Study on Precise Point Positioning Based on Combined GPS and GLONASS

A combined PPP(Precise Point Positioning) mode is implemented using GPS and GLONASS observations.The performance of the combined GPS and GLONASS PPP was assessed using observations from one of the IGS tracking network(IRKJ) and the currently available precise orbit and clock products.The corresponding positioning accuracy and convergence time were compared between GPS-only and GPS/GLONASS combined precise point positioning.The results show that GLONASS has caused a slight impact on positioning accuracy and convergence time in case of more than 8~9 GPS satellites are tracked.However,when the number of available GPS satellites is not enough,especially is less than 4~5,adding a couple of GLONASS satellites can improve positioning accuracy and shorten convergence time significantly.