Helmert方差分量估计在GPS/GLONASS/BDS/Galileo组合精密单点定位权比确定中的应用

Application of Helmert variance component estimation in GPS/GLONASS/BDS/Galileo combined precise point positioning weight determination

多星座组合定位可以提升导航定位性能,但不同星座观测量组合时需要考虑合适的随机模型.传统方法是根据经验直接设定各系统的等价权重,但会导致随机模型确定不精确,从而影响组合系统的性能提升.将Helmert方差分量估计方法应用于GPS/GLONASS/BDS/Galileo组合精密单点定位(PPP)中,以自适应确定各系统间权比.采用国际GNSS服务(IGS)MGEX(Multi-GNSS Experiment)观测网的10个测站一周的观测数据进行静态和仿动态试验.结果表明:采用Helmert方差分量估计定权方法可显著提高GPS/GLONASS/BDS/Galileo组合PPP的收敛速度,与等权定权方案比较,静态模式下平均提高52%,仿动态模式下平均提高64%.因定位精度主要由载波相位观测值精度和误差修正水平决定,在静态和仿动态测试中Helmert方差分量估计方法对定位精度没有明显改善.

Multi-constellation combined positioning can improve the performance of navigation and positioning,but a suitable stochastic model needs to be considered when combining observations from different constellations.The traditional method is to directly set the equivalent weight of each system based on experience,which will lead to inaccurate determination of the stochastic model,and thus affect the performance improvement of the combined system.In this paper,Helmert variance component estimation method is applied to GPS/GLONASS/BDS/Galileo combined precise point positioning to adaptively determine the weight ratio between systems.The static and pseudo-dynamic tests were carried out using the daily observation dataset collected at 10 stations in the global International GNSS Service(IGS)Multi-GNSS experiment(MGEX)observation network over one week of February 8 to February 14,2021.The results show that the Helmert variance component estimation weighting method can significantly improve the convergence speed of GPS/GLONASS/BDS/Galileo combined precise point positioning(PPP),with an average increase of 52%in static mode and 64%in pseudo-dynamic mode.Because the positioning accuracy is mainly determined by the carrier phase observation accuracy and error correction level,the Helmert variance component estimation method has no obvious improvement on positioning accuracy in static and pseudo-dynamic tests.