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Entry  Wed Dec 7 18:47:36 2011, Jenne, Update, RF System, RAM Mon is now being demodulated 
    Reply  Thu Dec 8 00:04:50 2011, rana, Update, IOO, RAM Mon is now being demodulated 
       Reply  Thu Dec 8 14:47:28 2011, Jenne, Update, IOO, EOM aligned to minimize RAM 
    Reply  Thu Dec 8 00:45:13 2011, Koji, Update, RF System, 4ch demod is ready 
       Reply  Thu Dec 8 22:44:55 2011, Koji, Update, RF System, 4ch demod test result RF_DEMOD_TEST_111208.pdf
Message ID: 6089     Entry time: Thu Dec 8 14:47:28 2011     In reply to: 6084
Author: Jenne 
Type: Update 
Category: IOO 
Subject: EOM aligned to minimize RAM 


Monitoring good, but remember that the EOM alignment must be done carefully to minimize the RAM before we can use these trends.

 I temporarily diverted the output of the RAMmon PD to a spectrum analyzer (4195 in Spectrum Analyzer mode), and tweaked the EOM alignment until I minimized the 11 and 55 MHz peaks as much as possible.  It was possible to get each individual peak to disappear into the noise (about -70dBm), but to get both minimized simultaneously I wasn't able to get both down into the noise.  I left the 11MHz at about -55dBm, and the 55MHz at about -60dBm.  If Kiwamu's simulation tells us that one is more significant than the other (55, because we use it for MICH?), then we can decide to favor putting that peak in the noise and sacrifice ~10dB in the other peak. 

When I first plugged the PD into the analyzer, I saw 22MHz and 44MHz (small) peaks, but they went away after the first bit of tweaking.

Before having used the analyzer, I was trying to minimize the demodulated signals via StripTool, but that was a slow process.  The spectrum analyzer was obviously much faster.

The PD has been returned to the regular RAMmon electronics.

Next up: putting in the new demod box that Koji tested last night.

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