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Entry  Mon Sep 19 23:19:40 2011, Keiko, Update, IOO, AM modulation mistery 
    Reply  Tue Sep 20 23:01:37 2011, Keiko, Update, IOO, AM modulation mistery 
       Reply  Wed Sep 21 16:44:18 2011, Keiko, Update, IOO, AM modulation mistery P9210138.JPGP92101381.jpg
          Reply  Wed Sep 21 17:42:35 2011, rana, Update, IOO, AM modulation misery 
             Reply  Wed Sep 21 18:53:03 2011, Keiko, Update, IOO, AM modulation misery AM0.pngAMratio1.pngAMratio50.png
                Reply  Wed Sep 21 21:13:35 2011, rana, Update, IOO, AM modulation misery 
                   Reply  Thu Sep 22 17:29:42 2011, Keiko, Update, IOO, AM modulation mistery AMmod0MICH.pngAMmod1e-1MICH.pngAMmod0SRCL.pngAMmod3e-3SRCL.pngAMmod3e-3SRCL-AS55I.png
                      Reply  Sat Sep 24 09:55:42 2011, Keiko, Update, IOO, AM modulation mistery 
Message ID: 5504     Entry time: Wed Sep 21 18:53:03 2011     In reply to: 5503     Reply to this: 5506
Author: Keiko 
Type: Update 
Category: IOO 
Subject: AM modulation misery 

The signal offset due to the AM modulation is estimated by a simulation for PRCL for now. Please see the result below.

Too see how bad or good the AM modulation with 1/50 modulation depths of PM, I ran a simulation. For example I looked at PRCL sweep signal for each channel. I tried the three AM modulation depths, (1) m_AM=0 & m_PM = 0.17 (2) m_AM = 0.003 & m_PM = 0.17 which is the current modulation situation (3) m_AM = 0.17 & m_PM = 0.17 in which AM is the same modulation depth as PM.  For the current status of (2), there are offsets on signals up to 0.002 while the maximum signal amplitude is 0.15. I can't tell how bad it is.... Any suggestions?

 

(1) m_AM=0 & m_PM = 0.17. There is no offset in the signals.

AM0.png

(2) m_AM = 0.003 & m_PM = 0.17. There are offsets on signals up to 0.002 while the maximum signal amplitude is 0.15.

AMratio50.png

(3) m_AM = 0.17 & m_PM = 0.17. There are offsets on signals up to 0.1 while the maximum signal amplitude is 0.2.

AMratio1.png

I will look at MICH and SRCL in the same way. 

Quote:

I'd like to see some details about how to determine that the ratio of 1:50 is small enough for AM:PM.

* What have people achieved in past according to the elogs©  of the measurements?

* What do we expect the effect of 1:50 to be? How much offset does this make in the MICH/PRC/SRC loops? How much offset is too much?

Recall that we are using frontal modulation with a rather small Schnupp Asymmetry...

 

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