[opendtv] Re: Satellite radio
----- Original Message ----- From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>
What this has to do with COFDM is that the modulation scheme employed by XM 
-- as trumpeted by Bob Miller years ago -- is COFDM.
The Terrestrial Repeaters use COFDM. The Satellites use single carrier QPSK. 


I don't know that the XM setup actually uses a single frequency, but I
suspect that it does. I don't know that their network in LA uses a SFN, but 
I suspect that it does.
XM has six frequencies. Four are used for Satellite to receiver, and two are used for TR to receiver. 

http://www.patentstorm.us/patents/7075946-description.html

John




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