GPS Multipath Modeling and Verification Using Geometrical Theory of Diffraction

Susan Gomez, Robert Panneton, Penny Saunders, Shian Hwu and Ba Lu

Abstract:	In this paper, Uniform Geometrical Theory of Diffraction (GTD) is applied to model and verify the differential carrier phase errors due to multipath for a series of GPS multipath ground tests. The computer simulation technique for predicting GPS signal strength and phase shift is presented. A comparison with experimental measurements was made for two typical International Space Station interference structures: a plate and a cylinder. Differential carrier phase error results obtained with the GTD model are compared with field test data. Good agreement was noted as well as some discrepancies observed, probably due to the antenna phase center deviation in the low elevations and background noise present in the field test data. Selected measured and predicted differential carrier phase error results are presented and compared. Obtained results indicate that reflections from and diffractions around the multipath producers, located near the GPS antennas, can produce phase shifts of greater than 10 mm. The multipath effects are evident in both the phase shift patterns and in the gain patterns.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	195 - 204
Cite this article:	Gomez, Susan, Panneton, Robert, Saunders, Penny, Hwu, Shian, Lu, Ba, "GPS Multipath Modeling and Verification Using Geometrical Theory of Diffraction," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 195-204.
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