DGPS RTK Positioning Using a Reference Network

This paper describes the design, operation and testing of a RTK GPS system based on the use of a multireference station approach. The use of a multireference station network, as opposed to a single reference station, results in a larger service area coverage, a lower number of reference stations, increased robustness, and a higher positioning accuracy. The effective distance to the nearest reference station required to resolve the carrier phase ambiguities increases by a factor of 1.5 to 3. Carrier phase observable errors in the coverage area are modeled using the differential carrier phase observables between the reference stations. Corrections that are generated in real-time using the reference station network are broadcast to mobile users. Differential errors such as that caused by ionospheric activity can be more effectively modeled. A series of real-time tests conducted using a regional reference network in Japan and a local reference network in Calgary, demonstrate the effectiveness of the approach.