Virgo Logbook

AdV-ISC (Alignment control scheme conceptual design)

casanueva, pinto, ruggi, masserot - 17:25 Monday 18 March 2024 (63660)

Preparing Noise Injection scripts

This morning the scope was to re-commission the scripts that inject noise on the LSC / ASC / SSFS loops. The LSC script was already ready, so we just run it to check that it was working properly. All the injections showed coherence with Hrec (SRCL wsa slighlty worse than the others, on Wednesday we would like to try a nosie injection at slightly lower frequencies 5-50Hz). The script can be found and launched at: /virgoDev/Automation/scripts/LSC/inject_lsc.py. Today's injections GPS can be found at /virgoData/NoiseInjections/LSC/LSC_injection-1394783415. Notice that during these injections the Galvo of B4 QD1 opened. To be checked if it was a coincidence or if this happens consistently.

Next activity was to inject noise in the angular loops closed on QPD error signals (Commp, DIFFp and PR) in order to adjust the amplitudes of the noise injected. Note that BR TX loop is also measurable but we mispelled the DOF name in the function to perform the injection (to be repeated on Wednesday)

Clean data: Same for the LSC noise injections.
ASC noise shape = Butterworth bandpass between 5 and 50 Hz.
GPS time stamps of the injections:
- 8.21.15 UTC + 120 sec, DIFFp TX inj ampl 8e-6.
- 8.32.10 UTC + 120 sec, DIFFp TX inj ampl 1e-4.
- 8.55.00 UTC + 120 sec, PR TX inj ampl 1e-4.
- 9.06.15 UTC + 120 sec, PR TY inj ampl 2e-4.
- 9.22.30 UTC + 120 sec, COMMp TX inj ampl 9e-4.
- 9.33.40 UTC + 120 sec, COMMp TY inj ampl 1e-3.

We also wrote a symmetric code in order to inject noise in these loops, and we tested it. It can be found at: /virgoDev/Automation/scripts/ASC/inject_asc_test.py. The .txt file with the measurements is stored in the folder 'virgoData/NoiseInjection/ASC/ASC_injection-*GPS*.txt'. We would like to finish with the BS TX on Wednesday, and then inject noise through the driving to the remaining angualr DOFs (SR and softs).

As side activity we performed an OLTF measurement of the BS TY loop through the DSP (HF brench, optical lever sensing), in order to have a response of the roll-off of the loop tf.
Noise shape: bandpass 'bpass.flt' centered at 3.5 Hz.
- 9.54.30 + 120 sec, BS TY inj ampl 5e.3
We tested again the control filter for BS TX tested last thursday. This time, it was possible to appreciate the effect of the filter (gain more at 200 mHz). GPS of the test:
- 10.36.00 + 120 sec, clean data with standard filter.
- 10.39.30 + 120 sec, test with new filter (txCorrAA2.flt).
We left the new filter as default. In Fig.s 1 is reported the measurement of the HF brench of the open loop of the BS TY, while in Fig.2 is plotted the spectra with the response of the new control filter for BS TX (red) with respect the current one (blue).

FInally, we tried to inject noise to the SSFS. The first thing we did was to comment the "define SSFS_FLT_NOISE" in order to be able to change the filters online, and then we restarted SSFS_phi, SSFS_noise and SSFS_Ctrl. We relocked and we started to try to make nosie injections. After some trials, we managed to inject noise around the UGF, and we already created a dedicated script that can be found: /virgoDev/Atomation/scripts/LSC/inject_ssfs.py. On Wednesday we would like to add two more dedicated noise injections at lower frequencies.

We will work on the script to produce the noise budget online.

Images attached to this report

Comments to this report:

pinto - 14:10 Tuesday 19 March 2024 (63671)

Angular injections performed yesterday march 18th and last march 14th have been preliminary analyzed. A noise budget wrt HREC has been produced.

In order:

In Fig.1 is reported the projection of the DIFFp, PR and COMMp loops on Hrec, from the first set of measurments taken by hand, in order to set the 'ASC_NOISE' amplitude;
In Fig.2 is reported the projection of the DIFFp and COMMp loops on Hrec, from the second set of data taken with the automatic script. N.B. Due to the mispelling of the PR loops channel, the PR injections didn't go through. Addittionally, the stored GPS for the clean data (2024,03,18,10,10,01) was affected by a glitch, which spoiled the projection. Good clean data GPS is taken: 2024,03,18,08,16,30. ----> txt file has to be updated with this GPS.
In Fig.3 is reported the noise budget of the remaining loops (i.e. PR TX, PR TY and BS TX) , using the sensing noise injections performed last march 14th, plus the injections at the MAR level of BS TY, performed march 18th. For PR and BS TX loops (QPD sensing) the post channel to compute the transfer function wrt Hrec was 'ASC_DoF_CORR+Sc_DoF_noise', while for BS TY (op lev sensing), the post channel was 'Sc_BS_MAR_TY + Sc_BS_noise'.

For the results of Fig.s 1 and 2, DIFFp TY looks the one more limiting (to be investigated). Concerning the projections of Fig.3, results of BS both TX and TY are not reliable due to a lack of coherence with Hrec, probably due to the shape of the noise filter (bandpass centered at 5 Hz and 3.5 Hz respectively). Such measurements need to be taken again.

Images attached to this comment

pinto, casanueva - 14:33 Friday 26 April 2024 (64106)

given that the past injections performed on CARM SLOW loop through the automatic script in /virgoDev/Automation/scripts/LSC/inject_lsc.py were not sufficiently accurate (fig.1), today we increased of a factor 5 the noise amplitude. If this noise amplitude is not enough, we could increase it even further, there should be margin, see fig.2 and 3.

Images attached to this comment