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Entry  Fri Sep 23 17:57:34 2011, Paul, Update, SUS, Oplev filter optimization for 2 poles and 2 zeros optimised2p2z_v1.pngoptimised2p2z_v1_TFs.png
    Reply  Sat Sep 24 01:51:02 2011, rana, Update, SUS, Oplev filter optimization for 2 poles and 2 zeros 
       Reply  Tue Sep 27 08:51:29 2011, Paul, Update, SUS, Oplev filter optimization for 2 poles and 2 zeros 
    Reply  Sat Sep 24 02:09:43 2011, kiwamu, Update, SUS, Re:Oplev filter optimization for 2 poles and 2 zeros 
       Reply  Sat Sep 24 17:45:56 2011, Paul, Update, SUS, Re:Oplev filter optimization for 2 poles and 2 zeros 
Message ID: 5537     Entry time: Sat Sep 24 02:09:43 2011     In reply to: 5532     Reply to this: 5540
Author: kiwamu 
Type: Update 
Category: SUS 
Subject: Re:Oplev filter optimization for 2 poles and 2 zeros 

Good work for the oplev noise simulations. Here are some comments/questions:

 (A) The noise looks suppressed but the open-loop transfer function doesn't look so good, because it doesn't have sufficient phase margins at the UGFs (0.01 and 10 Hz).

      I guess it is better to have a phase margin detector in your code so that the code automatically rejects a bad phase margin case.

      Actually since the number of data points are finite, the rms detector in the simulation can not always find a sharp loop oscillation.

 (B) The resultant poles and zeros seem canceling each other but the filter still has a structure. Is something wrong ?

Quote from #5332

 Pole 1 frequency = 0.0497181 Hz 

 Pole 2 frequency = 2.01809 Hz 

 Zero 1 frequency = 0.0497181 Hz 

 Zero 2 frequency = 2.01809 Hz

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