复合高斯杂波下距离扩展目标斜对称自适应子空间检测器
Persymmetric Adaptive Subspace Detectors for Range-Spread Targets in Compound-Gaussian Clutter
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摘要: 针对非高斯杂波背景中距离维扩展的多秩线性子空间信号自适应检测问题,本文基于两步法设计了广义似然比(GLRT)、Rao、Wald检测器。为解决训练样本有限情况下自适应检测器性能急剧下降的问题,本文在检测器设计阶段利用了协方差矩阵的斜对称结构特征。考虑到高分辨率雷达目标回波除了具有沿雷达径向的平动分量之外,还能观测到偏航、横滚、俯仰等转动分量,将目标信号建模为距离扩展子空间信号,以充分利用多普勒信息;为弱化纹理分量先验分布选择的困难,减小模型失配导致的检测性能损失,将杂波建模为纹理分量为未知常数且散斑协方差矩阵具有斜对称结构的复合高斯杂波模型。经过蒙特卡洛仿真实验验证,在训练样本数量受限的情况下,本文所提三种斜对称检测器检测概率达到0.5所需的信杂比相比传统检测器平均低20 dB。同时,分析表明提出的三个斜对称自适应检测器均对散斑协方差矩阵具有恒虚警特性。Abstract: In this paper, the persymmetric adaptive detection problem of multidimensional subspace range spread targets under the background of non-Gaussian clutter is studied. Considering that the high-resolution radar targets echo has a translational component along the radial direction of the radar, the rotational components such as yaw, roll, and pitch can also be observed, thus the target signal is modeled as a range spread subspace signal to make full use of the Doppler information. In order to weaken the difficulty of the prior distribution selection of texture components and reduce the detection performance loss caused by model mismatch, the clutter is modeled as a compound Gaussian clutter model with a texture component of unknown constant and the speckle component with a persymmetric covariance matrix. The generalized likelihood ratio test (GLRT), Rao, and Wald detectors are designed according to the two-step method. Firstly, the detectors are derived under the premise that the clutter covariance matrix is assumed known, and then the estimation of the clutter covariance matrix is obtained by using the training data around the cell to be detected, and finally the estimates are brought into the previously obtained detector to obtain its adaptive version. In order to solve the problem of sharp decline in adaptive detector performance under limited training samples, the persymmetric structure feature of speckle covariance matrix is used in the detector design stage to reduce the number of samples required for clutter covariance matrix estimation. The independently repeated Monte Carlo experiments based on both simulation data and measured data show that compared with the existing traditional detectors, the range spread target subspace detectors based on persymmetric structure proposed in this paper has better detection performance, especially when the number of training samples is limited, for example, taking the P-Wald detector as an example, the signal-to-clutter ratio required is about 20 dB lower than that of the Wald detector when the detection probability reaches 0.5. In addition, with the increase of the number of training samples, the detection performance of the persymmetric detectors also improves to a certain extent. At the same time, theoretical analysis and numerical experiments show that the three proposed persymmetric adaptive detectors all have constant false alarm characteristics for the speckle covariance matrix.