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Fri Dec 16 13:29:15 2011, kiwamu, Update, Green Locking, Y arm noise budget : 60Hz line noise is killing us
Sat Dec 17 00:00:03 2011, kiwamu, Update, Green Locking, 60 Hz line nose gone
Sat Dec 17 00:00:03 2011
In reply to:
60 Hz line nose gone
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.