Characterization & Mitigation of Multipath in GNSS

Multipath is the phenomenon whereby a transmitted signal arrives at a receiver via multiple paths due to reflection and diffraction. These non-direct-path signals distort the received signal and cause errors in GNSS pseudorange and carrier-phase measurements. Differential techniques do not eliminate multipath and thus multipath is a critical error source in high precision applications. The physical surroundings around the user’s antenna dictate the multipath environment and thus cause significant differences for land, marine, airborne, and spaceborne applications. This lecture describes the multipath environment and the impact of multipath on code and phase measurements. The influence of the type and rate of the broadcast code as well as the receiver architecture will be presented. Mitigation strategies will also be described along with multipath measurement techniques.