four part forms. The following configuration was found to be optimum: Each magnet is a rectangle approximately 1 by 1/2 inch and 1/4 inch thick magnetized through the thickness. A total of four are used. Obviously the unit can be enlarged or shrunk. CCMagnetsCC BNS C NSB C C B C B CCMagnetsCC BSN C SNB B B BBBBBBBBB The above are two views of the assembly. The NS is the end of a magnet indicating the direction of the poles. In the right view, the flux is from right to left in the upper gap, and from left to right in the lower. The gap between opposing magnets are about 1/4 inch. The BBB represents the end view of a magnet support bracket made from iron to provide a low reluctance path for the unused part of the flux path. The bottom should not be too close to the lower magnets, or it will restrict the coil motion and short out some of the useful flux. The coil,C, is rectangular about 1/8 inch thick and wound between two metal plates then glued into a solid as was suggested previously. Motion of the coil is up and down as shown. It should be pointed out that a coil which produces an efficient force is that same configuration which produces a large voltage when moved in the same direction. To produce a voltage, the wire should be as fine as can be easily wound. To generate a force, the wire size and voltage/current product are adjusted based on the maximum safe dissipation in the coil. In the size suggested, a watt or two can be safely dissipated, and the wire size and voltage should be adjusted to generate this wattage when the maximum force is required. For instance, if the voltage drive is 5 volts, the maximum current should be about 200 or 300 ma. This means the wire size should be adjusted to give a resistance between 17 and 25 ohms. George Harris - harris@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: coil for lehman Date: Mon, 08 Jun 1998 09:33:10 -0700 Jim, I like the superglue idea and I use the mandrel approach myself, so the question I have is how to prevent gluing the coil and mandrel into one unitized thing (assuming I want to make a free standing coil without sidewalls)? Wax, wax paper, Saran wrap or something else? Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Lead weights Date: Mon, 08 Jun 1998 10:05:30 -0700 Another type of 5# lead weight is the weight used on "Bull" floats. These are the large flat blade push-broom shaped things for smoothing wet concrete. Anyway, 5# bricks of lead are used on them sometimes to aid in the action. So any good hardware store (my local Ace hardware store carries them) that has concrete finishing tools should have the weights. They were only a few dollars as I recall. Charles R. Patton _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: 4 Pole Butterfly Neo's & Relay Coil combination Date: Mon, 08 Jun 1998 10:38:33 -0700 At 10:37 PM 6/7/98 +0000, George Harris wrote: >Motion of the coil is up and down as shown. It should be pointed out >that a coil which produces an efficient force is that same configuration >which produces a large voltage when moved in the same direction. George's description was very enlightening for me, and brought to mind something that I have wondered about: Intuitively, it seems to me that a coil/magnet combination that produces an efficient force would be optimum for producing a large *current* when moved (with the coil working into a low-impedance load), but not necessarily optimum to produce a large open-circuit voltage. One factor is the number of turns and the impedance of the coil, with low favoring current and high favoring voltage. I suspect the magnetic impedance of the field may be important too, but here I'm getting near the limit of my knowledge of magnetics. Comments, anyone? Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "James M Hannon" Subject: Re: coil for lehman Date: Mon, 8 Jun 1998 13:07:18 -0500 "Charles R. Patton" on 06/08/98 11:33:10 AM >Jim, >I like the superglue idea and I use the mandrel approach myself, so the >question I have is how to prevent gluing the coil and mandrel into one >unitized thing (assuming I want to make a free standing coil without >sidewalls)? Wax, wax paper, Saran wrap or something else? >Charles R. Patton _____________________________________________________________________ Charles, There are a lot of solutions to keeping the glue from sticking. What I use is some drafting mylar which is thin enough to not be problem if left on and stiff enough to stay put on the sides of the coils while winding. Spraying the aluminum with a mold release compound would work also. There are some plastics like polyethelyne, or teflon which the glue doesn't stick too well to also. You could also coat almost anything with wax to prevent sticking. Jim Hannon _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Leveling Screw Sources Date: Mon, 8 Jun 1998 15:27:42 -0400 Rex, A source of fine pitch screws and nuts has been posted on this list several times. The latest was by Meridith Lamb and is www.lasersur.com/laseraccessories.htm They offer 1/4" by 80 TPI screws and nuts. I consider 20 TPI screws weofully inadequate for this use. 80 TPI might be OK. Of course, you ne= ed only 2. A 1/4" dia. micrometer head (40 TPI) is plenty strong but I thin= k 80 TPI would be better. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Coil design for Lehman Date: Mon, 8 Jun 1998 15:27:40 -0400 Hi gang, This is to try to clarify the design principles of the coil-magnet pick-up for a Lehman seismometer. Many on this list already know all thi= s stuff but maybe it will help a few. The drawing in the original paper of 1979 in Sci. Am. shows good relati= ve sizes of coil and magnet for the pick-up (or to be pedantic, the "transducer"). The objective is to produce the maximum voltage with a given velocity of the magnet relative to the coil. Maximizing the outpu= t helps to reduce electrical noise contributions of the amplifier. = The voltage induced in a coil moving in a magnetic field is proportiona= l to the velocity, the number of turns and the strength of the magnetic field. (Lehman shows the magnet attached to the boom but putting the on the boom is better because varying external magnetic fields cannot deflect the boom.) The field strength around a horseshoe magnet is highly variable and is maximum in the gap between the ends of the magnet. This is easliy seen b= y placing a sheet of paper on top of a magnet (lying down) and sprinkling iron filings onto the paper. The filings will form lines showing the strength and shape of the field lines. The lines will be straight and close together between the ends and farther apart and curved at locations= farther out. If you have never seen this, try it. Your kids will be enchanted. It is also a great way to visualize the field from other magnetic structures. Clearly, the coil will produce max. output when moving in the gap betwe= en the ends. Ideally, only one side of the coil should be moving thru the field. What is "one side of the coil"? If you take a bite out of a doughnut in the normal way, this is biting "one side" of the doughnut. = If both sides of the coil move thru the same field, the voltage induced= in the two sides of the coil will have opposite polarity and will cancel and will produce no output. Since the mag. field is less farther from th= e magnet ends, one side of the coil should be as far from the magnet as is convenient. This is the reason Lehman showed a coil diameter considerabl= y larger than the magnet. This allows placing only one side of the coil between the ends of the horseshoe where the field is maximum. The other side of the coil is in the field but the field falls off pretty rapidly away from the magnet ends so there is no necessity to have a coil a foot = in diameter, 4 or 5" is enough. Since the field is different at different positions, the induced voltag= e varies depending on the position of the coil. This means that the output= will be a non-linear function of the velocity. However, the amplitude o= f motion for a Lehman is very small and the output will be very nearly proportional to velocity. How many turns? The more the merrier. To get the max. number of turns= between the magnet ends suggests fine wire-#42 or #44 is fairly easy to handle. I used 12,000 wound on a built-up plastic spool and the magent i= s Alnico about the size of my fist. The spool should be about 1/8 to 3/16"= narrower than the gap in the magnet. An aluminum spool is not a good ide= a because is will act as a damper. Jim Hannon's coil made by super-gluing the turns together and removing the side plates seems workable and would save space between the magnet ends but would make the coil more easily damaged. All this is not very critical because high voltage gain in the amplifie= r is easy with op-amps. The resistance of the coil is not important because the input impedence= of the amplifier will normally be much higher. If a coil is to be used f= or damping, the resistance does matter because it will limit the max. dampin= g. Bob Barns = = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: 4 Pole Butterfly Neo's & Relay Coil combination Date: Mon, 08 Jun 1998 13:13:32 -0700 (MST) On Mon, 8 Jun 1998, Karl Cunningham wrote: > George's description was very enlightening for me, and brought to mind > something that I have wondered about: Intuitively, it seems to me that a > coil/magnet combination that produces an efficient force would be optimum > for producing a large *current* when moved (with the coil working into a > low-impedance load), but not necessarily optimum to produce a large > open-circuit voltage. One factor is the number of turns and the impedance > of the coil, with low favoring current and high favoring voltage. I > suspect the magnetic impedance of the field may be important too, but here > I'm getting near the limit of my knowledge of magnetics. Well, the voltage is proportional to the current always. What a magnetic field in motion does is set up an electric field at right angles to the direction of motion and the direction of the magnetic field. When this is done in a wire, the electric field creates a potential for the current to flow. Some impedance characteristics involved in this process are due to the "lag time" between the applied electric field and the induced current. One way of characterizing impedance is by measuring this time lag (phase angle) and extrapolating it back to the general real/non-real components which are parametric when plotted in imaginary space: A*sin(2*pi*f*t + b) = A*sin(b)*cos(2*pi*f*t) + i*A*cos(b)*sin(2*pi*f*t) where b is the phase angle and 2*pi*f is the frequency, i is the imaginary number, A is the amplitude, the first term is the real component and the second term is the imaginary component... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: magnet configurations Date: Mon, 8 Jun 1998 22:10:36 -0500 (CDT) Re magnet configurations: A drawback of using a horseshoe magnet is that most of the coil is not within the magnetic field, and the field is not uniform unless the gap is narrowed with added pole pieces. as: CCCCCCCCX X NNNNNNNNNNNNN X Coil << --- >>> movement x X x CCCCCCCCC X X SSSSSSSSSSSSS Horseshoe Magnet Whereas, with a cylindrical magnet with a center pole piece, the entire coil is within the magnetic field (this is the way Stereo speakers and seismometer coils have been made for years) I will attempt to ascii-up a cross section: (XXX is soft iron (washers), NNNN is rhe north pole, SSS is ...) as: XXXXXXNNNNNSSSSXXXXX XXXXXXNNNNNSSSSXXXXX <<< This is a circular south pole XX XX XX XX CCCCCCCCCX XX X center XXXXXXXXXXXXXXXXXXXX X pole XXXXXXXXXXXXXXXXXXXX X Coil (the CCCs) << moves >> is NORTH XXXXXXXXXXXXXXXXXXXX X XX X XX CCCCCCCCCX XX XX XX XXXXXXNNNNXSSSSXXXXX <<< This is a circular south pole XXXXXXNNNNXSSSSXXXXX MAGNET ` The added soft iron extends the working length of a more compact cylindrical, circular or ring magnet. This type of coil and magnet can be seen in the drawing of the S-5000 LPH seis on the web page. The coil is made long enough that a uniform part of it is always in a uniform part of the annular gap of the magnet as the boom drifts +-5mm. Circular speaker magnets already have a center pole, but the gap is pretty small; the center pole can be replaced by a piece of say 1" dia bolt or steel rod. Alternately, there are strong large (1"dia x 3" long) rod magnets that can be used as the center pole, and the outer pole can be made by large flat washers at the back and a section of iron pipe as the outer cylindrical pole. (this is the construction of most small geophones: the magnet is the center pole, and the steel case is the outer cylindrical pole.) Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Just out of curiousity Date: Mon, 08 Jun 1998 19:18:53 -0700 Norman I'll send you the Basic conversion routine, but I currently run the routine in assembly for speed. Give me a day or so. Barry Norman Davis WB6SHI wrote: > > At 06:37 PM 6/6/98 -0700, you wrote: > >Hi > > I don't use it for seismic applications, but I use it at work to tie > >my parallel port to a signal conditioning box I made which has the MAX > >inside. I use it to measure deflections and loads/pressures. I wrote my > >own software using Quickbasic though. > > Barry > > > I havn't writen any heavy duty basic but have played around the edges. I > have visual basic. Could you email me the source code on that so I could > take a look at it. Maybe I could use it. The guy the wrote the stuff called > a2dmax uses c and I don't have that. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "gg" Subject: Re: magnet configurations Date: Mon, 8 Jun 1998 20:34:38 -0700 This is not a reply to your e-mail. I have been trying to unsubscribe to this mailing list for weeks. Using the instruction : leave PSN-L and UNSUBSCRIBE, directed at the PSN-L mailing list. Maybe you can help by relaying the request. Part of the reason is because I am getting too much SPAM.. Someone incharge of the server keeps deleting (censoring?) my requests when I mention SPAM. Please remove me from PSN Mailing list. (P.S. - It seems to be easy to subscribe, but difficult to unsubscribe. Something is amiss. Thanks for all the EQ info.) > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: 4 Pole Butterfly Neo's & Relay Coil combination Date: Mon, 08 Jun 1998 19:14:15 -0700 Hi George I have arranged my magnets/coil generally as you have described. I have had very good luck with it over the years. I have a few variations though. I use two coils in parallel ,with common axis (~1" apart) and magnets also between them. I also agree with Robert, I used as many turns of 40+ ga wire as I could possibly use. I have only begun to try the solenoid coil/magnet arrangement. It seems the field strength would be greater with the above description than with a cylindrical coil with a cow magnet inside. However the speaker arrangement of coil/magnet may be the best since more turns cut strong flux lines. Barry George Harris wrote: The following configuration was found to be optimum: > > Each magnet is a rectangle approximately 1 by 1/2 inch and 1/4 inch > thick magnetized through the thickness. A total of > four are used. Obviously the unit can be enlarged or shrunk. > > CCMagnetsCC BNS C NSB > C C B C B > CCMagnetsCC BSN C SNB > B B > BBBBBBBBB > The above are two views of the assembly. The NS is the end of a > magnet indicating the direction of the poles. In the right view, the > flux is from right to left in the upper gap, and from left to right in > the lower. The gap between opposing magnets are about 1/4 inch. The BBB > represents the end view of a magnet support bracket made from iron to > provide a low reluctance path for the unused part of the flux path. The > bottom should not be too close to the lower magnets, or it will restrict > the coil motion and short out some of the useful flux. The coil,C, is > rectangular about 1/8 inch thick and wound between two metal plates then > glued into a solid as was suggested previously. > > Motion of the coil is up and down as shown. It should be pointed out > that a coil which produces an efficient force is that same configuration > which produces a large voltage when moved in the same direction. To > produce a voltage, the wire should be as fine as can be easily wound. > To generate a force, the wire size and voltage/current product are > adjusted based on the maximum safe dissipation in the coil. In the > size suggested, a watt or two can be safely dissipated, and the > wire size and voltage should be adjusted to generate this wattage > when the maximum force is required. For instance, if the voltage > drive is 5 volts, the maximum current should be about 200 or 300 ma. > This means the wire size should be adjusted to give a resistance > between 17 and 25 ohms. > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Just out of curiousity Date: Mon, 08 Jun 1998 20:08:49 -0700 Norman I just realized that the code is of no good if the port lines go to different chip pin #'s. I use the status and data lines to program the MAX 186. Quickbasic uses out() and inp() to sent data and receive data. My code will be meaningless if your hardware is different than mine. You might read the parallel port literature by Jan Axelson. I found her very helpful. Barry Barry Norman Davis WB6SHI wrote: > > At 06:37 PM 6/6/98 -0700, you wrote: > >Hi > > I don't use it for seismic applications, but I use it at work to tie > >my parallel port to a signal conditioning box I made which has the MAX > >inside. I use it to measure deflections and loads/pressures. I wrote my > >own software using Quickbasic though. > > Barry > > > I havn't writen any heavy duty basic but have played around the edges. I > have visual basic. Could you email me the source code on that so I could > take a look at it. Maybe I could use it. The guy the wrote the stuff called > a2dmax uses c and I don't have that. > > Norman Davis WB6SHI > Shingle Springs, Ca > normd@............. > http://www.directcon.net/normd/index.htm > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Event at 03:00:48UTC 060998 Date: Mon, 08 Jun 1998 20:19:38 -0700 Did anybody record a large event? It looks to be 4000km 7.2-7.3 range at 03:00:48. I don't see anything posted but I watched it roll in... Regards, Steve Hammond PSN San Jose _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: BIG BIG EVENT Date: Mon, 08 Jun 1998 22:32:10 -0700 My system just saturated BIG time!!!!! 05:25:18 UTC Stephen Pilot Hill Ca. USA lat / lon 38.828N / 120.978W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Canie Brooks Subject: Re: BIG BIG EVENT Date: Mon, 08 Jun 1998 22:44:54 -0700 At 10:32 PM 6/8/98 -0700, you wrote: >My system just saturated BIG time!!!!! >05:25:18 UTC >Stephen >Pilot Hill Ca. USA >lat / lon 38.828N / 120.978W Here it is: - and still shaking 1.9 98/06/08 22:33:32 37.58N 118.81W 7.0 7 mi WNW of TOMS PLACE 2.2 98/06/08 22:33:07 37.58N 118.79W 7.0 6 mi WNW of TOMS PLACE 2.2 98/06/08 22:29:55 37.59N 118.80W 6.5 7 mi WNW of TOMS PLACE 2.5 98/06/08 22:29:26 37.59N 118.80W 7.4 7 mi WNW of TOMS PLACE 3.3 98/06/08 22:27:30 37.64N 118.80W 21.8 8 mi NW of TOMS PLACE 5.1 98/06/08 22:24:40 37.59N 118.79W 6.6 7 mi WNW of TOMS PLACE canie > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: BIG BIG EVENT - Mammoth Lakes again... Date: Mon, 08 Jun 1998 22:52:04 -0700 From the Berkeley finger system: 98/06/09 05:24:40 37.59N 118.80W 6.7 4.9Mw A* 17 km ESE of Mammoth Lakes, CA -Larry Cochrane Redwood City, PSN At 10:32 PM 6/8/98 -0700, you wrote: >My system just saturated BIG time!!!!! >05:25:18 UTC >Stephen >Pilot Hill Ca. USA >lat / lon 38.828N / 120.978W > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "John Krempasky" Subject: Re: BIG BIG EVENT - Mammoth Lakes again... Date: Tue, 9 Jun 1998 09:47:02 -0400 Just had a 3.9 and 3.0 at the same location as the 5.1 (In case you can't tell, I'm one of what I suspect is a vast, secret pool of http://quake.wr.usgs.gov/recenteqs/Maps/Long_Valley.html addicts; I check it every morning when I log on, if stuff is happening, a lot more often...a great time-waster :-). According to the current status report (after the 5.1, but before the most recent 3.9) "This activity has the character of a mainshock-aftershock sequence and, at this stage, appears to be more closely related to tectonic than to magmatic processes. We are currently seeing no evidence for significant ground deformation, aside from the small coseismic displacements normally expected for an earthquake of this size. As long as this holds and the aftershock activity continues its present rate of decline, we will maintain a condition GREEN (no immediate risk)." Is a 3.9 and 3.0 inconsistent with a mainshock-aftershock seqeunce and tectonic processes? I would think not, would seem normal to have an aftershock as high as 3.9 for a 5.1. But what really would characterize whether this is tectonic or magmatic? The location is in sort of an iffy area....the very edge of the caldera. John Krempasky _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Canie Brooks Subject: Re: BIG BIG EVENT - Mammoth Lakes again... Date: Tue, 09 Jun 1998 08:09:32 -0700 At 09:47 AM 6/9/98 -0400, you wrote: > >Just had a 3.9 and 3.0 at the same location as the 5.1 (In case you can't >tell, I'm one of what I suspect is a vast, secret pool of >http://quake.wr.usgs.gov/recenteqs/Maps/Long_Valley.html addicts; I check >it every morning when I log on, if stuff is happening, a lot more often...a >great time-waster :-). Me too! > >According to the current status report (after the 5.1, but before the most >recent 3.9) > >"This activity has the character of a mainshock-aftershock sequence and, at >this stage, appears to be more closely related to tectonic than to magmatic >processes. We are currently seeing no evidence for significant ground >deformation, aside from the small coseismic displacements normally expected >for an earthquake of this size. As long as this holds and the aftershock >activity continues its present rate of decline, we will maintain a condition >GREEN (no immediate risk)." > > Is a 3.9 and 3.0 inconsistent with a mainshock-aftershock seqeunce and >tectonic processes? I would think not, would seem normal to have an >aftershock as high as 3.9 for a 5.1. But what really would characterize >whether this is tectonic or magmatic? The location is in sort of an iffy >area....the very edge of the caldera. Good question. I also suspect they will resist mightily changing that status from green to Yellow! Channel 5 just reported it on their news - they say there have been about 38 aftershocks measuring 1.7, 1.9, 2.1 - a bit of wrong informations there - I suspect he's talking about 2> mag quakes... but that's not how they've reported it.. canie > >John Krempasky > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: A very sensitive displacement detector Date: Tue, 09 Jun 1998 18:15:30 -0700 There have been several discussions about very sensitive displacement detectors for use on seismometers. On 4/17/98 Sean-Thomas stated in part: But the resolution we need for seismic instruments is of the order 1 nanometer and less. Right now the sensor here has the normal background noise of microseisms of about 3mv amplitude, which at my current gains (3240v/m/sec) is a ground motion of about 1 micron at 6 seconds. On the power spectral density noise model this is about normal at about -140 db. But if we are interested in someting small and local, like a magnitude 3.0 at 200 km, it will have a peak amplitude of about 100 nm (using Mblg = 3.75 + log(distance in degrees) + log A (microns)). But I can easily resolve 0.1 mv at 10 hz, which is a ground motion of 0.5 nanometers, or about -170 db in power spectra. The smallest event I have recorded is a Mb 2.7 at 265 km, which had a peak motion of 34 nanometers at 3 hz. I just pulled down the NASA tech brief "Micromachined Tunneling Accelerometer for use in Outer Space" from http://www.nasatech.com/ (Unfortunately this site will not allow download of documents outside of the USA) The article discusses the use of tunneling sensors for displacement sensing in a silicon micro-machined accelerometer. A number mentioned for the tunneling tip sensor sensitivity is 3*10^(-14) meters/ Hz^(-2) at 10Hz. This article answered one question I've had for some time and that was the need for a sharp (and I mean atomically sharp -- 1 atom or so) point. They experimented with blunt points and couldn't see the difference. They theorized that the tunneling action starts with some arbitrary sharp projection on the point they were using. The levels involved are approximately 15 mV across 10 Mohms with a 1 nm separation with the current changing by a factor of 2 per 0.1 nm change. Not as bad as one might expect. My take on it would be to cannibalize a small relay, like a reed relay, with gold (the need for absolutely clean, non oxidizable metals cannot be overemphasized) points and turn those into the tunneling sensor. It has to be used in a force-feedback arrangement. Converting to Sean-Thomas sensitivity numbers 15 mV / nm = 150*10^6 V/m . Obviously there not much measurement range, but the sensitivity is there. Anyway, a thought for the day for anyone who wants a really sensitive displacement detector. Charles R. Patton, Editor, Geo-Monitor changing my email- send to: charles.r.patton@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Leveling Screw Sources Date: Tue, 09 Jun 1998 23:00:02 -0700 robert barns wrote: > > Rex, > A source of fine pitch screws and nuts has been posted on this list > several times. The latest was by Meridith Lamb and is > www.lasersur.com/laseraccessories.htm > They offer 1/4" by 80 TPI screws and nuts. I consider 20 TPI screws I was just thinking about cutting some 20 tpi threads into my spiffy new aluminum base. If anyone has these (laser surplus screws), I'm concerned about the strength. I expect the final weight of my Lehman to be over 50 lbs. The base is 3/4" thick and I was thinking of doubling some other things up to waste time before I buy an ADC and an amp ;) Also what is the thread around the brass insert? A new tap and matching bolts would cost more than these would. Also I appreciate all of the ideas for lead wieghts. I haven't bought it yet, though. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: Leveling Screw Sources Date: Wed, 10 Jun 1998 14:01:19 -0400 Greg, If your Lehman has three legs, that makes <20 lbs/screw. 80 TPI screws= should easily support that. You can produce more than 20 lbs force with your hand and I don't think you can strip an 80 TPI thread with your hand= =2E Bob Barns -I'm not cheap but I am on special this week. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Hi-res microbarometer Date: Wed, 10 Jun 1998 11:32:46 +0000 Hello Sean, Cool. I like it, nifty idea. The LVDT sensor somewhere is attached to the aneroid bellow? The Validyne web site at: http://www.validyne.com/index.htm Is this the company? Thank you. Walter Williams, 98.06.10 ====================================================== ------- Forwarded Message Follows ------- Date: Sun, 7 Jun 1998 00:22:30 -0500 (CDT) From: S-T Morrissey To: psn-l@............. Subject: Hi-res microbarometer Reply-to: PSN-L Mailing List Re Microbarometers: Another way to make a very sensitive microbarometer is to install a VRDT or LVDT in an aneroid type barometer. It is an expensive arrangement, though. For years I have been making a microbarometer with an output of 100mv/millibar before amplification by installing the Schaevitz 005MHR LVDT ($100) in the Taylor thermally compensated dial barometer ($300), using the Validyne VRDT electronics module ($100). It allows in-situ calibration by turning the altitude compensation screw and watching the dial. For high resolution, the coupling pins to the dial mechanism then have to be disconnected. A 1000 second high-pass buffer amplifier removes the ambient pressure, and provides additional gain for a signal of 10mv/microbar. We test the instrument by raising it up or down a few centimeters, which produces an output in the atmospheric gradient of about 10mv/cm. We have made about ten of these. One can avoid the cost by buying the dial aneroid device at a flea market ($25) and use a VRDT and homemade electronics. This is the instrument used for the study to remove barometric noise from horizontal VBB data as outlined in the abstracts on my web page re Barometric Studies. No data is presented there, but I will post some of the results if there is an interest. Another source of data on acoustic gravity waves IS a VBB vertical sensor that is not shielded from barometric pressure. Latelely here in St. Louis the Lows have been sliding along the cold front and producing lots of symmetric pressure waves with periods from 1 to 10 minutes. I will scan a plot of one to the web site next week. Unfortunately, this output from a VBB vertical is "noise", and is not calibrated. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Larry P. Thomas WA0GWA" Subject: Re: Leveling Screw Sources Date: Wed, 10 Jun 1998 15:11:35 -0500 I follow this group but seldon take time out to contribute ... sorry. Thought I would mention concerning the use of brass threads or inserts in aluminum base plates. Brass and aluminum are at the opposite ends of the spectrum concerning dissimilar metals. You may get corrosion in the long run with brass in direct contact with aluminum. Just an idea. Could just as easily be a non-issue. Later Larry Thomas wa0gwa At 11:00 PM 6/9/98 -0700, you wrote: >robert barns wrote: >> >> Rex, >> A source of fine pitch screws and nuts has been posted on this list >> several times. The latest was by Meridith Lamb and is >> www.lasersur.com/laseraccessories.htm >> They offer 1/4" by 80 TPI screws and nuts. I consider 20 TPI screws > >I was just thinking about cutting some 20 tpi threads into my spiffy new >aluminum base. If anyone has these (laser surplus screws), I'm concerned >about the strength. I expect the final weight of my Lehman to be over 50 >lbs. The base is 3/4" thick and I was thinking of doubling some other >things up to waste time before I buy an ADC and an amp ;) Also what is >the thread around the brass insert? A new tap and matching bolts would >cost more than these would. > >Also I appreciate all of the ideas for lead wieghts. I haven't bought it >yet, though. > >,Greg > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > ----------------------------------------------------------------------- Larry P. Thomas wa0gwa voice : 1 913 888-0282 Krell Technologies fax : 1 913 782-9359 8960 Bond pager : 1 816 989-HELP Overland Park, KS www : http://www.krell.com 66214-1764 e-mail : lpthomas@................ ----------------------------------------------------------------------- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Rex Klopfenstein Jr Subject: RE: Leveling Screw Sources Date: Wed, 10 Jun 1998 17:22:08 -0400 -----Original Message----- From: Larry P. Thomas WA0GWA [SMTP:lpthomas@................. Sent: Wednesday, June 10, 1998 4:12 PM To: PSN-L Mailing List Subject: Re: Leveling Screw Sources Brass and aluminum are at the opposite ends of the spectrum concerning dissimilar metals. You may get corrosion in the = long run with brass in direct contact with aluminum. =20 I recently ordered the 1/4-80 leveling screws from the Laser Surplus = source. If possible, I plan to make an insulating insert around the = brass nut housing-Haven't seen the units yet? From: John Hernlund Subject: coil and magnet design images Date: Wed, 10 Jun 1998 15:19:24 -0700 (MST) Hello All, I finally posted two .gif images that roughly describe the coil and magnet design I discussed earlier. It is similar to the one discussed as a cylindrical magnet, but those are not always readily available. There are two images: http://www.public.asu.edu/~hernlund/coil_magnet.gif This one shows how the magnets are arranged in relation to the coil http://www.public.asu.edu/~hernlund/flux.gif This one shows the desired magnetic field lines for this arrangment. Note that you can get the field flux to be pretty uniform only between each pair of magnets but the field lines will always intersect the coil wall at a 90 degree angle, which will assure maximum induced potential... The hardest part of this design is getting the magnets into place so close to one another... Super glue is probably best, any kind of heat bonding will contribute to de-magnetization of the magnets... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: Leveling Screw Sources Date: Wed, 10 Jun 1998 16:10:10 -0600 Greg wrote: > I was just thinking about cutting some 20 tpi threads into my spiffy new > aluminum base. If anyone has these (laser surplus screws), I'm concerned > about the strength. I expect the final weight of my Lehman to be over 50 > lbs. The base is 3/4" thick and I was thinking of doubling some other > things up to waste time before I buy an ADC and an amp ;) Also what is > the thread around the brass insert? A new tap and matching bolts would > cost more than these would. > It looks like the Laser Surplus screws are NOT 80 t.p.i., at least in the english system. I got a english thread gauge and could not find a match. Per the thread gauge they look more like a 40 tpi., but aren't. Don't have any metric thread gauges, and 2 local machine shop supply houses (catalog), don't even have gauges either. The whole world is metric except for the U.S. If you are comtemplating buying some, there is no guarantee they are even metric yet..., and, you may not get all the bushings/nuts, like I didn't. So...until I find out, hold off on any purchase. The bushing/nuts that I did get, are really more like inside threaded round spacers. The outside is not threaded. This means to use them you would have to drill, ream the base plate, and either press fit, or, drill/tap set screws in the base frame sideways, or, solder a brass washer, and do more drilling and tapping of the washer to attach to your base. Whew! The Laser Surplus screws are really beautifully made, but, there is probably simplier ways which sure look alot more attractive now. You may want to check past emails on set screws....which is a chore to do, unless someone has files categorized into subjects, and is willing to forward them. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: coil and magnet design images Date: Wed, 10 Jun 1998 15:53:37 -0700 (PDT) Thanks, John. This picture is worth a million words. Ted Blank San Jose, California _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Leveling Screws Date: Wed, 10 Jun 1998 16:11:19 -0700 Something to throw in to the leveling screw subject... I used four 10-32 socket-head cap screws on my horizontal force-balance. They threaded into stainless captive lock nuts pressed into the base from the bottom. These nuts (from a surplus store) are press-fit devices containing a locking elastomer that require some moderate torque on the screw to overcome, and prevent the screws from adjusting themselves when you don't want them to. Gluing a foot-long brass tube over a right-angle hex key (Allen wrench) provided fine enough control to adjust the natural period to 20 seconds or more. BTW, I sharpened the ends of the screws to a point so that the contact point of the screw doesn't change during adjustment. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Calibration Date: Wed, 10 Jun 1998 21:00:22 -0500 Friends, It has now become apparent to me that different teleseismic seismographs have different, perhaps even rather individual, responses to different frequencies. These are often set by coil/magnet/silicon physics on the low end, for one thing. And then everyone, myself included, may add on their own low pass filter. I imagine that if the individual instrument's peculiarities were accurately known, then something like an electronic sound frequency equalizer could be used to compensate two seismographic instruments, to make their side by side teleseismic responses comparable. There was talk on PSN a while back about calibrating seismos by tilting them slightly to give, as I recall, a static measure of their sensitivity, since a change in the vertical gravity vector with change in angle looks like a slight acceleration to the instrument. If they were tilted according to variable sinusoidal periods, up and down just a few minutes or seconds of arc or whatever, which could be done with a simple long-lever arrangement, then we can study either the DC response, or various frequencies of AC response. If we mounted a stepping motor horizontally, then the shaft could be used to drive a small cam that lifts a lever that tilts the instrument ever so slightly. Since stepping motors are easy to control with computers, a computer could be used to turn the shaft to generate very small vertical sine waves of various frequencies from say one second and then gradually shifting in frequency down to a minute or so, over maybe ten minutes to generate an output response versus frequency chart. This would presumably produce data that could be used to generate equalization factors to compensate the responses of any given instrument, (assuming a stable natural period instrument, which the Lehman may too often not be, etc). Does this idea seem stupid, possible, necessary, useful, or maybe even even in common practice for many years now? Curious, Roger _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: coil and magnet design images Date: Wed, 10 Jun 1998 18:42:55 -0700 John I like your .gifs. I had problems keeping the magnets together when I tried it before. How do you keep like poles together? Barry John Hernlund wrote: > > Hello All, > I finally posted two .gif images that roughly describe the coil and magnet > design I discussed earlier. It is similar to the one discussed as a > cylindrical magnet, but those are not always readily available. There are two _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Calibration Date: Wed, 10 Jun 1998 18:56:06 -0700 Roger It doesn't sound stupid to me. I have been racking my brain to come up with an inexpensive calibration wigit. Larry mentioned using a stepper motor awhile back,with a low gain. I tried using a peizoelectric disk to generate motion. The problem I found with peizos was to get one with enough poop(force)to move a sensor, it cost an arm and a leg. They are used for micro positioning currently. They would be ideal since you could input any electrical signal and record the response. Maybe you could input one persons event and see how your system responds? They are expensive since they are made up of many wafers in a stack. The stack gives an increased output displacement. I think we all should put our heads together on this one, to try to relate all our sensors. The magnitude factors in Winquake are a start. Barry Roger Baker wrote: > > Friends, > It has now become apparent to me that different teleseismic > seismographs have different, perhaps even rather individual, responses to > different frequencies. These are often set by coil/magnet/silicon physics > on the low end, for one thing. And then everyone, myself included, may add > on their own low pass filter. > > I imagine that if the individual instrument's peculiarities were accurately > known, then something like an electronic sound frequency equalizer could be > used to compensate two seismographic instruments, to make their side by > side teleseismic responses comparable. > > There was talk on PSN a while back about calibrating seismos by tilting > them slightly to give, as I recall, a static measure of their sensitivity, > since a change in the vertical gravity vector with change in angle looks > like a slight acceleration to the instrument. > > If they were tilted according to variable sinusoidal periods, up and down > just a few minutes or seconds of arc or whatever, which could be done with > a simple long-lever arrangement, then we can study either the DC response, > or various frequencies of AC response. > > If we mounted a stepping motor horizontally, then the shaft could be used > to drive a small cam that lifts a lever that tilts the instrument ever so > slightly. Since stepping motors are easy to control with computers, a > computer could be used to turn the shaft to generate very small vertical > sine waves of various frequencies from say one second and then gradually > shifting in frequency down to a minute or so, over maybe ten minutes to > generate an output response versus frequency chart. > > This would presumably produce data that could be used to generate > equalization factors to compensate the responses of any given instrument, > (assuming a stable natural period instrument, which the Lehman may too > often not be, etc). > > Does this idea seem stupid, possible, necessary, useful, or maybe even even > in common practice for many years now? > Curious, Roger > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: coil and magnet design images Date: Wed, 10 Jun 1998 20:08:05 -0700 (MST) On Wed, 10 Jun 1998, barry lotz wrote: > I like your .gifs. I had problems keeping the magnets together when > I tried it before. How do you keep like poles together? > Barry Brute force! Some times the only way is to make a clamp out of two aluminum plates with holes at either end and screw them down one at a time... Careful not to pinch your fingers! ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Leveling Screw Sources Date: Wed, 10 Jun 1998 21:42:44 -0700 No way I'm going through all of that for leveling screws. I'll get a nice tap and 3 nice bolts when I go to the hardware store for lead. I kinda wanted to get some monster screws anyway. I also plan to sharpen the tips of the bolts. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: Calibration Date: Thu, 11 Jun 1998 11:16:09 -0400 Barry, A long time ago, I sent in a write-up of a calibrator for a Lehman usin= g a meter movement. A drawing and the procedure for constructing and calibrating the device are included. This info. can be found at psn.quake.net under "Information, Equipment & Software". The thing is cheap to make and would probably take 4-6 hrs. to build an= d calibrate. I still use mine-it is comforting to just push a button and see the deflection in SDR. I hit "c" to clear the max. and min. and observe the peaks due to the calibration pulse. Done daily or weekly, it checks the whole system for changes in gain. By substituting a fork which straddles the boom instead of the simple pointer, the boom could be driven sinusoidally at different frequencies t= o get the frequency response curve. Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Calibration Date: Thu, 11 Jun 1998 08:59:31 -0700 Bob, Why worry about sine excitation of your meter movement, especially since a saddle would not be sine (due to hysteresis effect of no-contact space of the saddle)? If it was in contact, then that would interfere with the seismograph. Since the meter movement impulse looks like a step input to the seismograph, use the FFT process as Sean-Thomas described some time back to extract the whole frequency/phase response of the seismograph from one step. There are articles (they are at home, I'm at work -- but if somebody wants them, I'll dig them up latter) where they just input a current pulse into the coil, remove it, and watch the response of the seismograph to that impulse and then extract the seismograph constants from it. This works very well and if you know the force constant of the coil (which could be ascertained using your meter as the transfer calibration method!) gives a full calibration also. Charles R. Patton Update email to: charles.r.patton@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Calibration Date: Thu, 11 Jun 1998 09:02:12 -0700 At 11:16 AM 6/11/98 -0400, Bob Barns wrote: > By substituting a fork which straddles the boom instead of the simple >pointer, the boom could be driven sinusoidally at different frequencies to >get the frequency response curve. I cut a v-shaped notch in the end of the boom with a file, and leaned the meter's pointer into the bottom of the notch to drive the boom sinusoidally. It served as a great end-to-end calibration means. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Calibration Date: Thu, 11 Jun 1998 17:11:00 -0700 Robert et al I saw your nice arrangement on Larry's site. What I was trying to achieve was a sensor response. As I see it, your setup nicely checks the electronics but does not check the response of the sensor as a whole. To do that one shold shake the base not the boom. If the sensor has a natural period of say 4 sec then a 20 sec wave should hardly show up due to the response of the system. Barry robert barns wrote: > > Barry, > A long time ago, I sent in a write-up of a calibrator for a Lehman using > a meter movement. A drawing and the procedure for constructing and > calibrating the device are included. This info. can be found at > psn.quake.net under "Information, Equipment & Software". > The thing is cheap to make and would probably take 4-6 hrs. to build and > calibrate. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: long distant wave Date: Thu, 11 Jun 1998 19:21:47 -0700 Hi all, I recorded a small long distant wave at 23:13:26 on June 11, 98 UTC. I went to the USGS Live Internet Seismic Server and found the waveforms at the Arizona, New Mexico, Texas and a little later at the Hawaii and Alaska sites (about 15 to 20 minutes later)! It appears to be the strongest and earliest on the Arizona site! But I can't find it on any lists????? Any ideas??? The waveform is only about 3 or 4 minutes long!! This is the second time I have noticed and recorded these little waveforms! The last one was at 20:19:35 on May 22, 98 UTC Thanks in advance for any help! Stephen PSN Station #55 Pilot Hill Ca USA lat / lon 38.828N / 120.978W _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Re: long distant wave Date: Thu, 11 Jun 1998 23:10:47 -0600 Stephen & Kathy wrote: > Hi all, > I recorded a small long distant wave at 23:13:26 on June 11, 98 UTC. > I went to the USGS Live Internet Seismic Server and found the waveforms > at the Arizona, New Mexico, Texas and a little later at the Hawaii and > Alaska sites (about 15 to 20 minutes later)! It appears to be the > strongest and earliest on the Arizona site! But I can't find it on > any lists????? Any ideas??? The waveform is only about 3 or 4 minutes > long!! > This is the second time I have noticed and recorded these little > waveforms! The last one was at 20:19:35 on May 22, 98 UTC > Stephen, you have picked up the Kuril Islands ~5.7 quake, off Alaska, and probably (?) got the Love wave form. Alot of people use the swiss report to check on events before it shows up on the USGS web sites: http://seismo.ethz.ch/redpuma/redpuma-ami-list.html Sounds like good news to have you recording....congratulations. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: Re: long distant wave Date: Thu, 11 Jun 1998 23:17:20 -0700 meredith lamb wrote: > > Stephen & Kathy wrote: > > > Hi all, > > I recorded a small long distant wave at 23:13:26 on June 11, 98 UTC. > > I went to the USGS Live Internet Seismic Server and found the waveforms > > at the Arizona, New Mexico, Texas and a little later at the Hawaii and > > Alaska sites (about 15 to 20 minutes later)! It appears to be the > > strongest and earliest on the Arizona site! But I can't find it on > > any lists????? Any ideas??? The waveform is only about 3 or 4 minutes > > long!! > > This is the second time I have noticed and recorded these little > > waveforms! The last one was at 20:19:35 on May 22, 98 UTC > > > > Stephen, you have picked up the Kuril Islands ~5.7 quake, off Alaska, > and probably (?) got the Love wave form. > > Alot of people use the swiss report to check on events before it shows > up on the USGS web sites: > > http://seismo.ethz.ch/redpuma/redpuma-ami-list.html > > Sounds like good news to have you recording....congratulations. > > Meredith Lamb Thanks for the response but that doesn't appear to be it. I did check the Swiss list and the Kuril Islands 5.6 was over an hour later than the one I'm talking about!! You can see the waveforms at: http://aslwww.cr.usgs.gov/Seismic_Data/heli.htm The waveform is strongest in the Arizona and New Mexico area. The Hawaii and Alaska waveforms are smaller and later and they don't even show the Kuril wave, Texas is also smaller. It would appear that whatever made the wave would have to be somewhere west of Arizona but a lot closer to Arizona than Hawaii or Alaska???? If you or anyone comes up with any other ideas please let me know!! And if I need to be corrected on something don't be afraid to let me know,, I'm here to question and learn!!! Stephen Pilot Hill Ca USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Marchal, Lare van" Subject: Re: long distant wave Date: Fri, 12 Jun 1998 08:02:19 -0400 Stephen, I think this event caused the waveform: 1998/06/11 23:09:12.8 25.02N 109.71W mb 4.3 Gulf of California The source is http://inge.css.gov:65120/web-bin/recentevents/ Cheers, Marchal van Lare, The Netherlands= _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: Calibration Date: Fri, 12 Jun 1998 10:18:15 -0400 Charles, I'd like to see the reference to those articles if you can find them. = I'll also try to locate Sean-Thomas's info. I think that the problem of having a little clearance on each side of t= he fork will not cause appreciable errors. If the current thru the meter is= varying sinusoidally, the jump at the ends (due to the clearance) will be= quite small because the mass of the fork and meter pointer is small wrt t= o the rotational inertia of the boom. One problem which has just occurred to me is that of beginning the push= on the boom at the zero point of current thru the meter, i.e., the phase.= = At the low frequencies of concern with a Lehman (.01 to 1 Hz, say), one could just observe the phase of the oscillator on a 'scope and close a switch when the voltage is zero. I had a further thought on how to generate sine waves in this frequency= range. I have a swell gadget called the "julie board" which was describe= d some years back in '73 magazine and works well for this applic. If you don't have this device, it should be easy to write a BASIC program to output the amplitudes as 8-bit nos. to the parallel port and convert thes= e to voltages via. a simple D/A converter such as an R-2R network or a chip= =2E Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: Calibration Date: Fri, 12 Jun 1998 10:18:17 -0400 Barry, The meter movement calibrator imparts a known force for a known time to= the boom. It doesn't matter if the base or the boom is moved--only the relative motion of boom and base matter. This is all that is required to check the whole system of seismometer, amplifier, A/D converter and computer response. = Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: Re: long distant wave Date: Fri, 12 Jun 1998 08:25:14 -0700 Marchal, Lare van wrote: > > Stephen, > > I think this event caused the waveform: > > 1998/06/11 23:09:12.8 25.02N 109.71W mb 4.3 Gulf of California > > The source is http://inge.css.gov:65120/web-bin/recentevents/ > > Cheers, > > Marchal van Lare, > The Netherlands Thanks,, that will work!!! It finally showed up on the NEIC list and the arrival time calculator put the S wave in the spot of my wave form!!! I also discovered why the Arizona and New Mexico waves were so big,,, they record at 6000 magnification whereas the others record at 3000! Thanks again,, next time I will try and be more patience!!!???? Stephen Pilot Hill Ca USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: long distant wave Date: Fri, 12 Jun 1998 12:51:43 -0700 (MST) I recorded the event here at ASU (Tempe, AZ), but it is does not look like a local event: long period waves only here. I would bet we are seeing surface waves from a distant event. I'll post the event to the web on Monday when I get more time... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Walt Williams" Subject: Seismic Detection of Lugo Bolide Date: Fri, 12 Jun 1998 15:27:41 +0000 In the search for information regarding detection and measurement of bolides, this interesting paper at: http://xxx.lanl.gov/PS_cache/astro-ph/pdf/9805/9805124.pdf Paper describes interesting use of seismic data to reanalyze the Lugo Bolide event over Italy in 1993. Document is available in Acrobat 3.0 format as well as other formats. Main e-Print archive URL at: http://xxx.lanl.gov Walter Williams, 98.06.12 dfheli@.............. http://www.pacificnet.net/~dfheli _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: Calibration Date: Fri, 12 Jun 1998 17:52:32 -0700 Robert Going back to the equations of motion,and to a college text, ..... "Comparing eqs. 12.6 and 12.10 it is apparent that the earthquake input is exactly equivalent to a dynamic load equal to the produce of the ground acceleration and mass of the structure". I was thinking you were forcing the boom with a prescribed deflection. With a coil you are applying a force to the mass. :-] Barry robert barns wrote: > > Barry, > The meter movement calibrator imparts a known force for a known time to > the boom. It doesn't matter if the base or the boom is moved--only the > relative motion of boom and base matter. > This is all that is required to check the whole system of seismometer, > amplifier, A/D converter and computer response. > Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Norman Davis WB6SHI Subject: Re: Just out of curiousity Date: Fri, 12 Jun 1998 07:57:10 At 08:08 PM 6/8/98 -0700, you wrote: >Norman > I just realized that the code is of no good if the port lines go to >different chip pin #'s. I use the status and data lines to program the >MAX 186. Quickbasic uses out() and inp() to sent data and receive data. >My code will be meaningless if your hardware is different than mine. You >might read the parallel port literature by Jan Axelson. I found her very >helpful. > Barry Well I have just about given up on that project anyway. I just got a cataloge from techamerica and they have a 8 channel a/d converter with software for $90. They don't say what the chip is that is in it. Norman Davis WB6SHI Shingle Springs, Ca normd@............. http://www.directcon.net/normd/index.htm _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: Calibration Date: Sat, 13 Jun 1998 00:08:35 -0700 Bob, The article on the step current calibration technique is: Signal-Coil Calibration of Electromagnetic Seismometers; Peter W. Rodgers, Aaron J. Martin, Michelle C. Robertson, Mark M. Hsu, and David B. Harris; Bulletin of the Seismological Society of America, Vol. 85, No. 3, pp. 845-850, June 1995 Regards, Charles R. Patton, Editor, Geo-Monitor new email: charles.r.patton@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Goof on wire size Date: Sat, 13 Jun 1998 10:03:54 -0400 Hi gang, I recently pontificated on Lehman pick-up coils and said that I used #4= 2 wire. That was wrong-I used #36. I think that wire finer than #40 or so= would be hard to handle. For the record, my coil was wound on a 2" core and the winding was 0.96= " wide and 0.5" deep. This was about 12,200 turns and has a resistance of 3,100 ohms. Calculated length of 7,200 ft. Bob Barns If everything seems to be going well, you have obviously overlooked something. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: RSAM amplitude? Date: Sat, 13 Jun 1998 12:40:12 -0700 A friend has pointed me to an usual set of data on this page: http://quake.wr.usgs.gov/QUAKES/crustaldef/plot.mam.gif The RSAM amplitude appears to go wacke late 1200 utc which seems odd givin that seismicity was dropping and there have been no further bursts of activity. Any suggestions? -- ---/---- Charles P. Watson Seismo-Watch _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: What kind of seismograph Date: Sat, 13 Jun 1998 13:33:54 -0700 (PDT) Hello All: Just came across a seismograph being offered for sale at Ebay Internet Auction. What kind of a seismograph is it? Looks to me as though it is some sort of a drum recorder. http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=17006493 Thanks Frank Condon frankcnd@.......... "Located in the seismic corridor somewhere between Fontana & Mammoth Lakes" _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: What kind of seismograph Date: Sat, 13 Jun 1998 16:52:49 EDT Hi Frank, I took a look at that seismo they are auctioning and it looks as though the drum is driven by a mechanical clock motor and the recording is done by an ink pen. the description says it is not electrical so if you plan to use it on the system, you would have to modify it. Also as the description says, "it is in rought condition". Might make an interesting collectors item if your into that. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Re: What kind of seismograph Date: Sat, 13 Jun 1998 15:56:44 -0700 I looked at it. Mighty beat, really. The drum looks pitted. One could clean it up I suppose. -- ---/---- Charles P. Watson Seismo-Watch W6JRF@....... wrote: > > Hi Frank, I took a look at that seismo they are auctioning and it looks as > though the drum is driven by a mechanical clock motor and the recording is > done by an ink pen. the description says it is not electrical so if you plan > to use it on the system, you would have to modify it. Also as the description > says, "it is in rought condition". Might make an interesting collectors item > if your into that. > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: What kind of seismograph Date: Sat, 13 Jun 1998 21:43:41 -0700 (PDT) Thanks for the information. I think I'll pass on this one. It's true that it might make for an interesting conversation piece. Frank... >Hi Frank, I took a look at that seismo they are auctioning and it looks as >though the drum is driven by a mechanical clock motor and the recording is >done by an ink pen. the description says it is not electrical so if you plan >to use it on the system, you would have to modify it. Also as the description >says, "it is in rought condition". Might make an interesting collectors item >if your into that. > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: Re: What kind of seismograph Date: Sat, 13 Jun 1998 21:49:59 -0700 (PDT) Hi charles: Yeah, looks like it might make for an interesting project for some boy scouts. I've already got too many doorstops to keep the wind from shutting the door. I think it best to wait this one out.. Frank >I looked at it. Mighty beat, really. The drum looks pitted. >One could clean it up I suppose. > >-- >---/---- >Charles P. Watson >Seismo-Watch > >W6JRF@....... wrote: >> >> Hi Frank, I took a look at that seismo they are auctioning and it looks as >> though the drum is driven by a mechanical clock motor and the recording is >> done by an ink pen. the description says it is not electrical so if you plan >> to use it on the system, you would have to modify it. Also as the description >> says, "it is in rought condition". Might make an interesting collectors item >> if your into that. >> >> _____________________________________________________________________ >> >> Public Seismic Network Mailing List (PSN-L) >> >> To leave this list email listserver@............. with the body of the >> message: leave PSN-L > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: New event Date: Sun, 14 Jun 1998 18:06:10 -0700 Somethings coming now! 02:02:00 UTC + _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Stephen & Kathy Subject: Re: New event Date: Sun, 14 Jun 1998 19:15:06 -0700 barry lotz wrote: > > Somethings coming now! 02:02:00 UTC + > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L Got it here also,, 4.0 at GILROY Stephen Pilot Hill Ca USA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: RE: old test equipment Date: Wed, 17 Jun 1998 00:39:42 -0700 > -----Original Message----- > From: S-T Morrissey [mailto:sean@............ > Sent: Friday, May 15, 1998 9:21 PM > To: psn-l@............. > Subject: old test equipment > > > Jim, and the other ham radio operators, and everyone else; > > I have a collection of older test equipment that was Hi Sean-Thomas, I was just wondering what has happened regarding the test equipment. I managed to get some of my mail from my son's place in Calif. but got my mailbox screwed up and think I missed some. I think I will be home for a while now so I can keep up on things. Al _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Geophones again Date: Mon, 15 Jun 1998 09:28:19 -0700 I poked around the internet and after pulling some teeth I managed to get prices. Someone on the list might be interested in these. The company is GeoSpace and the instruments brand new. > Thanks for your continued interest in Geo Space products. > > Find the prices you requested. > > HS-10-1 and HS-10-2 are $ 2,000.00 USD each. Multi-unit > discounts are available on these models. > > HS-1, 4.5 Hz -- $72.00 USD ea > McSeis 101LT 5.5 Hz -- no longer available > GS 11D 4.5 Hz -- $60.00 USD ea > > Volume price discounts on HS-1 and GS 11D are available in > quanities over 1000 pcs. The first two are 1 and 2 Hz, which is probably why they're so expensive. I doubt we could pull together an order for 1000 instruments. I think the HS-1/GS-11D look attractive? I have their physical catalog if anyone wants "details" about them. They have a web site, but it's not as complete as the catalog. On a side note I was testing my computer for year 2000 issues and I remembered that SDR filenames use a 2 digit year. Will it work with the date set to 2000+ ? ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Lucas Haag Subject: Re: Geophones again Date: Mon, 15 Jun 98 15:28:37 CDT what is their web address. I think that maybe we need to dedicate a homepage to seismology using geophones to collect this data, amp schmatics, etc. Theres several pages relating to lemans, if somebody has space I'd be willing to design the page. Just my 2c worth. Thanks Lucas At 09:28 AM 6/15/98 -0700, you wrote: >I poked around the internet and after pulling some teeth I managed to >get prices. Someone on the list might be interested in these. The >company is GeoSpace and the instruments brand new. > >> Thanks for your continued interest in Geo Space products. >> >> Find the prices you requested. >> >> HS-10-1 and HS-10-2 are $ 2,000.00 USD each. Multi-unit >> discounts are available on these models. >> >> HS-1, 4.5 Hz -- $72.00 USD ea >> McSeis 101LT 5.5 Hz -- no longer available >> GS 11D 4.5 Hz -- $60.00 USD ea >> >> Volume price discounts on HS-1 and GS 11D are available in >> quanities over 1000 pcs. > >The first two are 1 and 2 Hz, which is probably why they're so >expensive. I doubt we could pull together an order for 1000 instruments. >I think the HS-1/GS-11D look attractive? I have their physical catalog >if anyone wants "details" about them. They have a web site, but it's not >as complete as the catalog. > >On a side note I was testing my computer for year 2000 issues and I >remembered that SDR filenames use a 2 digit year. Will it work with the >date set to 2000+ ? > >,Greg > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > ************************************************ Lucas Haag HCR 66 Box 25A Bartley, Nebraska 69020-9717 Email: lhaag@.............. World Wide Web: http://www.swnebr.net/~lhaag KC0BJB, Amateur Radio Tecnician Class License ****************************************************** ----- ---- NEBRASKA CORNHUSKER FOOTBALL --- -- NATIONAL CHAMPIONS -- -- -- 1970 -- -- -- 1971 -- -- -- 1994 GO BIG RED!! -- -- -- 1995 -- -- -- 1997 ---- ----- ****************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Rex Klopfenstein Jr Subject: PSN - Misc Stuff Date: Mon, 15 Jun 1998 18:50:03 -0400 I have tried to order the leveling screws at the LASER Surplus Outlet, = got a note today that they are out and don't know when they will be = getting any more. Any other suggestions of a source of fine threaded = rods with mating "nut"? There has been several discussions in the past about using sine waves = for capacitive sensors. I noticed a circuit listed in ELECTRONIC DESIGN = Vol 46(12), Pg 118 (5/25/98) by F. Michele. This short article = describes a circuit that uses 3 ic's (4040, 4030, and OP77), a few = resistors, and will generate a sine wave between 0.01 Hz to 1MHz with a = low or high pass filter. One does have to provide a clock signal into = the 4040. I have not tried the circuit, just posted for information. I don't remember if this has been posted before? I have found a source = of a WWV receiver kit ($59 w/o case, power supply, etc) at a company = called Hamtronics http://www.hamtronics.com It runs at 10 MHz. I have = ordered one, several people referred me and seem to be pleased. Rex Klopfenstein Jr _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: peaches@............ (Donna Whitaker) Subject: Re: Geophones again Date: Mon, 15 Jun 1998 12:57:33 -1000 (HST) Lucas, The GeoSpace website is at >http://www.geospacecorp.com< Dave N.in New Zeland and I are both running the GS-11D 4.5 Hz 380 ohm vertical geophone and would probably be the first choice for seismic monitoring. Note: This geophone requires 3X or 4X atenuation on Larrys amp/filter board. If you live in a noisy area then you might consider using the horizontal model as they arent as sensitive to manmade noise as the vertical is from what I've heard. Tony >what is their web address. I think that maybe we need to dedicate a homepage >to seismology using geophones to collect this data, amp schmatics, etc. >Theres several pages relating to lemans, if somebody has space I'd be >willing to design the page. >Just my 2c worth. >Thanks >Lucas > > >At 09:28 AM 6/15/98 -0700, you wrote: >>I poked around the internet and after pulling some teeth I managed to >>get prices. Someone on the list might be interested in these. The >>company is GeoSpace and the instruments brand new. >> >>> Thanks for your continued interest in Geo Space products. >>> >>> Find the prices you requested. >>> >>> HS-10-1 and HS-10-2 are $ 2,000.00 USD each. Multi-unit >>> discounts are available on these models. >>> >>> HS-1, 4.5 Hz -- $72.00 USD ea >>> McSeis 101LT 5.5 Hz -- no longer available >>> GS 11D 4.5 Hz -- $60.00 USD ea >>> >>> Volume price discounts on HS-1 and GS 11D are available in >>> quanities over 1000 pcs. >> >>The first two are 1 and 2 Hz, which is probably why they're so >>expensive. I doubt we could pull together an order for 1000 instruments. >>I think the HS-1/GS-11D look attractive? I have their physical catalog >>if anyone wants "details" about them. They have a web site, but it's not >>as complete as the catalog. >> >>On a side note I was testing my computer for year 2000 issues and I >>remembered that SDR filenames use a 2 digit year. Will it work with the >>date set to 2000+ ? >> >>,Greg >> >>_____________________________________________________________________ >> >>Public Seismic Network Mailing List (PSN-L) >> >>To leave this list email listserver@............. with the body of the >>message: leave PSN-L >> >> >************************************************ >Lucas Haag >HCR 66 Box 25A >Bartley, Nebraska 69020-9717 >Email: lhaag@.............. >World Wide Web: http://www.swnebr.net/~lhaag >KC0BJB, Amateur Radio Tecnician Class License >****************************************************** > ----- ---- NEBRASKA CORNHUSKER FOOTBALL > --- -- NATIONAL CHAMPIONS > -- -- -- 1970 > -- -- -- 1971 > -- -- -- 1994 GO BIG RED!! > -- -- -- 1995 > -- -- -- 1997 > ---- ----- >****************************************************** > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: used equipment Date: Mon, 15 Jun 1998 19:02:17 -0500 (CDT) Raul, I have not had time to work on the used equipment sale; I've been busy writing research proposals, etc. I probably won't get to it until July. None of it has gone anywhere. regards, Sean-Thomas. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Local Arizona event? Date: Mon, 15 Jun 1998 17:06:22 -0700 (MST) Hello Everyone, We picked up a small quake here at ASU in Tempe Arizona this morning (6/15/98) at around 12:56 UTC time, and the distance appears to limit this event to Arizona. Please send any info you guys can harvest... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: PSN - Misc Stuff Date: Mon, 15 Jun 1998 16:34:29 -0700 Rex I have used a "phase shift oscillator which are 3 single pole low pass filters(R-C) in series(60 degrees shift each) followed by an op amp with a gain of about 30. It works well but I am not sure how stable the frequency is with temperature etc. Frequency of oscillation is (1/(2*pi*R*C*sqrt(6)) .A better bet might be a intersil 8038 function generator chip. It is limited to a high frequency of about 350k hz. Rex Klopfenstein Jr wrote: > > > There has been several discussions in the past about using sine waves for capacitive sensors. I noticed a circuit listed in ELECTRONIC DESIGN Vol 46(12), Pg 118 (5/25/98) by F. Michele. This short article describes a circuit that uses 3 ic's (4040, 4 030, and OP77), a few resistors, and will generate a sine wave between 0.01 Hz to 1MHz with a low or high pass filter. One doe s have to provide a clock signal into the 4040. I have not tried the circuit, just posted for information. > Radio shack's clock works well with a similar price. I have hooked it up as Larry has described. Next is to include some software. Barry > I don't remember if this has been posted before? I have found a source of a WWV receiver kit ($59 w/o case, power supply, et c) at a company called Hamtronics > > Rex Klopfenstein Jr > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Local event Date: Mon, 15 Jun 1998 17:36:40 -0700 (MST) A .gif file of the event I mentioned in the last mail can be found at the following URL: http://www.public.asu.edu/~hernlund/06151256.GIF ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: seis calibrators Date: Mon, 15 Jun 1998 20:00:02 -0500 (CDT) Re: seismometer calibration: There are several ways to determine the response of a seismograph system (seis + amp + filters + recorder + etc), and it is a noteworthy cause if PSN waveform data are going to be used for scientific pursuits. The most direct way to characterize a seismograph is to know the transfer function. With a VBB response, it is a broad flat response to velocity that is readily determined, and if the external filter responses are well away from the flat portion of the response, radically different seismometers can have their data readily compared by converting it from digital counts/micron/second or volts/micron/second to a velocity of microns/second. This can be seen in the data comparing the STM-8 with the STS-1s; even though the sites are more than 100 km apart, the waveforms and power spectra agree nicely. Another direct method is to apply a step response, either by lifting a small weight off the mass (or the 45 deg thread arrangement for the horizontal) or by turning off a DC calibration current that is applied either through a 5 to 10 turn calibration coil, or uses the main coil in a balanced bridge configuration when a cal coil is not available or has been burned out. The step response, either due to a current in the calibration coil or the lifting of a small test mass, contains all frequencies of interest. It is also a change in force: aka acceleration. So to compare it with the velocity response predicted by the transfer function, isolate the data segment and take the FFT of it (I use MCADs complex FFT), and then divide the FFT values through by omega**2 (once is because of the step, the second is because the output voltage is velocity and the input is acceleration). The resulting response should look like the transfer function within the limits of your digitizer. An example of this is in figure 10 (I think; I rearranged them) of my web page of figures and schematics. The agreement is good from 10 seconds to 500 seconds. Local and microseismic noise dominates the spectrum at less than 10 seconds. I could use a larger step pulse, but my digitizer is limited to 12-bits. My digitizer is also one sample/second, so the nyquist (minimum useful frequency) is 2 seconds. I have to rely on my monitor recorder for short period data, like local events. (Teleseisms are generally more interesting to me.) The calibration coil can also be used with a function generator to input sine waves of constant P-P current. The output amplitudes are then measured (either digitally or on a monitor recorder) and divided by their respective omega, and the resulting plot is the velocity response. Or you can scale the input current by a 1/omega series resistance to provide a constant-velocity calibration directly. If you calibrate the calibration coil (weight to balance a given current), you can calculate the absolute magnification of the instrument. We make a low frequency function generator calibrator for our telemetry electronics that provides two sequential sine wave frequencies on a daily basis (triggered by a $15 alarm watch). It uses the 4047 oscillator, 4518 dividers, and a pair of 4018s to provide a 20-step sine wave at outputs between 10 hz and 20 seconds. It could be set up with a potentiometer to provide a continuously variable swept frequency output. There are also integral function-generator ICs that can do the job, but are generally too power hungry for a battery operated telemetry station. I could post the calibrator schematic if anyone wants it; it drives either a cal coil or a bridge with the main coil. A shake table is a rare luxury; the AFOSR paid for the one in our department back in the 60s. It is driven by a 5hp hydraulic system (to handle the Big Benioff seismometers that weigh 400 lbs), and operates from DC to 40 hz, 0.1 to 100 microns, with separate vertical and horizontal tables. We generally let anyone use it. Call me if you want to come to St. Louis and use it. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Y2K and WinQuake and SDR Date: Mon, 15 Jun 1998 21:19:56 -0700 At 09:28 AM 6/15/98 -0700, Greg wrote: >>On a side note I was testing my computer for year 2000 issues and I >remembered that SDR filenames use a 2 digit year. Will it work with the >date set to 2000+ ? This is on my to do list... I have look at the code for both WinQuake and SDR to see where there many be problems with the year. I think I corrected everything, but have not tried it. I'll try and do this test soon. If someone has SDR and WinQuake running, and has some time to do the testing, please let me know. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Subject: Re: Y2K and WinQuake and SDR Date: Tue, 16 Jun 1998 00:46:02 EDT I have the time.. e-mail sw6079 Mike Sellman _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: 5/16" diameter 24 tpi NF Base screws with ball points Date: Tue, 16 Jun 1998 00:26:32 -0600 Hi all, Ran across some screws at a local surplus acouple weeks back, that are of some interest especially because of their fair ball tip. They are 5/16" in diameter with a 24 t.p.i., (threads per inch), National Fine (NF), and the overall length is 2.445" in length. The head is 3/8" (.375") in diameter and .555" long with a side hole of .187" thru it. The threaded shaft is 1.795; but the effective thread to use is ~ 1.7", with the head/thread clearance. On the bottom is a lathe rounded 1/2 ball shape (.175 - .180" diameter), which is ~ .095" in length. Dimensions probably vary + - .015" or so. The material appears to be simple, magnetic, cold rolled bar steel. The advantage with these are the ball end which means very little bolt "walking" on the pier, and the head hole means that with a suitable "lever" (hex wrench, screwdriver etc.), one can tweak in a fair adjustment for probably coil/magnet combo's with patience. Have already mounted 3 in a prospective seismo base, with a thickness of ~.450" aluminum that was tapped for the screw, and a test weight of 45 lbs, and they seem to do OK, but they are not exactly precision stuff...more like a lunch bucket seismometrist would use-ha. Not much to look at, but better than the normal hardware store selection. I used 2 nuts each for the top of the base and underneath to finger tighten and brace up. There is some wobble, but it seems to be greatly alleviated with the nuts being tightened. I used a home drill press, which is important for a straight in drill/tap and as little screw "walking". On my test base, I could not see any screw "walking". With a home hand drill, you results may drastically vary due to sensed angle variation results. Don't know what they were originally made for but obviously of some kind of vise type screw with "T" handle use. They may need some finishing touchs with a file around the head cutoff top and head bottom edge. Have some 8 sets of 4 screws (one spare), with 2 ugly nuts each, and a hex wrench "holder" thru the heads made up. Also I did clean up the thread with a die. Suggest Vaseline (petrolium jelly) thin coating for use or storage. You will need a tap and drill (letter I size is standard). The non-profit price is postage and a complete mailing address. Send me an email with the complete name/address. Shipping weight will likely be around 8 ounces per set, and you can send a check or stamps later. My source has perhaps hundreds of these screws, but, I'am not overly thrilled about a perpetual availablility. If anyone has a better means, let me know...but... they will have to bear the full expense for them; and the tooling/expense/work/risk/reward involved. Offer is limited till August 1st, and only amateurs please. Additional sets to individuals may/maynot be available as written here, and they may have to do their own die re-threading cleanup etc., and full cost. Don't know about any foreign shipments, as the world is metric and they may not have access to having/buying/ borrowing a tap??? ....and, any other problems involved??? Meredith Lamb P.S., Rex, Thanks for the note on Laser Surplus. Doesn't sound good for me and my quest for nuts from them. Life...I guess. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: M6 + quake south of New Zealand Date: Tue, 16 Jun 1998 22:46:22 +1200 will post soon very inpressive surface waves DAve Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: Local Arizona event? Date: Tue, 16 Jun 1998 08:36:34 -0700 At 05:06 PM 6/15/98 -0700, you wrote: >Hello Everyone, > We picked up a small quake here at ASU in Tempe Arizona this morning >(6/15/98) at around 12:56 UTC time, and the distance appears to limit this >event to Arizona. Please send any info you guys can harvest... John -- I got the same event. My data shows a M4.0 at about 12:56:22UTC (6/15/98) 322km from me (I am east of San Diego by 20km). Quite possibly in Mexico or the Gulf of California. Let me know if you find anything out. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: watson@................ (Charles Watson) Subject: Good news/Bad news Date: Tue, 16 Jun 1998 09:03:41 -0700 Good News: I have been asked by the Mammoth Times, the local newspaper in the Mammoth Lakes region, to put together a web site showing the information currently featured in their newspaper edition. Here is a URL show the layout of the Mammoth Times's Seismo-Watch Earthquake Report: http://www.seismo-watch.com/EQNEWS/Newspaper/MT.html The Mammoth Times does not pay for Seismo-Watch and financial support for the feature comes from generous contributions and limited sponsorships or advertisements. Parties interested in supporting the Mammoth Times newspaper or web site editions should contact Charles Watson at numbers below. Bad News: The Alameda Newspaper Group in the East San Francisco Bay Area has decided to drop the Seismo-Watch Earthquake Report in favor of Weather-Central's "Quake-Watch". Seismo-Watch began in the ANG newspapers in August 1995 and has been a popular feature since then. We were on a program to upgrade the Seismo-Watch Earthquake Report to color when the notice was given. ANG gave no reason for their change in vendors. This is sad not only for the producers of Seismo-Watch, but for the people of the East Bay Area as the "Quake-Watch" graphic shows less information and is of lower quality. -- ---/---- Charles P. Watson, Consulting Geologist Advanced Geologic Exploration/Seismo-Watch P.O. Box 18012, Reno, Nevada 89511 Voice: 702-852-0992 / Fax: 702-852-3226 mailto:watson@................ http://www.seismo-watch.com _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: frankcnd@.......... (Frank Condon) Subject: What kind of a compass is this? Date: Tue, 16 Jun 1998 09:31:05 -0700 (PDT) Hello All: Here is another one of those items that I'm curious what it's for, being auctioned off at Ebay. Basically, it looks like a compass that has a coil under it with two external terminals. http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=17711564#BID Frank... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Y2K and WinQuake and SDR Date: Tue, 16 Jun 1998 12:42:44 -0700 Larry Cochrane wrote: > everything, but have not tried it. I'll try and do this test soon. If > someone has SDR and WinQuake running, and has some time to do the testing, > please let me know. I have the time, but no equipment to generate events. I suppose that's useless ? BTW I made a sorry looking dipole and managed to get my scanner to pick up both WWV and WWVH last night. The bad news is that I lost WWV during the day. I guess I need to get some nice copper wire for the dipole. I'm still slowly building my Lehman. I bought all kinds of junk at the hardware store and this thing costs a heck of a lot more than a new geophone. I guess it helps to have a shop full of tools and scraps from other projects. Not counting the aluminum that I somehow managed to get for free, this thing is over $90. I melted the lead mass into a cylindrical shape with a gas grill and two propane torches. Even then it took a while and a lot of gas. I got a tap and some bolts. The best I could find was 1/4-20. This is out of a large selection of bolts, studs, screws and stuff. I don't know if I'll use them yet. Sorry, Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: David Wolny Subject: Re: Ariz. event Date: Tue, 16 Jun 1998 16:53:16 -0600 (MDT) The following is from the NEIC. Though it isn't stated, I believe the magnitude was supposed to be around 4.0. I'm not sure why it is listed at 0.0. All solutions are reviewed (M for manual) by the NEIS (source NEI) HHMM is the hour and minute (UTC) when the event was first located D a t e Time (UTC) Location Dep Magni. T AGY R e g i o n HHMM 15Jun1998 12:56:09.9 31.1N 114.4W 10 HN=0.0 M NEI GULF OF CALIFORNIA 1355 Dave _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: leveling screws Date: Tue, 16 Jun 1998 18:35:27 -0500 (CDT) Meredith and co. I am just wondering about all the fuss to find a fine thread leveling screw. Looking for a 1/4" or 3/8" fine thread is a good idea, but I don't think we are needing to jack up something really heavy., If the 1/4-28 stainless hardware can't be found in the special hardware drawers at your nearest True Value, (Builders Square has them in the wall of little bags of nuts and bolts and screws, among other sources, and there are endless varieties in McMaster Supply), why not use #10-32 threaded screws or rod? It is available in stainless or brass, and the brass nuts can be soldered into place, even stacked in a tube to make a jiggle-free mounting. It also readily attaches to a low RPM (like 1) gearmotor for remote centering of the seis. And regarding the rounded contact point of the seismometer feet: it is usually used in conjunction with small glass plate placed under it on the pier. The glass minimizes lateral torqueing as the screw is turned, and also allows the contact point to slide freely as the base expands with temperature. Disadvantage: a careless move or nasty quake can slide the foot of the seis off of the glass plate. Glossy glazed ceramic tiles will also work. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Local Arizona event? Date: Tue, 16 Jun 1998 16:42:30 -0700 (MST) On Tue, 16 Jun 1998, Karl Cunningham wrote: > At 05:06 PM 6/15/98 -0700, you wrote: > >Hello Everyone, > > We picked up a small quake here at ASU in Tempe Arizona this morning > >(6/15/98) at around 12:56 UTC time, and the distance appears to limit this > >event to Arizona. Please send any info you guys can harvest... > I got the same event. My data shows a M4.0 at about 12:56:22UTC (6/15/98) > 322km from me (I am east of San Diego by 20km). > Quite possibly in Mexico or the Gulf of California. Let me know if you > find anything out. Yes, the event was in the gulf of california. The horizontal component I was using for this event is oriented so that it swings in a direction almost exactly 90 degrees to the azimuth for the arrival which made my P arrival non-existent. ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Y2K and WinQuake and SDR Date: Tue, 16 Jun 1998 22:06:34 -0700 Thanks for the offer Mike. Are you running SDR? Most of the testing will be on SDR, not WinQuake. -Larry At 12:46 AM 6/16/98 EDT, you wrote: >I have the time.. e-mail sw6079 Mike Sellman > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: TYRRENIAN SEA Date: Wed, 17 Jun 1998 17:22:18 +0200 12.42 UTC Mb 4.5 Loc.: SOUTHWESTERN TYRRENIAN SEA; NEAR COAST OF NORTHERN SICILY = (Trapani) I.ES.N. - PSN ITALY
12.42 UTC
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I.ES.N. - PSN = ITALY
From: Karl Cunningham Subject: Re: Ariz. event Date: Wed, 17 Jun 1998 08:29:40 -0700 At 04:53 PM 6/16/98 -0600, David Wolney wrote: > >The following is from the NEIC. Though it isn't stated, I believe the >magnitude was supposed to be around 4.0. I'm not sure why it is listed >at 0.0. > > All solutions are reviewed (M for manual) by the NEIS (source NEI) > HHMM is the hour and minute (UTC) when the event was first located > > D a t e Time (UTC) Location Dep Magni. T AGY R e g i o n HHMM > >15Jun1998 12:56:09.9 31.1N 114.4W 10 HN=0.0 M NEI GULF OF CALIFORNIA 1355 > Dave -- Thanks for the info on the mystery event. Do you have a URL for a list that shows this event? BTW, an event appears on the SCEC list of recent event in CA & NV ( http://www.scecdc.scec.org/recenteqs/Quakes/quakes0.html ) that is virtually coincident in time: 98/06/15 12:56:33 32.56N 114.99W 0.0 M2.7 24 mi WSW of YUMA, AZ Don't know if these are really separate events. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: Ariz. event Date: Wed, 17 Jun 1998 13:05:32 -0700 (MST) On Wed, 17 Jun 1998, Karl Cunningham wrote: > >15Jun1998 12:56:09.9 31.1N 114.4W 10 HN=0.0 M NEI GULF OF CALIFORNIA > 1355 > 98/06/15 12:56:33 32.56N 114.99W 0.0 M2.7 24 mi WSW of YUMA, AZ Boy, this is a dilemma. I talked to Terry Wallace at UofA who identified the event as being the former, in the gulf of CA. I think the latter may be a mislocated event...it is around the same time but differs by more than one degree of arc. ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: Geophones again Date: Thu, 18 Jun 1998 15:22:42 +1200 At 03:28 PM 6/15/98 CDT, you wrote: >what is their web address. I think that maybe we need to dedicate a homepage >to seismology using geophones to collect this data, amp schmatics, etc. >Theres several pages relating to lemans, if somebody has space I'd be >willing to design the page. >Just my 2c worth. >Thanks >Lucas YEP Lucas i will dedicate pages to geophones lets go for it im a dedicated user of geophones so lets work together and see what we can put together Dave Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: /recenteqs/ Web site Date: Thu, 18 Jun 1998 10:00:10 -0400 Hi gang, Science magazine of 12 June (p 1663) mentions quake.wr.usgs.gov/recenteqs/ . I tried it and was greatly impressed by t= he ingenious and user-friendly presentation. The maps are spectacular! Many on this list are probably familiar with this site but it seems to = be relatively new and if you haven't seen this, try it! Bob Barns _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: Geophones again Date: Thu, 18 Jun 1998 10:11:46 -0400 Hi gang, I have great reservations about creating a separate group or source of info on geophones. A good bit of the info on geophones and longer period= seismographs overlap. One troublesome question which would arise is wher= e to draw the line between short and long period. If there were two lists, reading only one might miss some good stuff (e.g., amplifier design) so many would have to read both lists. This wou= ld be inconvenient compared to the present arrangement. Ths combined info (as at present) is not so large as to be a burden. Bob Barns If you ain't makin' waves, you ain't kickin' hard enough! _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Geophones again Date: Thu, 18 Jun 1998 10:02:42 -0700 robert barns wrote: > If there were two lists, reading only one might miss some good stuff I think they were only suggesting a web page with information and resources. Denying that would be like denying me from putting up pictures of circuit boards or water skis or baby clothes or etc... ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "David A. Nelson" Subject: Re: Geophones again Date: Fri, 19 Jun 1998 08:34:46 +1200 Robert u mis understand not a separate e-mail list!!! but webpages dedicated to geophone systems, so many are dedicated to lehmans but NOTHING to phones. So about time we got info up there for ppl who want to know more abt them and their abilities Dave At 10:11 AM 6/18/98 -0400, you wrote: >Hi gang, > I have great reservations about creating a separate group or source of >info on geophones. A good bit of the info on geophones and longer period >seismographs overlap. One troublesome question which would arise is where >to draw the line between short and long period. > If there were two lists, reading only one might miss some good stuff >(e.g., amplifier design) so many would have to read both lists. This would >be inconvenient compared to the present arrangement. > Ths combined info (as at present) is not so large as to be a burden. >Bob Barns > >If you ain't makin' waves, you ain't kickin' hard enough! Co-ordinator: New Zealand Public Seismic Network Dave A. Nelson ZL4TBN 24 Jensen St., Green Is., Dunedin, South Is.. New Zealand. http://psn.quake.net/dave/home.htm IF there indeed are other parallel universes... I can now rest in the knowledge, that in at least one of them, I am filthy rich and drive a red Ferrari _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Greg Subject: Re: Geophones again Date: Thu, 18 Jun 1998 13:59:50 -0700 David A. Nelson wrote: > ppl who want to know more abt them and their abilities And prices ;) I'll offer my time and effort to put the html together. I also have several MB of server space left for the pages. I can even clear some of my junk off to put even more on them. ,Greg _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: quake rolling in now 21:19 utc Date: Sat, 20 Jun 1998 15:20:51 -0600 fair quake rolling in now. Looks to be not too far from Denver, Colo.....maybe 2,000 Km or so. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "John Krempasky" Subject: Re: quake rolling in now 21:19 utc Date: Sat, 20 Jun 1998 19:04:03 -0400 >fair quake rolling in now. Looks to be not too far from Denver, >Colo.....maybe 2,000 Km or so. > >Meredith Lamb > I would assume it is the 4.7 in Wyoming at 21:16 listed on NEIC http://wwwneic.cr.usgs.gov/neis/bulletin/980620211620.HTML John Krempasky _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Tom Frey Subject: Re: quake rolling in now 21:19 utc Date: Sat, 20 Jun 1998 16:14:54 -0700 Arrival at Tacoma WA is 21:18:32.5 UTC >At 03:20 PM 6/20/98 -0600, you wrote: >>fair quake rolling in now. Looks to be not too far from Denver, >>Colo.....maybe 2,000 Km or so. >> >>Meredith Lamb >> >> >> >> >>_____________________________________________________________________ >> >>Public Seismic Network Mailing List (PSN-L) >> >>To leave this list email listserver@............. with the body of the >>message: leave PSN-L >> > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: The S-G hinge Length v/s vertical vibration Date: Sat, 20 Jun 1998 21:16:50 -0600 Larry, Arie, or anyone Have been making up a simple S-G type seismo. Initially my hinge has a space of some 1 inch from the top clamp to the boom clamp. Can't really change it and make it shorter because of mechanics involved. Anyway...I notice it is fairly susceptible to tabletop vertical jars, which of course won't be as prominate on a pier. Question is; did you experience the same oscillation on initial building or followup operation? Or is there much that can be done at all, or is it kind of a necessity? Most seismometers use as short a space between the clamping blocks as possible. Of course most seismometers aren't a S-G type. Perhaps if it was too short, then the hinge wouldn't have the freedom it possibly needs? Think I could even install stiff metal shims between the clamping blocks to effectively reduce the hinge length and perhaps the susceptibliy to vertical vibration. The damping I'am using is magnetic induced eddy currents with aluminum plates, and it seems to be critical on any distance span with simple visual offset checks. I used this old method because I have the magnets, and it fortunately worked well here. Another question: Have you tried reducing the width of the hinges at any time? If so,...what were the results sensitivity wise, better or worse? I started with 1/2", but the max is 5/8". Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: The S-G hinge Length v/s vertical vibration Date: Sun, 21 Jun 1998 07:23:31 -0500 Meredith, Ideally the hinge should be as short as possible or even a crossed flexure. As you have observed a longer hinge allows the pendulum to have some extra degrees of freedom of motion that can cause unwanted responses in the instrument. If the hinge material is stiff and short it can shorten the period of the instrument by adding extra restoring force. This can be offset by using a thinner or more flexable material. At one time I considered making a tiny SG. It was to use a piece of Scotch tape for the hinge.:) -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Francesco" Subject: SICILY LARGE AFTERSHOCK Date: Sun, 21 Jun 1998 17:23:36 +0200 INTENSIVE AND LARGE AFTERSHOCK IN THE LAST HOURS 12.58 MB 4.3 SAME LOCATION-SAME DEPTH NO MATERIAL DAMNAGES MANY MICROSISMIC ACTIVITY
INTENSIVE AND LARGE AFTERSHOCK IN = THE LAST=20 HOURS
 
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From: S-T Morrissey Subject: crossed flexure hinges Date: Sun, 21 Jun 1998 12:29:12 -0500 (CDT) Meredith, A note on hinges in large seismometers (geophones use etched diaphram springs that are also the suspension): It is important to constrain the degrees of freedom of the boom to ideally one, the direction of sensitivity. This is because other movements, eg lateral in a vertical, require compensating clearances in the transducers of the seis, which usually implies reduced sensitivity. For years the crossed-flexure hinge has been the usual hinge for vertical sensors. Horizontals also use the very short (1-2 mm) taught wire hinge, or the push-pull "Press-Ewing" crossed flexures along a vertical support (the upper hinge pulls at the front, the lower pulls from the back side). As Jim H. noted, the stiffness of the hinge is important in a non-fedback sensor, and also affects the mechanical period in a fedback sensor. The stiffness is proportional to the square of the thickness, so wider-thinner is preferred. I have been using 0.005" bronze or stainless shim stock. In the STM seis, it is 3/8" wide. I have not experimented with thinner/narrower; the limit is wherever they break from tension, which is how the force is applied in the crossed flexure configuration. I have found that using epoxy to fasten the hinge strips is quite satisfactory. Prepare both surfaces (of the hinge strips and the (aluminum in my case) support brackets) by sanding with 200+ grit emory paper. Where the hinge angle brackets almost touch, file the corners back about 2 mm, so that the axis of the crossed flexures is clear of any hard contacts. Also, make sure that no glue gets into this area. I have seen no indication of the hinge flexures coming unglued in the STM prototype of April '97. The latest thing (the last 10 years) in commercial seis hinges is a prefabricated crossed flexure connecting two small parallel rings (1/2"dia) that are simply fitted to drilled holes in the frame and the boom. The Bendix version costs $50 and up, but is compact and low noise, providing about 15 degrees of rotation with less than a micron of orthogonal movement. Regards, Sean-THomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: crossed flexure hinges Date: Sun, 21 Jun 1998 21:39:04 -0600 Sean-Thomas, Thanks for the broad notes on hinges. I'll have to see what, how, and if reparations are possible with this seismo in the future. Also, thanks for the notes on the hinge preparation for the STM-8, I don't recall reading the sanding and filing elsewhere before. Your note regarding crossed flexures connecting 2 small parallel rings in the frame is new too me. Am not picking up the picture though... Hate to guess? Sounds real good, but is it possible to clarify or show the basic configuration? Like everything else, its quite possible to adopt it into amateur use. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: crossed flexure hinges Date: Mon, 22 Jun 1998 16:05:09 -0600 Jim Hannon, Sean-Thomas Morrissey and Larry Cochrane, Thanks for the assistance with the hinge subject. It didn't take long to change the old into a much better arrangement. The S-G type seismo hinge now has a space of .0875" between clamps, by some reworking of the clamp mechanism. Also retired the somewhat flimsy boom, and that also eliminated alot of vibration "ringing". Also put in wider hinges and that really reduced the mass orthogonal movement from about .0625" to about .015" or less (somewhat forced). I no longer see movement visually with a induced table vertical impact ....the whole frame seems to move in unison. Glad I asked. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond Subject: Re: documentation request Date: Tue, 23 Jun 1998 11:14:08 -0500 Bob, >If anyone has (or can suggest a source for) a copy of the manual for >the IBM Acquisition & control adapter assy 6323710 I would like to >obtain one. Did you ever get a copy of the manual? I just found your message as I was clearing out old email. I have a copy and could xerox some of it for you, if you needed. Charlie Rond -\/\--Public Seismic Network-Memphis http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Ted Blank Subject: Re: documentation request Date: Tue, 23 Jun 1998 09:33:29 -0700 (PDT) Charlie, I believe the doc for the IBM DACA card was part of the XT or AT technical manual, right? I don't need the doc, but if anyone knows where to get any of the cards, let me know. Question for any of you who've played around with QuickBasic 4.5. I am trying to add support for the DataQ DI-190 serial A/D gizmo. I open the com port and talk to the device just fine. However, when I issue the basic SCREEN 2 command to put the screen in to graphics mode, it closes the com port. Is this normal or a bug in the compiler? I can move the SCREEN command around so it is after the com port open, but I jump in and out of graphics mode a lot in error situations so I'd like to avoid a big rewrite. Regular bus-attached A/D cards have always been immune to changes to screen mode. Thanks! Ted Blank San Jose, California _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Re: documentation request Date: Tue, 23 Jun 1998 21:50:58 -0400 Ted, I have used QuickBasic some but not in such a way as to see your proble= m with SCREEN 2 closing the COM port. This sounds to me like you should take the problem to Microsoft. Bob Barns Black holes are where God divided by zero. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: George Bush Subject: Howard Grebin Date: Tue, 23 Jun 1998 20:54:34 -0700 This is directed mainly to those of you who know Howard Grebin (Jan Froom, Frank Mead, Steve Hammond, and many others), but might also be of interest to the rest of the PSN-List. Last Saturday (June 14th), I was in Sebastipol on other business so I called and then visited Howard. I want to share my visit with you. But first a very brief background on how I came to know of Howard: He built the seismometer system that I am presently using. It consists of a fine old Geotech 8700A Long-Period Horizontal Seismometer connected to a United Electro Dynamics DR271 Photographic Drum Recorder that Howard had modified by adding a clock drive and an ink-pen to the galvonometer. The galvonometer is driven by an amplifier/filter box built by Frank Mead. Howard sold the unit to our local fire chief who has loaned it to me until he retires and can put it into a quieter environment than the firehouse. Howard is now well over 90. He has been interested in seismography for a long time and I had heard some fine yarns about him: I read a delightful newspaper article on Howard from The Times, Dec. 25, 1980 about how he had reported a M7.6 quake on Vancouver Island to the Associated Press and KCBS. Unfortunately, some facts got switched-around and it was reported that the quake was centered in Sebastipol! This mis-news triggered about 60 phone calls from worried out-of-town family members before the story was corrected on the radio 15 minutes later! The other story comes from Steve Hammond about how in the early 50's, the guys at Berkely would call Howard to second-source their distance and magnitude data from time to time. When I arrived, Howard and I had a nice chat and I was able to show him some Winquake plots from the system that he had originally made. He took me into his ham shack (he is WA6IAP) and seismo lab. He has a Geotech 8700A mounted on a concrete slab out in his back yard and it is hooked-up to a drum recorder. He has ingeniously fixed a vane on the galvonometer pen that for large excursions, interrupts a light beam and the amplified photocell signal is used as an earthquake warning via a buzzer. He has a second drum recorder that is complete except for a pen. Howard had more interesting equipment to show me, but standing-up had tired him and so we went back to the living-room to sit down. He's not too well, is on an inhaler, and has an oxygen bottle in the living room behind the couch. I am impressed with how he has things organized and accomodates to his age and infirmities. The living room looks like the cockpit of the space shuttle in that all the things he needs are carefully arrayed around his chair. A table with his magnifying glass and papers is just in front of him, to the right is a bench with various items arrayed in dishes and plastic containers, with medicines behind. Just in front of the table in front of him is his audio system, tapes and TV remote with the TV across the room. He has even taught his care-giver to change the paper on the drum recorder! Harold has had a stroke and has to talk slowly, his hearing is failing, and he needs the magnifier to read. Conversations with visitors or phone calls are difficult but he really enjoys to correspond by letter. He is sharp as a tack, very interested in what we are doing, and since he does not have a computer and is not on the PSN-list is sort of isolated and cut-off from others who are interested in seismology. I thought that Harold would appreciate a note from those of you he knows (and anyone else too), and his address is: Harold Grebin 6666 harvard Drive Sebastopol, CA 95472 George _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Rex Klopfenstein, Jr." Subject: PSN - Kinda Dumb Question Date: Wed, 24 Jun 1998 19:49:19 -0400 I am in the process of building a S-G seismometer. I am working on the "transmitter" and "receiver" paddles. Does anybody have have suggestions to remove copper foil from pc board core short of using etching solution? I thought I had a solution. Whenever I try to repair a pc board and get too much heat into the foil presto the foil lifts off followed by a few choice words! Well, I thought I had a solution--use a hot soldering iron. I even used a large roofer's iron and guess what? The foil didn't move! Any hints would be appreciated Rex Klopfenstein, Jr. Bowling Green, OH _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Roger Baker Subject: Re: PSN - Kinda Dumb Question Date: Wed, 24 Jun 1998 19:03:56 -0500 Rex, assuming you are really committed to solving this problem, you will notice that with care you can usually strip off copper by peeling it up at a corner with a razor blade and then pulling it off with a pliers. Try that first. Heat can only weaken most organic bonds, so there is probably a temperature that allows you to heat the board evenly, like in the bottom of a gently heated skillet, and to easily pull off any area that you have slightly detached at the edge and pull at with a needle-nose pliers, while holding the board down flat in the skillet with something else. --Yours, Roger At 07:49 PM 6/24/98 -0400, you wrote: >I am in the process of building a S-G seismometer. I am working on the >"transmitter" and "receiver" paddles. Does anybody have have >suggestions to remove copper foil from pc board core short of using >etching solution? > >I thought I had a solution. Whenever I try to repair a pc board and get >too much heat into the foil presto the foil lifts off followed by a few >choice words! Well, I thought I had a solution--use a hot soldering >iron. I even used a large roofer's iron and guess what? The foil >didn't move! > >Any hints would be appreciated > >Rex Klopfenstein, Jr. >Bowling Green, OH > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Charles R. Patton" Subject: Re: PSN - Kinda Dumb Question Date: Wed, 24 Jun 1998 17:11:28 -0700 Rex wrote: Does anybody have have suggestions to remove copper foil from pc board core short of using etching solution? Rex, To remove foil on large areas using heat, start at one corner and get it hot enough that you can lift it with a knife edge, Xacto, or similar. Once you have a tab up large enough to grip with a needle nose or regular pliers, just pull perpendicular to the board. At this point you have two paths you can take. 1) Pull hard enough to just rip the copper off. Usually the result is that you take off an uneven strip. But if the board foil is cooperative enough this is still fast as a fairly large chunk will come off with one pull. You then repeat the starting procedure on the remaining foil with the iron. Repeat until all the foil is removed. (Typically you'll notice that there is a "grain" to the copper pulling exercise -- it will pull off better in one direction than the orthogonal of that direction.) 2) The other way is to continue applying the the soldering iron along the parting line between the the foil and the epoxy, sliding the iron along the whole seam, back and forth, incrementally removing the foil. It helps to tin the foil in order to get enough heat into the foil to make it release. Charles R. Patton new email address: charles.r.patton@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: documentation request Date: Wed, 24 Jun 1998 19:12:52 -0700 Ted, I have used QuickBasic quite a bit. Most of my data acquisition is thru the parallel port but I have a program for use at work which inputs ASCII data from a testing machine output thru the serial port. It plots data in screen 2 also. This is about as close as I have gotten to your situation. I haven't had a problem as you have described though. Sorry. Barry robert barns wrote: > > Ted, > I have used QuickBasic some but not in such a way as to see your problem > with SCREEN 2 closing the COM port. > This sounds to me like you should take the problem to Microsoft. > Bob Barns > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Shackleford-Gunderson seismometer questions Date: Wed, 24 Jun 1998 20:55:14 -0600 Hi all, Have a question on the free period of the S-G seismometer. What constitutes an ideal period to have? With a simple hanging pendulum, only the length of the pendulum has any influence...outside of the influence of the hinge and its material tension "Q" factor. Am using phosphor bronze hinges (2), with a thickness of .005" X 5/8" wide. The spacing between the hinge clamps is now .025" Am getting a free period of 1.09 seconds, from a hinge to mass center length of about 12 & 1/2 inches. The mass is 4 lbs but with the boom etc., the weight is about 5 lbs. The "Q" seems to be in excess of 25 minutes of free oscillations. Is this good or fair or average? Would thinner hinges improve the "Q", like around .003"? No experience on the S-G, and precious little else-ha. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Al Allworth" Subject: RE: PSN - Kinda Dumb Question Date: Fri, 26 Jun 1998 20:49:23 -0700 > -----Original Message----- > From: Rex Klopfenstein, Jr. [mailto:rklopfen@.......... > Sent: Wednesday, June 24, 1998 4:49 PM > To: psn-l@............. > Subject: PSN - Kinda Dumb Question > > > I am in the process of building a S-G seismometer. I am working on the > "transmitter" and "receiver" paddles. Does anybody have have > suggestions to remove copper foil from pc board core short of using > etching solution? > I have made crude circuit boards by peeling the copper off the board and leaving strips of copper where I wanted conductors. Use a rule and an Exacto knife to scribe lines on the board. Use the back edge of the Exacto knife. Hold it at an angle around 45 degrees and scribe several times being careful to get it in the same cut each time. About 3 times will get most of the way through. It's best not to try to get all the way through the copper. If you do the knife will be dulled by the glass fibers. If it's necessary to sharpen the knife keep the back edge square. You can use a whetstone or fine emory paper laid on a smooth metal surface. If the point breaks off restore it to a V shape with the above method. You can get the peeling started with the soldering iron but wipe off all solder before starting to peel. I have been able to peel G-10 grade material but some materials are so easy to peel you can start without heating. just get the Exacto hnife point under the edge and you will soon get the feel of it. (but NOT of the knife , I hope. Be very carefull, they are very sharp.) I haven't tried this method with some of the newer materials but I don't think they are any harder than G-10 I have done curves but it is very difficult to get the line scribed accurately. I hope this helps. Let me know how you do. Al _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Steve Hammond Subject: Howard update Date: Wed, 24 Jun 1998 21:02:58 -0700 Thanks for the update on Howard. I'll drop him a line. Regards, Steve Hammond _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: Geosource model MD-100 Geophone Date: Thu, 25 Jun 1998 13:59:19 -0600 Hi all, Just got a mailed July 1998 blurb ad sheets from the Electronic Goldmine P.O. Box 5408 Scottsdale, AZ 85261 ... titled Hot specials & new arrivals. This is a separate ad sheet from their normal catalog, and it maybe best to ask for it by mail. Their web site and normal email catalog request site is: http:/www.goldmine-elec.com On the bottom right front cover sheet, they list a Geosource model MD-100, 14hz, 325 ohm, 1&1/4" tall X 1" diameter, brand new item # G9621, $8.95 plus shipping weight which probably isn't much, but no weight listed. They supple a circuit diagram of ? value, with LED output. They did not list what kind it is...either vertical or horizontal. Their is no spike...just alittle cannister. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: Geosource model MD-100 Geophone Date: Thu, 25 Jun 1998 14:55:11 -0600 Additional information for those interested. Electronic Goldmine is a electronics surplus outlet, and only does mail order. Minimum order is $10.00. Shipping & handling $5.00 minimum. Toll free order line: 1-800-445-0697 Fax: 602-661-8259 Customer service line: 602-451-7454 Personal check, company check, money order, cashiers check, visa/mastercard accepted. I've bought from them on other items, and have not had problems. Again, it would be best to get their July 1998 "Hot Specials & New Arrivals" issue, by mail request, that way you can see the ad yourself. Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "William England" Subject: Re: PSN - Kinda Dumb Question Date: Fri, 26 Jun 1998 23:52:08 -0500 a dremel tool works well. and is fast........radio shack sells the ferric chloride and fingernail polish works well for masking the copper area. bill nj0x -----Original Message----- From: Al Allworth To: PSN-L Mailing List Date: Wednesday, June 24, 1998 10:52 PM Subject: RE: PSN - Kinda Dumb Question > > >> -----Original Message----- >> From: Rex Klopfenstein, Jr. [mailto:rklopfen@.......... >> Sent: Wednesday, June 24, 1998 4:49 PM >> To: psn-l@............. >> Subject: PSN - Kinda Dumb Question >> >> >> I am in the process of building a S-G seismometer. I am working on the >> "transmitter" and "receiver" paddles. Does anybody have have >> suggestions to remove copper foil from pc board core short of using >> etching solution? >> > I have made crude circuit boards by peeling the copper off the board and >leaving > strips of copper where I wanted conductors. Use a rule and an Exacto knife >to > scribe lines on the board. Use the back edge of the Exacto knife. Hold it >at an > angle around 45 degrees and scribe several times being careful to get it in >the > same cut each time. About 3 times will get most of the way through. It's >best not > to try to get all the way through the copper. If you do the knife will be >dulled > by the glass fibers. If it's necessary to sharpen the knife keep the back >edge > square. You can use a whetstone or fine emory paper laid on a smooth metal >surface. > If the point breaks off restore it to a V shape with the above method. > > You can get the peeling started with the soldering iron but wipe off all >solder > before starting to peel. I have been able to peel G-10 grade material but >some > materials are so easy to peel you can start without heating. just get the >Exacto > hnife point under the edge and you will soon get the feel of it. (but NOT >of the > knife , I hope. Be very carefull, they are very sharp.) I haven't tried >this method > with some of the newer materials but I don't think they are any harder than >G-10 > > I have done curves but it is very difficult to get the line scribed >accurately. > > I hope this helps. Let me know how you do. > > Al > > > > > > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Charlie Rond Subject: Re: documentation request Date: Sat, 27 Jun 1998 03:36:21 -0500 Ted, >I believe the doc for the IBM DACA card was part of the XT or AT >technical manual, right? I don't need the doc, but if anyone knows where >to get any of the cards, let me know. The doc I have is a separate hardbound - like one of the technical manuals - called "Guide to the Data Acquisition and Control Adapter Programming Support." I do not have the XT or AT tech manuals, so can't vouch for whether DACA is included. I also would like to know where to obtain any of the cards. >Question for any of you who've played around with QuickBasic 4.5. I am >trying to add support for the DataQ DI-190 serial A/D gizmo. I open the >com port and talk to the device just fine. However, when I issue the >basic SCREEN 2 command to put the screen in to graphics mode, it closes >the com port. Is this normal or a bug in the compiler? > >I can move the SCREEN command around so it is after the com port open, >but I jump in and out of graphics mode a lot in error situations so I'd >like to avoid a big rewrite. Regular bus-attached A/D cards have always >been immune to changes to screen mode. Thanks! Wish I could help out the "Master" of programming! It's been about six years since I was doing some of that, and mine wasn't up to your level. I had originally brought the seismo signal into the gameport of an Apple II, and then did the same to an IBM PC. But as you know, the gameport really didn't provide adequate resolution. I did some more of it later, starting a prototype of the "storm tracking" system for tornadoes and severe weather before the weather service was doing it. I became exasperated with the official system one afternoon when the tornado warning sirens blew continuously for two hours throughout the entire Memphis metro area with the absurd warning that "everyone" should take cover! Instead, everyone was out on the front walk looking up at the sky. It seemed apparent that sightings and radar fixes would allow a path and track to be projected for neighborhoods, communities, small towns, etc. When the weather service and TV stations finally got it together, there was no longer any need for mine - which still had a long way to go. Charlie Rond -\/\--Public Seismic Network-Memphis http://gandlf.ceri.memphis.edu/~rond/psn _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: S-G period and Q Date: Sat, 27 Jun 1998 14:33:45 -0500 (CDT) Meredith, re simple pendulums as in the SG design: Simple means that the support has minimal mass, like a string. The period is independent of the mass for small angles. This is why kids and their parents swing at about the same period on the swing set in the park. The period is: Tn = 2*pi*sqrt(L/g), L in meters, g=9.806. So a 1-second pendulum is 0.248 meters long, or 9.78 inches, which is a very handy length for pendulum escapement wall clocks. If we want a real long period, like 20 seconds, the length is about 100 meters. 30 seconds takes 225 meters, or the atrium of a 80 story building (makes a nice Focault (spelling?) pendulum.) But impractical for a seismometer. But a real physical pendulum has distributed mass, and Tn= 2*pi*sqrt(k/(M*g*r)), where k is the moment of inertia, r is the distance from the pivot to the Cm (center of mass), and M is the mass. So now the L of a simple pendulum is equal to k/(m*r), which is called the "reduced" pendulum length. Hence the desire to make seismometer booms very lightweight compared to the mass on the end, generally a ratio greater than 10. In the case of the horizontal boom pendulum as in the Lehman: The period determining factors are L and g. So if you can reduce the proportion of g acting on the mass, the period lengthens by the square root of the change. So if we make a "rigid" hinge, and turn the suspension sideways to become a boom, we can get 1% of g at a small angle, and our 9.78 inch pendulum now has a period of 10 seconds rather than 1. As the angle approaches true horizontal, the percentage of g goes to zero, and neglecting the hinges, the period becomes infinite. This is not possible with the simple pendulum of the SG design. The question of Q and the intrinsic damping factor Bo is related to how long the pendulum will swing freely without further input, and is determined by the "logrithmic decrement" of successive swings, NOT the length of time the oscillations can be observed. Bo = LOGe (A1/A2) / sqrt[ pi^2 + (LOGe (A1/A2))^2 ] where A1 and A2 are successive peak-peak amplitudes of a free oscillation produced by a step input. One usually needs an oscilloscope or recorder to measure these amplitudes. So Q is a function of the mechanical system, so it is also related to the product of the mass and the period as well as various viscous (air) and dissipative damping. The general agreement for the definition of the Q of a mechanical pendulum system is that it is the INVERSE of the mechanical damping Bo. Ie. if the pendulum swings forever, the Q is infinite. For most commercial seismometers, Bo ranges from 0.1 to 0.3, or Q values from 10 to 3.3. It is generally agreed that the M*T*Q product should be greater than 1 for acceptable Brownian noise levels. (M in kg, T in seconds). Since Q IS related to the air damping of the mechanical design, it decreases dramatically when the coil moves in the confines of the magnet gap. It is also related to the "work" done by bending the hinges by the momentum of the mass, so thinner hinges and larger mass reduce this factor, and free oscillations of the pendulum will persist longer, as you observed. Of course, determining if the pendulum is moving depends on the detector you are using, ie. your eyes or something electronic, which will usually show that a very underdamped pendulum will oscillate for some time at the mechanical period after various energy inputs, such as drafts or tilts. Of course, the SG is a fedback instrument, so as long as these parameters are "reasonable", the feedback will control the effective period and the damping. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: John Hernlund Subject: Re: S-G period and Q Date: Sat, 27 Jun 1998 15:41:40 -0700 (MST) On Sat, 27 Jun 1998, S-T Morrissey wrote: > For most commercial seismometers, Bo ranges from 0.1 to > 0.3, or Q values from 10 to 3.3. I always like the idea of using Q=3.3, because the individual wave arrivals are more easily picked out. When the pendulum swings around too much after an impules it has a greater probability of bleeding into or making indistinct the next wave arrival. Of course you don't want to damp it so much that the impulses are themselves squashed out of the record, because that defeats the purpose. So there is a tiny bit of trade off in the right region of damping between the amplitude of arrivals and the ability to keep the swinging pendulum from disguising the next arrival. By damping a lot you can get sharper arrivals, but have a little less amplitude; basically this means that a low noise environment is one in which you can use this method to the maximum potential, because you can trade a little amplitude for a sharper arrival scheme... ****************************************************************************** John Hernlund E-mail: hernlund@....... WWW: http://www.mc.maricopa.edu/academic/phy_sci/Geology/hernlund/ http://www.public.asu.edu/~hernlund/ "Enlightenment is man's emergence from his self-imposed immaturity. Immaturity is the inability to use one's understanding without guidance from another. This immaturity is self-imposed when its cause lies not in lack of understanding, but in lack of resolve and courage to use it without guidance from another. Sapere Aude! "Have courage to use your own understanding!"- that is the motto of enlightenment. -Immanuel Kant: "An Answer to the Question: What is Enlightenment?" ****************************************************************************** _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: SG feedback Date: Sat, 27 Jun 1998 17:23:02 -0700 Larry, Sean Thomas et al I had thought in the past that the low frequency (below natural freq) component of the SG was due to the integrator. The cap in the feedback loop of the opamp increased the gain at lower frequency until the feedback resistor held the gain to a limit. The magnet/coil has been described as the damping component. If I substitute a coil/magnet/shunt resistor instead w/o the opamp am I acomplishing the same damping or is the opamp in the coil/magnet doing something wrt the frequencies that the SG is sensitive to? Barry _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: S-G period and Q Date: Sun, 28 Jun 1998 13:49:53 -0600 Sean- I am confused by your remarks in the paragraph below. The period of a simple pendulum is independent of mass for all angles of deflection. The pertinent characteristic of the pendulum is that its period is approximately *constant* for all small angles. The difference in mass between parent and child is irrelevant (unless, of course, the parent is too fat to get on the swing in the first place). -Edward S-T Morrissey wrote: > Meredith, > re simple pendulums as in the SG design: > > Simple means that the support has minimal mass, like a string. > The period is independent of the mass for small angles. This > is why kids and their parents swing at about the same period > on the swing set in the park. -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Gary Lindgren" Subject: How Many Messages a Day Date: Sun, 28 Jun 1998 13:23:43 -0700 I haven't been getting as many messages as I use to get. How many messages are sent to the network each day. Gary Lindgren Palo Alto CA _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: Tony (Donna Whitaker) MI 3.7 Hawaii Island Date: Sun, 28 Jun 1998 15:37:02 -0600 Tony- "Looks kind of strange" -- the WinQuake FFT spectrum shows that your signal is "up against the wall" at 0.1 Hz of a "brick-wall" type filter, i.e., a filter with a very steep roll-off (the decay of amplitude as a function of frequency), and that is responsible for the monochromatic (single-frequency content) appearance of the seismogram. How did you make that filter? -Edward Subject: MI 3.7 Hawaii Island Date: Sat, 27 Jun 1998 16:50:03 -1000 (HST) From: peaches@............ (Donna Whitaker) To: events@............. This is the first time I have clipped with the 16 bit A/D and is by far the highest amplitude I have recorded at this station. I was awake and felt this event as a modest jolt and then a few seconds of mild shudder. I also think that this event was the closest to this station that I have recorded at only 2 km. Also, the HVO's tako listed magnitude is probably a bit low. And I thought this might be a good time to post the first trace from my new channel 3 (ko3) which is a 0.1 lo-pass version of the Lehman (ko1) and is intended for teleseismic events. I dont know if any station in PSN has posted a lo-pass version of a local event, so here is mine. Looks kind of strange. It was fun! Aloha Tony -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: How Many Messages a Day Date: Sun, 28 Jun 1998 15:40:48 -0600 Gary- How many earthquakes a day are there? -Edward Gary Lindgren wrote: > I haven't been getting as many messages as I use to get. How many messages > are sent to the network each day. > Gary Lindgren > Palo Alto CA > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: S-G period and Q Date: Sun, 28 Jun 1998 18:38:20 -0600 Sean-Thomas Morrissey, Thanks for your detailed reply, and I appreciate your time and effort to make it more understandable for non-engineers. Guess it maybe some time or perhaps ? longer, in regard to my obtaining and using a oscilloscope to measure the A1/A2 amplitudes to determine Bo/Q. Any more, it seems, that an oscilloscope is of more value than a chart recorder what with computer recording and electronic circuit accessory use. Anyway...I can use the computer and my old chart recorder as somewhat of a reference, once the seismo is up and running. >From your message, it looks like it maybe of interest to reduce the thickness somewhat from .005 to maybe .003 or so; even though I have no means of accurately evaluating other than the inferance of time ....for the moment. The 1 second S-G, I'am trying to build uses eddy current damping from aluminum plates into 2 samarium "U" magnet assemblys. Here again, I have to use my eyes and a reference "stop" and light between to evaluate the damping. There is no recording yet, as it is in the building stage. Anyway, at no deflection does the mass travel past the "zero" and push the temporary stop away, nor, does it stop short. I believe this is a critical damping. Future recording will likely show a validation or error of course. The air damping dissipation is probably almost null with this scheme, as the distance between plates and magnets is about 1/16" on either side. My ratio of Mass to boom weight seems to fall short; 8 to 1, instead of the 10 to one or greater preference, hence the "reduced" pendulum length effect which you explained. I originally tried using round stainless steel tubes, but the set screw pressure and compression techniques deformed them fairly readily. I'am trying to adopt misc., material from what I have in my garage storage, for the most part, or commercial/surplus sources. Eventually, I would like to try some form of feedback, but with the 4 lb mass, I would imagine that it would have to be a fairly powerful coil & magnet damping system...but I don't know yet. Intend to leave the eddy current damping as is for time being...being as it is sort of a "no power consumption" method. You know...this is the first seismo I've tried to build. Most of my past projects have all been related to chart/drum recorders...but, with computer recording now,...thats of no interest now. Its been a incredibly fun and frustrating experience with this "very old & newer" seismo combination. Eventually, I shall get back to your STM-8 seismo, now that I've obtained more electronic parts. I guess from my own brief "hand" at the seismo game, I can more readily appreciate the effort you put into the STM-8 over time. Somehow...the appeal to follow your design doesn't seem as bad as my first apprehensions made it seem-ha. Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Jim Hannon Subject: Re: S-G period and Q Date: Sun, 28 Jun 1998 20:19:50 -0500 Edward Cranswick wrote: > > Sean- > I am confused by your remarks in the paragraph below. The period of a > simple pendulum is independent of mass for all angles of deflection. The > pertinent characteristic of the pendulum is that its period is > approximately *constant* for all small angles. The difference in mass > between parent and child is irrelevant (unless, of course, the parent is > too fat to get on the swing in the first place). > -Edward > > S-T Morrissey wrote: > > > Meredith, > > re simple pendulums as in the SG design: > > > > Simple means that the support has minimal mass, like a string. > > The period is independent of the mass for small angles. This > > is why kids and their parents swing at about the same period > > on the swing set in the park. > > -- > Edward Cranswick Tel: 303-273-8609 > US Geological Survey, MS 966 Fax: 303-273-8600 > PO Box 25046, Federal Center cranswick@........ > Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > In one of my physics classes the instructor derrived the equation of motion for a simple pendulum. You go through a lot of math and at the end a simplyfing approximation is made, which is the reason everyone says (the equation applies only for small angles). That approximation is that for small angles the sine of the angle equals the angle in radians. I can't remember for sure but I think mass is still in the equation until that assumption is made. Which would make the period dependant on mass for at least large angles. Does someone have a physics book handy? -- Jim Hannon http://soli.inav.net/~jmhannon/ 42,11.90N 91,39.26W WB0TXL _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: S-G period and Q Date: Sun, 28 Jun 1998 19:15:17 -0700 Jim Looking back @ Physics 4A text: For a simple pendulum w/ small angles: T=2*pi*sqrt(m/k) but k=mg/l so the mass cancels. For a pendulum with larger angles: T=2*pi*sqrt(l/g*factor) where factor=1+1/4*(sin(phi/2))**2+1/4*9/16*sin(phi/2)**4 +..... & phi=maximum angular displacement. With smaller angles the terms go to smaller values.eg. for a 15 degree angle the error is about 0.5%. The physics book has an interesting support invented by Huygens where the support is a cycloid curve so that the period becomes independent of the angle. Barry Jim Hannon wrote: > > In one of my physics classes the instructor derrived the equation of > motion for a simple pendulum. You go through a lot of math and at the > end a simplyfing approximation is made, which is the reason everyone > says (the equation applies only for small angles). That approximation is > that for small angles the sine of the angle equals the angle in radians. > I can't remember for sure but I think mass is still in the equation > until that assumption is made. Which would make the period dependant on > mass for at least large angles. Does someone have a physics book handy? > > -- _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: SG feedback Date: Sun, 28 Jun 1998 21:57:51 -0700 At 05:23 PM 6/27/98 -0700, Barry Lotz wrote: >Larry, Sean Thomas et al > I had thought in the past that the low frequency (below natural >freq) component of the SG was due to the integrator. Thats correct. Since the pendulum and the displacement sensor measures acceleration below the natural frequence of the pendulum and a integrator will convert the acceleration to velocity, the end product out of the integrator is velocity. >The cap in the >feedback loop of the opamp increased the gain at lower frequency until >the feedback resistor held the gain to a limit. Not sure what schematic and cap your looking at. On my SG electronics board (see the schematic at http://psn.quake.net/sg-schm.gif) there is one cap and resistor (C48 and R59) combination in the feedback loop. This is a lead circuit (or a lag circuit I'm not 100 % sure) that was needed to stop the system from oscillating. >The magnet/coil has been >described as the damping component. Yes... >If I substitute a coil/magnet/shunt >resistor instead w/o the opamp am I acomplishing the same damping or is >the opamp in the coil/magnet doing something wrt the frequencies that >the SG is sensitive to? I think it would accomplish the same thing if you could get enough damping using this method. The feedback loop in the SG sensor is simply to dampen the natural freq. of the pendulum and does not change or extend the period of the device, from what I understand. I think one would get the same response out of the system if you use oil or any other type of damping. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: How Many Messages a Day Date: Sun, 28 Jun 1998 22:18:14 -0700 At 01:23 PM 6/28/98 -0700, Gary Lindgren wrote: >I haven't been getting as many messages as I use to get. How many messages >are sent to the network each day. >Gary Lindgren >Palo Alto CA Gary and Others, This list is archived on my system. You can view the archives at http://psn.quake.net/maillist.html. If your not sure if your getting all of the messages, you can check the archives. As far as how many messages per day, I varies, so its hard to say. -Larry Cochrane Redwood City, PSN _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: SG feedback Date: Mon, 29 Jun 1998 05:08:21 -0700 Larry Cochrane wrote: Larry The resistor-cap I was refering to was the integrator. As I understand it a pure integrator has just a cap in the feedback loop. This would lead to very high gains at low frequencies. The resistor limits this. Barry > Not sure what schematic and cap your looking at. On my SG electronics board > (see the schematic at http://psn.quake.net/sg-schm.gif) there is one cap > and resistor (C48 and R59) combination in the feedback loop. This is a lead > circuit (or a lag circuit I'm not 100 % sure) that was needed to stop the > system from oscillating. > > >The magnet/coil has been > >described as the damping component. > > Yes... > > >If I substitute a coil/magnet/shunt > >resistor instead w/o the opamp am I acomplishing the same damping or is > >the opamp in the coil/magnet doing something wrt the frequencies that > >the SG is sensitive to? > > I think it would accomplish the same thing if you could get enough damping > using this method. The feedback loop in the SG sensor is simply to dampen > the natural freq. of the pendulum and does not change or extend the period > of the device, from what I understand. I think one would get the same > response out of the system if you use oil or any other type of damping. > > -Larry Cochrane > Redwood City, PSN > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Robert Avakian Subject: Re: S-G period and Q Date: Mon, 29 Jun 1998 10:09:04 -0700 Barry, what is the book you used? I teach and it sounds really good. Bob Avakian barry lotz wrote: > > Jim > Looking back @ Physics 4A text: > For a simple pendulum w/ small angles: > T=2*pi*sqrt(m/k) but k=mg/l so the mass cancels. > For a pendulum with larger angles: > T=2*pi*sqrt(l/g*factor) > where factor=1+1/4*(sin(phi/2))**2+1/4*9/16*sin(phi/2)**4 +..... > & phi=maximum angular displacement. With smaller angles the terms > go to smaller values.eg. for a 15 degree angle the error is about 0.5%. > The physics book has an interesting support invented by Huygens where > the support is a cycloid curve so that the period becomes independent of > the angle. > > Barry > Jim Hannon wrote: > > > > In one of my physics classes the instructor derrived the equation of > > motion for a simple pendulum. You go through a lot of math and at the > > end a simplyfing approximation is made, which is the reason everyone > > says (the equation applies only for small angles). That approximation is > > that for small angles the sine of the angle equals the angle in radians. > > I can't remember for sure but I think mass is still in the equation > > until that assumption is made. Which would make the period dependant on > > mass for at least large angles. Does someone have a physics book handy? > > > > -- > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: peaches@............ (Donna Whitaker) Subject: Re: Tony (Donna Whitaker) MI 3.7 Hawaii Island Date: Mon, 29 Jun 1998 06:02:07 -1000 (HST) Hi Ed. The filter is a Max 293 8th-order, lowpass, elliptic, switched- capacitor filter IC from Maxim (http://www.maxium-ic.com) that I purchased from Digi-key. It has a sharp rolloff at 0.1Hz. I think it was about $6. Because I'm not too good with electronic circuts, I gave the filter chip to Karl Cunningham, who is very familiar with this type of circut, and he built up the filter board for me and helped me install it inline at the output from Larry's amp/filter board while he was here last week. He also made up a schematic of the entire lpf circut board which I can send to you, or anyone else who may be interested, via e-mail. Any tecnical questions about this circut should be directed to Karl here on psn-l or to his e-mail at: karlc@....... This filter is working very well with Larry's amp and is intended for teleseismic events with much greater amplitude of the surface waves similar to the aslwww grams. It allows you to really crank up the gain without worring about the 6 sec background noise. But say good-bye to the P waves and any other Hz above about 0.12Hz. Tony >Tony- > "Looks kind of strange" -- the WinQuake FFT spectrum shows that your >signal is "up against the wall" at 0.1 Hz of a "brick-wall" type filter, >i.e., a filter with a very steep roll-off (the decay of amplitude as a >function of frequency), and that is responsible for the monochromatic >(single-frequency content) appearance of the seismogram. How did you >make that filter? >-Edward > >Subject: > MI 3.7 Hawaii Island > Date: > Sat, 27 Jun 1998 16:50:03 -1000 (HST) > From: > peaches@............ (Donna Whitaker) > To: > events@............. > > >This is the first time I have clipped with the 16 bit A/D and >is by far the highest amplitude I have recorded at this >station. I was awake and felt this event as a modest jolt and >then a few seconds of mild shudder. I also think that this event >was the closest to this station that I have recorded at only 2 >km. Also, the HVO's tako listed magnitude is probably a bit low. >And I thought this might be a good time to post the first trace >from my new channel 3 (ko3) which is a 0.1 lo-pass version of the >Lehman (ko1) and is intended for teleseismic events. I dont know >if any station in PSN has posted a lo-pass version of a local >event, so here is mine. Looks kind of strange. >It was fun! > >Aloha > >Tony > >-- >Edward Cranswick Tel: 303-273-8609 >US Geological Survey, MS 966 Fax: 303-273-8600 >PO Box 25046, Federal Center cranswick@........ >Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Warren Shedrick" Subject: Re: Tony (Donna Whitaker) MI 3.7 Hawaii Island Date: Mon, 29 Jun 1998 09:43:55 -0700 > Date: Mon, 29 Jun 1998 06:02:07 -1000 (HST) > To: PSN-L Mailing List > From: peaches@............ (Donna Whitaker) > Subject: Re: Tony (Donna Whitaker) MI 3.7 Hawaii Island > Reply-to: PSN-L Mailing List > Hi Ed. > > The filter is a Max 293 8th-order, lowpass, elliptic, switched- > capacitor filter IC from Maxim (http://www.maxium-ic.com) that > I purchased from Digi-key. It has a sharp rolloff at 0.1Hz. I > think it was about $6. Because I'm not too good with electronic > circuts, I gave the filter chip to Karl Cunningham, who is very > familiar with this type of circut, and he built up the filter > board for me and helped me install it inline at the output from > Larry's amp/filter board while he was here last week. He also > made up a schematic of the entire lpf circut board which I can > send to you, or anyone else who may be interested, via e-mail. > Any tecnical questions about this circut should be directed to > Karl here on psn-l or to his e-mail at: karlc@....... > This filter is working very well with Larry's amp and is intended > for teleseismic events with much greater amplitude of the surface > waves similar to the aslwww grams. It allows you to really crank > up the gain without worring about the 6 sec background noise. But > say good-bye to the P waves and any other Hz above about 0.12Hz. > > Tony > > > >Tony- > > "Looks kind of strange" -- the WinQuake FFT spectrum shows that your > >signal is "up against the wall" at 0.1 Hz of a "brick-wall" type filter, > >i.e., a filter with a very steep roll-off (the decay of amplitude as a > >function of frequency), and that is responsible for the monochromatic > >(single-frequency content) appearance of the seismogram. How did you > >make that filter? > >-Edward > > > >Subject: > > MI 3.7 Hawaii Island > > Date: > > Sat, 27 Jun 1998 16:50:03 -1000 (HST) > > From: > > peaches@............ (Donna Whitaker) > > To: > > events@............. > > > > > >This is the first time I have clipped with the 16 bit A/D and > >is by far the highest amplitude I have recorded at this > >station. I was awake and felt this event as a modest jolt and > >then a few seconds of mild shudder. I also think that this event > >was the closest to this station that I have recorded at only 2 > >km. Also, the HVO's tako listed magnitude is probably a bit low. > >And I thought this might be a good time to post the first trace > >from my new channel 3 (ko3) which is a 0.1 lo-pass version of the > >Lehman (ko1) and is intended for teleseismic events. I dont know > >if any station in PSN has posted a lo-pass version of a local > >event, so here is mine. Looks kind of strange. > >It was fun! > > > >Aloha > > > >Tony > > > >-- > >Edward Cranswick Tel: 303-273-8609 > >US Geological Survey, MS 966 Fax: 303-273-8600 > >PO Box 25046, Federal Center cranswick@........ > >Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". > > > > > > > > > >_____________________________________________________________________ > > > >Public Seismic Network Mailing List (PSN-L) > > > >To leave this list email listserver@............. with the body of the > >message: leave PSN-L > > > > > > > > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L > I am interested in this type of filter. Please send me the schematic. Thank you Warren Shedrick _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Switched Capacitor Filters Date: Mon, 29 Jun 1998 09:40:29 -0700 The correct link for Maxim is http://www.maxim-ic.com/ The typo gremlins struck again. Switched capacitor filters are wonderful little tools in terms of design simplicity, attenuation characteristics, and general performance. The biggest limiting factor I keep hitting is the dynamic range, typically 70 dB. That is about equivalent to a 12-bit A/D converter. So, if you are building a system with a 16-bit or better A/D converter, you need a different filter type to exploit your capabilities. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: SG damping Date: Mon, 29 Jun 1998 13:24:46 -0500 (CDT) Meredith, Regarding your question about the damping for the SG pendulum. The damping is achieved directly by amplifying a high-pass component of the displacement output and feeding a proportion of it to the damping coil. The SG displacement voltage is AC coupled to both the damping amplifier and the integrator, so I am at a loss as to how to calculate the effective response. My observations: 1. The coil should be mounted on the boom; the magnet on the frame, for reasons I have mentioned earlier. 2. I do not currently have a method to calculate the actual damping that is achieved by this method. Maybe I can come up with some formula for a DC coupled method. 3. Fedback damping is not dissipative as is resistive, etc.,; but resistive damping is just as effective for the SG, as Larry has just pointed out; I would avoid oil/dashpot or eddy current schemes because the effect is very difficult to calculate, as compared to electromagnetic (coil-magnet-resistor). I have recently posted the formulas to determine it. (need a repeat?). The feedback of the SG does not extend the period, as Larry notes and based on Larrys' schematic. The longer period response is achieved by integrating a high-pass component of the displacement output and then low-pass filtering it. Nothing (electronically) after the integrator is fedback to the mass of the seis. However, if one wanted to extend the period of the SG, there is no reason that the triple feedback used in the STM cannot be used. All it needs is a good displacement detector and a strong feedback coil attached to a pendulum of reasonable period Tn. A one second Tn will work, but I think that your 4 lb mass might be too much unless you have a powerful coil-magnet. With the S5000 seis with the 11 kg mass the coil constant is nearly 100 Newtons/Ampere. With the STM seis with 0.5 kg mass, the constant is 12 N/A. A large mass is not necessary for a fedback system other than for Brownian noise, where M*T*Q should be greater than 1. The problem as I see it is making a homemade feedback coil with a large constant. I could try to model the transfer function of an SG using the triple feedback if I new the sensitivity of the displacement detector; else I could assume some values. I think it should be easy to make the 1 second pendulum perform as a 30 second broadband sensor. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: "Steve Carniglia" Subject: Re: S-G period and Q Date: Mon, 29 Jun 1998 11:43:42 -0700 > >In one of my physics classes the instructor derrived the equation of >motion for a simple pendulum. You go through a lot of math and at the >end a simplyfing approximation is made, which is the reason everyone >says (the equation applies only for small angles). That approximation is >that for small angles the sine of the angle equals the angle in radians. >I can't remember for sure but I think mass is still in the equation >until that assumption is made. Which would make the period dependant on >mass for at least large angles. Does someone have a physics book handy? > >-- >Jim Hannon >http://soli.inav.net/~jmhannon/ >42,11.90N 91,39.26W >WB0TXL > > I dusted off some of the cobwebs from my Physics memory and if I remember correctly, all of this would be much easier to work with if you use "vectors". Vectors take into consideration both moment and mass....I have not seen anyone talking about this...... Any thoughts??? Steve kv6a steve@........ _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: barry lotz Subject: Re: S-G period and Q Date: Mon, 29 Jun 1998 19:18:04 -0700 Robert It's "Physics for students of science and engineers" by Resnick & Halliday. It's a two volume set , but about 30 years old. published by John Wiley& sons. Barry Robert Avakian wrote: > > Barry, what is the book you used? I teach and it sounds really good. > > Bob Avakian > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Edward Cranswick Subject: Re: S-G period and Q Date: Mon, 29 Jun 1998 22:08:48 -0600 Barry- Having been forced to examine textbooks ("Mechanics", Symon; "Physics", Resnick & Halliday) from physics classes I failed, I think that your statements below confirm my belief that the frequency of a simple pendulum is independent of its mass for all angles. Please correct me if I am wrong. -Edward barry lotz wrote: > Jim > Looking back @ Physics 4A text: > For a simple pendulum w/ small angles: > T=2*pi*sqrt(m/k) but k=mg/l so the mass cancels. > For a pendulum with larger angles: > T=2*pi*sqrt(l/g*factor) > where factor=1+1/4*(sin(phi/2))**2+1/4*9/16*sin(phi/2)**4 +..... > & phi=maximum angular displacement. With smaller angles the terms > go to smaller values.eg. for a 15 degree angle the error is about 0.5%. > The physics book has an interesting support invented by Huygens where > the support is a cycloid curve so that the period becomes independent of > the angle. > > Barry > Jim Hannon wrote: > > > > In one of my physics classes the instructor derrived the equation of > > motion for a simple pendulum. You go through a lot of math and at the > > end a simplyfing approximation is made, which is the reason everyone > > says (the equation applies only for small angles). That approximation is > > that for small angles the sine of the angle equals the angle in radians. > > I can't remember for sure but I think mass is still in the equation > > until that assumption is made. Which would make the period dependant on > > mass for at least large angles. Does someone have a physics book handy? > > > > -- > > _____________________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email listserver@............. with the body of the > message: leave PSN-L -- Edward Cranswick Tel: 303-273-8609 US Geological Survey, MS 966 Fax: 303-273-8600 PO Box 25046, Federal Center cranswick@........ Denver, CO 80225-0046 USA E.M. Forster said, "Only connect". _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: meredith lamb Subject: RE: SG Damping Date: Mon, 29 Jun 1998 22:36:25 -0600 Sean-Thomas, Thanks for the further notes on the S-G seismometer. I understand the weight problem of the mass in relation to the feedback damping. My curiosity with this present seismo and its eddy current damping as is, is going to see some eventual trials...the damping just seems too good to be true as is....its looks the same as on the Sprengnethers in response (visual for the moment). Of course with feedback, control is much easier, and thats understood. Regardless of the outcome, I figure I can create another boom and mass, and venture from there in feedback with more reasonable damping requirements. Figure that the old boom and mass can make a quick swap into a horizontal even though the boom to mass weight ratio is not exactly preferred (8 to 1), if I wanted to. My S-G unit has alot of flexibility and space for changes...its a "big one"-ha. I've done some tinkering with various materials for the feedback scheme...but so far, it looks like the speaker coil & magnet approach is about the only way to go. Theirs a way to make 4 pole neo's deliver double the output on coil sensors. Of course making it work for feedback, hasn't shown any significant appealing results yet. From your past formula it would seem that one would have to base the mass weight entirely on the feedback coil constant,...before creating the appropriate mass and its weight. Reverse engineering. Outside of my present seismo setup....yes, the appealing thought of using your circuit on the S-G has much interest. I would think that because of the minute small pendulum drift (long term stability), and the relative simplicity of the mechanical design in themselves, would have more than passing appeal. If the device can be configured for 30 seconds as you estimate, that would carry alot more influence than anything else about it without any doubt what-so-ever. Alot of speculation here of course. Don't recall any sensitivity figure on the S-G as per Larrys or Aries existing units. Of course you STM-8 VRDT is about 35v per micron. I'd imagine it would need something of a similar nature....sensor and feedback likely per your unit for any modeling, but the mass weight and math evade me alot because of the unknown feedback coil & magnet still too be determined. Have wanted to go into more detail on your arrangement for determining sensitivity. Believe it is composed of a micrometer and a linear moving platform, where with micrometer movement of the sensor or transformer moving flange and readout you have derived your reading and determination. Thats my impression of your setup, but, with about zero experience here, and with your background you may have gone into more details and/or my guess is far off base? Am I missing things? Believe their is 25.4 microns per millimeter. Anyway, with the huge deversity of instruments, determining individuals sensors sensitivity is probably not often sought after...unless it doesn't work good enough-ha. Outside of the above... have you located a suitable fish tank that could cover your STM-8 seismo? Thanks, Meredith Lamb _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Larry Cochrane Subject: Re: Switched Capacitor Filters Date: Mon, 29 Jun 1998 23:09:26 -0700 I use a switched cap filter on my telemetry demodulator board. As Doug pointed out the chips have one problem and that's the dynamic range of the device. I use one on my demodulator board because the analog telemetry system used by the USGS only has the dynamic range of a 11 to 12 bit converter system. The LM60 has a better dynamic range, about 80 db, but it only has 6 poles not 8 like the one Tony is using. -Larry Cochrane Redwood City, PSN At 09:40 AM 6/29/98 -0700, you wrote: >The correct link for Maxim is http://www.maxim-ic.com/ >The typo gremlins struck again. > >Switched capacitor filters are wonderful little tools in terms of design >simplicity, attenuation characteristics, and general performance. The >biggest limiting factor I keep hitting is the dynamic range, typically >70 dB. That is about equivalent to a 12-bit A/D converter. So, if you >are building a system with a 16-bit or better A/D converter, you need a >different filter type to exploit your capabilities. >-- >Doug Crice web site http://www.georadar.com >GeoRadar Inc. e-mail dcrice@............ >19623 Via Escuela Drive phone 408-867-3792 >Saratoga, CA 95070 USA fax 408-867-4900 > > >_____________________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email listserver@............. with the body of the >message: leave PSN-L > _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Doug Crice Subject: Re: Switched Capacitor Filters Date: Tue, 30 Jun 1998 07:54:18 -0700 Back in my youth, I made an FM telemetry demodulator with a switched capacitor filter (back when you made them from scratch with real capacitors and analog switches). I used the switched cap filter as the bandpass filter for the carrier. Then, by phase-locking the switched cap filter to the carrier, I made the filter track up and down with the carrier. I was able to use a narrower bandwidth on the carrier filter than would normally be required, and got an extra 10 dB of dynamic range out of the telemetry system. Probably an obsolete idea these days. -- Doug Crice web site http://www.georadar.com GeoRadar Inc. e-mail dcrice@............ 19623 Via Escuela Drive phone 408-867-3792 Saratoga, CA 95070 USA fax 408-867-4900 _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: Karl Cunningham Subject: Re: SG damping Date: Tue, 30 Jun 1998 08:44:03 -0700 Sean Thomas and others -- At the expense of noise, I think one could insert an op-amp amplifier to increase the coil constant of the feedback coil to any amount needed. (Analogous to driving a speaker through an audio amplifier.) This would need to be a current input / constant current output circuit so as not to change the nature of the feedback signal. I haven't done any calculations on how much noise this would introduce, but since many people are only running 16-bit A/Ds, the requirements might not be out of the range of a good chopper-stabilized op-amp. Karl Cunningham La Mesa, CA. PSN station #40 karlc@....... At 01:24 PM 6/29/98 -0500, Sean-Thomas wrote: >With the S5000 seis with the 11 kg >mass the coil constant is nearly 100 Newtons/Ampere. With the STM >seis with 0.5 kg mass, the constant is 12 N/A. A large mass is not >necessary for a fedback system other than for Brownian noise, where >M*T*Q should be greater than 1. The problem as I see it is making >a homemade feedback coil with a large constant. _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: robert barns <75612.2635@..............> Subject: Nuclear? tests? Date: Tue, 30 Jun 1998 13:28:14 -0400 Hi gang, Has solid evidence been presented that the Indian and/or Pakistani "nuclear" tests were really nuclear events and not just large explosions = of conventional explosives? I suppose that the logistics of using very large amounts of conventiona= l explosives are formidable but perhaps not impossible. I know that there are ways of isolating an explosion so as to make the seismic effects appe= ar smaller than normal so it may be possible to amplify the seismic effects.= = This would require smaller amounts of TNT or whatever. Bob Barns Energizer bunny arrested--charged with battery. = _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L) From: S-T Morrissey Subject: VBB feedback current Date: Tue, 30 Jun 1998 13:09:32 -0500 (CDT) Karl, I must again emphasize that in the triple feedback VBB configuration the CURRENTS that flow through the force coil are controlled by the actual reactances of the three feedback elements, whose input is either the displacement voltage or the integral of it. These passive elements actually convert the mass displacement voltage into the characteristic current that shapes the acceleration response of their respective portion of the response curve. There can be NO amplifier or other device between the summing junction of Rp, Cp, and RI and the force coil, since this would prevent these currents from flowing. Some experiments with a Norton, OTA (operational transconductance amplifier) or similar current amplifiers have been done and the feedback SEEMS to work, but the response is not linear (as expected from the transfer function), and has stability problems, possibly because of the non-linear low frequency phase response of the current amplifier used. The transfer function actually describes an assembly of equations of accelerations that are produced by each characteristic feedback path. THe parameters include Rf, the resistance of the feedback coil; if it is too large, the response is unstable at short periods (which is why most seis signal coils cannot be used for feedback, since they are designed for high voltage (velocity) output which usually means a high DC resistance). Also, the constant G in the transfer function is the ratio of Gn, the constant of the force coil, divided by M. So if Gn is "small", reducing M will accommodate it. The value of G (=Gn/M) can cover a wide range and is of the order of 10 to 200, with the higher values of G needed for linearity at the short period response. Some commercial fedback seismometers have masses as small as 0.1 kg because of this consideration. Another important point to notice is that the VBB output voltage is obtained from the displacement transducer output, which BECOMES the VBB output WHEN and ONLY when the triple feedback is functioning. THis is a unique feature of this VBB circuit. Turn off the feedback, as when the boom needs to be recentered, and the output is that of an undamped mechanical sensor swinging freely at To. Re-connect the feedback, and the seismometer output immediately recovers as a VBB sensor with a period of Tn . Also notice that the output still contains the DC displacement information, which is reduced (by the current feedback parameters) by about a factor of ten or more. ie if the VBB output indicates 5 volts, and r=500mv/micron, the mass offset is 10 microns with the feedback on, but will shift to 100 microns if I disconnect the feedback. Also, if 5 volts is the limit of the displacement amplifier output, it is also the limit of the feedback DC operating range, in this case, +- 100 microns. (NOT to be confused with the dynamic range of the velocity output). Other force balance feedback configuations obtain a voltage function of acceleration across the force coil, and can use an amplifier within the feedback loop. This is not the case with this triple feedback configuration. As far as I know, none of the commercial VBB sensors have any amplifier within the feedback loop. Regards, Sean-Thomas _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L)