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Entry  Fri Mar 1 01:17:06 2013, Jenne, Update, LSC, Xarm oscillation POX11_630Hz_osc.pdf
    Reply  Fri Mar 1 16:58:37 2013, yuta, Update, LSC, Xarm oscillation stopped POX11_630Hz.png
       Reply  Sat Mar 2 00:09:31 2013, rana, Update, LSC, Xarm oscillation stopped 
Message ID: 8210     Entry time: Sat Mar 2 00:09:31 2013     In reply to: 8208
Author: rana 
Type: Update 
Category: LSC 
Subject: Xarm oscillation stopped 

  Don't use resonant gain - it can lead to a loop instability since it makes the loop have 3 UGFs.

Just use a elliptic bandstop filter at this harmonic frequency separately for each test mass. There are many detailed examples of this in elog entries from Rob and I over the past ~10 years. This bandstop should get clicked on automatically after lock acquisition.

ELOG V3.1.3-