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Entry  Thu Aug 14 20:52:36 2014, rana, Update, Wiki, Violin Mode table added to Wiki 
    Reply  Thu Aug 14 22:16:02 2014, Jenne, Update, SUS, Violin Mode filters for ETMs 
Message ID: 10394     Entry time: Thu Aug 14 22:16:02 2014     In reply to: 10393
Author: Jenne 
Type: Update 
Category: SUS 
Subject: Violin Mode filters for ETMs 

The instigator of this was that we were seeing ring-ups of ETMs during our ALS locks this evening.  We measured the ETMY violin resonance to be 624.10 Hz, and Rana found an elog saying that the ETMX was around 631 Hz, so we made a 2 notch filter and added it to FM4 of the LSC-SUS filter banks for both ETMs. 

For the ETMY resonance, we measured the frequency in the DARM spectrum, and when we looked at the FINE_PHASE_OUT channels, the resonance was only in the Yarm sensor.  So, we conclude that it is coming from ETMY.

Also in the realm of filter modules, the FM3 boost for CARM, DARM, XARM and YARM was changed from zero crossing to ramp with a 1sec ramp time.

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