The Application of NAVSTAR Differential GPS in the Civilian Community*

Abstract

The NAVSTAR Global Positioning System (GPS), currently being developed for the Department of Defense, is a space based navigation system that will provide the user with precise position, velocity and time information on a 24-hour basis and in all weather conditions at any point on the globe. The potential unauthorized use of this source of very precise navigation information has prompted the DoD to intentionally contaminate the signals and to provide only authorized users with the necessary information to recover the original signals. The high probability of the implementation of these techniques, known as Selective Availability, indicated the need for a variation of the baseline GPS, so as to allow for an assured, uninterrupted level of accuracy, if the system was to be used effectively in the civilian sector. Differential GPS provides such a capability.