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Entry  Wed Jan 14 03:42:31 2015, Jenne, Update, LSC, Thoughts on going forward with variable finesse 
    Reply  Thu Jan 15 04:41:01 2015, Jenne, Update, LSC, Thoughts on going forward with variable finesse 
       Reply  Thu Jan 15 14:28:14 2015, Jenne, Update, LSC, LSC model change idea SwitchableErrorSignalProposal_Jan2015.pdf
          Reply  Fri Jan 16 03:31:35 2015, Jenne, Update, LSC, LSC model change implemented LSCorig_15Jan2015.pngLSCpost_15Jan2015.png
             Reply  Fri Jan 16 18:46:15 2015, Koji, Update, LSC, LSC model change implemented 
                Reply  Fri Jan 16 20:01:32 2015, Jenne, Update, LSC, LSC model change implemented 
             Reply  Tue Jan 20 15:09:01 2015, Jenne, Update, LSC, LSC model change implemented 
             Reply  Sat Mar 7 18:53:48 2015, Jenne, Update, LSC, DoF selector matrices replaced with filter banks DoFselectors_7March2015.png
Message ID: 10904     Entry time: Thu Jan 15 14:28:14 2015     In reply to: 10903     Reply to this: 10910
Author: Jenne 
Type: Update 
Category: LSC 
Subject: LSC model change idea 

Something that kind of drives me crazy with our current LSC model setup is that I can't make "finished" error signals before blending them.  The blending happens before the normalization matrix, and there is no place to put an offset to help match a new error signal to the current offset.  So.  While I'm sure this is not going to be immediately popular, here's a cartoon of a proposed model change to the LSC. 

The most important difference between this and the ramping matrix that is used at the sites is that you can put in offsets before the blend.  Also useful is the fact that the normalization can happen before the blend.  This proposal would make the LSC input matrix  and the normalization matrix have twice as many rows, and add an extra "selector matrix" just before the triggering at the error point of the loops. 

I've only drawn one degree of freedom in my cartoon, but assume that they all have the same capability (maybe we don't have to do XARM, YARM and MC this way).  One row is currently being used for the error signal, while the other row is just used to prep a new singal.  For a first transition (say, ALS to DC transmission), maybe the ALS signals are on row 1, and the DC trans is on row 2.  Once the transition is complete, row 1 is available to prep for the next transition (such as AS55Q).

 

Thoughts?  Is there a better way to achieve what I'm going for here?

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