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Message ID: 1765     Entry time: Wed Sep 12 20:56:59 2012
Author: tara 
Type: Electronics 
Category: General 
Subject: seismometers installed 

Zach and I borrowed 2 seismometers from the 40m. Den gave us Guralp and Barcadi with their breakout boxes.

We added the seismometers to compare it with gyro readout noise in hope that we can see any coherence between gyro noise and seismometer noise. Since, at low frequencies, tilt and seismic noise will both show up on seismometers, but only tilt will show up in gyro. Any coherence between gyro and seismic signal should confirm us that the measured gyro signal is real (coming from tilt).

The signals from Guralp are ~ +/-1.5 V for all 3 channels. Signals from Barcadi are much smaller ~+/- 50mV because the gain stages are broken and not in used. We will add some preamps  before DAQ. However, the signals between the two seismometers appeared to be the same. We did a quick check by tapping the table and looking at the response. We could see table's frequency at 9 Hz (for Horizontal motion).


fig1: breakout boxes are on the ground next to DAQ. fig2,3 Guralp and Barcadi on gyro table.


fig4: orientations and positions of the two seismometers.

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