I noticed that in the previous lock (5 Feb 23:50UTC) mode 18 peak was not in DARM, yet the monitor filter was flatlined at around 2.6, and the mode 20 peak was in the spectra and flatlined at around 3.25.  Looking at the monitor filters, they were both centered on the peaks (mode 18 at 1000.296Hz, mode 20 at 1000.307Hz).  The gain at the frequencies was 120dB, and each filter overlapped the other frequency at around 112dB.  I moved the monitor filters appart, which lowered the overlap gain to be around 86dB.  Attached is an ndscope trend of the previous lock and current lock, which shows that in this current lock mode 18 monitor filter is now decreasing as mode 18 is damped, and mode 20 is flatlined at around 2.93, which accurately reflects both peaks in DARM.

• mode 18 monitor filter: 1000.296Hz
  • OLD: butter("BandPass",8,1000.286,1000.306)gain(120,"dB")
  • NEW: butter("BandPass",8,1000.2805,1000.3005)gain(120,"dB")
• mode 20 monitor filter: 1000.307Hz
  • OLD: butter("BandPass",8,1000.297,1000.317)gain(120,"dB"
  • NEW: butter("BandPass",8,1000.302,1000.322)gain(120,"dB")

Attachments:

1. old filters, cursors show 1000.296 (mode 18) and 1000.307 (mode 20)
2. new filters, cursors show 1000.296 (mode 18) and 1000.307 (mode 20)
3. ndscope of monitor filters, previous lock, current lock
4. shows the power spectra, previous lock (black) to current lock soon after going back into Observe (green), and about 2 hours into the current lock (red).