Testing of a Multi-Reference Station Network for RTK DGPS Positioning in Italy

G. Pugliano

Abstract:	The use of a multi-reference station approach has been proposed to overcome the limitations of the standard single reference station differential carrier phase positioning method. Differential GPS (DGPS) positioning at the cm-level is provided by resolving the carrier-phase ambiguities as integer values and using only short observation time spans. However, this process becomes increasingly difficult as the distance between a GPS user and a reference station increases, due to the decorrelation of GPS errors with distance. The baseline length over which the distance dependent errors are differenced away is generally limited to about 10-15 km, especially when the ionosphere is very active. In order to perform a cmlevel on-the-fly (OTF) positioning over greater distances, the solution is to generate the carrier-phase corrections for a user by means of a reference station network where the reference station data is used interactively. This paper presents the results of an implementation of the one advanced multiple reference station method, known as MultiRef, on a regional test network established in the Campania Region of Italy. The study is characterized by the ultimate of objective of analysing and developing methodological aspects of the multi-reference station technique in general with a more specific focus on the MultiRef method. The primary objective of the processing and analysis of the results was to evaluate the improvements made in GPS data following application of the MultiRef method. The results were obtained by an initial calculation of corrections to carrier-phase observables through the multi-reference station approach and subsequently compared with the standard mode of differential positioning whereby only one station with known coordinates is used as a reference station located in the vicinity of the rover. In more specific terms, the analysis involved observation, position and ambiguity domains. The experimental research was developed as a function of the geometric characteristics on diverse network configurations for an established measuring day (7 February 2002) as well as a function of measurements conducted over a six day period (7-12 February 2002) for a previously established network configuration.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	1406 - 1416
Cite this article:	Pugliano, G., "Testing of a Multi-Reference Station Network for RTK DGPS Positioning in Italy," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1406-1416.
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