一种针对恒模信号的运动单站直接定位算法

相比于常规的"测向+位置估计"两步定位模式,以Weiss等提出的目标直接位置确定(DPD)算法具有估计精度高、分辨能力强和无需数据关联等诸多优点。基于该类定位算法的基本理念,提出了一种利用单个运动天线阵列对恒模(即相位调制)信号的DPD算法。首先,依据最大似然(ML)准则以及恒模信号的恒包络特征,建立了相应的直接定位优化模型;接着,根据优化函数的代数特征提出了一种有效的多参量交替迭代算法,用以获得ML估计器的最优数值解;此外,推导了针对恒模信源的位置直接估计方差的克拉美罗界(CRB),从而为新算法的定位精度提供定量的理论下界。仿真实验表明:相比于已有的基于单个运动天线阵列的直接定位算法以及传统的两步定位算法,通过利用恒模信号的恒包络特征可以明显提高目标直接定位的估计精度。

A direct position determination algorithm for constant modulus signals with single moving observer

Compared with the conventional two-step (including direction finding and position estimation) localization mode, the direct position determination (DPD) algorithm presented by Weiss et al have more advantages, such as higher estimation accuracy, strong resolution capability, no data association issue, etc. Based on the idea behind this novel localization mechanism, a new DPD algorithm for constant modulus (also called phase-modulated) signals with a moving antenna array is presented in this paper. First, the DPD optimization model is constructed based on maximum likelihood (ML) criterion as well as the constant modulus property of phase-modulated source. Then, an effective alternating iteration algorithm is devised according to the algebraic property of the cost function, which can provide the optimal numerical solution of the ML estimator. In addition, the Cramér-Rao bound (CRB) on the position estimation variance for constant modulus signals is also derived, which can be used as the theoretical lower bound for target position estimation. Simulation results demonstrate that compared to the existing DPD algorithm with single moving observer and the conventional two-step localization algorithm, the DPD estimation accuracy can be considerably improved if the constant modulus characteristic is incorporated into the localization algorithm.