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Reports until 15:15, Friday 03 February 2017
H1 SUS (SUS)
corey.gray@LIGO.ORG - posted 15:15, Friday 03 February 2017 (33873)
PI Mode Homework

After the PI Mode activity on Wed night, and after Keita asked me to measure the modes, I went through an exercise of looking at some of the PI Modes (mainly for my own "homework" since I've luckily not had to deal with needing to change filters to damp these out (changing phase has worked for me...and sometimes gains on rarer occassions---perhaps I've been lucky).

While going over the PI Damping wiki (& also having Jim & Nutsinee show me) & went about exploring the frequencies of PI Modes which either (1) have PLL on and/or (2) have a phase value.  For these PI Modes, I looked at:

Here's what I recorded:

Mode Basic BP Filter peak in Bode Plot BP Notch Value Meas Today
MODE1 14985 186.6(14986.6) 185 14985.6
MODE2 15520 717.8(15517.8) 720 15521.6
MODE3 15606 807.2 (15607.2) 806.5 15607.4
MODE9 14980 177.8 (14977.8) 180 14980.6
MODE10 15518 717.8 (15517.8) 718 15516.9
MODE17 15542 743.0 (15543.0) 742.2 15542.9 or 15543.5
MODE18 15008 207.0 (15007.0) 207.9 15008.5
MODE25 15541 741.2 (15541.2) 741.2 15542.9
MODE26 15010 209.9 (15009) 209.5 15010
MODE27 18043  237.7 (18037) 237.5 18037.5 & 18040.2
MODE28 18059  254.7 (18055) 255 18055.2
 
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