BeiDou Satellites Multi-GNSS Precise Orbit Determination with Ambiguity Fixed

Using the global distributed IGS and Multi-GNSS experiment(MGEX) data, a method of multi-GNSS integrated double-difference precise orbit determination(POD) of BeiDou navigation satellites is studied. Then a specific double-difference ambiguity fixing strategy for BDS is proposed. The orbit determination precision of using single system and multi-GNSS, as well as ambiguity-fixed solution and ambiguity-free solution, are compared based on real observation data. The results show that, compared with single system processing, the multi-GNSS integrated method can effectively improve the orbit precision of IGSO and MEO, but except for GEO. The result of IGSO and MEO ambiguity fixing by the proposed strategy is well. The ambiguity fixing success rate has been improved significantly, especially for long baselines. The ambiguity fixed success rateimproves form 40% to 60% or more on the whole. Ambiguity fixing shows a positive contribution to orbit accuracy of IGSO and MEO from the overlapping RMS with that of the free solution for comparison. The 3D-RMS of IGSO could reach 0.048 m, and that of MEO could reach 0.066 m.