DGPS Positioning Accuracy Performance Analysis with RTCM Message Types 1/9 and 18-21 Using Various Receiver Technologies

G. Lachapelle, M. E. Cannon, H. Lan, C. Tang, S. Wee and S. Ryan

Abstract:	The synchronous and asynchronous RCTM message Types 1 and 9, respectively, which can be generated using either code or carrier phase smoothed code, are used in single differencing mode to obtain DGPS positions. Types 18-21 messages contain carrier phase and range measurements and corrections thereof which can be used in double differencing mode. In the latter case, two options are possible, namely integer ambiguity resolution on the fly if dual-frequency data is available, or/and ambiguity float solution if only Ll data is available. The results of an investigation performed to analyse the accuracy performance achievable using both Type l/9 and Types 18-21 with the ambiguity float option are described. In order to assess the impact of the receiver technology used, three all-in-view receiver Types were tested, namely standard wide correlator C/A code, Narrow CorrelatorTM C/A code and Super C/A codeNl/Y2 semicodeless. Extensive land tests with reference station- remote separations of over 400 km and airborne and shipbome trials were used to generate and intercompare DGPS positions using the approaches and equipment described above. The data was post-processed and time latencies of 5 to 25 seconds were successively introduced to analyse corresponding effects on accuracy performance. While a horizontal accuracy of 5 m (95th percentile) required by the Canadian Coast Guard was met by all receivers and all methods, it was found the the ambiguity float method implemented using Types 18-21 messages produced better positioning results in most cases, namely 1 m (horizontal - 95th percentile) for distances between the reference station and remote in excess of 100 km and 50 cm for distances less than 100 km, assuming latencies of up to 15 seconds.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	899 - 906
Cite this article:	Lachapelle, G., Cannon, M. E., Lan, H., Tang, C., Wee, S., Ryan, S., "DGPS Positioning Accuracy Performance Analysis with RTCM Message Types 1/9 and 18-21 Using Various Receiver Technologies," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 899-906.
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