Measurement and Calibration of Amplitude-phase Errors in Wideband Multi-channel SAR
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摘要: 多通道技术可以用来提高系统的频带宽度,是实现分辨率优于0.1 m的超高分辨率机载合成孔径雷达(SAR)系统的一种有效的技术途径。该文针对实际雷达系统中采用的单通道宽带信号发射、8通道下变频接收来完成宽带信号收发的方案,提出一种对该收发系统的幅相误差进行测量和校正的方法,该方法采用空间闭环辐射提取宽带收发通道的幅相误差,采取具有频偏误差修正的矢量网络分析技术完成多通道接收单元中各子通道幅相误差的提取,将两者结合用于补偿整个系统误差对信号合成和成像处理所带来的影响。实际测试数据和外场飞行试验结果验证了该系统测量和校正方法的有效性和可行性。Abstract: Multi-channel SAR technique is an effective solution to obtain high-resolution images with better than 0.1 m. A radar transceiver channel scheme which consists of one wideband transmit channel and 8 down-converter receive channels is designed and implemented in an airborne SAR system. According to the frame design of the transceiver channel, this paper focuses on proposing one solution for obtaining and calibrating the real system amplitude-phase errors accurately. A closed-loop space radiation method is used to extract amplitude-phase errors of the broadband transceiver unit and a frequency-offset error correction technique is used to extract the sub-channel amplitude-phase errors in multi-channel receiver unit. Then the combination of the two is used to compensate the entire system error which will impact bandwidth synthesis and image processing seriously. An acute test and analysis of the system error is performed. The final airborne experiments demonstrate the validity and feasibility of the system calibration.
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Key words:
- SAR /
- Amplitude-phase errors /
- Ultra-high resolution /
- Multi-channel technique
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