多系统非差非组合精密单点定位电离层延迟约束权阵的确定

摘要

非差非组合精密单点定位需要估计电离层延迟参数,采用电离层先验改正模型约束可以辅助电离层参数解算.针对先验电离层改正量与实际观测量之间权比关系难以确定的问题,本文提出一种电离层约束权因子搜索算法,采用权因子对先验电离层改正量的方差进行调整,根据验后残差加权平方和最小原则通过搜索找出较优的权因子,利用验后残差动态调整先验电离层改正量的方差从而达到改善定位结果的目的.采用8个MGEX跟踪站的GPS/BDS观测数据对该算法进行验证.静态结果表明:对比传统约束方法,采用搜索算法后平均三维定位精度由3.96 cm提高到3.40 cm,平均收敛时间由76.3 min缩短为59.9 min.%The ionospheric delay parameters in the precise point positioning (PPP) using raw observations must be considered.The estimation of theionospheric delay parametersis strengthened by priori ionospheric correction models.But it is difficult to determine the relative weight ratios between the priori ionospheric corrections and the observations.A weight factor searching algorithm based on ionospheric delay constraint for multi-GNSS PPP using raw observations is proposed in which weight factors are utilized to adjust the variances of priori ionospheric corrections.According to the principle thatthe sum of the quadratic forms of weighted residuals be the minimum,the optimal weight factors are searched for and the variances of priori ionospheric corrections are adjusted dynamically in order to promote the positioning results.Data sets collected from 8 stations of the multi-GNSS experiment(MGEX)tracking network are processed to validate the proposed algorithm.The results of PPP in static mode show that the RMS values of the positioning errors are improved from 3.96 cm to 3.40 cm andthe convergence time is reduced from 76.3 min to 59.9 min whenthe searching algorithm is used,in comparison with the traditional priori ionospheric constraint.