hugh.radkins@LIGO.ORG - posted 13:52, Friday 31 October 2014 - last comment - 14:26, Friday 31 October 2014(14774)
WBSC9 ETMX EndX HEPI X & Y Isolation Loop Boost's Gain 'UGF' Lowered
Jim Krishna Hugh
The gain was too close to the UGF and there was very little margin. The zero in the boost where it meets the main controller was lowered from 1.75 to 0.75 hz. This lowered the boosted gain but it is only a position loop anyway.
Here is before and after plots--it seems pretty obvious that this was a problem. Very interesting how it affects things below 100mHz--see Krishna's alog. The first is before, the second after the change.--Need to svn the foton file.