Test of a 400 km x 600 km Network of Reference Receivers for Precise Kinematic Carrier-Phase Positioning in Norway

J. Raquet, G. Lachapelle, T. E. Melgard

Abstract:	There is currently great interest in using regional area reference receiver networks (on the order of hundreds of km) to perform precise ( 10 cm or better) positioning using GPS carrier-phase measurements. This has been brought about by the proliferation of existing reference receivers, and an ever increasing desire for improved accuracy. In previous work, an algorithm has been developed which uses a network of reference receivers to significantly increase the distance over which kinematic carrier-phase ambiguity resolution can be performed without sacrificing accuracy or increasing the time to resolve the ambiguities. The NetAdjust method is based upon a least-squares condition adjustment of the measurements from the network of reference receivers, and it minimizes the differential error variances. When using this algorithm, information from the reference receiver network is “encapsulated” into the measurements from a single reference receiver, so standard ambiguity resolution techniques can be used between that reference receiver and a mobile receiver. In this paper, the NetAdjust method is applied to a 400 km x 600 km network of eleven reference stations positioned throughout the southern portion of Norway. Dual frequency data was collected over a 24 hour period using combination of Ashtech Z-12 and Trimble 4000 SSi receivers. (The Trimble receivers are part of the Norwegian SATREF@ system operated by the Norwegian Mapping Authority and currently used for code differential GPS positioning inland and in the waterways around Norway). Application of the NetAdjust algorithm resulted in significant reductions in the double difference differential errors and improved positioning performance. Most importantly, NetAdjust yielded a significant improvement in the ability to resolve WL carrier-phase integer ambiguities, and a modest improvement in the ability to resolve L1 ambiguities. Results are presented for a number of different network configurations (involving different combinations of the 11 reference receivers). This paper is a demonstration, using real field data, of the performance that can be expected from the use of a regional area differential network.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	407 - 416
Cite this article:	Raquet, J., Lachapelle, G., Melgard, T. E., "Test of a 400 km x 600 km Network of Reference Receivers for Precise Kinematic Carrier-Phase Positioning in Norway," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 407-416.
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