keita.kawabe@LIGO.ORG - posted 19:37, Thursday 09 June 2016 - last comment - 21:42, Monday 13 June 2016(27680)
bounce damp
Bounce damping setting was changed for IY and EX so they damp at all. Don't know why the old settings don't work.
For EX I just flipped the sign.
For IY, I rotated the phase by 210 degrees in effect and increased the gain significantly. Gain increase might be unnecessary but I leave it like that because it seems to work faster.
| Old | NEW | |
| EX |
Gain= -0.03 (negative), FM1 (+60dg), FM4 (bp) |
Gain=+0.03, FM1 (+60dg), FM4 (bp) |
| IY |
Gain= -0.03 (negative), FM1 (+60dg), FM3 (BP), FM6 (+30dg) negative sign + 60 deg + 30deg = -90 deg total |
Gain= -0.15 (negative), FM2 (-60dg), FM3 (BP) negative sign -60 deg = +120 deg total |
ISC_Lock was changed but not loaded.
Travis and I added a filter with negative gain to IY bounce (and EX) damping, so the gains for all bounce and roll damping filters will be positive from now on. The guardian is updated for this.
We found that in the state DARM offset, we got good damping for ETMX with a positive gain and -60 degrees of phase. This worked better than the settings that Keita described in the DARM offset state, but we also used Keita's settings sucsesfully in DHARD WFS.
TJ and I saw that with the Keita settings at DARM_OFFSET we were ringing up the bounce mode for ETMX. So, now in the Resonance state the bounce damping gets set to the Sheila settings. Unclear why this one needs a 120 deg phase change but no others do. Perhaps related to why the settings needed changing in the first place? When the bounce damping is first turned on in DHARD_WFS, it goes back to the Keita settings.
We have been using a bandpass filter for ETMX bounce mode damping that is designed for the ETMY bounce frequency. For the other optics we use a broad bandpass, so I've now set the gaurdian to do that for ETMX as well. The new settings are:
FM3 (broad BP), and FM8 (gain -1). These are in the guardian for now, to be used in all states, so I've commented out the filter change in RESONANCE.
When we have the notches in the ASC off, we can damp the bounce modes as seen in the DARM spectrum. However, even when they appear to be reduced in the DARM spectrum they seem to be increasing in the MICH ASC signals.
I copied quad bounce and roll notches to the BS ASC loops as well.
I looked at a 1 mHz spectrum of the bounce modes from last nights lock, and the frequencies are consistent with what we reported one year ago:
The confusion about the ITMY mode frequency (corrected by Evan in the comment) was unfortunately propagated to our monitoring filters. I've corrected the monitor bandpass for ITMY and made all of the bandpasses 10 mHz wide (before they were all 30 mHz wide, meaning that the monitors could not distinguish between the ITMs).