用于同步双星时频差定位系统的广域差分校正算法

Wide Area Differential Calibration Algorithm for Dual-Satellite TDOA/FDOA Geolocation System

在双星时频差定位中,传统的差分校正算法在目标辐射源远离参考站时对星历误差的校正性能会迅速恶化,针对同步双星时频差定位系统,提出一种基于虚拟参考站(Virtual Reference Station,VRS)的广域差分校正算法。首先通过对差分校正性能分析,发现两参考站信号时/频差的差分残差可近似为两参考站位置矢量之差的线性函数;然后基于多个参考站的时/频差观测值通过线性拟合在目标辐射源位置附近生成一个虚拟参考站;最后将虚拟参考站与目标辐射源的时/频差观测方程差分,从而实现对星历误差的高精度大范围校正。仿真结果表明,该算法可在参考站周边数千公里范围内实现对星历误差的高精度校正。

The calibration performance of traditional differential calibration algorithm decreases rapidly when target emitter is far away from reference station in dual-satellite TDOA/FDOA geolocation system.A wide area differential calibration algorithm based on virtual reference station is proposed to solve this problem.Firstly,it is proved that the differential residual of TDOA and FDOA between two reference stations is a linear function of the connecting line of two reference stations.Then,TDOA and FDOA measurements of virtual reference station,which is in the vicinity of emitter source,is estimated by linear fitting based on TDOA and FDOA measurements of the existing reference stations.Finally,TDOA and FDOA measurements of the virtual reference station is subtracted from that of target emitter to remove the effect of ephemeris error and system error on location error.Theoretical analysis and simulation results indicate that the proposed algorithm can eliminate the effect of ephemeris error and system error on location error of dual-satellite TDOA/FDOA geolocation system in wide area.