A new imaging algorithm for geosynchronous sar based on the fifth-order doppler parameters

This paper proposes a new imaging algorithm based on a novel accurate range model to process the data acquired by Geosynchronous-Earth-orbital Synthetic Aperture Radar (Geo-SAR). The new range model, called DRM-5, is obtained from the 1-5th order Doppler parameters of spaceborne SAR. It is employed to describe the slant range of Geo-SAR during the super-long integration time. Furthermore, the two-dimensional frequency spectrum of point targets based on the new range model is derived and analyzed. An advanced Frequency Domain Algorithm (FDA) based on DRM-5 is proposed to process the data of stripmap mode Geo-SAR. The varied Doppler parameters in the cross-azimuth direction are considered in the new imaging algorithm, and the space-varied range-azimuth coupling phase term is compensated through data blocking. A simulation experiment is performed to verify the effciency and superiority of the new algorithm, and the results show that it has a good effect on an L-band stripmap mode Geo-SAR system with azimuth resolution around 5m and 300km range swath.