论文部分内容阅读
归一化最小均方误差(NLMS)算法被广泛应用于无源相干定位(PCL)雷达系统的直达波和多径干扰对消。该文提出NLMS干扰对消器与雷达模糊函数结合可以等效为凹槽滤波器,该滤波器在雷达模糊函数平面中的零多普勒处产生一个凹槽。分析显示凹槽的宽度和深度与NLMS算法的步长密切相关。文章分析了凹槽对PCL雷达目标检测的影响,结果显示宽的凹槽会使PCL雷达系统的目标检测性能恶化。文章进一步提出了非均匀归一化最小均方误差(Non-uniform NLMS,NNLMS)算法,该算法能有效抑制具有多普勒频率的杂波,并且能有效降低雷达模糊函数的底噪。该算法引进了步长矩阵,利用该矩阵可以实现在不同的距离单元产生不同宽度的凹槽,每个距离门的凹槽宽度取决于杂波干扰的能量和多普勒频率。与传统NLMS相比,NNLMS算法可以实现更快的收敛速度,试验结果验证了该算法的有效性及优越性。
The normalized least mean square error (NLMS) algorithm is widely used for direct wave and multipath interference cancellation in passive coherent positioning (PCL) radar systems. The paper proposes that the combination of NLMS interference canceller and radar ambiguity function can be equivalent to a notch filter, which produces a notch at zero Doppler in the radar ambiguity function plane. Analysis shows that the width and depth of the groove are closely related to the step size of the NLMS algorithm. The paper analyzes the influence of the groove on the target detection of PCL radar. The results show that the wide groove will deteriorate the target detection performance of the PCL radar system. In this paper, the non-uniform NLMS (NNLMS) algorithm is further proposed. This algorithm can effectively suppress the clutter with Doppler frequency and can effectively reduce the noise floor of the radar ambiguity function. The algorithm introduces a step matrix, which can be used to generate grooves of different widths in different distance units. The groove width of each distance gate depends on the energy of the clutter interference and the Doppler frequency. Compared with the traditional NLMS, the NNLMS algorithm can achieve faster convergence rate. The experimental results verify the effectiveness and superiority of the proposed algorithm.