Characterization of GPS multipath for passenger vehicles across urban environments

International audienceMultipath signals have a strong effect on position estimates; these are studied intensely theoretically and experimentally. In this paper a domain oriented perspective is presented, passenger vehicles traversing dense urban areas. The purpose is to examine the effects of multipath on pseudo-ranges and Doppler measurements. The approach combines a theoretical formulation with extensive testing. The experiment includes the acquisition of measurements provided by a low-cost automotive GPS receiver on-board a vehicle in real traffic conditions. In addition, the vehicle trajectory was measured precisely to allow for the quantification of measurement errors. Two approaches are used in the experimental part to determine the pseudo-range and Doppler errors: Vehicle on-board measurements plus post-processing; vehicle onboard measurements, data from an external GPS reference station and post-processing. The results enable the identification of satellites whose signals are corrupted by multipath, to plot the results with respect to the trajectory so as to provide contextual information that facilitates understanding. It was also possible to establish the discontinuous relationship between signal to noise ratio and pseudo-range & Doppler errors