dietz%usc-cse%USC-ECL%SRI-NIC@sri-unix.UUCP (01/28/84)
Geostar is superior to GPS for a number of reasons. First, the
portable units are much less complex. In GPS, the portable units don't
transmit any information (a good policy on the electronic battlefield)
and so have to do all the signal processing/position computation
themselves, and they must contain rather powerful little computers. In
Geostar, the hand held boxes contain simple microwave tranceivers and
some logic for sending/receiving encrypted digital messages. All the
smarts are in the ground station in New Jersey. Positions are
determined by triangulation between the three satellites in
geosynchronous orbit (so accuracy degrades to tens of meters at high
lattitudes and is not available near the poles).
Another advantage of Geostar is the positions of all the active units
are know at the control center; also, the system has the capability of
sending messages from the control center to the units. This
effectively rules out use of Geostar by potential enemies: no enemy is
going to want his position know to within meters!
Unlike GPS, Geostar allows applications such as:
(1) Truck/airplane fleet position monitoring/communication.
(2) Distress beacons. Each Geostar box has an SOS button; press it
and authorities are notified of your position (to within meters).
This is much more accurate than current distress beacons.
(3) Air traffic control. The control center can determine, in real
time, what aircraft (carrying beacons) are on collision courses
and send warning messages to them (via the satellites).
The last application is most exciting, and is the one O'Neill
originally targeted. The FAA is currently spending tens of billions of
dollars on an air traffic control system using radars and ground
computers; Geostar would be far more reliable and far less expensive.
An major airplane pilot's organization (AOPA?) has already endorsed the
system.
O'Neill envisions Geostar or a similar system allowing automated
personal aircraft; position information with accuracies of meters
allows automation of take-off and landing, the most dangerous portions
of a flight (when combined with some simple very short range terminal
sensors).
Geostar will require only 3 satellites; GPS needs up to 24 satellites,
so Geostar should be much cheaper. Unlike GPS, Geostar can only be
used by paying subscribers -- otherwise, the control computer won't
tell you your position -- so there's no need to worry about loss of
business to unregistered users.
Geostar is cheaper, less complicated, more functional, less useful to
an enemy than GPS. I don't see how the government could prohibit it,
especially with Reagan's push for space commercialization.
henry@utzoo.UUCP (Henry Spencer) (02/02/84)
Another advantage of Geostar is that a substantial fraction of the
proceeds from it go to the Space Studies Institute. If Geostar makes
it big, this could pump a lot of money into private space development.
The way I heard it, the obstacles to Geostar are not really a question
of the government banning it. They're just the usual problems of having
only so many orbital slots and so many frequencies available, and lots
of different proposals for how to use them. Geostar is in competition
for orbital slots and frequency assignments with various other things,
some of which have lots of backing.
--
Henry Spencer @ U of Toronto Zoology
{allegra,ihnp4,linus,decvax}!utzoo!henry