Carrier Phase Differential GPS for Approach and Landing: Algorithms and Preliminary Results

Russell A. Paielli, B. David McNally, Ralph E. Bach, and David N. Warner

Abstract:	NASA Ames Research Center is conducting research to develop and demonstrate DGPS carrier-phase algorithms for aircraft precision approach and landing. An algorithm is described that combines carrier smoothing with a “special” wide-lane version of the Hatch integer-ambiguity resolution method to determine aircraft position. This algorithm, which realizes the small search space of wide- lane operation and the low noise performance of narrow- lane operation, has been validated with simulation data. The NASA King Air 200 aircraft equipped with an Ashtech P-12 GPS receiver was used to provide approach and landing flight data for testing the algorithm. In 11 of 12 approaches, the integer ambiguities were resolved at a minimum distance of 2.7 km from landing, and the solution was maintained through touchdown. However, the results, which include a comparison of carrier- smoothed and integer-resolved solutions, indicate that in five of the final approach and landing segments, wrong integers were determined. The continuing work necessary to achieve “robust” integer-ambiguity resolution without the use of pseudolites is discussed.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	831 - 840
Cite this article:	Paielli, Russell A., McNally, B. David, Bach, Ralph E., Warner, David N., "Carrier Phase Differential GPS for Approach and Landing: Algorithms and Preliminary Results," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 831-840.
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