BDS/GPS组合精密单点定位精度分析与评价

精密单点定位（precise point positioning，PPP）已经广泛应用于许多领域，如测绘、交通、导航、地震监测等。近些年来，随着卫星数量的增多，多系统组合呈现越来越明显的趋势。利用全球MGEX（Multi-GNSS Experiment）网数据研究了BDS（BeiDou navigation satellite system）/GPS（global positioning system）组合精密单点定位技术，并与BDS单系统和GPS单系统进行了对比。结果表明，在静态定位中，BDS PPP在E、N、U方向的均方根误差分别为4.35 cm、3.01 cm、6.40 cm；GPS PPP在E、N、U方向的均方根误差分别为1.21 cm、0.48 cm、1.79 cm；BDS/GPS组合PPP在E、N、U方向的均方根误差分别为1.21 cm、0.50 cm、1.87 cm。在动态定位中，BDS PPP外符合精度水平方向优于10 cm，高程方向优于15 cm；GPS PPP和BDS/GPS组合PPP的外符合精度水平方向均优于5 cm，高程方向均优于8 cm。另外，无论是在静态还是动态的PPP中，组合系统相对于单系统，能大大缩短收敛时间，减少定位结果抖动，尤其是相对于BDS PPP来说，优势更为明显。

Analysis and Assessment of BDS/GPS Combined Precise Point Positioning Accuracy

The precise point positioning (PPP) mode has been widely used in many fields, such as vehicle navigation, surveying and mapping, and earthquake monitoring etc. In recent years, multi-GNSS is an obvious trend with the increasing number of satellites. In this paper, BDS/GPS PPP is researched by comparing the calculation of the data from global Multi-GNSS Experiment (MGEX) with BDS and GPS PPP. The results show that the average RMS of BDS static PPP is 4.35 cm, 3.01 cm, 6.40 cm while the average RMS of GPS static PPP is 1.21 cm, 0.48 cm, 1.79 cm in east, north and up directions, respectively. The average RMS of BDS/GPS static PPP is 1.21 cm, 0.50 cm, 1.87 cm in east, north and up directions, respectively. In kinematic PPP, the accuracy of positioning in BDS is better than 10 cm and 15 cm in horizontal and vertical directions respectively. While the accuracy of GPS and BDS/GPS is all better than 5 cm and 8 cm in horizontal and vertical directions, respectively. The number of satellites in BDS/GPS is the double of that in single system. And the spatial structure of combined system is greatly enhanced which can improve the stability of positioning. In addition, whether in static PPP or kinematic PPP, the combined system can greatly shorten the convergence time and reduce jitter compared with single system especially with BDS PPP.