Gabriele, Elenna

Today we implemented a new DHARD P cutoff that maintains the low frequency suppression but reduces noise injection at 20 Hz by close to 6 dB. This has been implemented as a combined high power controller and rolloff in FM4. This filter uses the same gain. It will be engaged in lownoise ASC in conjunction with the low power controller filters in FM2,3, and 6.

The new CHARD Y filter maintains the same high frequency cutoff but boosts the microseismic suppression starting at 0.5 Hz. It is in FM3 and will replace FM4. It is also engaged at lownoise ASC and uses the same gain. The guardian has been updated accordingly.

I have not taken a new ASC noise budget at this time, but these changes leave CHARD P as the last main contributor to ASC noise at 20 Hz.

I have attached a screenshot of both the error signals and control signals of each loop. The blue reference traces show the signals before any changes and the red live traces show the current signals. We see improved lew frequency suppression in CHARD Y and decreased control output from DHARD P.