Detection and Analysis of GNSS Multipath

Sammanfattning: Multipath effect is generated when a signal arrives at the antenna by multiple paths instead of one direct path. It is, to a large extent, dependent on the surrounding environment of the antenna and the satellite geometry. Despite all the efforts put into the mitigation of multipath errors, it remains the dominant error source that cannot be ignored for GNSS precise positioning and other GNSS applications. In this thesis report, two methods have been developed with Trimble Business Center and MATLAB to study the presence and performance of multipath effect. The first method – Trimble baseline analysis focuses on the height change pattern of the study station with regard to its reference station over time. The second method – RINEX analysis focuses on the change of the geometry-free combination of pseudorange codes and carrier phase measurements over time. These two methods have been firstly tested on station KTH and then applied on station Vidsel and station Botsmark. Various forms of results all indicate the existence of multipath effect on the three suspicious stations. The height value of the study station has a variation pattern on a daily basis because of multipath. Multipath errors also cause noise in the satellite signals, with pseudorange more affected than carrier phase. It is also worth-noted that satellite at low elevation angle is more susceptible to multipath errors than that at high elevation angle.