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Entry  Tue Dec 10 15:13:55 2013, Koji, Update, IOO, IMC servo inspection 
    Reply  Thu Dec 12 14:57:01 2013, Koji, Update, IOO, IMC servo inspection OLTF_IMC.pdfAOTF_IMC.pdf131209.zip
       Reply  Fri Dec 13 18:03:00 2013, Den, Update, IOO, common mode servo CM_OL.pdfCM_CL.pdf
          Reply  Fri Dec 13 23:07:04 2013, Koji, Update, IOO, common mode servo 
          Reply  Sat Dec 14 11:56:54 2013, rana, Update, LSC, common mode servo 
             Reply  Sat Dec 14 14:21:46 2013, Den, Update, LSC, common mode servo 
Message ID: 9474     Entry time: Sat Dec 14 14:21:46 2013     In reply to: 9472
Author: Den 
Type: Update 
Category: LSC 
Subject: common mode servo 

Quote:

 

 These seem like pretty terrible loop shapes. Can you give us a plot with the breakdown of several of the TFs and some .m file?

Attached is matlab code that I used

 % IMC OL
G = zpk(-2*pi*8964, 2*pi*[-10; -10; -10; -1000; -274000], db2mag(242.5)) * ...
    tf([1 0.8*1.55e+05 3.1806e+10], 1);

% CARM PATH
CARM = G/(1+G);

% Common mode boosts
BOOST = zpk(-2*pi*4000, -2*pi*40, 1);
BOOST1 = zpk(-2*pi*20000, -2*pi*1000, 1);
BOOST2 = zpk(-2*pi*20000, -2*pi*1000, 1);
BOOST3 = zpk(-2*pi*4500, -2*pi*300, 1);

% Coupled cavity pole
CCPole = zpk([], -2*pi*100, 2*pi*100);

% Servo gain
Gain = db2mag(43);

% CARM OL with boosts
H = CARM * CCPole * BOOST * Gain;
H1 = H * BOOST1;
H2 = H1 * BOOST2;
H3 = H2 * BOOST3;

% Plot
% bode(H, H1, H2, H3, 2*pi*logspace(3, 5, 10000));
% bode(1/(1+H), 1/(1+H1), 1/(1+H2), 1/(1+H3), 2*pi*logspace(3, 5, 10000));

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