基于GPS和BDS组合精密单点定位精度分析

北斗定位导航系统(BDS)于2012年底开始向亚太大部分地区正式提供连续无源定位、导航、授时等服务。本文简要介绍GPS和BDS精密单点定位(PPP)的原理,给出了无电离层组合模型及Kalman滤波模型,并利用实测的GPS和BDS静态与动态观测数据进行精密单点定位实验。实验改正了对流层延迟影响、相对论效应、地球自转、多路径影响和观测噪声等误差,比较了GPS、BDS和二者组合定位的实验结果。实验结果表明:通常情况GPS平均可视卫星颗数多于BDS系统,但在特殊情况下,BDS卫星颗数多于GPS;BDS卫星星座分布良好,系统性能稳定,静态PPP收敛后精度达到9.89 cm,动态PPP精度能达到分米级,且运动轨迹和动态GPS定位轨迹整体一致,达到BDS设计要求;GPS和BDS组合定位的精度最优,静态实验精度处于1 cm~2 cm,动态实验精度优于10 cm。

Accuracy Analysis of Precise Point Positioning Based on Combined GPS and BDS

Beidou navigation positioning system ( BDS) has begun to provide such services as continuous passive po-sitioning,navigation and timing to most areas of the Asia Pacific since the end of 2012.In the article,theory of GPS and BDS precise point positioning (PPP) is described briefly.The ionosphere-free model and Kalman filtering model are given here.Then several static and dynamic measurement data of GPS and BDS are used to calculate PPP .Before calcu-lating the station position , we correct the tropospheric delay , relative error , the earth rotation error and so on .And we make a comparison of standalone experiment result between BDS and GPS .The experimental results show to us that the number of visible GPS satellites is a little more than BDS normally ,but sometimes just the opposite .The constellation of BDS is well and it has good performance .Therefore,the precision of static PPP reaches to 9.89 cm and the dynamic ex-periment reaches to the level of dm.As to the positioning trajectory,the BDS’s is just the same as the dynamic GPS’s, which conforms to the demand of BDS design .When combined GPS and BDS, we get a more precise result with static precision 1~2cm and the dynamic result within 10cm.