Characterization of GPS Carrier Phase Multipath

J.K. Ray, M.E. Cannon

Abstract:	GPS carrier phase measurements are affected by multipath signals that can significantly affect the quality of data used for static and kinematic positioning applications. It is generally difficult to characterize this multipath using field data whereby the exact sources of the errors cannot be easily isolated. In this paper, carrier phase multipath parameters are identified and their influences on measurements are investigated through a theoretical analysis. Multipath effects are analyzed from a geometrical perspective whereby GPS signals are assumed to propagate through the advancement of a plane wavefront on which the phase of the GPS signals is the same. The differential path delay of the reflected signal with respect to the direct signal is then calculated. A multipath simulation model is developed and described wherein the multipath parameters can be varied and their influences observed. These parameters include i) the reflection coefficient, ii) the antenna to reflector distance, iii) the azimuth and elevation of the reflected signal iv) the existence of multiple reflectors, and v) satellite dynamics. Mulipath characteristics such as frequency, error envelope, spatial correlation, and signal to noise ratio are studied by varying these parameters. Only the specular component is addressed in this paper as the diffused component is random in nature and difficult to model in a deterministic form.
Published in:	Proceedings of the 1999 National Technical Meeting of The Institute of Navigation January 25 - 27, 1999 Catamaran Resort Hotel San Diego, CA
Pages:	343 - 352
Cite this article:	Ray, J.K., Cannon, M.E., "Characterization of GPS Carrier Phase Multipath," Proceedings of the 1999 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1999, pp. 343-352.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In