GPS AUGMENTATION WITH PSEUDOLITES FOR NAVIGATION IN CONSTRICTED WATERWAYS

T. Morley and G. Lachapelle

Peer Reviewed

Abstract: This paper investigates the use of portable ground- based transmitters, or pseudolites (PLs) (pseudo- satellites), to augment the existing space-borne GPS satellite constellation, with emphasis on the marine environment. A simulation analysis is conducted to investigate the effect of increasing mask angle on GPS availability, accuracy, and reliability measures. Up to three PLs at various locations are then introduced in the simulation to illustrate the improvements in performance. Finally, results from a field test conducted with one PL on Lake Okanagan in British Columbia, Canada, are presented. As expected, the use of a shore- based PL increased the number of observations and improved the availability of GPS. With appropriate estimation of the multipath component between the PL and the reference receiver, it was found that the accuracy of the DGPS position solution for the PL-augmented configuration was consistently better than that of the unaugmented GPS constellation. The use of a PL also improved the fault detection capability. An intentionally induced error on the remote receiver’s pseudorange measurement to a satellite was detected after the error reached 7.75 m for the unaugmented GPS constellation and 4.75 m for the PL-augmented constellation. The resulting horizontal errors were 9.4 m and 3.7 m, respectively.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 44, Number 3
Pages: 359 - 372
Cite this article: Morley, T., Lachapelle, G., "GPS AUGMENTATION WITH PSEUDOLITES FOR NAVIGATION IN CONSTRICTED WATERWAYS", NAVIGATION, Journal of The Institute of Navigation, Vol. 44, No. 3, Fall 1997, pp. 359-372.
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