Real-Time on-the-Fly Kinematic GPS System Results

Abstract

The development of a real-time positioning system using GPS carrier phase was formally initiated by the U.S. Army Corps of Engineers in 1988. The end goal of this effort was to have ready by 1993 an operational prototype capable of subdecimeter positions in three dimensions in real time. This goal has been met. Testing of this prototype began in March 1993. The first demonstration was in August 1993, with the first public demonstration following in October. The system typically resolves integer ambiguities on-the-fly (OTF) in 15 s or less, and requires no static initialization. It is robust and reliable to use for precisely positioning any mobile platform out to approximately 20 km. Testing has been performed under varying operating conditions to evaluate the limits of OTF ambiguity resolution for precisely positioning moving platforms. This paper summarizes the results of those tests. Early real-time tests performed have shown accuracies of 1–3 cm in all three dimensions. Design of the final real-time system and its integration with hydrographic survey platforms are also discussed.