Reports until 14:49, Monday 07 November 2016
H1 SUS
corey.gray@LIGO.ORG - posted 14:49, Monday 07 November 2016 (31277)
A Look At Violin Mode 2nd Harmonics (Namely 1005.94Hz)

Sheila has mentioned Operators should take a look at squashing down some of the 2nd Harmonics of the Violin Modes.  Using Nutsinee's procedure, I went about taking a First Look.   Attached you will see a power spectrum during our current 10+hr lock.  On here we get the following which are above a 10/23/16 reference:  (freq & wiki notes)

Decided to look at ETMx's 1005.94.  On its Damping Filter medm, we had a filter bank already set up for this:  MODE10.

1005.94Hz

This squashed this line.  This has been entered in the Violin Mode wiki.


Addressed the next biggest line of 1003.78 for ETMx.  This is taken care of in MODE9.  A positive gain rung it up, so tried some negative gains which was fine.  Then I tweaked phase from -60deg and went to 0deg.  This was fine.  Unfortunately, when I tried a gain of +60deg, this rung it up.  And it looks like it excited the neighboring line of 1003.667.   I've been trying to now damp out the latter (1003.667), but it is going reeeealllly slow.

Since I wasn't successful with the 1005.94, I will not make a note of what I attempted and won't update the wiki.

Images attached to this report