Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!philabs!seismo!hao!hplabs!sri-unix!dietz%usc-cse%USC-ECL@SRI-NIC From: dietz%usc-cse%USC-ECL%SRI-NIC@sri-unix.UUCP Newsgroups: net.space Subject: Re: O'Neill's GEOSTAR Message-ID: <16100@sri-arpa.UUCP> Date: Sat, 28-Jan-84 11:24:00 EST Article-I.D.: sri-arpa.16100 Posted: Sat Jan 28 11:24:00 1984 Date-Received: Tue, 31-Jan-84 02:00:21 EST Lines: 52 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.