Based on the two-step imaging algorithm and the extended chirp scaling (ECS) algorithm,an approach for spotlight mode of spaceborne synthetic aperture radar(SAR), which combines the deramp processing and ECS algorithm was proposed. The deramp processing is based on SPECAN algorithm, and passes the raw data through a space invariant azimuth matched filter. The azimuthal spectral folding caused by insufficient sampling rate especially in high resolution spaceborne spotlight SAR was overcomed through the deramp processing. Although the division into subappertures in ECS can reduce the system requirement of the pulse repetition frequency(PRF), the PRF is restricted to higher than the accumulated doppler frequency bandwidth of a single point target. The presented method further reduces the requirement of the PRF in subapperture processing without the resolution loss. Thereby the ECS algotithm can be applied easily. The simulating and imaging results of point targets demonstrate the validity of this approach.
Ding Zegang, Long Teng, Zeng Tao, et al. Deramp range migration processing for space borne spotlight synthetic aperture radar[J].Advances in Space Research.2008, 41:1822-1826
Moreira Alberto, Mittermayer Josef, Scheiber Rolf. Extended chirp scaling algorithm for air-and spaceborne SAR data processing in stripmap and scanSAR imaging modes[J].IEEE Transactions on Geoscience and Remote Sensing.1996,34(9):1123-1136
Mittermayer Josef, Moreira Alberto. Spotlight SAR processing using the extended chirp scaling algrithm IEEE International Conference on Geoscience and Remote Sensing. :IEEE, 1997,4:2021-2023
Sun Jinping, Wang Jun, Yuan Yunneng, et al. Extended chirp scaling algorithm for spotlight SAR[J]. Chinese Journal of Aeronautics, 2002,15(2):103-108