PSN-L Message - Subject: Re: Digest from 09/11/2009 00:00:44

The seismograms look like they came from the same sensor to me. But...if they didn't, I'll be building one of your FBV instruments! Could you show us another two seismograms with background noise and then physically/electrically offset the FBV to identify it? Regards, Bob Hammond PSN-Alaska http://wulik.com >-----Original Message----- >From: psn-l-digest-request@.............. [mailto:psn-l-digest-request@............... >Sent: Friday, September 11, 2009 11:00 PM >To: psn-l-digest@.............. >Subject: Digest from 09/11/2009 00:00:44 > > >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 1 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Which is which? >From: Brett Nordgren >Date: Fri, 11 Sep 2009 10:00:30 -0400 > >Hi All, > >A few days ago, Dave Nelson in California was able to obtain the loan of a >Nanometrics Trillium Compact-120, a professional quality triaxial packed >into a can only slightly larger than a large geophone. Our plan is to >compare its output with the home-built Force Balance Vertical running >beside it. > >Soon after it was installed, California obliged with a nice 3.9 up the >coast which gave us a modest sized test signal containing some higher >frequency energy, which we could use to compare the two instruments. Both >instruments' outputs were filtered with a 20Hz 4-pole low pass and the >Trillium had a two pole high-pass added at 1/50Hz, in order to match the >50-second low frequency rolloff of the FBV, since its own rolloff was at >120 seconds. > >The results are shown at http://bnordgren.org/seismo/TvsFBV01.gif or the >somewhat larger http://bnordgren.org/seismo/TvsFBV01.jpg > >Question: Which is the $7000 Trillium and which is the FBV built by Dave? > >Regards, >Brett . > > >Watch our wiggles >http://bnordgren.org/seismo/gif_images.htm > >or watch some very very good wiggles >http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html > > > > >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 2 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Re: Which is which? >From: Kevin Brunt >Date: Fri, 11 Sep 2009 15:19:51 +0100 (GMT Daylight Time) > > >On Fri, 11 Sep 2009 10:00:30 -0400 Brett Nordgren >wrote: > >> Hi All, >> >> A few days ago, Dave Nelson in California was able to obtain the loan of a >> Nanometrics Trillium Compact-120, a professional quality triaxial packed >> into a can only slightly larger than a large geophone. Our plan is to >> compare its output with the home-built Force Balance Vertical running >> beside it. >> >> Soon after it was installed, California obliged with a nice 3.9 up the >> coast which gave us a modest sized test signal containing some higher >> frequency energy, which we could use to compare the two instruments. Both >> instruments' outputs were filtered with a 20Hz 4-pole low pass and the >> Trillium had a two pole high-pass added at 1/50Hz, in order to match the >> 50-second low frequency rolloff of the FBV, since its own rolloff was at >> 120 seconds. >> >> The results are shown at http://bnordgren.org/seismo/TvsFBV01.gif or the >> somewhat larger http://bnordgren.org/seismo/TvsFBV01.jpg >> >> Question: Which is the $7000 Trillium and which is the FBV built by Dave? >> >> Regards, >> Brett . > >You have checked that you haven't connected both channels to the same sensor? :) > > > > > >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 3 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Re: Which is which? >From: Brett Nordgren >Date: Fri, 11 Sep 2009 11:29:04 -0400 > >Kevin, > >I have to admit that the thought had crossed my mind, but Dave assured me >that they were connected as advertised. In fact, I could confirm that to >some degree, as the DC offsets were quite different. > >Brett > > >At 03:19 PM 9/11/2009 +0100, you wrote: > > >>You have checked that you haven't connected both channels to the same >>sensor? :) >> > >Watch our wiggles >http://bnordgren.org/seismo/gif_images.htm > >or watch some very very good wiggles >http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html > > > > >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 4 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Re: Which is which? >From: ChrisAtUpw@....... >Date: Fri, 11 Sep 2009 12:33:46 EDT > > >-------------------------------1252686826 >Content-Type: text/plain; charset="US-ASCII" >Content-Transfer-Encoding: 7bit > > >In a message dated 11/09/2009, brett3nt@............. writes: > >A few days ago, Dave Nelson in California was able to obtain the loan of a > >Nanometrics Trillium Compact-120, a professional quality triaxial packed >into a can only slightly larger than a large geophone. Our plan is to >compare its output with the home-built Force Balance Vertical running >beside it. > >Soon after it was installed, California obliged with a nice 3.9 up the >coast which gave us a modest sized test signal containing some higher >frequency energy, which we could use to compare the two instruments. > > >Hi Brett, Dave, > > I am glad to see that the Trillium checked out OK. Well done! > > Regards, > > Chris > >-------------------------------1252686826 >Content-Type: text/html; charset="US-ASCII" >Content-Transfer-Encoding: quoted-printable > > > > > >ole_body=20 >bottomMargin=3D7 leftMargin=3D7 rightMargin=3D7 topMargin=3D7>ole_document=20 >color=3D#000000 size=3D2 face=3DArial> >

In a message dated 11/09/2009, brett3nt@............. writes:

>style=3D"BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"= >> style=3D"BACKGROUND-COLOR: transparent" color=3D#000000 size=3D2 face=3D= >Arial>A few=20 > days ago, Dave Nelson in California was able to obtain the loan of a=20 >
Nanometrics Trillium Compact-120, a professional quality triaxial pa= >cked=20 >
into a can only slightly larger than a large geophone. Our pla= >n is=20 > to
compare its output with the home-built Force Balance Vertical run= >ning=20 >
beside it.

Soon after it was installed, California obliged wi= >th a=20 > nice 3.9 up the
coast which gave us a modest sized test signal conta= >ining=20 > some higher
frequency energy, which we could use to compare the two= >=20 > instruments.

Hi Brett, Dave,

I am glad to see that the Trillium checked ou= >t OK.=20 >Well done!

Regards,

Chris

> >-------------------------------1252686826-- > > >.------ ------ ------ ------ ------ ------ ------ ------ ------ ------. >| Message 5 | >'------ ------ ------ ------ ------ ------ ------ ------ ------ ------' >Subject: Welcome home Discovery >From: Brett Nordgren >Date: Fri, 11 Sep 2009 21:46:41 -0400 > >Hi All, > >On its approach to Edwards AFB in California today, the space shuttle >Discovery apparently came right over our seismo site. Dave reports that >its sonic boom shook the whole house (though the really solid pier he made >possibly shook less). > >Check the 'gif_images.htm' file below and look at the low-gain, 10Hz >channel heliplot. At 12 Sept, 2009 00:47:47 UTC Discovery's sonic boom >shows up quite clearly. It's even more impressive when we look at it on >the high gain channel with the low pass filter set up to10Hz. > >Regards, >Brett > > > >Watch our wiggles >http://bnordgren.org/seismo/gif_images.htm > >or watch some very very good wiggles >http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-DIGEST-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L)

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