Real-Time GPS Reference Network Carrier Phase Ambiguity Resolution

H. Sun, M.E. Cannon, T.E. Melgard

Abstract:	GPS carrier phase ambiguity resolution has been limited to relatively short inter-receiver distances due to the rapid error decorrelation process that occurs as a function of distance. A network of reference stations can however be used to model errors as a function of user location within the network coverage area. Using this procedure, the user can correct its measurements with the error model and improve Real Time Kinematic (RTK) positioning performance. In order for this to be optimal however, network double difference carrier phase ambiguities must be resolved to integers before network error modeling. This presents a challenge for real-time operations when the separation between reference stations is long, i.e. typically 200 km or more. This paper introduces a sequential least-squares estimation algorithm for real-time integer ambiguity resolution over such a network. Various methods for modeling the carrier phase errors within the network are analyzed and the use of network constraints for improved ambiguity resolution during the network and new satellite initialization stages are investigated and tested. Multiple ambiguity validation tests are demonstrated and the reliability of the approach is also presented.
Published in:	Proceedings of the 1999 National Technical Meeting of The Institute of Navigation January 25 - 27, 1999 Catamaran Resort Hotel San Diego, CA
Pages:	193 - 199
Cite this article:	Sun, H., Cannon, M.E., Melgard, T.E., "Real-Time GPS Reference Network Carrier Phase Ambiguity Resolution," Proceedings of the 1999 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1999, pp. 193-199.
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