ELOG - ALS noisy

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Fri Apr 18 20:17:17 2014, Jenne, Update, LSC, ALS noisy

Mon Apr 21 22:53:16 2014, manasa, Update, LSC, ALS noise

Tue Apr 22 01:11:42 2014, Jenne, Update, LSC, TRY 60Hz noise

Tue Apr 22 21:54:50 2014, manasa, Update, LSC, TRY 60Hz noise

Tue Apr 22 22:49:10 2014, rana, Update, LSC, TRY 60Hz noise

Wed Apr 23 19:58:00 2014, manasa, Update, LSC, TRY 60Hz noise

Tue May 6 18:32:14 2014, steve, Update, LSC, TRY 60Hz noise hunt

Wed May 7 14:01:36 2014, steve, Update, LSC, TRY 60Hz noise hunt

Thu May 8 17:25:17 2014, steve, Update, LSC, TRY 60Hz noise hunt

Fri May 16 16:08:12 2014, steve, Update, LSC, Isolating base plates

Wed Apr 23 23:48:30 2014, manasa, Update, LSC, Y end whitening board

Thu Apr 24 14:23:09 2014, not manasa, Update, LSC, Y end whitening board

Thu Apr 24 23:55:31 2014, Koji, Update, LSC, Y end whitening board

Fri Apr 25 10:43:57 2014, Koji, Update, LSC, (Fixed) Y end whitening board

Thu Dec 11 18:12:46 2014, ericq, Update, LSC, (Fixed) Y end whitening board

Thu Dec 11 22:44:23 2014, rana, Update, LSC, QPD screens

Thu Apr 24 00:11:35 2014, Jenne, Update, LSC, Yend shutter back.

Sun Apr 27 20:26:19 2014, Koji, Update, LSC, Phase Tracker servo characterization

Sun Apr 27 21:30:59 2014, Koji, Update, LSC, ALS servo characterization

Mon Apr 28 10:24:10 2014, Koji, Update, LSC, error signal characterization

Mon Apr 28 10:34:51 2014, Koji, Update, LSC, new ALS servo design

Mon Apr 28 10:48:48 2014, Koji, Update, LSC, new ALS servo design: comparison

Mon Apr 28 10:59:54 2014, Koji, Update, LSC, New ALS servo design: expected error signals

Mon Apr 28 11:08:11 2014, Koji, Update, LSC, New ALS servo design: expected error signals

Message ID: 9832 Entry time: Fri Apr 18 20:17:17 2014 Reply to this: 9836

Author:	Jenne
Type:	Update
Category:	LSC
Subject:	ALS noisy

Last night, as well as tonight, the ALS seems not quite as robust as it was earlier in the week.

I have just taken noise spectra, and ALS is definitely more noisy than usual.

These plots are with the arms held in CARM and DARM mode, with servo gains of 8. I was seeing the beginnings of gain peaking at a gain of 10, so I turned it back to 8. Our ALS in-loop RMS is usually something like a few hundred Hz, but I'm seeing over 1kHz, so I have a factor of 4 or 5 too much noise. Why?!?!?

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