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Entry  Mon Jul 27 16:47:53 2015, ericq, Update, IOO, MC2 -> MCL Actuator TF mc2_2_mcl.pngMC2_2_MCL_TF.txt.zip
    Reply  Thu Jul 30 02:06:20 2015, Ignacio, Update, IOO, MC2 <-> MCL Actuator TF fitted TF_BODE.pngMC2_2_MCL.pngTF_INV_BODE.pngMCL_2_MC2.png
    Reply  Wed Aug 12 22:33:36 2015, Ignacio, Update, IOO, Re-measured MC2 -> MCL TF bode_TF.pngCoherence.png
    Reply  Fri Aug 28 20:15:49 2015, rana, Update, IOO, MC2 -> MCL Actuator TF 
       Reply  Mon Aug 31 07:49:11 2015, ericq, Update, IOO, MC2 -> MCL Actuator TF 
          Reply  Mon Aug 31 14:15:23 2015, Ignacio, Update, IOO, Measured the MC_F whitening poles/zeroes Data.ziptf.png
Message ID: 11447     Entry time: Mon Jul 27 16:47:53 2015     Reply to this: 11462   11501   11539
Author: ericq 
Type: Update 
Category: IOO 
Subject: MC2 -> MCL Actuator TF 

Our noise cancellation SURFS will be doing online subtraction on the mode cleaner length, among other things. 

I made a measurement of the MC2 actuator transfer function by injecting noise from 1-100Hz into LSC_MC2_EXC for about 15 minutes, then estimating the TF from MC2_OUT to IOO_MC_L with CSD/PSD. The inverse of this TF will be applied to their Wiener target data to give us the direct subtration filter we want. 

I figured I would post the results here for posterity. The last time this seems to have been done is in ELOG 5900. There are some differences found here, the effective Q of the 1Hz pendulum resonance seems lower, and the behavior above 20Hz has definitely changed. 

IIR fits will be done by one of the SURFs to be used in their Wiener filter calculations. 

Data attached!

Attachment 1: mc2_2_mcl.png  86 kB  | Hide | Hide all
Attachment 2: MC2_2_MCL_TF.txt.zip  112 kB
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