BDS-2/BDS-3组合长基线三频RTK算法

Algorithm of three-frequency RTK at long baseline for BDS-2/BDS-3 combination

针对在长基线动态实时差分定位技术(RTK)中,由于整周模糊度容易受到大气延迟误差的影响,导致其固定率偏低,从而影响定位精度的问题,提出一种基于北斗卫星导航(区域)系统即北斗二号(BDS-2)和北斗三号全球卫星导航系统(BDS-3)组合的长基线定位方法:组合方法中BDS-2采用B1I、B2I和B3I 3种信号,BDS-3采用B1I、B2b和B3I 3种信号,充分利用三频中存在电离层延迟极小且具有整数特性的组合,同时考虑对流层延迟的影响,建立基于弱电离层组合的几何相关中长基线解算模型,并利用卡尔曼(Kalman)模型对天顶对流层延迟误差、三维坐标和弱电离层组合模糊度进行参数估计;再结合部分模糊度固定方法加快模糊度搜索效率,最终实现长基线RTK定位。实验结果表明,该方法能够在长基线下基本实现单历元模糊度固定,定位结果与流动站真值之间的定位偏差可达到厘米级。

Aiming at the problem that because it is susceptible to atmospheric delay error for the integer ambiguity,the fixed rate is low,which affects the positioning accuracy,the paper proposed a long baseline positioning method based on the combination of BeiDou navigation satellite(regional)system(BDS-2)and BeiDou-3 global navigation satellite system(BDS-3):in the combination method,BDS-2 adopted B1I,B2I and B3I signals,while BDS-3 adopted B1I,B2b and B3I signals,making full use of the combination with minimal ionospheric delay and integer characteristics in the three-frequency;at the same time,considering the influence of tropospheric delay,a geometry-based middle-long baseline solution model based on weak ionospheric combination was established,and Kalman model was used to estimate the parameters of zenith tropospheric delay error,three-dimensional coordinates and fuzzy degree of weak ionosphere combination;then combined with partial ambiguity fixed method,the efficiency of ambiguity search was accelerated;finally,the long-baseline RTK positioning was realized.Experimental result showed that the proposed method could basically achieve the fixed ambiguity of single epoch under long baseline,and the positioning deviation between the positioning result and the true value of the rover station could be up to centimeter level.