双星定位系统定位精度的Cramer-Rao下界分析

介绍了双星时频差定位原理，在此基础上研究了在地球表面约束条件下的双星定位系统的定 位精度理论下界。利用推导的定位精度Cramer-Rao下界，仿真分析了定位参数估计精度、卫 星星历、目标辐射源位置以及辐射源载波频率等因素对定位精度的影响，并给出了物理解释 。定位仿真试验结果表明，定位精度变化趋势与Cramer-Rao下界一致，证明了理论推导的正 确性。

Cramer-Rao lower bounds for position estimation in dual-satellite geolocation system

The principle of transmitter location using TDOA(Time Difference of Arrival) and FDOA(Frequency Difference of Arrival) of two satellites i s introduced in this paper. Then, the Cramer-Rao Lower Bound (CRLB) for the loca tion accuracy is studied. In the CRLB, the factors such as the estimation accura cy of positioning parameters, the ephemeris, the position of transmitter and the carrier frequency are analysed. The physical explanations are also given. Simul ations show the consistance between location accuracy change trend and CRLB and also confirm the correctness of theoretical analysis.