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fabian.arellano - 11:21 Friday 09 August 2019 (9876) Print this report
Whitening chassis replacement.

Yesterday I installed a new whitening chassis (JGW-S1808664) which happens to have a whitening filter board. The old chassis (JGW-S1808109), which doesn't have the whitening filter board, remanined disconnected in the rack. I didn't remove it because a heavy DC power supply on top.

The current settings of the 32 bit dip switch boards are different to the ones reported in entry 9823 because the gain was saturating some of the QPD quandrant:

  • Oplev tilt QPD: S1809024, No 50,
  • Oplev length QPD: S1809021, No 47,
  • The following switches are on in both boards: 3, 4, 11, 12, 19, 20, 27, 28. A letter B preceeds these numbers.
  • The rest are of the switches are off.
  • Just for the record, the transfer functions of the whitening filters have been measured. An example can be found at JGW-S1605071.
Comments to this report:
fabian.arellano - 16:59 Friday 09 August 2019 (9904) Print this report

With Miyakawa-san, Nakano-san and Enomoto-kun.

After the replacement of the whitening chassis I took a transfer function (TM-L) in order to assess the change:

  • The first picture shows the TF with both, hardware whitening filter and software anti-whitening filter on.
  • The second picture shows the measurement with no filter at all, and
  • The third picture shows the measurement with the software anti-whitening filter on ONLY.
  • The software anti-whitening filter is shown in the fourth picture.
  • An example of a transfer function of a hardware whitening is shown in the fifth picture. See JGW-S1605071.

Directory: /kagra/Dropbox/Subsystems/VIS/TypeBData/SR3/TF/Measurements/20190809

Files: SR3_FLOAT_TML_exc_BOTH_ON_hard_soft_whitening.xml, SR3_FLOAT_TML_exc_NO_hard_soft_whitening.xml, SR3_FLOAT_TML_exc_only_soft_whitening.xml.

By the way, for some reason the coil drivers for the optic (TM) coil-magnet actuators were off. The other authors of this post helped me in troubleshooting.

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ayaka.shoda - 13:32 Tuesday 13 August 2019 (9947) Print this report

I still see the phase delay at around 10 Hz. And I found that it appears also in other suspensions... 

It would not affect the control systems, but doesn't sit right with me...

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