While OBSERVING with a glitchy H1 for the last 19hrs, there was mention of a possible culprit being noisy violin modes.
Before taking any action, I consulted with Keita (Run Coordinator) to ask whether this would be acceptable (because L1 is currently down and we would not jeopordize double coincidence). Keita pointed me to a note about diagnosing violin modes here, (alog 32615). So, I went through is diagnostics for determining whether we have ADC or DAC saturations (which is a main symptom of big violin modes).
Diagnostics for saturations due to violin modes:
1) Make sure OMC DCPD is far from +/- 32k, and ESD is far from +/- 131k, and this can be checked via timeseries.
2) Make sure there are no large values for a a spectrum of these channels
Both of these measurements are attached, and I believe they look OK (please check me on this). So I will not bother with an attempt of violin mode damping.
The decision not to damp violin modes seems like a good one today, but I would add two more things to check, since we have seen glitches around the violins and harmonics even when we are not close to having saturations. (ie alog 32026 for the symptom, for a solution see 32050)
First, you can check the glitch plot on the wall or the summary page (under Lock> glitches)for a line of glitches around the violin modes or harmoincs (500Hz, 1kHz, 1.5kHz ect).
Second, you can look at the main spectrum on the wall and see if the violin modes are high compared to the reference.