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线频调变标(CS)算法是合成孔径雷达(SAR)中经典的成像方法,它使用Fourier变换对回波信号进行匹配滤波而实现成像。因为Fourier变换下的匹配滤波没有考虑chirp信号频率和时间之间的线性关系,故没有发挥chirp信号的潜在性能。为了更有效利用chirp信号时频关系,改进成像分辨率,本文引入分数阶傅立叶变换的方法,提出并分析了基于分数阶Fourier变换的线频调变标算法(FrCS)。对机载SAR系统的仿真结果表明,FrCS算法提高了信噪比,有更好的聚焦性,改善了主旁瓣比。结论是,FrCS算法与传统的基于Fourier变换的CS算法相比有更优越的性能。
The CS algorithm is a classical imaging method in Synthetic Aperture Radar (SAR), and it uses Fourier transform to match the echo signals for imaging. Because the Fourier transform matched filtering does not take into account the linear relationship between chirp signal frequency and time, it does not play the potential performance chirp signal. In order to make more efficient use of the chirp signal time-frequency relationship and improve the imaging resolution, this paper introduces the fractional Fourier transform method, and proposes and analyzes the Frquency Modulation Algorithm (FrCS) based on fractional Fourier transform. The simulation results of the airborne SAR system show that the FrCS algorithm improves the signal-to-noise ratio, has better focusing and improves the mainlobe ratio. The conclusion is that the FrCS algorithm has superior performance compared with the traditional CS algorithm based on the Fourier transform.