高低轨双星定位中的时变时频差参数估计

针对卫星干扰源高低轨组合双星定位中，同步和低轨卫星相对干扰源的径向速度差值大、变化快，引起的时频差定位参数时变的问题，分析出同步、低轨卫星到干扰源的径向距离之差随时间的变化近似满足匀加加速运动模型，据此建立了两卫星平台接收信号的表达式，解析了径向速度、加速度和加加速度差各自对信号包络和载频部分的影响，并在此基础上结合互模糊函数提出了一种基于运动补偿的时变时频差参数估计方法，仿真和试验结果表明了该方法能够有效消除运动参数的影响，准确地估计出时频差定位参数，并能逼近时差、频差估计精度的理论下界。 

Estimation of the Time Varying TDOA and FDOA in GEO-LEO Dual-satellites Location System

To solve the problem that can’t estimate the time varying TDOA (time difference of arrival) and FDOA (frequency difference of arrival) used to locate the interference source resulted from the high-speed movement characteristics of the low earth orbit satellite in Geo-Leo dual-satellites location system. It analyzed the variation of the radial distance difference relative to the interference source between the geostationary satellite and low earth orbit satellite, found it approximately matches Jerk model. Then it built the expressions of the two signals received by the two satellite platforms. After that, it discussed the influences to the envelope and carrier frequency of signals caused by the velocity difference, acceleration difference and jerk difference, showed what should be considered and what needn’t. Finally, it gave a method of joint estimation the time varying parameters for location, which is via suppressing the influence of movement parameters and based on the Cross Ambiguity Function (CAF). The results of simulations and experiments show it can eliminate the effects of movement parameters effectively, estimate the location parameters accurately, and the estimation accuracy of the TDOA and FDOA can approach the theoretical lower bound.