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Entry  Thu Oct 9 16:31:53 2014, ericq, Update, LSC, CARM W/N TFs carm2SQRTinv.pdfcarm2REFLDC.pdf
    Reply  Thu Oct 9 18:30:59 2014, Jenne, Update, LSC, CARM W/N TFs 6x
       Reply  Fri Oct 10 00:20:37 2014, rana, Update, LSC, CARM W/N TFs carm40.pngcarm.pdf
          Reply  Wed Oct 15 02:59:04 2014, rana, Update, LSC, CARM W/N TFs spring.pdfantispring.pdf
             Reply  Thu Oct 16 22:35:05 2014, rana, Update, LSC, CARM W/N TFs carm_spring.pdfcarm_antispring.pdf
       Reply  Wed Oct 15 13:38:33 2014, Jenne, Update, LSC, CARM W/N TFs 7x
          Reply  Mon Oct 20 17:50:30 2014, Jenne, Update, LSC, CARM W/N TFs (Others were all wrong!) 7x
Message ID: 10620     Entry time: Thu Oct 16 22:35:05 2014     In reply to: 10608
Author: rana 
Type: Update 
Category: LSC 
Subject: CARM W/N TFs 

In my last CARM loop modelling, all of the plots are phony, so don't trust them. The invbilinear function inside of StefanB's onlinefilter.m was making bogus s-domain representations of the digital filter coefficients.

So now I've just plotted the frequency response directly from the z-domain SOS coeffs using MattE's readFilterFile.m and FotonFilter.m.

Conclusions are less rosy. The anti-spring side is still easier to compensate than the spring side, but it starts to get hopeless below ~130 pm of offset, so there we really need to try to get to REFL_11/(TRX+TRY), pending some noise analysis.

** In order to get the 80 and 40 pm loops to be more stable I've put in a tweak filter called Boost2 (FM8). As you can see, it kind of helps for 80 pm, but its pretty hopeless after that.

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