J. Kissel, E. Bonilla, I. Zhong, B. Lantz, O. Patane

Per LHO:86563, Edgard found/noticed that the H1SUSSR3 M1 Pitch Estimator system wasn't using the Sus Point L to M1 P contribution that had been a part of the design intent. I used 
    /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/
        make_SR3_pitch_model.m      rev 12618
to install the extra filters into FM1 and FM2 of the H1:SUS-SR3_M1_EST_P_FUSION_MODL_SUSP_L_2GAP filter bank.
The script uses 
    /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Estimator/
        Clean_fits_H1SR3_P_2025-08-05.mat      rev 12594

Steps to install:
(0) From the sitemap, open up the SR3 overview screen, and find the pitch estimator overview screen as well as the Sus Point to M1 filter bank collection.
(1) Open matlab, navigate to the above directory and open the script.
(2) TURN THE ESTIMATOR OFF, by using the the fader switch: H1:SUS-SR3_M1_EST_P_SWITCH_NEXT_CHAN goes from 3.0 to 2.0 (but you can do this with the "Use OSEM" button on the estimator overview screen)
(3) Run the matlab script -- this uses autoquack (LIGO's home brewed matlab-to-foton filter install function) to push the matlab filter to SR3's foton file.
(4) Open up the SR3 GDS_TP screen, where there should now be a "Modified Filter File" message shown on the channel H1:FEC-44_MSG2. Use the !DIFF button -- which pops up a screen showing the diff between what's installed and what you're about to install -- to validate at least that "the only filter bank that's been touched or modified is the new L to P filter" (since it's tough to validate Second Order Sections by eye).
(5) THE ESTIMATOR IS OFF, RIGHT? OK, then hit the "COEFF LOAD" button. The filter names listed below should appear in FM1 and FM2 of the EST_P_FUSION_MODL_SUSP_L_2GAP bank.
(6) THE ESTIMATOR IS OFF, RIGHT? OK, then use the MEDM interface on the EST_P_FUSION_MODL_SUSP_L_2GAP screen to turn on the input, output, FM1 and FM2, and set the gain to 1.0
(7) While the impulse response of the filter settles, set the H1:SUS-SR3_M1_EST_P_FUSION_MODL_SUSP_L_2GAP_STATE_GOOD filter module state checker bit word to match the current state's word H1:SUS-SR3_M1_EST_P_FUSION_MODL_SUSP_L_2GAP_STATE_NOW. Should need a change from 0x2000000 to 0x6000f4.
(8) Turn the estimator back ON. And at least look at the estimator overview screen to confirm that sensor signals are not going bonkers. In fact, they really shouldn't look that different at all.
(9) If you like what you see, go back to the GDS_TP screen and accept the new EPICs settings with this new filter ON in both the safe and observe snap files:
    /opt/rtcds/userapps/release/sus/h1/burtfiles/
        h1sussr3_safe.snap
        h1sussr3_observe.snap
commit these to the userapps svn with the appropriate message when you're done.
(10) Commit the updated foton file to the userapps svn with a similar message
    /opt/rtcds/userapps/release/sus/h1/filterfiles/
        H1SUSSR3.txt
(11) Profit! Start looking at the performance!

Here's the design explicitly:
SR3_M1_EST_P_FUSION_MODL_SUSP_L_2GAP
FM1        "ISI_fit_L"      Fit to (M1 Response / Sus. Point L Excitation) TF, plus calibration from nm to um.
    sos(0.0001142264006754552, 
        [-2.0000000000000009; 1.0000000000000011; 
         -1.999975478282779; 0.99997585128576594; 
         -1.999816005993748; 0.99982977526725314; 
         -1.999982188592295; 0.99998283118601283; 
         -1.999884963247067; 0.9998851520162283; 
         -1.999988292191436; 0.99998835461999513; 
         -2.0001080651245839; 1.0001082464362681; 
         -1.999989760987597; 0.99998984142840619; 
         -2.000082349605993; 1.0000836590827351; 
         -1.9999909890250209; 0.99999272379034698])
FM1        "to_um/nm"       Vestigial Organ; calibration is folded in to FM1's filter these days.
     zpk([],[],1.000000000000000,"n")