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Entry  Thu Apr 3 18:55:10 2014, ericq, Summary, LSC, Some CARM related modeling asIsPRCRes.pdfidealPRCRes.pdf3fPrclAnglesCarm.pdf
    Reply  Fri Apr 4 18:51:29 2014, ericq, Summary, LSC, MORE CARM related modeling 9x
Message ID: 9785     Entry time: Fri Apr 4 18:51:29 2014     In reply to: 9784
Author: ericq 
Type: Summary 
Category: LSC 
Subject: MORE CARM related modeling 

In today's ISC call, Kiwamu was comparing two ways to approach resonance: 

  • "C-Type": The scheme we currently think about; zero DARM offset and slowly reduce the CARM offset
  • "D-Type": Start with no CARM offset, but a DARM offset and reduce that. 

D-type might be interesting to check out, since things change a little less dramatically when you reduce the DARM offset. Maybe this makes signal hopping easier? Signal recycling may complicate things, though. 

So, I've simulated CARM and DARM offset effects on CARM and DARM signals. (As with the previous plots, this is for the PRFPMI configuration.) From moving both offsets around, it looks like the resonance peak is about 5x wider in DARM than in CARM, so I simulated a 50pm offset range for CARM and a 250pm offset range for DARM. 

Here are some CARM signal transfer functions subject to CARM offsets in the top plot, and DARM offsets in the bottom plot. 

 carm2REFL11.pdfcarm2REFL55.pdf

carm2REFLDC.pdfcarm2TRX.pdf

 

It's looks like the DARM offset changes cause much less dramatic changes in the CARM plant features. It's conceivable that this would make CARM locking easier. 

Here are some DARM plant transfer functions. 

 darm2AS11.pdfdarm2AS55.pdf

darm2ASDC.pdfdarm2TRX.pdf

In these plots, I did something kind of artificial: when we move the CARM offset, it changes the proper demodulation phase to get DARM in the Q of the AS 1F RFPDS. So, at each CARM offset, I re-phased the AS 1F demodulators, to show the total DARM information available at the AS RFPDs at each offset, rather than what one would actually see in them with a static demod phase. 

ASDemodAngles.pdf 

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