Azimuth Multichannel Reconstruction for Moving Targets in Spaceborne Squinted Multichannel Synthetic Aperture Radar
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摘要: 在星载方位多通道SAR斜视模式下，方位斜视角度和运动目标的速度分别导致回波多普勒频谱发生2次混叠和通道失衡，影响运动目标方位多通道信号重建。针对该问题，该文提出一种适用于多通道斜视模式下的运动目标的重建方法。首先通过方位向去斜预处理消除了斜视导致的2次多普勒混叠，然后通过修正的多通道重建矩阵来解决目标速度导致的通道失衡。此外，该文还研究了通道冗余情况下的杂波抑制能力，分析了估计速度误差带来的残余相位误差，给出了一种星载方位多通道SAR斜视模式下的运动目标速度快速估计搜索方法。最后，通过点目标仿真验证了方法的有效性。Abstract: In the spaceborne azimuth multichannel SAR squinted mode, the squint angle and the velocity of moving target will cause the 2-D spectrum of echo signal to be aliased and the multichannel imbalance, respectively. Both phenomena would affect the azimuth multichannel reconstruction for moving targets. To resolve this problem, an azimuth multichannel reconstruction method for moving targets in the azimuth multichannel squinted mode is proposed. It eliminates the secondary Doppler aliasing problem caused by the squint angle through azimuth de-ramp preprocessing, and then the multichannel imbalance caused by the moving target velocity is resolved by the improved multichannel reconstruction matrix. The clutter suppression ability in the case of channel redundancy is analyzed, and the residual phase error caused by the estimated velocity error is discussed. Furthermore, an effect moving target velocity estimate approach is proposed. Finally, the simulation results on point targets validate the effectiveness of the proposed approach.
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表 1 仿真参数
参数 值 载频 5.6 GHz 子孔径长度 4 m 子孔径数目 3 斜视角度 20° 系统PRF 1400 Hz 发射脉冲宽度 4 μs 发射脉冲带宽 100 MHz 采样频率 120 MHz 卫星速度 7200 m/s 最短斜距 600 km 
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表 2 性能指标
方法 点目标 航迹向 斜距向 Res(m) PSLR(dB) ISLR(dB) MFTA(dB) Res(m) PSLR(dB) ISLR(dB) 传统 P1 2.83 –13.22 –9.77 –63.59 1.42 –12.97 –9.40 P2 2.99 –15.17 –3.55 –24.29 1.72 –11.74 –5.94 P3 9.54 –18.61 –5.95 –22.12 4.57 –13.41 –5.56 改进 P1 2.83 –13.22 –9.77 –63.59 1.42 –12.97 –9.40 P2 2.81 –13.25 –9.69 –61.15 1.41 –12.79 –9.37 P3 2.82 –13.24 –9.69 –62.08 1.43 –13.02 –9.49
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