Ground Experimentation of a Pseudolite-Only Method for the Relative Positioning of Two Spacecraft

Geoffrey Wawrzyniak, E. Glenn Lightsey and Kevin W. Key

Abstract:	This paper investigates the use of GPS pseudolites and a carrier-aided-code algorithm as tools for relative positioning in the Navigation Systems Testing Labo- ratory (NSTL) at NASA's Johnson Space Center in Houston, Texas. Before applying this technology in space, it must be fully understood in a terrestrial setting. This investi- gation explores what has been learned about pseudo- lite transmitters and their receivers in the NSTL. A data filtering technique that uses the change in carrier phase double-difference measurements as the position changes to increase the precision of the pseudorange double-differences is discussed as a possible method for accurate navigation in the laboratory and future applications. The environment of the laboratory and its effect on the measurements is also discussed. It is shown that in this laboratory the multipath noise on the pseudorange measurement limits any practical system to a carrier phase only solution. However, if multipath is overcome and the noise on the pseudo- range is within normal levels of a GPS system, the carrier-aided-code technique could be incorporated to produce acceptable measurements for navigation. Results from simulations are presented to verify that carrier-aided-code will work within acceptable noise parameters. Recommendations and test results for mitigating the current challenges of indoor pseudolite positioning and potential future applications are also discussed.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	1468 - 1478
Cite this article:	Wawrzyniak, Geoffrey, Lightsey, E. Glenn, Key, Kevin W., "Ground Experimentation of a Pseudolite-Only Method for the Relative Positioning of Two Spacecraft," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 1468-1478.
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