Differential GPS navigation

Differential navigation means either that one user set is navigating relative to another user set via a data link or that the user has been at the destination at some prior time and is navigating relative to coordinates measured at that point. This technique provides increased accuracy because a number of bias errors are canceled out. A differential navigation capability for the Global Positioning System (GPS) is considered. Differential GPS represents a cost-effective method to significantly improve the accuracy of GPS user sets. Attention is given to aspects of system implementation, field test results, and future applications. Such applications are related to area navigation precision approach for aircraft, ship navigation in narrow waterways, close air support, artillery surveying, and seismic geophysical exploration.