基于子空间方位稳定性的弱目标检测方法

The Weak Target Detection Method Based on the Subspace Bearing Stability

针对在水下未知目标检测和方位估计中,无法同时对强目标和弱目标实现检测和方位估计的问题,提出一种基于子空间方位稳定性的弱目标检测方法.该方法首先对阵元接收信号协方差矩阵进行特征分解;然后利用目标子空间波束形成所得方位估计值在真值附近、比较稳定,背景噪声子空间波束形成所得方位估计值随机分布在[0°,180°]、比较随机的特点;最后对各子空间归一化空间谱进行方位方差加权,可以进一步抑制背景噪声子空间空间谱对弱目标子空间空间谱的干扰,缩小强目标与弱目标所在方位处空间谱幅值差异.理论分析、数值模拟和实测数据处理结果均证明,在同一频带和同一波束图中,相比分子带波束形成检测法,该方法可有效增强弱目标子空间空间谱幅值,缩小强目标与弱目标所在方位处空间谱幅值差异,同时实现对强目标和弱目标的检测和方位估计.

In unknown underwater target detection and bearing estimation,the weak targets are covered by strong targets,which cannot be detected and estimated at the same time.A weak target detection method based on the subspace bearing stability is proposed to solve the problem.Firstly,this method makes eigen decomposition for covariance matrix of array element receiving data.Then,it utilizes the characteristic that the beam-forming bearing estimation values of targets subspace are stable and close to the true values,and the beam-forming bearing estimation values of background noise subspace are randomly distributed in[0°,180°].Lastly,the method statistically weights the normalized spatial spectra of each subspace by the bearing variance,so it can further restrain the spatial spectrum disturbances of background noise subspace,and can decrease the spatial spectrum difference between strong targets and weak targets subspace.The theoretical analysis,numerical simulation and experimental results show that,at the same frequency band and the same beam,compared with sub-band conventional beam-forming(SBCBF)detection method,our method can well enhance the spatial spectrum amplitude of weak target subspace,and decrease the spatial spectrum difference between strong targets and weak targets subspace,and detect strong targets and weak targets at the same time.