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From: VLSI%DEC-MARLBORO@sri-unix.UUCP
Newsgroups: net.space
Subject: re: G.K. O'Neill's satellite plan
Message-ID: <16075@sri-arpa.UUCP>
Date: Fri, 27-Jan-84 16:00:00 EST
Article-I.D.: sri-arpa.16075
Posted: Fri Jan 27 16:00:00 1984
Date-Received: Tue, 31-Jan-84 01:55:59 EST
Lines: 42

From:  John Redford 

    So Gerard O'Neill is going to put up his own communications/navigation
satellite.  I find this sort of idea really exciting.  Information is the 
one commodity that we know can be produced in space.   Advanced materials
processing may or may not work, and solar power satellites may or may
not be a economical, but space info is already a billion dollar industry.
    But if O'Neill's system can actually let you find your position to within
meters, then the government may not let him build it.  The DoD is already
building an elegant navigation system, the Global Positioning System or Navstar,
and wants to keep it to itself.  They figure that if they can find their way
around with it then so can the enemy. There's a good description of the system
in the October '83 Proceedings of the IEEE. The original proposal for GPS had
several classes of equipment. There were to be expensive receivers with accuracies
of under ten meters and cheap backpack units with accuracies of a hundred
meters.  Then when they actually tested the equipment they found that the
backpack guys were good to forty meters. There was rejoicing among the
engineers, but the military became worried.  The portable units can be built
and used by anyone.  There's less advantage to knowing where you are if your
enemy also knows where he is. They decided to degrade the accuracy of the
signals that the portable units used, and to encrypt the signals for the
accurate receivers. Military receivers get the key to the encryption and
civilian ones don't. The cheap receiver's accuracy dropped to 200 m, although
it's still apparently possible to get it down to 100 m. 
      A hundred meters isn't bad, but it isn't good either.  Ships and
airplanes could still use it, but it doesn't seem quite accurate
enough to be useful for cars or hikers.   There's also no guarantee that they
won't degrade it again.  The receivers could be produced
for only a couple of hundred dollars and could be shrunk to handheld
units, but only if they are built in volume.  Without better accuracy the
volume applications aren't there.
      It makes you sick at heart.  With a system like this no one need ever be
lost anywhere in the world.  In rain or in snow, in Oklahoma or Antarctica, you
could always find out where you were.  But the people with the purse strings
decided that it was more important to hurt the Russians than to help civilians.
If O'Neill wants to build his own system, then more power to
him. Anyone want to lay bets, though, that the FCC will be pressured not to
permit it? 

John Redford
DEC-Hudson
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