Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!rutgers!att!cbnews!khb@fatcity.Sun.COM
From: khb@fatcity.Sun.COM (Keith Bierman Sun Tactical Engineering)
Newsgroups: sci.military
Subject: Re: Spoofing GPS signals?
Message-ID: <6102@cbnews.ATT.COM>
Date: 1 May 89 03:01:46 GMT
References: <5984@cbnews.ATT.COM>
Sender: military@cbnews.ATT.COM
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From: khb@fatcity.Sun.COM (Keith Bierman Sun Tactical Engineering)

In article <5984@cbnews.ATT.COM> doug@loihi.hig.hawaii.edu (Doug Myhre) writes:
>
....>along with the time and other quality data.  This might give a
>position to within 3 meters.

It all depends on how long you watch, how many "birds" you can see,
your a priori, and the quality of your sattelite emphermis. NASA/JPL
routinely uses the civilan signals to obtain millimeter accuracies.

>     The second set is a encrypted set of signals that is for military
>use only.  The position data available to the military is much more
>accurate than for civilians.  Undoubtedly they don't want the Soviets,
>or any other unfriendly force having accurate enough data for military
>uses.

What you get is range data, from which one derives the position.

Spoofing presents some tricky problems. I don't know how current
receivers would handle it; it is very receiver dependent.




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