Jennie W, Sheila

Jeff reminded me that we should notch out the bounce mode from the ASC MICH loops wich also feedback to the beamsplitter if we are correcting its notch in the LSC loops as per this entry.

The filter module I used was FM9 in ASC-MICH_P and Y. This is the orginal contents for MICH_P and this is it for MICH_Y. I checked the guardian code and neither of these were used in ISC_DRMI or ISC_LOCK guradians currently.

I copied the filter design from the LSC loop but without the roll mode notch at 25Hz as this was not in the ASC MICH loop already and we might want to tune this later if we can see it in DARM.

I tuned the magnitude to make it 0dB at high and low frequency. The filter design is here and the plot is here for pitch. And the same filter design and plot for yaw.

I don't have an OLG measurement to verify this mode shows up in ASC-MICH but Sheila pointed out that the ASC MICH loops are lower bandwidth than the LSC MICH loops so we shouldn't lose too much phase margin with this filter.

These new filters are saved and loaded in the ASC model coefficients but we will not test them till our next commissioning period.