Last night, EricQ and I were concerned that we might need some CARM UGF servoing, so I added a UGF servo block, copied from the aLIGO LSC model, to our LSC model. The block is inline with the CARM servo, after the output triggering, just before the output matrix. Q put together some screens, which are accessible from the main LSC screen.
The model is compiled and running. We didn't get very far in testing it though before Koji pointed out that it is a slow solution, and not a fast one like we were searching for. We were hoping to deal with the momentary power buildup, and thus optical gain change, as the arms flash close to resonance. The UGF servo will not work nearly that fast though. We may want it for slow UGF servo-ing, but it's not the solution to what Q and I were thinking about yesterday. Regular ol' dynamic normalization is closer to the right answer for this.
In tonight's activities, Koji and I found that we probably want a CESAR block for DARM as well as CARM, so that we can independently normalize AS55Q.
To solve the DARM oscillation issue from last night (that I discovered this evening when I finally looked at the time series data), we may want to implement a DARM UGF servo. For tonight, as we reduced the CARM offset and started seeing gain peaking in the DARM spectra, I hand-reduced the DARM gain.