title: A Wide-Swath Spaceborne TOPS SAR Image Formation Algorithm Based on Chirp Scaling and Chirp-Z Transform.
abstract: Based on the terrain observation by progressive scans (TOPS) mode, an efficient full-aperture image formation algorithm for focusing wide-swath spaceborne TOPS data is proposed. First, to overcome the Doppler frequency spectrum aliasing caused by azimuth antenna steering, the range-independent derotation operation is adopted, and the signal properties after derotation are derived in detail. Then, the azimuth deramp operation is performed to resolve image folding in azimuth. The traditional dermap function will introduce a time shift, resulting in appearance of ghost targets and azimuth resolution reduction at the scene edge, especially in the wide-swath coverage case. To avoid this, a novel solution is provided using a modified range-dependent deramp function combined with the chirp-z transform. Moreover, range scaling and azimuth scaling are performed to provide the same azimuth and range sampling interval for all sub-swaths, instead of the interpolation operation for the sub-swath image mosaic. Simulation results are provided to validate the proposed algorithm.
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. yangweigigi@buaa.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. chenjie@buaa.edu.cn.|Collaborative Innovation Center of Geospatial Technology, Wuhan 430079, China. chenjie@buaa.edu.cn.
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. zenghongcheng@buaa.edu.cn.
authors.forename: Hong Cheng
authors.initials: HC
authors.lastname: Zeng
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. wangpb7966@buaa.edu.cn.
authors.forename: Peng Bo
authors.initials: PB
authors.lastname: Wang
authors.affiliation: Electronic and Electronic Engineering Department, University of Sheffield, Sheffield S1-3JD, UK. w.liu@sheffield.ac.uk.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
keywords: SAR; TOPS; chirp-z; modified azimuth deramp