Receiver for global positioning system

The Navstar satellite GPS is characterized, and the design of a prototype GPS receiver for civil use is discussed. The GPS space segment will comprise 18 satellites orbiting in six 12-hour planes and transmitting at two L-band frequencies with two pseudorandom modulation codes; the user segment can be realized with varying degrees of accuracy depending on the application, but must be capable of measuring its range from four satellites. The main features of the Navex experiment package to be flown on the German Spacelab mission D-1 in 1985, designed to test several clock-synchronization, time-transfer, and one-way-ranging concepts, are summarized and illustrated with diagrams.