Ed, Kiwamu,

During the course of relocking effort today, we ran into three issues associated with the guardian automation. Two of them are fixed/improved by editing the guardian codes while we were not able to fix the last one.

Here is some notes.

• Issue 1 (fixed), INPUT_ALIGN of IFO_ALIGN does not lock the X arm.
  • We found that this was due to a too high gain which had been increased in this afternoon (alog 23532) with an aim to improve the loop stability. We reverted the gain back to the nominal of 0.05 in lscparams.py.
  • The new code is submitted to SVN. It works fine with the nominal gain so far. We have no idea why it needed to be increased by a factor of 3. Perhaps related to the bad input pointing (alog 23538) ?
• Issue 2 (fixed), OMC_LOCK was consistently unable to find the carrier resonance.
  • This was found to be due to a unfortunate PZT scan range -- the peak-finding algorithm was unable to identify three high peaks (two from 45 MHz sidebands and one from the carrier). We have been mitigating this issue by adjusting the scan range so that the three peaks are separately captured in different segmented time series. This time, one of the segmented data chunk tended to capture one of the 45 MHz sideband as well as carrier. This situation ended up forcing the algorithm to pick only one of them and abondon the other. This in turn let the algorithem think there were only two peaks. I changed the scan starting voltage from -30 to -24 V so that three peaks are captured in different segments.
  • The latest code (OMC_LOCK.py) and parameter file (omcparams.py) are checked into SVN.
• Issue 3 (not fixed), CAGE_SERVO did not warn us that it was railing.
  • No idea why. It is supposed to give us a notification message when the amount of feedback is high. However it did not behave that way and simply kept servoing SR3 without giving a notification/warning message. We reloaded the code, but it did not seem to enter the if statement in which the warning message is given.
  • We manually offloaded the control signal to the upper stage in SR3.