Alexa Dan Evan Lisa Sheila
Today the ETMY bounce mode was ringing up during our many lock attempts. We rediscovered Nic's work to damp this mode using DARM feedback to the pitch drive of ETMY L2. We have been able to damp the mode while hanging out in ALS_DIFF, but progress is slow. We suspect that the high noise floor of DARM when locked on ALS_DIFF is limiting our ability to damp the mode. Transitioning to RF DARM may let us damp the mode more quickly, but this carries it's own inconvenience.
Anyways the way to damp the mode is to enable ETMY L2 DAMPDARM MODE1 --> PIT, with FM1-3 turned on. (FM3 is a 206dB gain stage, I have never seen so many dB in one place before.) With the bounce mode very high we had to reduce the overall filter gain to -0.04 to keep the SUS L2 drive from saturating. (Nic recommends -1, probably this is good once the mode has damped a little.)
- Dan as Sheila