Local DGPS With Pseudolite Augmentation and Implementation Considerations for LAAS

K. J. Barltrop, J. F. Stafford and B. D. Elrod

Abstract:	Pseudolites that provide an in-band data link and ranging source with negligible interference to GPS are being considered as potential elements of a Local Area Augmentation System (LAAS) that will complement the FAA’s Wide Area Augmentation System (WAAS). If validated by further testing, this will enable the use of GPS to support sole means navigation through all phases of flight in the National Airspace System (NAS) with “all-in- one-box” navigation sensor equipment based on the notion of a seamless GPS/WAAS/LAAS operations concept. Test results to-date with code-based differential GPS augmented with an in-band pseudolite have been encouraging in terms of satisfying Category III navigation sensor accuracy requirements. Additional investigations are continuing to develop and assess methods for: achieving improved accuracy and integrity margins; increasing the effective capacity of a pseudolite data link; and mitigating potential implementation issues including potential interference to GPS or between pseudolites in a multiple pseudolite/multiple airport environment. This paper presents some new considerations and test results relevant to the implementation of a LAAS architecture based on augmenting GPS with one or more in-band pseudolites (time synchronized to GPS) that support both ranging and data link functions. These pertain to pseudolite signal pulsing, message format and content, and measurement processing techniques, which can affect acquisition and tracking, data link, and/or ranging performance. Results from recent road tests to assess pseudolite ranging performance are also included.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	449 - 459
Cite this article:	Barltrop, K. J., Stafford, J. F., Elrod, B. D., "Local DGPS With Pseudolite Augmentation and Implementation Considerations for LAAS," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 449-459.
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