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Entry  Fri Dec 16 13:29:15 2011, kiwamu, Update, Green Locking, Y arm noise budget : 60Hz line noise is killing us Yarm_ALS_2011DEC16.png
    Reply  Sat Dec 17 00:00:03 2011, kiwamu, Update, Green Locking, 60 Hz line nose gone 
Message ID: 6127     Entry time: Sat Dec 17 00:00:03 2011     In reply to: 6126
Author: kiwamu 
Type: Update 
Category: Green Locking 
Subject: 60 Hz line nose gone 

Quote from #6126
As shown in the noise budget below, the 60 Hz line noise currently dominates the arm displacement.

 The 60 Hz line noise has gone away.

It turned out that the line noise came from an oscilloscope.
The oscilloscope had been connected to a SR560, which amplifies the frequency-discriminated signal before the ADC as a whitening filter.
I still don't have a good explanation for it, but somehow connecting the oscilloscope made the line noise pretty high.
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