Iteration algorithm for joint TDOA＆FDOA location and its performance analysis

Based on the FDOA and TDOA united location of the radiative source using moving observations, an iterative algorithm which solves the location of the target is proposed, which overcomes the difficulty in solving FDOA and TDOA united location. The proposed algorithm sets the carrier frequency as the unknown parameter, and under the condition of omitting the higher order items, the measured time difference and frequency equations are used to figure out both of the target position and carrier frequency from the emitter in the iterative way. The location accuracy of the TDOA and FDOA united location algorithm is analyzed in detail; furthermore, elaborative simulation is given, which proves the accuracy and effectiveness of the theoretical analysis and provides TDOA and FDOA united location algorithm with theoretical foundation.     

到达时差和频差搜索算法的非线性约束最优化研究

基于复模糊函数的到达时差和到达频差无源定位方法研究较多,但实际工程应用往往受到估计精度和计算量的矛盾制约。通过研究复模糊函数的特性,并结合硬件代价受限的实际应用需求,对抽取因子、搜索步长等相关参数进行非线性最优化,提出了到达时差和到达频差的搜索优化算法。经过仿真验证,所提出的算法在不降低精度的条件下大大降低了运算量,缩短了运算时间。     

三站频差定位性能分析

三站频差定位是一种重要的无源定位方式,其典型的应用场景之一就是机载运动平台对固定辐射源的无源定位。为了给工程实践提供理论支撑,需要首先分析机载三站频差定位性能。鉴于此,本文首先描述了定位模型,包括频差观测方程、导航观测方程及地球表面约束条件。然后在考虑频差测量偏差及地心距偏差条件下,基于加权最小二乘准则,采用扰动法导出了辐射源位置估计均方误差的表达式,其表征了均方误差与各影响因素(载机速度、辐射源频率、频差误差、导航参数误差、地心距偏差等)的关系,可作为定位性能分析的依据。最后,通过算例仿真,在典型参数条件下分析了多种因素对定位性能的影响,得到了若干结论,并进一步指出了所获结论可能的实际应用价值。      

校正源条件下基于双星序列观测量的地面运动目标定位算法及理论性能分析

The method for locating a moving source on earth using a sequence of time difference of arrival(TDOA)and frequency difference of arrival(FDOA)measurements pairs obtained by dual-satellites was presented in the presence of calibration sources with accurate positions.First,the difference calibration(DC)location algorithm aiming to the mobile target was derived,and its theoretical performance was also analytically derived.The result demonstrates that the DC localization variance could not reach the CRB,although it could eliminate the location bias produced by the position and velocity errors of the dual-satellites.For this reason,a two-step optimal association location algorithm was proposed,and its theoretical performance was proved to be equal to the CRB.Finally,a variety of numerical experiments are performed to corroborate the superiority of the geolocation algorithms and the effectiveness of the performance analysis.     

基于 FDOA 的无源定位算法研究现状与展望

为更好地解决在时间和方向测量精度低的情况下,仅利用到达频差(frequency difference of arrival,FDOA) 进行定位求解的问题,对基于 FDOA 的无源定位算法现状和发展方向进行分析。在阐述 FDOA 无源定位基本原理的 基础上,分析了定位问题的本质和定位算法的分类方法,结合基于定位观测量数据的定位算法和接收信号直接定位 法的国内外研究现状,分析了 FDOA 无源定位算法存在的问题,指明了基于 FDOA 的定位算法的未来研究方向。该 研究可为基于 FDOA 定位算法的研究提供参考依据。     

利用TDOA和FDOA的单站多外辐射源目标定位算法

针对利用单个观测站接收多个外辐射源信号从而实现对运动目标定位的问题,以直达信号和目标回波信号之间的到达时差和频差为观测量,采用Taylor迭代方法,得到了目标位置和速度估计。迭代的初值由最小二乘方法得到。最后,推导了算法的克拉美罗界和理论误差。仿真结果表明,算法仅需1次迭代即可收敛至全局最优解;在一般测量误差条件下,算法的实际定位误差逼近克拉美罗界;对系统几何精度因子图的分析表明,目标及外辐射源位置也是影响定位精度的重要因素。     

一种低轨双星窄带信号定位方法

针对低轨双星系统对窄带辐射源无源定位的应用场景,基于双星观测到的辐射源到达频率差,提出了一种多次频差测量联合估计辐射源位置的方法.详细描述了算法原理、算法处理步骤,并通过计算机仿真分析了信号频率、频差测量误差、观测时长等因素对定位精度的影响.仿真分析表明,在观测时间大于20 s、频差测量精度0.1 Hz时,该方法定位精...