基于单个GPS/BDS信标台增强的实时精密单点定位

摘要

随着IGS实时服务的推广,实时轨道、钟差产品可用于实时PPP;然而,在一些通讯条件差的地方,如偏远山区和广袤的海洋,差分信号的播发与接收仍然是实时PPP的障碍.文中提出一种基于单个GPS/BDS信标台的实时PPP定位方法:基站采用广播星历和无电离层伪距、相位观测值,实时估计耦合轨道、钟误差;单向通讯的方式播发给用户端,减小通讯量,提高用户端的定位性能.经过分别距参考站约200 km和300 km的流动站进行验证,通过约10~12 min收敛,GPS/BDS组合可得到水平优于20 cm的定位精度.本案验证了采用广播星历进行实时PPP的可行性,为海洋和偏远地区提供一种高精度定位方法.%With the availability of the IGS real-time service(RTS),near real-time clock and orbit products are possible for real-time precise point positioning(RT-PPP).However the real-time broadcast of these products may be still a severe challenge for some areas(e.g.the areas with very weak communication signals covered,such as the remote mountainous or broad water area).Besides,the latency during the calculation and spread process of the real-time products is also a limitation for the real RT-PPP.This paper proposes an alternative RT-PPP method based on the augmentation of single beacon reference station with GPS+ BDS observations,where the coupling clock bias and orbit errors are estimated together.The advantage that the beacon station can broadcast correction information in one-way mode is used.At the beacon station,the fused corrections(mainly including satellite clock and orbit bias)are generated in real time by using broadcast ephemeris and ionosphere-free carrier and pseudorange observations.Then the generated correction is broadcasted to users for RT-PPP with broadcast ephemeris.The simulated experiments with about 200km and 300 km distance are carried out.The results indicate that using the proposed method,with GPS + BDS observations,a reliable convergence is possible with about 10~ 12 minutes to get the horizontal positioning accuracies better than 20 cm.The contents researched in the paper verify the feasibility of real-time PPP based on broadcast ephemeris,which can provide an alternative strategy for the precise positioning application of oceanic or remote areas.