基于阵列子通道投影图的雷达图像增强算法
Radar Image Enhancement Algorithm Based on Array Sub-channel Projection Map
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摘要: 随着深度学习在图像增强领域快速发展,其在超宽带多输入多输出(Multiple-input Multiple-output,MIMO)雷达图像超分辨领域展现出优越的性能。然而,现有研究大多基于雷达图像恢复理想图像,但雷达成像过程常需要近似、量化操作,且依赖目标散射截面积各向同性假设,导致信息损失,会影响雷达图像增强性能上限。并且,超宽带雷达获取的成像结果通常还存在分辨率低、栅旁瓣高及严重杂波污染等问题,制约了其实际应用。针对上述问题,本文结合卷积神经网络的特征学习及投影图的相关性展开研究,提出了一种基于阵列子通道投影图的超宽带雷达图像增强算法。首先,利用了超宽带雷达成像系统阵列子通道回波的相关性等特征,构建了阵列子通道投影和位置编码模块,将投影图和位置编码图作为网络扩展输入来增强雷达图像,提升网络对雷达图像栅旁瓣的抑制效果,从而获得更高精度的雷达图像。本文从超宽带雷达成像原理、雷达图像增强网络结构框架、基于阵列子通道投影图的雷达图像增强方法多个角度全面阐述了端到端的超宽带雷达图像增强方法。文章利用仿真和实测结果验证了本文所提算法的准确性,与传统算法相比,该方法能有效地锐化主瓣、抑制雷达图像栅旁瓣和杂波、提高雷达图像质量,为后续雷达图像检测识别、及人工辨别等抽象化应用提供更高质量的雷达图像作为输入。Abstract: With the rapid development of deep learning in the field of image enhancement, it has shown superior performance in the field of ultra-wideband multiple-input multiple-output (MIMO) radar image super-resolution. However, most of the existing research is based on radar image to recover ideal image, but the radar imaging process often requires approximation and quantization operations and relies on the assumption of isotropic target scattering cross-sectional area, which leads to information loss and can affect the upper limit of radar image enhancement performance. Moreover, the imaging results obtained by ultra-wideband radar usually have problems such as low resolution, high grating side lobes and serious clutter pollution, which restrict its practical application. In order to solve the above problems, this paper combines the feature learning of convolutional neural networks and the correlation of projection maps to carry out research, and proposes an ultra-wideband radar image enhancement algorithm based on array subchannel projection maps. Firstly, the correlation of the array subchannel echo of the ultra-wideband radar imaging system is used to construct the array subchannel projection and position coding module, and the projection map and position coding map are used as network extension inputs to enhance the radar image, improve the suppression effect of the network on the radar image grid sidelobe, and obtain higher precision radar image. This paper comprehensively describes the end-to-end ultra-wideband radar image enhancement method from the perspectives of ultra-wideband radar imaging principle, radar image enhancement network structure framework, and radar image enhancement method based on array subchannel projection map. The paper verifies the accuracy of the proposed algorithm using simulation and measurement results. Compared with the traditional algorithm, this method can effectively sharpen the main lobe, suppress the radar image grid sidelobe and clutter, improve the radar image quality, and provide higher quality radar image as input for subsequent abstract applications such as radar image detection and recognition and manual identification.