时空域联合的水下未知线谱目标检测方法

水下线谱目标被动检测中，目标辐射线谱信号的方位、频率、个数等信息通常未知，且线谱检测性能容易受到宽带干扰及背景噪声的影响。针对此问题，该文提出一种时空域联合的未知线谱目标检测方法(STJD)。首先，利用线谱信号的相干特性，构建了一种能够自主匹配未知线谱信号的时空域联合滤波器，用以滤除接收信号中的宽带背景干扰及噪声。之后，对滤波信号进行常规频域波束形成得到空时2维波束输出，其具有相对纯净的线谱谱峰。在此基础上提取线谱并利用线谱信息计算空间方位谱，进而实现对线谱目标的检测。理论推导及仿真结果表明该文方法能够对未知线谱信号进行最小均方误差意义下的时空滤波，并能充分地利用线谱信息进行线谱目标的被动检测。与已有基于线谱特征的线谱目标检测方法相比，该文方法对信噪比(SNR)的要求较低，在多目标、多线谱等复杂情况下具有较好的线谱目标检测性能。

Detection of Unknown Line-spectrum Underwater Target Using Space-time Processing

For the passive detection of underwater line-spectrum target, the information such as the azimuth, frequency and the number of the line-spectrum signals is usually unknown, and the line-spectrum detection performance is affected by broadband interferences and noise. For this issue, a Space-Time Joint Detecion (STJD) method of detecting the unknown line-spectrum target by space-time domain processing is proposed. Firstly, a space-time filter that autonomously matches the unknown line-spectrum signals is constructed to filter out the broadband interferences and noise. Secondly, the conventional frequency domain beamforming is performed on the filtered signals, and then a space-time two-dimensional beam output with relatively pure line-spectrum spectral peaks is obtained. The line-spectrum signals are extracted from the space-time two-dimensional beam output, and the spatial spectrum is calculated using the extracted line-spectrum information. Then, the detection of the line-spectrum target is realized. Theoretical derivation and simulation results verify that the proposed method performs the spatiotemporal filtering on the unknown line-spectrum signals in the minimum mean square error sense, and fully utilizes the line-spectrum information for the passive detection of underwater line-spectrum target. Compared with the existing line-spectrum target detection methods utilizing the line-spectrum features, the proposed method requires lower Signal to Noise Ratio (SNR), and has better detection performance under the complex multi-target multi-spectrum-line conditions.