Results from the GPS Shuttle Training Aircraft Flight Test Part II

Moises N. Montez, Lonnie M. Rater and Somkiat Sangchat

Abstract:	The Communications and Tracking Division of the Johnson Space Center performed a series of Global Positioning System (GPS) flight tests on a Shuttle Training Aircraft (STA) in April 1991. The objective of the tests was to evaluate the GPS navigation performance for representative Shuttle approach and landing trajectories and determine if a GPS based system can replace the Shuttle Microwave Scanning Beam Landing System (MSBLS). This paper updates the results presented previously and expands on the scope of the analysis. Previous results reflected Kalman filter gains optimized on a case by case basis. The updated results used a robust set of filter gains which give satisfactory performance for all the passes evaluated. The scope of the analysis was extended to investigate the cancellation of the system error when operating in the differential GPS mode (SPS only) in the presence of selective availability (SA) induced errors. In performing the GPS navigation performance study, two Kalman filter configurations were evaluated. The first configuration models twelve states and was used to evaluate the absolute GPS navigation performance in the inertially aided and unaided modes. Radar altimeter aiding of the vertical channel was also investigated. The twelve states were position (3) velocity (3) acceleration (3), receiver clock bias, receiver clock drift, and altitude bias. The filter incorporates delta- range and pseudorange measurements. The second configuration models 15 states and was used to evaluate the relative and differential GPS navigation performance. The 15 states are position (3), velocity (3), acceleration (3), receiver clock bias, receiver clock drift, and Doppler constants of integration (4). This filter incorporates integrated Doppler and pseudorange measurements.
Published in:	Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992) September 16 - 18, 1992 Albuquerque, NM
Pages:	235 - 245
Cite this article:	Montez, Moises N., Rater, Lonnie M., Sangchat, Somkiat, "Results from the GPS Shuttle Training Aircraft Flight Test Part II," Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992), Albuquerque, NM, September 1992, pp. 235-245.
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