marc.pirello@LIGO.ORG - posted 16:38, Wednesday 06 June 2018 - last comment - 12:45, Wednesday 12 September 2018(42361)
Modifidcation applied to OMC DCPD Whitening Filter Chain & PI Readbacks
J. Kissel, M. Pirello
Applied the following ECR's to the primary chassis (S1101627) and the spare (S1101603).
The existing Whitening Amplifier (D1002559) needs modification to accommodate the violin modes of the main LIGO optics in the vicinity of 500Hz that have a tendency to saturate the existing whitening chain’s pole-zero filters. (E1600252-v2)
Implement separate higher bandwidth readbacks for the OMC DCPDs to support PI damping. (E1600192-v2)
Both ECR's implemented to both chassis, the primary chassis testing is complete and the data is attached to this report.
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Here's a Bode Plot of the different response for ST2 of the chassis as a result of this change / ECR completion.
The data has been downloaded and committed to:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Common/Electronics/H1/Data/OMCWhiteningChassis/2018-06-04/
The script that plots the results is:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Common/Electronics/H1/Scripts/plot_omcdcpdwhiteningmods_20180604.m
The digital compensation for this filter has been *roughly* installed, with the design string
zpk([50],[504],-1,"n")
and I've changed the name of the filter to be called "AntiLP" instead of "AntiWh" so as to help alleviate confusion.
Note, we (the calibration group) still needs to make to fit this data more precisely, compensate it precisely, and with an uncertainty estimate on the poles and zeros.
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