This morning I put the DRMI ASC engagement back in, so that we're not only doing MICH ASC but all vertex ASC loops are closed and get offloaded before we start the CARM offset reduction sequence. This should remove the need for us to constantly be adjusting the alignment of mirrors by hand in DRMI.
So far this morning, however, I can't sit at full RF lock with the ASC loops closed. I didn't try before I put the DRMI ASC back in, but the change in optic position is pretty small (as one would expect) when they get offloaded, so I don't see a reason why this would cause trouble. Both by hand and with ASC engaged, I cannot get the POP18_I_NORM above 85, when normally (before yesterday's TCS tunings) we could reliably get to 93. So, not a big difference, but certainly noticeable.
The oscillation we see happens after we've finished SRC_ASC, after several tens of seconds. It's about 1Hz, so not the same as the 20Hz oscillation that they were seeing last night at 20W. Under investigation...
In full lock right now, we're hitting the ADC limit of 32k counts on the AS_C segment inputs. Each time we hit the limit, the SRC2 error signals get a glitch. I have lowered the analog gain of the AS_C segments by 9dB, which is one default-sized click on the analog gain slider. Now the inmons go about +- 20k counts.
I have not yet reset the dark offsets with this new analog gain.
The high violin modes can cause AS_C to saturate the ADC.
Jeff K and I talked about adding a monitor for all the violin modes (or all the fundamentals, 1st harmonics, second harmonics, ect) in the new OAF model. That way the guardian can check the level of these monitors before engaging the SRC ASC (to check that we are not high enough to saturated the AS_C ADC) and before going to DC readout (to check that we are not saturating the DCPDs).
For now the monitor is in ETMY MODE9. the gain is set so that the amplitude of the monitor is roughly the amplitude of the highest individual mode monitor. I added a check in ENGAGE_SRC_ASC that will notify the user if the amplitude is above 6.3, the threshold might need adjustment (this threshold might be too strict).
After Sheila's reminder, I have reverted my change to the analog gain of AS_C.