PSN-L Message - Subject: Re: Old hobby resurgence

=C2=A0 Software is available for period extension. Please note the = following letter from Larry.

Bob

from: Larry Cochrane lcoch= rane@..............

date: = Tue, Feb 7, 2012 at 1:11 AM

subject: Robert's circuit and ne= w WinQuake / WinSDR releases

http://www.seismicnet.com/psnlist/120206_221= 156_1.html

Hi Everyone,

Last year I incor= porated Bob McClure's inverse filter into WinQuake and WinSDR. See http://site= s.google.com/site/bobmcclure90/inversefilter for more information on Bo= b's filter. You can try the filter in WinQuake if you install this beta= release:

32-Bit: http://www.seismicnet.com/software/wq323b_32bit.exe

64-Bit: http://www.seismicnet.com/software/wq323b_64bit.exe

And if you have a PSN ADC board you can use the filter = in real-time by using the current WinSDR beta release available here:

http://www.= seismicnet.com/winsdr/winsdr4x.html.

Please Note! In WinQuake the pendulum frequency is ente= red in seconds so a 4.5 Hz geophone would be entered as 0.222. In WinSDR th= e frequency is entered in Hertz, so a 20 second Lehman would be entered as = ..05. I should normalize this, I'm just not sure if I should change WinQ= uake or WinSDR...

In WinQuake the inverse filter can be found in the Time= -Domain Filter dialog box and in WinSDR the Channel Settings -> Integrat= e / Filter tab dialog box.

A few days ago there we= re some emails on the list regarding what numbers to use for the pendulum f= requency and high-pass filter. The pendulum frequency is the undamped perio= d of your sensor. If you have a geophone this would normally be 4.5 Hz (Win= SDR, .222 in WinQuake) or maybe 1 if you gave a 1 Hz geophone or AS1 type o= f sensor. This number sets where the filter starts to boost the lower frequ= encies to compensate for the drop off of sensitivity below the period of th= e sensor. The high-pass filter sets how much you want to extend the period = of the sensor. It should be set to some number below the period of the sens= or. Depending on the sensor and electronics, mainly the first op-amp, you m= ight be able to extend the period by one decade.

Before adding the software filter to WinSDR and WinQuak= e I played around with the Robert's circuit. My results regarding using= this filter, both in hardware and software, can be found here: http://www.seismicnet.com/epf/

Below is some information on the event files on my syst= em that use this filter in WinSDR:

*.LCSV1.psn - T= his is a volume set from a Kinemetrics SV-1 5-Second intermediate-period ve= rtical sensor. The LCZS1 channel is the raw data from the sensor. The LCZS2= channel has been period expended to 25 seconds (.04Hz) and then a 2 pole 2= Hz low-pass filter is applied to the data. This helicoder plot (updated ev= ery 5 min) ht= tp://www.seismicnet.com/quakes/images/lczs2.png shows the 24 hour graph= from this channel. Teleseismic events show up much better on the inverse f= ilter channel then the raw data channel.

*.LC45v.psn - This is a volume set from a horizontal 4.= 5 Hz geophone. The LCEG1 channel is the raw data from the sensor and the LC= EG2 channel has been period extended to 5 seconds or .2 Hz. This PSN event = file

http://www.seismicnet.com/quakes/1201/120126.021845.lc45v.psn is a = good example of an earthquake recorded from this sensor.

I would like to thank Bob McClure for supplying the Visual Basic code = so I could add this feature to my programs.

Regard= s,

Larry Cochrane

Webtronics

=3D=3D=3D=3D

On Mon, Sep 17, 2012 at 9:22 AM, Gerald Payton <= span dir=3D"ltr"><jerry@...........> wrote:

<= p class=3D"MsoNormal">You may find your info = at:=C2=A0 http://www.jclahr.com/science/psn/roberts/index.html<= u>

Regards,=
Jerry
= =C2=A0

From:<= /span> Edward Ianni [mailto:edwianni1@...........] Sent: Monday, September 17, 2012 5:52 AM
To: psnlist@..............Subject: Re: Old hobby resurgence

=C2=A0
=
Hi Chris;
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 I see th= at you are still giving out great information and advice. Could you possibl= y " point" me to the schematic of the serial AS-1 period "ex= tender". As I recall I built the Roberts circuit years ago with limite= d success. I'm pretty sure I did not get the component values correct. = I will try the Roberts circuit again after I try the AS1 "electronics&= quot;. I searched for the AS1 schematic/detail but only found very general = info on it. I haven't "played" with this "stuff" fo= r years but I feel a very strong resurgence of interest in Seismology since= I started this project again.=C2=A0 Thanks, Ed.

On 9/17/2012 5:22 AM, chrisatupw@....... wrote:
Edward Ianni <edwianni1@...........>
To: psnlist <psnlist@..............>
Sent: Mon, 17 Sep 2012 0:53
Subject: Old hobby resurgence<= /span>
Hi all: =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0

I ha= ve two very old seismometers and I would like to extend their "periods= ", electronically and EXTERNALLY if that is possible. I tried this a l= ong time ago but I am not heavy into electronics and could not come up with= the right values for some of the circuits that I looked at. The two Seismo= meters are a Kinemetric SH1 "Intermediate"(about 5 second period)= , and a Sprengnether (square box type) with a 1.5 second period. Is it poss= ible to do this easily and is there a circuit somewhere with relatively sim= ple instructions for calculating component values? Thank You. Ed.
=C2=A0
Hi = Ed,
=C2= =A0=C2=A0=C2=A0 The short answer is Yes ! =
=C2=A0=C2= =A0=C2=A0=C2=A0You can extend the period of a seismometer electronically by= about x10 with two stages of the parallel Robert's circuit, or you can= use the simpler serial type used in the AS-1. So the Sprengnether could ea= sily go out to 15 seconds and bring in the surface waves fairly respectably= .. I suggest that you extend the SH1 only to about 25/30 seconds and this is= a bit more difficult since you may have to suppress 1/f noise. You have th= e problem with requiring a 1/f^2 amplifier characteristic and this gain has= to go to periods beyond what you require and the excess 1/f noise has to b= e filtered out. Rega= rds, Chris Chapman=

= =C2=A0

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