Sheila, Ross

We've put together a couple of screens for monitoring PI. The dtt shows a few spectrums of regions where PI may ring up and there is also a striptool which has rms monitors of some of the more problematic of the modes. These are stored in the /ligo/home/ops/Templates/ folder and are under dtt and StripTool PI_monitoring_ER9.

If any of these modes become unstable it should be visible in the RMS monitor screen. You can then get to the damping filter for that mode by going to the from the PI medm screens which are split into each test mass. There are overview screens for either QPDs or OMC. Most of these modes are damped using OMC signal at the moment apart from the 15541Hz ETMX mode and the 15542Hz ETMY mode which are damped using QPD signals. An example damping filter for the 15541 ETMX mode is attached in the third image. The damping filter settings may need to be changed if a line is ringing up i.e. the phase can be changed from +60 degrees to -60 degrees. Also increasing the gain may help to damp a mode if it is particularly rung up (around 100 magnitude). Right now the filter settings seem to keep the modes stable.

There is also a PI wiki page which is useful for identifying which modes  relate to which test mass.