Reports until 16:44, Friday 21 October 2016
H1 ISC
stefan.ballmer@LIGO.ORG - posted 16:44, Friday 21 October 2016 - last comment - 16:46, Friday 21 October 2016(30730)
Towards a low-noise Guardian at any operating power

- Started with checking the ISC guardians into svn.

- Designed a set of arm ASC filters for 25W using the following simple interpolation for the filter zeroes and Qs:
   f^2 = (f_0)^2  + [(f_50)^2-(f_0)^2]*P/50W  (Frequency squared should be linear in power, with the offset given by the stand-alone suspension.)  
   Q  =interp1([f_0,f_50],[Q_0,Q_50],f,'linear')  (Linear interpolation for the Q's between the stand-alone frequency and 50W frequency)
  The same procedure was applied to both resonences in each transfer function. The detailed frequencies and Qs are in the attachement.
   Looking at Jenne's full model, this should be relatively close to the truth.

- Then I rewrote the LOWNOISE_ASC guardian state to choose the new 25W filters below 40W, and the old 50W filters above 45W.

- We'll test all this as soon as the IFO is back.

Comments related to this report
stefan.ballmer@LIGO.ORG - 16:46, Friday 21 October 2016 (30731)

At 0W:

CHARD_P:
fa = 0.75Hz ; Qa = 6
fb = 1.55Hz ; Qb = 8.5
CHARD_Y:
fa = 0.5Hz ; Qa = 3
fb = 1.2Hz ; Qb = 10
DHARD_P:
fa = 0.75Hz ; Qa = 6
fb = 1.55Hz ; Qb = 8.5
DHARD_Y:
fa = 0.5Hz ; Qa = 3
fb = 1.2Hz ; Qb = 10

 

At 25W:

CHARD_P:


fa = 0.83Hz ; Qa = 6.52
fb = 1.73Hz ; Qb = 9.29
CHARD_Y:
fa = 0.79Hz ; Qa = 4.74
fb = 1.77Hz ; Qb = 10
DHARD_P:
fa = 0.83Hz ; Qa = 6.52
fb = 1.73Hz ; Qb = 9.29
DHARD_Y:
fa = 0.79Hz ; Qa = 4.74
fb = 1.77Hz ; Qb = 10

 

At 50W:

CHARD_P:
fa = 0.9Hz ; Qa = 7
fb = 1.9Hz ; Qb = 10
CHARD_Y:
fa = 1Hz ; Qa = 6
fb = 2.2Hz ; Qb = 10
DHARD_P:
fa = 0.9Hz ; Qa = 7
fb = 1.9Hz ; Qb = 10
DHARD_Y:
fa = 1Hz ; Qa = 6
fb = 2.2Hz ; Qb = 10