The change of guardian code to allow violin mode damping gain changes during Observe has paved the way to damp previously undamped modes, reducing the peaks in DARM.   To capture what I've learned, changes I've made, planned changes, I'm putting in a summary.

Overall, I've found a number of filters that need to be adjusted, both damping and monitor filters, and typically the damping filters need to be more narrow, and monitor filters need to be biased to reduce the overlap for two close peaks.

Status, text in red indicates critical information:

• ETMY modes 12, 18, and 20 Damping: 
  • modes 18 and 20 are damping well, mode 12 is damping slowly, and the current gains have worked well during relocking at least 3 times - testing phase is over, gains are stable, mode 12 could use some attention, but it's not the highest priority
• ETMY modes 12, 18, and 20 Monitor Filters: 
  • currently reading each peak separately, in the stated where all three are small
• ETMY modes 1 and 6 Monitor Filters:
  • adjusted, improved, and would benefit from another look to see if there could be more separation
• ITMX modes 7 and 8 Damping:  
  • mode 7 peak is abscent from DARM, mode 8 peak is small but still visible, mode 7 gain is tested and stable at 10, but mode 8 gain last relocked at -4, and is now set to relock at -20.  Guardian will return this gain to -4 at relocking.  Please continue testing, by manually setting the gain to -20 gain at relocking H1, and then keep an eye on both modes 7 and 8
• ITMX modes 7 and 8 Monitor Filters: 
  • I've updated these, but they are not loaded, and until loaded, readback for mode 8 is only somewhat reliable, will have to see how much it improves
• ETMX mode 6 Damping: 
  • I've updated this damping filter, but it is not yet loaded, and until it is, it's not possible to damp both ETMY and ETMX mode 6 peaks.   ETMX mode 6 frequency is correct, as shown by the fact that I damped this peak until it was not visible above the background, with the filters that are currently in ETMX mode 6, but only with with ETMY mode 6 damping disabled

Filtering I've changed, as of 22 Dec 2019:

• ETMY modes 18 and 20 Damping: filters on mode 18 and 20 adjusted
• ETMY modes 18 and 20 Monitor Filters: modes 18 and 20 filters adjusted
• ETMY modes 1 and 6 Monitor Filters: filters on mode 1 and 6 adjusted
• ITMX mode 8 Damping:  filter on mode 8 adjusted
• ITMX modes 7 and 8 Monitor Filters:  filters on mode 7 and 8 adjusted (not yet loaded)
• ETMX mode 6 Damping: filter on mode 6 adjusted (not yet loaded)

Planned Changes on ITMX modes 2 and 3 Damping Filters:

• Current Filters:
  • mode 3: butter("BandPass",6,504.689,504.749)gain(120,"dB")
  • mode 2: butter("BandPass",4,504.841,504.941)gain(120,"dB")
• Change To:
  • mode 3: butter("BandPass",6,504.709,504.729)gain(120,"dB")
  • mode 2: butter("BandPass",6,504.881,504.901)gain(120,"dB")
• Bode plots attached:
  • LEFT = mode 3, RIGHT = mode 2
  • black = current, red = changed
  • vertical cursor at 504.8Hz on each plot shows changes at about half way between the two peaks

Current Mode "Pairs:"

• ETMX mode 6, ETMY mode 6 - this may change after the new ETMY mode 6 filter is loaded
• ETMY modes 1 and 6
• ETMY modes 11, 12, 18, and 20 - I've included mode 11, which hasn't consistantly participated with modes 12/18/20, but has come into play more than once, so is something to watch if driving any of the modes 12/18/20 with a higher than nominal gain
• ITMX modes 7 and 8
• ITMX modes 2 and 3
• ITMX modes 13 and 18
• ITMY and ETMX have pairs, to be added at a future date, when identified/confirmed