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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: 2661     Entry time: Sun Mar 7 23:05:39 2010     In reply to: 2638     Reply to this: 2662
Author: rana 
Type: Update 
Category: PEM 
Subject: Seismic witnesses near MC1 tank moved 

Quote:

Since we're going to open the MC1 tank tomorrow, I've moved the MC1 accelerometers and the Guralp over to underneath MC2 for the vent.  I'll reconnect them later.

 I've put both Guralps next to the Ranger and connected them to the breakout box. The data is now good.

I found that the Ranger was not centered and so it was stuck (someone kicked it in the last 2 weeks apparently). I recentered the mass according to the procedure in the manual. Its now moving freely.

In order to do a better huddle test, I increased the gain of the Ranger's SR560 preamp to 100 from 10 and put it on the low noise setting. I also enabled a 2x lowpass at 3 kHz for no good reason.

I couldn't find what the actual value of the gain of the Guralp breakout box is, but I assume its 10. With this assumption the calibrations are this:

Guralp: 800 V/(m/s)  *  10  (V/V)   *  16384  cts/V   =>    7.63e-9  (m/s)/count           (0.03 - 40 Hz)

Ranger:  345 V/(m/s)  * 100 (V/V)  *  16384 cts/V   =>     1.77e-9  (m/s)/count          (above 1Hz)

To account for the fact that I am not damping the Ranger with an external damping resistor, I have changed the calibration poles and zeros: in DTT we now use 2 poles @ 0 Hz and a complex pair at 1 Hz:

G = 1.77e-9

Poles = 0, 0

Zeros = 0.15 0.9887

I think that the Guralp gain is too high by a factor of 2. To really do this right, we should attach a known voltage to the input pins of the Guralp breakout and then read off the amount of counts.

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