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Entry  Wed Feb 24 16:11:15 2010, Jenne, Update, PEM, Seismic witnesses near MC1 tank moved 
    Reply  Sun Mar 7 23:05:39 2010, rana, Update, PEM, Seismic witnesses near MC1 tank moved seis.png
       Reply  Mon Mar 8 18:15:27 2010, rana, Update, PEM, Styrofoam Cooler on the Seismos SeismometersHuddled.jpg
          Reply  Tue Mar 9 12:06:53 2010, rana, Jenne, Update, PEM, Styrofoam Cooler on the Seismos 
             Reply  Wed Mar 10 15:02:58 2010, rana, Update, PEM, Styrofoam Cooler on the Seismos Seismic-Ref_100310.pngUntitled.gif
                Reply  Sat Mar 13 21:30:22 2010, rana, Update, PEM, Styrofoam Cooler on the Seismos Untitled.png
                   Reply  Mon Mar 15 16:39:36 2010, steve, Update, PEM, Guralp2 centered grlp2ffst.jpg
                      Reply  Thu Mar 18 08:49:51 2010, steve, Update, PEM, Guralp2 centered again ? grlp2xadj.jpg
                         Reply  Fri Mar 19 18:00:14 2010, jenne, Update, PEM, Guralp2 centered again 
                            Reply  Fri Mar 19 21:15:33 2010, rana, Update, PEM, Guralp2 centered again Untitled.png
                            Reply  Fri Mar 19 23:03:41 2010, rana, Update, PEM, Guralp2 centered again huddlez.png
                               Reply  Sun Mar 21 19:25:29 2010, rana, Update, PEM, Guralp2 centered again huddlez.png
                               Reply  Thu Mar 25 09:07:08 2010, steve, Update, PEM, Guralp2 x problem is back grlp2xproblm.jpg
                                  Reply  Wed Mar 31 16:31:44 2010, steve, Update, PEM, Guralp interface box turned off grlpntrfcbxoff.jpg
                                     Reply  Mon Apr 5 01:02:07 2010, rana, Update, PEM, Guralp interface box turned off Untitled.png
Message ID: 2666     Entry time: Wed Mar 10 15:02:58 2010     In reply to: 2665     Reply to this: 2671
Author: rana 
Type: Update 
Category: PEM 
Subject: Styrofoam Cooler on the Seismos 

This is the spectra and coherence from a quiet time last night. I've lowered the Guralp cal by a factor of 2 to account for the fact that the gain in the breakout box is actually 20 and not 10 as I previously said.

The AD620 stage in the front part has a gain of 10 and then there's a single-to-differential stage in the output which gives us a gain of 2. The DTT cal in counts is now 3.8e-9 (m/s)/count.

The second plot shows the Guralp and Ranger signals at the ADC input (converted from counts to Volts for usefulness). The thick grey line is the expected noise of the Guralp breakout box

(mainly the AD620) propagated to the ADC (via multiplication by 2). It looks like the preamp board should not be a problem as long as we can reach the AD620 limit.

So the excess noise in the Guralp is not the fault of the preamp, but more likely the mounting and insulation of the seismometers.

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Seismic-Ref_100310.png
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Untitled.gif
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