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Entry  Wed Nov 23 17:48:16 2016, rana, koji, Update, IOO, How bad is the McWFS? 
    Reply  Sat Nov 26 19:16:28 2016, Koji, Update, IOO, IMC WFS Demod board measurement & analysis WFS_demod_response.pdfWFS_demod_noise.pdfWFS_demod_noise_plan.pdfScreen_shot_2011-07-01_at_11.13.01_AM.png
       Reply  Tue Nov 29 17:45:06 2016, Koji, Update, IOO, IMC WFS Demod board measurement & analysis demod.pdfWFS_demod_response.pdfWFS_demod_noise.pdf
          Reply  Tue Nov 29 18:35:32 2016, rana, Update, IOO, IMC WFS Demod board measurement & analysis 
             Reply  Fri Dec 2 18:02:37 2016, Koji, Update, IOO, IMC WFS Demod board measurement & analysis WFS_demod_noise_orig.pdfWFS_demod_noise_mod.pdf
                Reply  Sat Dec 3 13:27:35 2016, Koji, Update, IOO, IMC WFS Demod board measurement & analysis WFS_demod_noise.pdfdemod.pdf
                   Reply  Tue Dec 6 13:37:02 2016, Koji, Update, IOO, IMC WFS Demod board measurement & analysis demod.pdfWFS_error_noise.pdf
                      Reply  Tue Dec 6 16:47:40 2016, Koji, Update, IOO, IMC WFS whitening filter investigation D990196-C.pdf
                         Reply  Tue Dec 6 17:54:08 2016, Koji, Update, IOO, IMC WFS whitening filter investigation 34.png
                            Reply  Tue Dec 6 22:41:49 2016, Koji, Update, IOO, IMC WFS whitening filter investigation 
                               Reply  Tue Dec 13 17:26:42 2016, Koji, Update, IOO, IMC WFS whitening filter investigation 
                                  Reply  Thu Dec 15 03:46:19 2016, rana, Update, IOO, IMC WFS whitening filter investigation 
Message ID: 12678     Entry time: Thu Dec 15 03:46:19 2016     In reply to: 12676
Author: rana 
Type: Update 
Category: IOO 
Subject: IMC WFS whitening filter investigation 

https://dcc.ligo.org/LIGO-D1400414

As it turns out, its not so old as I thought. Jenne and I reworked these in 2014-2015. The QPD whitening is the same as the IMC WFS whitening so we can just repeat those fixes here for the IMC.

Quote:

Rana pointed out that this modification (removal of 900Ohm) leave the input impedance as low as 100Ohm.
As OP284 can drive up to 10mA, the input can span only +/-1V with some nonlinearity.

Rather than reinstalling the 900Ohms, Rana will investigate the old-days fix for the whitening filter that may involve the removal of AD602s.
Until the solution is supplied, the IMC WFS project is suspended.

 

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