Precise Orbit Determination of BeiDou Regional Navigation Satellite System Via Double-Difference Observations

The precise orbit determination (POD) for BeiDou satellites mainly relies on a regional tracking network distributed in China area at the present time. The multi-satellite POD for BeiDou regional navigation satellite system via double-difference observations is presented. First, the double-difference phase measurements are modeled on ionosphere-free combination of B1 and B2 signals. The POD strategies are detailed, followed by a brief data-processing flow. Then, the POD tests based on regional network of domestic monitoring stations are developed, and the orbit quality assessed by arc overlaps and Satellite Laser Ranging (SLR) residuals shows an accuracy of about 20 cm in radial direction. Finally, contributions of the overseas monitoring stations to the POD accuracy of BeiDou satellites are investigated by introducing several IGS Multi-GNSS Experiment (IGS M-GEX) monitoring stations with BeiDou tracking capability into the multi-satellite POD test. The improved orbit accuracy indicates that more BeiDou observing sites should be established worldwide in future.