gabriele.vajente@LIGO.ORG - posted 15:39, Friday 04 August 2023 - last comment - 16:02, Friday 04 August 2023(71969)
The next non-stationary noise in DARM
Now that the main source of non-stationary noise has been removed (71927), we already have another candidate.
A DARM spectrogram shows bursts of noise below 60 Hz, happening from time to time. A better view is provided by a spectrogram of DARM whitened with the median.
There are two interesting features:
- Wide bumps that appears spaced by 10 Hz at 30, 40, 50 Hz. They look very much like scattered light
- Bursts of noise around the 60 Hz line
Images attached to this report
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Robert had me investigating something similar to this, specifically around the input power changes (4/7 and 6/21). I found that the noise seemed to be strongest after the power increase on 4/7. But it's been hard to tell how it changed after the decrease on 6/21. (I have tons of other reference images but I've attached one from each time period - before the power increase, during, and after.)
Images attached to this comment
