基于二维deramp处理的高分辨率聚束SAR成像算法

Imaging algorithm for high-resolution space-borne spotlight SAR data based on two dimension deramp processing

有效解决回波信号的数据率是高分辨率聚束式星载SAR的难点之一.基于两步成像算法和CS(Chirp Scaling)成像算法,提出了一种适用于高分辨率聚束式星载SAR的成像算法——TDDCS(Two Dimension Deramp Chirp Scaling)成像算法.该算法从距离dechirp处理后回波信号出发,首先利用二维deramp处理来消除频谱混叠现象,这不仅能实现以对应条带模式的脉冲重复频率来设计聚束SAR系统,也保证满足观测带宽度所需的回波窗长度,接着利用CS处理和相位补偿实现精确的距离徙动校正,最后利用方位相匹配滤波处理实现方位向压缩,得到最终的成像结果.基于等效斜视模型,给出了整个算法的详细推导过程和实现流程,通过计算机仿真验证了本算法的有效性.

Reduced the data rate is one of the diffieuhies in high-resolution space-borne spotlight synthetic aperture radar （SAR）. Based on two-step focusing algorithm and chirp sealing（CS） algorithm, two dimension deramp chirp sealing（TDDCS） algorithm for processing high-resolution space-borne spotlight SAR data was presented. The algorithm starts with raw data deehirped in range. First, the azimuth spectral folding phenomenon is overcome by using azimuth deramp processing, and the chirp signal is recovered by using range deramp processing. Second, the precise range cell migration correction is achieved by chirp sealing processing and phase compensation. Lastly, the azimuth compression is performed by match filter, and the image is received. Based on the squinted equivalent range model, the complete derivation of the algorithm was presented and the realizing approach was given. The computer simulation shows the validity of the algorithm.