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Tue May 26 02:15:36 2020, gautam, Update, LSC, Lock acquisition portal entry
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Tue May 26 02:31:00 2020, gautam, Update, LSC, Lock acquisition sequence
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Wed May 27 20:14:51 2020, Koji, Update, LSC, Lock acquisition sequence
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Tue May 26 02:37:19 2020, gautam, Update, LSC, DARM loop measurement and fitting 
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Tue May 26 03:01:35 2020, gautam, Update, LSC, CARM loop
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Wed Jun 3 01:46:14 2020, gautam, Update, LSC, CARM loop    
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Tue May 26 03:06:59 2020, gautam, Update, LSC, PRFPMI sensing matrix 
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Tue May 26 03:26:58 2020, gautam, Update, LSC, Preliminary noise budget
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Tue May 26 14:32:44 2020, gautam, Update, LSC, Arm transmission RIN
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Wed May 27 19:36:33 2020, Koji, Update, LSC, Arm transmission RIN
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Thu May 28 18:36:45 2020, gautam, Update, LSC, Arm transmission RIN  
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Fri May 29 00:34:57 2020, rana, Update, LSC, Arm transmission RIN
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Wed Jun 3 02:14:32 2020, gautam, Update, ASC, PRC ASC improves arm transmission RIN    
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Fri Jun 19 16:30:09 2020, gautam, Update, ASC, Some thoughts about ASC 
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Tue Jul 7 14:06:10 2020, gautam, Update, ASC, Some more thoughts about ASC
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Tue May 26 16:00:06 2020, gautam, Update, LSC, Power buildup diagnostics 
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Wed May 27 17:41:57 2020, Koji, Update, LSC, Power buildup diagnostics
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Wed Jun 3 02:08:00 2020, gautam, Update, LSC, Power buildup diagnostics 
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Wed Jun 3 01:34:53 2020, gautam, Update, LSC, Lock acquisition update portal
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Wed Jun 3 03:29:26 2020, Koji, Update, LSC, Lock acquisition update portal
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Wed Jun 3 11:40:56 2020, gautam, Update, LSC, Lock acquisition update portal
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Wed Jun 3 18:49:47 2020, gautam, Update, LSC, PRG and CARM signal sign   
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Message ID: 15361
Entry time: Thu May 28 18:36:45 2020
In reply to: 15359
Reply to this: 15362
15368
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Author: |
gautam |
Type: |
Update |
Category: |
LSC |
Subject: |
Arm transmission RIN |
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I agree, I think the PRC excess angular motion, PIT in particular, is a dominant contributor to the RIN. Attachments #1-#3 support this hypothesis. In these plots, "XARM" should really read "COMM" and "YARM" should really read "DIFF", because the error signals from the two end QPDs are mixed to generate the PIT and YAW error signals for these ASC servos - this is some channel renaming that will have to be done on the ASC model. The fact that the scatter plot between these DoFs has some ellipticity probably means the basis transformation isn't exactly right, because if they were truly orthogonal, we would expect them to be uncorrelated?
- In the corner plots, I am plotting the error signals of the ASC servos and the arm transmission. POP feedback is not engaged, but some feedback control to the ETMs based on the QPD signals is engaged.
- In the coherence plot, I show the coherence of the ASC error signals with the POP and TR QPD based error signals, under the same conditions. The coherence is high out to ~20 Hz.
I guess what this means is that the stability of the lock could be improved by turning on some POP QPD based feedback control, I'll give it a shot.
Quote: |
- PRC TT misalignment (~3Hz)
Don't can you check the correlation between the POP QPD and the arm RIN
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