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基于两步成像算法和ECS(Extended Chirp Scaling)成像算法,提出一种结合Deramp预处理的星载聚束式SAR(Synthetic Aperture Radar)改进的ECS成像算法.Deramp预处理是基于SPECAN算法的思想,将信号通过非空变的方位滤波器实现批压缩,该方法在保证成像分辨率的前提下,通过deramp处理消除了由采样率不足导致的方位频谱混叠特别是在星载SAR高分辨率聚束模式下.尽管ECS算法中的子孔径处理可以降低对系统脉冲重复频率的要求,但是脉冲重复频率依然受到单点多普勒带宽的限制.所介绍的方法可以进一步降低ECS算法中子孔径分割处理对脉冲重复频率的要求,使得ECS的算法的应用更为广泛.通过对点目标进行仿真和成像,成像指标评估验证了该算法的可行性.
Based on the two-step imaging algorithm and ECS (Extended Chirp Scaling) imaging algorithm, a modified ECS imaging algorithm based on Deramp preprocessing is proposed, which is based on the SPECAN algorithm, The signal is compressed by a non-varational azimuth filter to achieve batch compression. The method eliminates the aliasing of the azimuth spectrum caused by insufficient sampling rate, especially in the spaceborne SAR high-resolution poly Beam mode, although the sub-aperture processing in the ECS algorithm can reduce the pulse repetition frequency requirements, the pulse repetition frequency is still limited by the single-point Doppler bandwidth.The proposed method can further reduce the sub-aperture segmentation in the ECS algorithm To deal with the requirement of pulse repetition frequency, the algorithm of ECS is more widely used.Through the simulation and imaging of point target, the imaging index evaluation verifies the feasibility of the algorithm.