ACC-Q-POINT FM Subcarrier WADGPS

James McLellan, Mohamed Abousalem, Ed Whatley, Paul Galyean

Abstract:	With the growing need for accurate navigation, Differential GPS (DGPS) technology has been used to eliminate pseudorange measurement errors caused by atmospheric delays and dithering of satellite clocks and orbital parameters due to Selective Availability (SA). The performance accuracy of single-reference DGPS, however, is limited to short baselines and its coverage is limited to the range of its communications link. Therefore, there is a growing demand for accurate, reliable and low-cost Wide-Area DGPS (WADGPS) systems. WADGPS integrates DGPS corrections from various widely separated reference stations. The redundancy of the data is the prime cause for the system accuracy and reliability as the integrated solution cancels out spatial decorrelation of error sources at individual reference stations, and if one or more of the reference stations malfunction, the rest of the stations will still be available for generating accurate DGPS corrections. The user is therefore guaranteed continuous, accurate and reliable DGPS service. Moreover, in contrast to single-reference DGPS, WADGPS techniques have proven to reduce multipath effects existing at the individual reference stations. Pulsearch has recently developed its WADGPS module with special features to ensure the accuracy and reliability of the output. The module has been developed as part of the ACCQPOINT WADGPS service development; a low cost DGPS service which uses the existing CUE paging network to transmit multi-reference DGPS corrections combined from 10 reference stations located across the continental USA. The ACCQPOINT WADGPS system design is presented in this paper with a brief description of the project development plan and some test results.
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	1017 - 1024
Cite this article:	McLellan, James, Abousalem, Mohamed, Whatley, Ed, Galyean, Paul, "ACC-Q-POINT FM Subcarrier WADGPS," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 1017-1024.
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