相比于常规的两步定位方法,目标直接定位方法具有更高的定位精度,但现有的直接定位方法主要是针对静止目标所提出的,并具有较大的运算量.本文提出了一种针对匀速运动目标的多普勒频率直接定位方法.文中首先基于最大似然准则推导了直接估计目标初始位置和运动速度的优化模型,针对该优化模型是以矩阵特征值的形式给出而难以数值求解的问题,提出了一种基于矩阵特征值扰动定理的Newton型迭代算法,该算法可以避免多维参数网格搜索所导致的庞大运算量.此外,文中还推导了关于目标初始位置、运动速度以及运动航迹估计的克拉美罗界的闭式表达式.数值实验表明新方法的目标位置估计方差可以达到克拉美罗界,并且具有较少的运算量.%Compared to the conventional two-step localization method,the direct position determination (DPD) method has higher location accuracy.However,the DPD method is usually proposed for static target and is computationally expensive.This paper presents a novel DPD method for moving target at constant velocity based on the Doppler frequency shifts.First,the optimization model for directly determining the initial position and velocity of the emitter is constructed on the basis of maximum likelihood estimator (MLE),and the cost function is formulated as the maximal eigenvalue of the Hermitian matrix.In order to avoid multidimensional grid search,a Newton-type iterative algorithm based on matrix eigenperturbation theory is proposed,which involves lower computational complexity than the multidimensional grid search.In addition,the compact Cramér-Rao bound (CRB) expressions for initial position,moving velocity and track estimates are derived,which can provide a theoretical prediction for target position determination.Simulation results corroborate that the estimate variance of the proposed method is able to attain the CRB with lower computational complexity.
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