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Entry  Tue Oct 11 03:35:16 2011, kiwamu, Update, LSC, BS actuator reponse at low frequency : measured BSactuator.png
    Reply  Tue Oct 11 15:14:50 2011, rana, Update, LSC, BS actuator reponse at low frequency : measured 
       Reply  Tue Oct 11 19:11:25 2011, kiwamu, Update, LSC, Re: BS actuator reponse at low frequency : measured 
    Reply  Wed Oct 12 17:53:01 2011, kiwamu, Update, LSC, BS actuator response : fitting done and histroy of delays bode_BSactuator.png
Message ID: 5656     Entry time: Wed Oct 12 17:53:01 2011     In reply to: 5648
Author: kiwamu 
Type: Update 
Category: LSC 
Subject: BS actuator response : fitting done and histroy of delays 

An update on calibration of the BS actuator : A fitting has been done.

(Fitting)

 I used LISO for fitting the complex transfer function.
Because the data points around 1 Hz didn't have big coherence a few data points, which had coherence of less than 0.9, were excluded.
Also the fitting of the Q-factor wasn't successful due to the lack of good data points around the resonance.So I left Q fixed to be 5 in the fitting.
 

(Fitting result)

G =  2.18060874008e-8 +/- 6.425e-10 (2.95%)
f0 =  1.0100491195 +/- 1.51e-2 (1.49%)  [Hz]
Q = 5 (fixed)
delay =  423.2753462089e-6 +/- 4.989e-6 (1.18%)  [sec]

bode_BSactuator.png

 

(History of delay)
 Because we have been observing several different amount of delays in different configurations, perhaps it is worth to summarize those numbers.
     description  delay [usec]   elog entry
       MICH lock (BS actuation)  423 this entry
       LSC feed forward path  127 #5218
       MICH lock (BS actuation)  600 #4638
      ALS on X arm (ETMX actuation)  330 #4196
      RFM (from c1lsc to c1sus)  125 #4153
      from ADC to DAC (all the front end machine)  38-110 #3961
      from ADC to DAC (c1sus)  124 #3838
     RFM (c1ioo and c1sus)   8-62 #3855

Quote from #5648
Tomorrow I will do a serious fitting.

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