Newsgroups: comp.robotics
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From: deadslug+@CS.CMU.EDU (Richard Voyles)
Subject: RE: GPS (was elec compass)
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References:  <1994Apr24.233603.17656@wmichgw>
Date: Tue, 26 Apr 1994 15:42:17 GMT
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An article recently appeared in IEEE Spectrum (I believe) describing
GPS. (It may have been the February issue)
The GPS system relies on two codes: one "course" and one "fine".
The DoD figured they'd keep the fine code sequence secret and use
it for fine positioning. The fact is, the commercial guys have been 
able to get nearly equivalent accuracy out of hte course code.
I'm not sure about "under a foot" accuracy, but afordable units
are getting in the 10-20 meter range. (If I remember correctly,
affordable means around $1K...more or less....not affordable in
the sense that every grad student should run out and buy one... :-)

  -Richard Voyles

BTW, I'm no expert in this area and am just trying to 
remember ads and articles I've run across recently....

