调频连续波合成孔径雷达滑动聚束成像算法

调频连续波(FMCW)体制下,传统脉冲合成孔径雷达(SAR)的"走—停"回波模型已经不再适用,快时间走动项引入的距离-方位耦合项不可以忽略,否则会使图像质量的降低。该文首先构建FMCW回波模型,其次,提出了一种基于两步式的滑动聚束SAR成像算法。所提算法针对滑动聚束模式中,多普勒历程大于脉冲重复频率(PRF)所造成的频谱混叠问题,采用方位频域去斜的预处理加以解决。由于距离徙动校正(RCMC)后方位时域依旧混叠,该算法通过方位去斜在频域完成聚焦避免再一次的解混叠操作。通过仿真验证,该算法能够实现高精度的FMCW SAR滑动聚束成像。

Algorithm of FMCW Sliding Spotlight SAR Imaging

The traditional go-stop echo model of pulse synthetic aperture radar (SAR) is no longer applicable in frequency modulated continuous wave (FMCW) SAR. The range-azimuth coupling term introduced by the fast moving item cannot be ignored. Otherwise the resolution will decrease. This paper constructs the FMCW echo model first. Secondly, a two-step sliding cluster SAR imaging algorithm is proposed. The proposed algorithm solves the spectrum aliasing problem caused by the Doppler frequency history larger than the pulse repetition frequency(PRF)in the sliding bunching mode, and solves the problem by azimuth frequency domain de-skew pre-processing. Since the azimuth time domain is still aliased after the range cell migration correction (RCMC), the algorithm performs focusing on the frequency domain by azimuth de-skew to avoid another de-aliasing operation. The algorithm can realize high-precision FMCW SAR sliding bunching imaging, which is verified by simulation.