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From: budden@trout.nosc.mil (Rex A. Buddenberg)
Newsgroups: sci.military
Subject: Re: Pinpoint navigation around Baghdad
Message-ID: <1991Feb6.031256.20526@cbnews.att.com>
Date: 6 Feb 91 03:12:56 GMT
References: <1991Feb4.054457.16632@cbnews.att.com>
Sender: military@cbnews.att.com (William B. Thacker)
Organization: Naval Ocean Systems Center, San Diego
Lines: 24
Approved: military@att.att.com



From: budden@trout.nosc.mil (Rex A. Buddenberg)

There is a bit more usefulness to GPS.  The conventional solution
is a four-dimensional one (Lat, Long, Alt, time) which requires four
satellites in view.  However....two dimensional service is quite
useful in many cases (ships, for instance have little practical use
for the altitude figure) and if you have another source of stable
time (a cesium, for instance), then you get get effective two dimensional
coverage with only two GPS satellites.

While few vendors are building integrated Loran/GPS receivers, but
there is a highly effective ability to use the two systems in a
complementary fashion.  Roughly, two Loran stations = one GPS
satellite.  A line of position is a line of position whether it
is a Loran rho-rho range, a Loran time delay hyperbola or a GPS
pseudorange.
  To put this into perspective, there is a Loran chain in central
Saudi Arabia designed to provide service over the Arabian Gulf (currently,
the Kuwait station is off air...).  A second chain in western Saudi Arabia
provides Red Sea coverage.

b