GEO/IGSO/MEO多卫星类型共存是多GNSS时代的重要特征之一。卫星轨道综合时，目前IGS是以卫星轨道位置误差作为定权依据，但对于GEO卫星来说，其轨道位置误差是IGSO/MEO的10倍，而其径向误差只有2倍，这将造成轨道综合定权不合理。另一方面，在卫星钟差综合及用户精密定位时，同样存在类似问题。本课题提出以影响导航定位精度的主要因子——用户测距误差URE为依据的卫星轨道和钟差产品综合方法，通过构建不同类型卫星轨道、钟差与URE的函数模型，研究基于动力学拟合及URE中位数探测法的轨道质量控制方法和具有高崩溃污染率的钟差质量控制方法，建立适用于多类卫星在统一参考框架下的钟差/轨道/ERP改正模型，最终形成以URE为定权依据的GEO/IGSO/MEO产品综合和用户精密定位理论与方法，并开发相关软件系统。研究成果可提高综合轨道和钟差的精度和一致性，进一步提高用户精密导航定位的精度和可靠性。

The important feature in the era of multi-GNSS is that three types of GEO, IGSO and MEO satellites are coexisting. Weights of the analysis centers and satellites are achieved according to the satellites orbit position errors in IGS satellites orbit combination. GEO satellite orbit 3D position errors are 10 times those of IGSO and MEO satellites, but its radial errors are only 2 times, which will result in unreasonable weight for GEO satellite in satellites orbit combination. Meanwhile there are also similar problems in the satellites clock combination and precise point positioning (PPP). Hence this proposal would put forward a new satellites orbit and clock combination theory based on User Range Error (URE) which is one of the main factors affecting the accuracy of navigation and positioning. First, the mathematical model between orbit error, clock error and URE of different types of satellites are constructed. Then the methods of orbit quality control based on the dynamics fitting and URE median detection, and clock quality control with high pollution rate should be studied. Furthermore, orbit, clock and ERP correction model in the unified reference frame, which is suitable for different types of satellites, would be established. Finally theory of GEO, IGSO and MEO satellites orbit and clock combination and Precise Point Positioning based on URE would be researched. In addition, the software package for satellites orbit and clock combination would be developed. Results of this proposal could improve the accuracy and consistency of satellites orbit and clock products, and improve the accuracy of precise navigation and positioning.