Ivey, Edgard, and Brian have created new estimator fits (86233) and blend filters (86265) for the SR3 Y estimator, and we have new rate channels (86080), so we were excited to be able to take new estimator measurements (last time 85615).
Unfortunately, there were issues with installing the new filters, so I had to make do with the old filters: for the for the estimator filters, I used the fits from fits_H1SR3_2025-06-30.mat, and the blend filters are from Estimator_blend_doublenotch_SR3yaw.m, aka the DBL_notch filter and not the new skinny notch. These are the same filters used in the testing from 85615.
So the only difference between the last estimator test and this one is that the last test had the generic satamp compensation filters (85471), and this measurement has the more precise 'best possible' compensation filters (85746). Good for us to see how much of a difference the generic vs best possible compensation filters make.
Unfortunately, due to the filter installation issues as well as still trying to re set up the estimator channels following the channel name changes, I also didn't have much time to run the tests, resulting in the actual test with the estimator being only 5 minutes. Hopefully this is okay enough for at least a preliminary view of how it's working and then next week we can run a full test with the more recent filters. Like last time, the transition between the OSEM damping and the estimator damping was very smooth and the noise out of the estimator was visibly smaller than with the regular damping (ndscope1).
Measurement times
SR3 Y damp -0.1
2025-08-12 18:28:00 - 18:44:00 UTC
SR3 Y damp -0.1, OSEM damp -0.4
2025-08-12 18:46:46 - 19:03:41 UTC
SR3 Y damp -0.1, Estimator damp -0.4
2025-08-12 19:09:00 - 19:16:51 UTC
Attached below are plots of the OSEM yaw signal, the M3 yaw optical lever witness sensor signal, and the drive request from light damping, full damping (current setting), and estimator damping modes from Oli's recent estimator test.
The blue trace is the light damping mode, the red trace is the full damping mode, and the yellow trace is the estimator damping.
The first plot is of the OSEM signal. The spectrum is dominated by OSEM noise. The blue, light damping trace shows where the suspension resonances are (around 1, 2, and 3 Hz). Under estimator damping, the resonances don't show up as expected.
This second plot is of the OPLEV signal. It is much more obvious from this plot that the estimator is damping at the resonances as expected. Between the first and second, as well as the second and third peaks, the yellow trace of the estimator damping mode is below the red trace of the full damping mode. This is good because it is expected that the estimator damping is better than the current full damping mode between the peaks. There is some estimator noise between 3 and 4 Hz from the estimator. The light damping trace also sees a noticeable amount of excess noise between 10 to 15 Hz. We suspect this is due to ground motion from maintenance: third, fourth, and fifth plots show comparisons between ground motion in July (when the light damping trace was 'normal') and August. There is excess noise in X, Y, and Z in August when compared to July.
The sixth plot is of the drive requests. This data was pulled from a newly installed 512 samples/sec channel, while the previous analysis for a test in July (see: LHO: 85745) was done using a channel that was sampling at 16 samples/sec. The low frequency full damping drive request differs significantly between July and August, likely because aliasing effects caused the July data to be unreliable. Otherwise, the estimator is requesting less drive above 5 Hz as expected. We note that the estimator rolls off sharply above 10 Hz.
The last plot is of the theoretical drive requests overlaid onto the empirical drive requests. We see that the major features of the estimator drive request are accounted for, as expected.
Oli intends to install the filter and the new, clean fits (see LHO: 86366) next Tuesday to test the yaw estimator once more. Hopefully the installation is smooth!
I would like to clarify from my initial alog that when I said that "the only difference between the last estimator test and this one is that the last test had the generic satamp compensation filters", that was a lie!! The measurements taken for calibrating and figuring out the correct response drives were taken before the satellite amplifiers were swapped for SR3, so even just the OSEMINF calibration was not done with the new satellite amplifiers in mind, so the calibration we had in there at the time was not very accurate to what we had going on, so we can't really compare this measurement to the last one.