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Entry  Mon Dec 5 17:44:41 2011, kiwamu, Update, General, my plan tonight 
    Reply  Mon Dec 5 19:21:55 2011, kiwamu, Update, LSC, coarse beat note signal : ADC limited above 30 Hz Yarm_ALS_coarse.png
       Reply  Tue Dec 6 00:26:00 2011, kiwamu, Update, LSC, ALS became robust : UGF = 100 Hz 
Message ID: 6071     Entry time: Mon Dec 5 17:44:41 2011     Reply to this: 6072
Author: kiwamu 
Type: Update 
Category: General 
Subject: my plan tonight 

I am going to try handing off the ALS servo to the IR PDH servo on the Y arm and measure the noise.

 - first I need to investigate why the Y end PDH servo becomes unstable when the ALS is engaged with a high UGF.

 

(some notes)

 So far I still kept failing to increase the UGF of the ALS servo for some reason (see #6024).

Every time when I increased the UGF more then 50 Hz, the Y arm PDH lock became unlocked. It needs an explanation and a solution.

Another thing: During several trials in this evening I found the ETMY_SUSPOS_GAIN had been set to 1, so I reset it to 20, which gives us the damping Q of about 5.

 

(Temperature feedback activated)

 As planed in #6024 I have activated the temperature feedback, so that the PZT control signal is offloaded to the temperature. And it seems working fine.

Currently the gain is set to 0.03, which gives us a time constant of ~30 sec for offloading the control signal.

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