A Novel Clutter Suppression Approach for the Space-borne Multiple Channel in the Azimuth High-resolution and Wide-swath SAR-GMTI System with an Ambiguous Doppler Spectrum
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摘要: 该文提出了一种在多普勒频谱模糊情况下的星载方位向多通道高分宽幅合成孔径雷达地面运动目标检测(SAR-GMTI)系统的杂波抑制方法。首先,利用方位解线性调频对方位向多通道(HRWS) SAR-GMTI系统中的回波进行处理,得到杂波和动目标的粗聚焦图像。然后,将多通道SAR系统的粗聚焦图像表示为矩阵形式,并估计出相应的协方差矩阵。之后,用杂波协方差矩阵构造杂波空间的正交矢量,即最小特征值对应的特征向量。该方法需要一个冗余的通道自由度。由于杂波空间的正交矢量与杂波空间向量是正交的,因此可以用来抑制杂波。最后,通过仿真和实测数据实验结果验证该文所提杂波抑制方法的有效性。
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关键词:
- 星载方位向多通道合成孔径雷达 /
- 杂波抑制 /
- 高分宽幅(HRWS) /
- 方位解线性调频 /
- 正交矢量
Abstract: A low pulse repletion frequency is required and an ambiguous Doppler spectrum should be considered to obtain a high-resolution and wide-swath Synthetic Aperture Radar-Ground Moving Target Indication (SAR-GMTI) system in the azimuth direction. In this study, we have proposed a novel clutter suppression approach, where the Doppler spectrum of the single channel echo is ambiguous, with respect to the space-borne multiple channels in an azimuth high-resolution and wide-swath SAR-GMTI system. Initially, the azimuth deramping operation is utilized to compress the ambiguous Doppler spectrum, where the signal of clutter or the moving target is focused toward only some azimuth Doppler-frequency bins. Further, a covariance matrix corresponding to the clutter is estimated in the azimuth deramping and range compression domain. Subsequently, the matrix eigenvalue decomposition technique is employed to obtain an eigenvector corresponding to the minimum eigenvalue. Herein, we intend to achieve redundant channel freedom to ensure the suppression of clutter. The obtained eigenvector can be considered to be the orthogonality vector of the clutter space, which denotes the orthogonality with respect to the signal space vector. Hence, we adopt the obtained eigenvector to appropriately suppress the clutter. Simultaneously, the signal of the moving target can be appropriately preserved. Finally, some experiments are conducted to validate the proposed clutter suppression approach. -
表 1 单平台方位向多通道HRWS SAR系统的主要仿真参数
Table 1. Main system parameters for the simulation single-platform multi-channel in azimuth HRWS SAR system
参数 数值 参数 数值 载波频率 5.4 GHz 通道数 7 SAR的有效速度 7552 m/s 平台高度 600 km 中心线距离 800 km 多普勒模糊数 6 脉冲重复频率(PRF) 400 Hz 发送信号的带宽 200 MHz 表 2 实际机载验证系统(单平台方位向多通道HRWS SAR系统)主要参数
Table 2. Main system parameters for the airborne real single-platform multi-channel in azimuth HRWS SAR system
参数 数值 参数 数值 载波频率 5.0 GHz 通道数 6 SAR的有效速度 110 m/s 平台高度 5.5 km 中心线距离 15 km 多普勒模糊数 5 PRF 200 Hz 发送信号的带宽 150 MHz -
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