中文摘要：

为研究北斗卫星导航系统（BDS）和BDS/GPS组合系统的定位性能,根据实测数据对比分析了GPS、BDS及BDS/GPS组合系统的可见卫星数、空间位置精度因子（PDOP）和伪距定位结果,以及BDS地球静止轨道（GEO）和中圆轨道/倾斜轨道（MEO/IGSO）卫星的定位结果;针对BDS与GPS观测值之间的精度差异,分别采用等权模型、高度角模型和Helmert模型研究组合系统的最优随机模型。研究表明：组合系统卫星的空间几何分布优于单系统;BDS定位的平面精度低于GPS,高程精度高于GPS,而BDS/GPS组合系统平面和三维精度高于单个系统;Helmert验后估计模型能够提高BDS/GPS组合定位的高程和三维定位精度。

英文摘要：

To analyze the performance of Beidou navigation satellite System （BDS） and combined BDS/GPS, the number of visible satellites, PDOP and SPP solutions by BI）S, GPS and BDS/GPS as well as the SPP solution of GEO and MEO/IGSO by BI）S were investigated based on the real time tracking data. According to the precision difference in the observed values by BDS and GPS, equal weight, elevation and Helmert models were adopted respectively to find out the optimal stochastic models. The results show that the geometric distribution of combined BDS/GPS is hetter than that of any single system. Although horizontal precision of BDS is lower than that of GPS, height preci sion of BDS is higher than that of GPS. Both horizontal and three dimensional precisions of combined BDS/GPS are higher than those of either BDS or GPS. Relative to the other two models, Helmert model can improve height and three dimensional precision of positioning by combined BDS/GPS.