论文部分内容阅读
相比于传统的差分多普勒(DD)两步定位方法,以Amar和Weiss提出的基于多普勒频率的单步直接定位方法在低信噪比和小样本条件下具有更高的定位精度。在该类新型定位体制的基础上,提出了一种基于多普勒频率的恒模信号直接定位方法。首先,依据最大似然(ML)准则以及恒模信号的恒包络特征,建立相应的直接定位优化模型。然后,根据目标函数的代数特征将全部未知参量分成两组,并提出一种有效的多参量交替迭代算法,用以获得该优化问题的最优数值解。新算法包含了针对这两组未知参量的Newton型迭代公式,用以避免网格搜索,并能实现多维参数的“解耦合”估计。最后,推导出针对恒模信号的目标位置直接估计方差的克拉美罗界(CRB)。数值实验验证了新方法的优越性。
Compared with the traditional two-step positioning method based on differential Doppler (DD), the single-step direct location method based on Doppler frequency proposed by Amar and Weiss has higher positioning accuracy under low SNR and small sample conditions . Based on the new positioning system of this kind, a direct method of signal location based on Doppler frequency is proposed. Firstly, based on the maximum likelihood (ML) criterion and the constant envelope feature of the constant mode signal, a corresponding direct positioning optimization model is established. Then, based on the algebraic features of the objective function, all the unknown parameters are divided into two groups, and an effective multi-parameter alternating iterative algorithm is proposed to obtain the optimal numerical solution of the optimization problem. The new algorithm contains a Newton-type iterative formula for the two sets of unknown parameters to avoid grid search and to achieve a “decoupled” estimate of multidimensional parameters. Finally, we derive the Cramer Range (CRB) that directly estimates the variance for the target position of the constant-mode signal. Numerical experiments verify the superiority of the new method.