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From: rrw@naucse.cse.nau.edu (Robert Wier)
Newsgroups: sci.electronics
Subject: How to detect SLOOOOW AM?
Message-ID: <3632@naucse.cse.nau.edu>
Date: 16 Apr 91 08:06:00 GMT
Organization: Northern Arizona University, Flagstaff AZ
Lines: 33


 I'm wondering if anyone can point me in some direction to 
 figure out the following problem:

 We have GEOS weather satellite receiver.  The converter on the
 dish comes out with an AM signal representing pixel values
 from the images.  It is an a 2KHZ "carrier" (yup, that 
 2,000 Hz - audio).  There are about 500 pixels per line, so
 I guess that the detected signal I want varies at that rate.

 The question is, how does one detect such a low frequency
 AM signal with the information of interest being such a 
 large percantage of the carrier frequency?  

 Presumably, one could use a full wave detector, with a 
 capacitor to "smooth out" the carrier, but it seems like it
 would take a large (and lossy) cap to do this (not like 
 standard AM radio detectors).  (EE's - forgive this description,
 I'm a digital type :-)

 Any suggestions on this?

 Please either E-Mail me or post here.

 THANKS!

 - Bob Wier

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                      College of Engineering
         Northern Arizona University / Flagstaff, Arizona
  Internet: rrw@naucse.cse.nau.edu | BITNET: WIER@NAUVAX | WB5KXH
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