The soon to be made change to LHO calibration is planned for next Wednesday (20200108).

As a follow up to what the newly modeled UIM dynamics will change I have generated a couple more plots. Previously I looked at how the pyDARM calibration will change with the updated TF (the comment in a related report), highlighting the improvements to calibration, and how they line up with known discrepancies between DELTAL and Pcal.

Now I look at the difference between the new front end, foton filterbank, and the pyDARM calibration contributions to R (2020-01-03_H1_Rfoton_new_over_Rpydarm_new.pdf) - here you see that I am missing two features, one at ~90 Hz and at 134 Hz (you can see these in the comment to the related report as well).

Finally I look at the total change in the front end, as a change in contribution to R (2020-01-03_H1_Rfoton_new_over_Rfoton_old.pdf) . This is equivalent to the change in calibration on the DELTAL.

There is quite a lot of alterations at lower frequencies (<40) in the comparison of contributions from the foton filters. Other than the testmass correction and new 50-150Hz UIM features, nothing is supposed to impact these low frequencies. I suspect the reason is that in propagating the the SUSmodels (L1, L2 and L3 stage, i.e. the UIM, PUM and TST stages) to the foton filterbanks, and I optimising the minreal functions of matlab to keep absoluteley as many poles and zeros as I can get away with. For example the UIM stage (where I took the most time and care), is comprised of (ignoring the 1/f^6 filter bank and the gain only bank) 3 filter banks of 10, 10, and 9 Second Order Sections (the max allowed in foton is 10). I used this philosophy for the lower stages also - and I suspect the low frequency parts of the SUSmodels are better represented in this iteration of the filter - giving rise to corrective changes below 40Hz in 2020-01-03_H1_Rfoton_new_over_Rfoton_old.pdf.