BDS/GNSS Real-Time Kinematic Precise Point Positioning with Un-differenced Ambiguity Resolution

Abstract

BeiDou Navigation Satellite System (BDS) is constructed and operated by China independently. It has important significance in researching the real-time kinematic precise point positioning (PPP-RTK) based on BDS. The fusion of multi-GNSS in data processing can increase satellites observed, improve the geometric configuration of satellites constellation, enhance the accuracy, continuity and reliability in real-time kinematic positioning. This paper deduced the mathematical model of BDS/GNSS PPP-RTK, studied the theories and methods of BDS/GNSS un-difference ambiguity resolution, and realized multi-GNSS PPP-RTK by fixing the un-differenced ambiguities of BDS-only, GPS-only, both BDS and GPS satellites, respectively. Multi-GNSS data of reference stations from Crustal Monitor of Network of China (CMONOC) were processed. The experiment results showed that the values of fractional cycle bias (FCB) of BDS IGSO and MEO satellites kept stable; The precision were less than 1 cm in plane direction and 3 cm in vertical direction after the fusion of BDS, GPS and GLONASS even without ambiguity resolution, respectively; It not only raised the precision of positioning but also quicken the convergence speed after fixing the un-differenced ambiguities of BDS IGSO and MEO satellites; The performance of multi-GNSS PPP-RTK improved further after fixing the un-differenced ambiguities of both BDS and GPS satellites.