Positioning with BeiDou Satellite Navigation System

摘要

With the deployment of new satellites, Beidou satellite navigation system is now approaching its capabilities to provide high accuracy regional positioning services. This paper presents orbit determination strategy and positioning algorithm. Positioning results are also discussed using huge amount of observations from Beidou receivers under two different scenarios: the post-processing static positioning and real-time point positioning. Different from GPS, orbital and clock information of Beidou are generated by control segment based on data collected with a domestic monitoring network. Several challenges are facing Beidou precise orbit determination. This study applied the multi-satellite orbit determination strategy to compute orbit and clock errors. Beidou is unique among all working GNSS systems to incorporate a two-way time synchronization mechanism between all satellite clocks and system time standard, which is able to provide direct measurements of satellite clocks with accuracy better than 0.1ns. The discrepancies between estimated satellite clocks and the measured satellite clocks "ground truth", or errors of clock estimates, are actually useful indicators of the accuracy of precise orbit determination, with smaller discrepancy corresponds to better orbital accuracy. This study applied TS data to evaluate orbit accuracy. Post-processing mode is also named as Precise Point Positioning (PPP). This study reports centimeter-level accuracy of post-processing PPP with the Beidou regional satellite navigation system of the full satellite constellation (5GEO+5IGSO+4MEO). One of the major differences of Beidou system compared to the existing GNSS is that it is designed to simultaneously provide open service and authorized service using the same control and operation segment. This study describes the wide-area differential algorithm, which include ionospheric grid and equivalent satellite clock error. Experimenting with real data, user real-time positioning errors with pseudo range datum in both open and authorized services are evaluated.