Reports until 17:58, Saturday 17 September 2016
H1 ISC (ISC)
jenne.driggers@LIGO.ORG - posted 17:58, Saturday 17 September 2016 - last comment - 20:04, Saturday 17 September 2016(29779)
New SRCL FF

I have remeasured the SRCL feedforward transfer function, and put it into the SRCLFF1 filter bank, and into the guardian.

Injections were done: SRCL1_EXC from 22:24:30-22:28:40 UTC, SRCLFF1_EXC from 22:13:20-22:17:30 (no filters engaged, input off, gain=+1).

The matlab file SRCLff.m grabs the data from the injection times, and calculates what the feedforward filter ought to be.  The matlab file Fit_SRCL_Filter.m loads that filter and uses vectfit to find the appropriate poles and zeros. 

The first image (Measured_vs_fitted_SRCLff.png) shows the agreement between the calculated transfer function that we want, and the result that vectfit gives.

The second image (New_vs_old_SRCLff_filters.png) shows the difference between the old FF filter and the new one.

I then took 3 different spectra and coherences, as shown in the third image (NewSRCLff_works.png):  Blue is without any SRCL FF, brown is the old SRCL FF with the gain of -1.3 that Lisa found yesterday, and pink is the new SRCL FF with a gain of -1.  While it's not a lot, there is improvement between 10 Hz and 30 Hz with the new filter over the old.  Either one is better than nothing though.

Note also that the old feedforward scheme was using an elliptic 4.5 Hz highpass (FM8=AC2 in SRCLFF1) while I am using a much more gentle 1 Hz highpass that was already installed (FM3=AC in SRCLFF1) so that I don't change the phase of my filter as much above 10 Hz.  Both cases have the FM6 and FM7 SBVio1 and SBVio2 filters engaged. 

Images attached to this report
Non-image files attached to this report
Comments related to this report
jenne.driggers@LIGO.ORG - 20:04, Saturday 17 September 2016 (29781)

MICH injections were taken also, but I'm not yet happy with the TFs that I'm getting - I want coherence over a wider band so I can get a better fit.

MICH:  22:32:00-22:36:10 UTC on 17Sept2016

MICHFF:  22:41:20-22:45:30 UTC on 17Sept2016