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Reports until 18:29, Monday 12 February 2018
H1 CAL (CAL, ISC, SUS)
evan.goetz@LIGO.ORG - posted 18:29, Monday 12 February 2018 - last comment - 16:34, Wednesday 28 March 2018(40508)
Compensation zero moved from ESD output filter bank
Evan G., Jeff K.

We moved a compensation zero out of the ESD output filter bank for each quadrant that had generated an uncompensated 5.2 kHz pole in the DARM loop (see LHO aLOG 33927). This resulted in an effective delay of ~20 usec. There is adequate roll off already from a low pass filter in the ESD driver, so moving this out of the DARM loop will be minimally impactful. Instead, the compensation zero will be a compensation pole in the CAL-CS path and doesn't result in an additional 5.2 kHz zero being added to the Foton filter.

We leave the filter in place and turned on, but the design string is now simply zpk([], [], 1, "n")

The new filter is installed in CS_DARM_ANALOG_ETMY_L3, FM5: zpk([], [3245.33075], 1, "n") (this comes from the mean of the summing node poles, see 27619)

Removing this from the DARM path means that we need to include these as an uncompensated poles in the DARM model and reduce the unknown actuation delay by 20 usec. This will bring the unknown actuation delay down to ~40 usec.
Comments related to this report
jeffrey.kissel@LIGO.ORG - 16:34, Wednesday 28 March 2018 (41189)
Associated with FRS Ticket 7351.
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