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Entry  Mon Aug 10 22:18:19 2015, Ignacio, Update, IOO, Ready to do some online mode cleaner subtraction stsx.pngperformance.pngfilter.zip
    Reply  Tue Aug 11 11:30:19 2015, Ignacio, Update, IOO, SISO (T240-X) FF of MCL MCL.pngMCTRANS.pngYARM.png
       Reply  Wed Aug 12 01:32:18 2015, Ignacio, Update, IOO, Improved SISO (T240-X) FF of MCL filter.pngstsx.pngmclonline.pngyarmonline.pngsub.png
    Reply  Wed Aug 19 01:45:10 2015, Ignacio, Update, IOO, Doubly Improved SISO (T240-X) FF of MCL 6x
       Reply  Thu Aug 20 11:09:10 2015, rana, Update, IOO, some points about seismic FF 
       Reply  Thu Aug 27 01:41:41 2015, Ignacio, Update, IOO, Triply Improved SISO (T240-X) FF of MCL 1.png2.png4.png5.png3.png
          Reply  Fri Aug 28 00:59:55 2015, Ignacio, Update, IOO, Final SISO FF Wiener Filter for MCL bode.png2.png3.png4.png6.png
Message ID: 11492     Entry time: Tue Aug 11 11:30:19 2015     In reply to: 11488     Reply to this: 11496
Author: Ignacio 
Type: Update 
Category: IOO 
Subject: SISO (T240-X) FF of MCL 

Last night we finally got some online subtraction going. The filter used is described in the post this eLOG is @eLOG 11488

The results were as follow:

The filter worked as expected when subtracting noise out of MCL,

There is about a factor of 6 subtraction at the ~3Hz resonant peak. The static IIR filter predicted a factor of 6-7 subtraction of this peak as well.

The 1.2 Hz resenonant feature improved by a factor of 3. This should improve quite drastically when I implement the y-channel of the T240 seismo.

There is some high frequency noise being injected, not very noticeable, but present. 

We then took a look at the power in the MC when the filter was on,

The power being transmitted in the cavity was not as stable as with the feedforward on. We believe that the filter is not at fault for this as Eric mentioned to me that the MC2 actuator lacked some sort of compensation that I need to understand a bit better.

YARM was then locked when the filter was on and we took a look at how it was doing. There was stationary sound arising from the locking of the YARM, leading us to believe that the filter might have injected some noise in the signal. IT DID.

The filter injected nasty high frequency noise at YARM from 11 Hz and on. This is to be expected since the filter did not roll off to zero at high frequencies. Implementing a 1/f rolloff should mitigate some of the injected noise.

 Also, as one can see above, subtraction by around a factor of 2 or so, was induced by the mode cleaner feedforward subtraction.

Attachment 1: MCL.png  546 kB  | Show | Hide all | Show all
Attachment 2: MCTRANS.png  423 kB  | Show | Hide all | Show all
Attachment 3: YARM.png  463 kB  | Hide | Hide all | Show all
YARM.png
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