We need to reduce the DHARD rms to make our SRCL to darm coupling more stationary, (77729 77666) I ran a noise injection to measure the DHARD P loop this morning.
Elenna measured the hard loops and compared them to a model while we had 430kW in the arms in 69597, today's measurement is with 375kW. I used a template I found in userapps/h1/asc/templates/DHARD/DHARD_P_broadband_excitation.xml, which I think is the one that Elenna tuned in 69597.
Attached is a very simple script that uses dttxml to get the transfer function data from an xml file, getting the IN2/exc/IN1/exc unbiased transfer function. I also plotted uncertainties based on 10506, calculating an uncertainty for magnitude and phase from in1/exc and in2/exc separately and adding them in quadrature (this is not the correct way to add these uncertainties).
It seems like we have room to add a boost to this loop.
For modeling purposes, here's a fit to the DHARD_P plant obtained from this measurement, after factoring out the current controller.
Z = [-0.37656602]
P = [-0.00292406 +0.j ,-0.11496697 +6.49363092j,
-0.11496697 -6.49363092j,-0.19955184+16.53674456j,
-0.19955184-16.53674456j]
K = 2176.925725327256
Here's a possible design for a boost to improve suppression in the region below 0.7 Hz
zpk([-2.723526385480632+i*3.098947495963098;-2.723526385480632-i*3.098947495963098],[-0.6734376457906343+i*2.23044514115136;-0.6734376457906343-i*2.23044514115136],0.9990715840784479)
I have saved this new boost as GVboost in DHARD P FM8, but I haven't yet loaded the filter file.