Wide area differential GPS as a future navigation system in the U.S

The Global Positioning System (GPS) is an extremely accurate positioning sensor with an accuracy of 100 meters. However in aircraft precision approaches, higher accuracy is required. Conventional differential GPS (DGPS) usually has accuracies of 1-3 meters within 100 kilometers of the reference station, even with selective availability (SA) errors. If DGPS is implemented on a large scale, the total number of monitor stations needed to cover the continental U.S. to the same accuracy would exceed 500. Wide area differential GPS (WADGPS) is a system that can reduce the number of monitor stations substantially while achieving the same accuracy. Test results showed a meter 3D positioning error with zero latency and 2-5 m 3D positioning error with 5-10 seconds of latency using WADGPS which has 6 monitor stations with 1632 km minimum baseline to a dual frequency user