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H1 SUS
jeffrey.kissel@LIGO.ORG - posted 14:56, Thursday 28 August 2025 - last comment - 14:58, Thursday 28 August 2025(86628)
H1SUSPR3 Estimator: Local Metrics -- ON vs OFF and PR3 ON vs SR3 ON
J. Kissel, O. Patane 

Attached are the local performance metrics for the PR3 Pitch and Yaw estimators (explained with SR3's metrics and visual aides in LHO:86553).

Just to reduce plot overwhelm, in the main aLOG here I attach the performance metric comparisons ON vs. OFF for PR3.
I'll post the PR3 vs SR3 plots in the comments.

In summary -- the PR3 estimator performs just as well as the SR3 estimator, reducing the 1-50 Hz off-resonance motion by a factor of ~4x, but leaving the amount of on-resonance damping the same. As with SR3, the performance is limited by the remaining "light" "classical" "broadband" damping that is necessary to keep the estimator plant transfer functions reasonable (i.e. to keep the Q's sufficiently low that fitting and modeling the TFs is reasonable). 

However, because PR3 is sitting on HAM2 a worse performing ISI between 1-50 Hz because it doesn't have stage 0 L4C feed-forward, the estimated contribution of suspension point motion to M1 is much louder / noisier. As such, I provide zoom ins from 5 to 50 Hz. That motion is still *smaller* than the remaining light damping OSEM sensor noise, so it's not (yet) getting imprinted on the SUS. But it's still interesting.
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jeffrey.kissel@LIGO.ORG - 14:58, Thursday 28 August 2025 (86632)
Here's the PR3 to SR3 comparison.
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