BeiDou Satellite Navigation System (BDS) Real-Time Orbit Determination and Accuracy Analysis

摘要

BeiDou Satellite Navigation System requires accurate real-time orbit products to support high precision real-time PNT services. Currently, BDS treats broadcast ephemeris as real-time orbits, whose precision is poor (at the level of meter). Based on characteristics of stations distribution and satellites constellations structure of BDS, this paper studies the method of real-time orbit determination, designs the corresponding calculative strategy, discusses and analyzes the accuracy and update rate of real-time orbits, draws the following conclusions: (1) when 6-h real-time orbits are extrapolated by 72-h observed orbits calculated by BDS regional network, the accuracy of GEO and IGSO/MEO satellite orbits is about 3 m and better than 2.5 m; while by 72-h observed orbits calculated by BDS global network, the accuracy of GEO and IGSO/MEO satellite orbits is better than 3 m and 30 cm respectively. (2) The accuracy of prediction orbits extrapolated by 24-h observed orbits calculated by BDS global network attenuates fast with the time period of the prediction increases. The average accuracy of 1-h prediction orbits of GEO and IGSO/MEO is better than 70 cm and about 40 cm, when the prediction duration is 6 h, the average accuracy of GEO and IGSO/MEO is about 120 and 60 cm respectively. Based on the current status and characteristics of BDS, using 3-day measured orbits to predict real-time orbits is the best strategy. With the improvement of stability and accuracy of the orbits calculated by single-day observational data, the high-frequency single-day prediction orbits with 1 h update rate are the better choice as real-time orbits.