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Entry  Thu Feb 27 01:02:57 2014, Jenne, Update, SUS, Oplev Tuning Party - round 1 PRM_oplevTuning_26Feb2014.pdf
    Reply  Thu Feb 27 22:25:29 2014, rana, Update, SUS, Oplev Tuning Party - round 1 commentary 
       Reply  Wed Mar 5 09:52:31 2014, Jenne, Update, SUS, Oplev Tuning - Cartoon cost function CostFunctionOplev.pdf
          Reply  Thu Mar 6 17:34:03 2014, rana, Update, SUS, Oplev Tuning - Cartoon cost function 
Message ID: 9680     Entry time: Thu Feb 27 01:02:57 2014     Reply to this: 9682
Author: Jenne 
Type: Update 
Category: SUS 
Subject: Oplev Tuning Party - round 1 

[Jenne, Vivien]

We had an oplev tuning party this afternoon.  What we have learned is that we don't have a lot of intuition yet on tuning loops.  But, that was part of the point - to build some intuition. 

I took responsibility for the PRM, and Vivien took ITMX.  I think, in the end, all changes were reverted on ITMX, however Vivien took some data to try and make a computer-generated controller.  Before we got started, I locked and aligned the PRMI, and we centered the PRMI-relevant oplevs.

I moved my "boost bump" around a bit, to do more at higher frequencies, but had to sacrifice some of the "oomph", since it was starting to eat up too much phase at my UGF of ~8Hz.  I also made the stack resonant gain higher Q and lower height so that it didn't eat so much phase.  In the end, I have 25 degrees of phase margin, which isn't really great, but I do win a factor of 2 around 2 and 3 Hz.  Also, now I'm able to engage the 3.2 resgain at all, whereas with the previous filter shape I was not able to turn it on.

PRM_oplevTuning_26Feb2014.pdf

Maybe it's because I really want it to have helped, but I feel like the POP spot isn't moving as much when I'm locked on PRMI sidebands as it was earlier (we were seeing a lot of low frequency (few Hz) motion).  So, I think I did something good.

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