40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Sat Mar 14 01:14:09 2015, Jenne, Update, LSC, More stable DARM transitions DARM_RF-only_13Mar2015.pdf
    Reply  Sun Mar 15 18:49:57 2015, Jenne, Update, LSC, More stable DARM transitions DARM_modelVsmeas_15March2015.pngDARMresiduals.png
Message ID: 11144     Entry time: Sun Mar 15 18:49:57 2015     In reply to: 11143
Author: Jenne 
Type: Update 
Category: LSC 
Subject: More stable DARM transitions 

I have modified the DARM model from elog 11133, to include the fact that these are digital filters.

I have also extracted the data from elog 11143, and it together with the model.

The modeled loop has an arbitrary gain factor, to make it have the same 234Hz UGF as the measured data.

The modeled loop includes:

  • Actuators
    • Pendulum (1Hz, Q of 4)
    • Violin filters
      • ETMs 1st, 2nd, 3rd order
      • MC2 1st, 2nd order
    • 3 16kHz delays for computation on the rfm model, transfer to the end sus models, and computation on end sus models.
    • Digital anti-imaging to get up to the IOP model
    • Delay of 64kHz for computation on IOP model
    • Analog anti-imaging
  • Plant
    • Single 4.5kHz pole
  • Sensor
    • Analog anti-aliasing
    • 64kHz delay for computation on IOP model
    • Digital anti-aliasing to get to LSC model rate
  • Loop Shape (digital filters extracted from Foton file using FotonFilter.m)
    • DARM B's integrator (FM7)
    • DARM's low freq boost (FM3)
    • DARM's locking filter (FM5)
    • DARM's bounceRoll filter (FM6)
    • DARM's new lead filter (FM7)
    • Delay of 16kHz for computation on LSC model (includes Dolphin hop to c1sus rfm model)

There is a 1.5 degree phase discrepancy at 100Hz, and an 11 degree phase discrepancy at 900Hz, but other than that, the modeled and measured loops match pretty well.

For the measured frequencies, here are the residuals:

Attachment 1: DARM_modelVsmeas_15March2015.png  61 kB  | Hide | Hide all | Show all
DARM_modelVsmeas_15March2015.png
Attachment 2: DARMresiduals.png  583 kB  Uploaded Mon Mar 16 13:26:34 2015  | Show | Hide all | Show all
ELOG V3.1.3-