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Entry  Wed Aug 4 01:44:56 2010, Koji, Configuration, PEM, Accelerometer located on and below the PSL table IMG_2675.jpgIMG_2678.jpgIMG_2682.jpg
    Reply  Tue Aug 10 22:40:55 2010, Koji, Summary, PEM, Accelerometer located on and below the PSL table PEM_100809.pdf
Message ID: 3355     Entry time: Wed Aug 4 01:44:56 2010     Reply to this: 3395
Author: Koji 
Type: Configuration 
Category: PEM 
Subject: Accelerometer located on and below the PSL table 

[Jenne and Koji] 

In order to characterize the seismic vibration of the PSL table, we put the accelerometers on and below the PSL table.

On the PSL: MC2 Accelerometers (X, Y, Z) - being connected to CH1-3 of the preamps
East side of the PSL table. X, Y, and Z is directed to North, East, and Up.

On the ground: MC1 Accelerometers (X, Y, Z) - being connected to CH4-6 of the preamps
Beneath the West side of the PSL table. X, Y, and Z is co-aligned to the MC2 ACC.

I found that the C1:PEM-ACC_MC1_Z has large noise in the low freq (~1Hz) region. I tracked down the noise source
and found the noise is still present in the down stream even when the CH17 (C1:PEM-ACC_MC1_Z) of the ADC IF BNC
(@1Y7) was terminated.

I consulted with Jenne and decided to connect this channel to CH14, which is vacant and has name
C1:PEM-AUDIO_MIC2 (16k).
(for the details of the channel configurations, see /cvs/cds/caltech/chans/daq/C1ADCU_PEM.ini)

I first tried magnetometer channels to steal, but they didn't seem reacting (and the connected to the wrong channels).
I am feeling that we should once entirely check the I/F box.

Note that there looks the difference of the gain by x10 between C1:PEM-ACC_MC* channels and C1:PEM-AUDIO_MIC2.

[From Jenne:  The gain difference is because the C1:PEM-ACC_MC* channels have gain=10 in the .ini file, while C1:PEM-AUDIO_MIC2 uses the default gain=1. ]

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