Reports until 11:40, Friday 25 March 2016
H1 ISC (ISC)
jenne.driggers@LIGO.ORG - posted 11:40, Friday 25 March 2016 (26250)
Current DHARD loop shape

In preparation for designing ASC filters for increasing the laser power, I've looked at what we're actually using right now.  The filters that we are turning on during the "noise tunings" state is giving us 15dB of gain peaking in the pitch loop around 10 Hz.  Since the DHARD Yaw loop isn't so carefully tuned, it has much more phase margin, and so doesn't have egregious gain peaking.

I just noticed the noise tunings filter and its effect for the DHARD loops today. I didn't measure high enough frequencies to see the problem when I was measuring loops back in alog 25368.

Right now, I'm working on designing filters for DHARD Pit for power-up (almost done), designing filters for DHARD Yaw so that we have only a single UGF even at current powers (just starting), and doing similar work for the CHARD loops (not started).

Non-image files attached to this report