基于EKF/SF的BDS短基线多径抑制方法

多径是影响载波相位差分定位性能的主要误差源。针对传统恒星日滤波(sidereal filter, SF)无法同时抑制系统部分和随机部分多径误差影响的问题,提出一种扩展卡尔曼滤波(extended Kalman filter, EKF)和SF组合的北斗卫星导航系统(BeiDou navigation satellite system,BDS)短基线多径误差抑制方法(EKF/SF)。首先使用基于单差观测量的SF削弱多径系统误差带来的影响,再结合EKF的优势,对残余多径误差所包含的随机误差影响进行抑制,从而达到最大化抑制多径误差的目的。BDS短基线单频载波相位差分定位实验表明,相对于单纯的SF和EKF,采用EKF/SF方法的模糊度固定率分别提高了10%和43%,定位精度可分别提高84%和90%。

EKF/SF-based short-baseline BDS multipath mitigation method

Multipath has always been the main error source in high precision carrier phase differential positioning. Since the traditional sidereal filtering (SF) method has limitation in simultaneous suppressing the systematic error and random error of multipath, a multipath error mitigation method that combined the extended Kalman filter (EKF) with SF (EKF/SF) is proposed for the BeiDou navigation satellite system (BDS) short-baseline positioning case. The SF method is firstly implemented in single difference observation domain to mitigate the systematic error, then an EKF method is developed to mitigate the random noise contained in residual multipath error. The real world short-baseline BDS carrier phase differential positioning experimental result shows that, compared with the SF and EKF methods, the proposed EKF/SF method can achieve an ambiguity fixing rate improvement by 10% and 43%, and the positioning accuracy improvement by 84% and 90% respectively.