Looking at the measurement of CSOFT from this alog, and also remembering that CSOFT P tends to be highly coherent with DARM from 10-15 Hz, I decided to make some adjustments to the CSOFT P lowpass filter that would both suppress noise around 10 Hz, and also maybe buy back some phase at 1 Hz. I designed a 7 Hz low pass filter with only 40 dB of attentuation. The current lowpass filter design has 60 dB of attenuation, which seems like overkill. I adjusted the low pass to be elliptic, low Q, which gives us back about 5 degrees of phase, but reduces the gain at 10 Hz and above by a factor of 10. I didn't get a chance to try it in lock, but I changed the guardian to engage this filter on the way up to NLN (line 3341 of ISC_LOCK). There will be an SDF diff. The new filter is in FM7, the old filter is in FM9.