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From: jeff@hpuplca.nsr.hp.com (   Jeff Gruszynski  )
Newsgroups: sci.electronics
Subject: Re: GPS system receiver
Message-ID: <12780006@hpuplca.nsr.hp.com>
Date: 17 May 91 18:08:22 GMT
References: <0iP121w164w@ersys.edmonton.ab.ca>
Organization: Hewlett-Packard Pleasanton Ca. Sales
Lines: 29

> / hpuplca:sci.electronics / lharris@ersys.edmonton.ab.ca (Leonard Harris) /  8:17 pm  May 15, 1991 /
> Hi.  Does anyone know what would be involved in building your
> own global positioning satellite receiver?.  i know the frequencies 
> they transmit on, but what data does it send.  Also more than one 
> satellite has to be interrogated to calculate position.
> Any ideas?
> thanks /len
> 
> Leonard Harris              lharris@ersys.edmonton.ab.ca
> Edmonton Remote Systems:  Serving Northern Alberta since 1982
> ----------

	In my previous life I worked with military satellites including
	GPS.  I once considered building my own receiver, so I called up
	the GPS program office and asked for some unclassified technical
	data on the system.  Several boxes of stuff later I concluded
	it would be of the order of building a satellite TV receiver *and*
	descrambler from scratch.  You need to sync on to a spread spectrum
	signal and do a fair amount of post-processing.  Without good
	microwave and digital CAD tools it would be painful.  
	
	On the other hand I've heard a division of Rockwell Int'l is planning
	to come out with a ~$250 personal GPS receiver.

Jeff Gruszynski
T&M STE SE
Santa Clara NSR
Hewlett Packard
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