title: Correcting Spatial Variance of RCM for GEO SAR Imaging Based on Time-Frequency Scaling.
abstract: Compared with low-Earth orbit synthetic aperture radar (SAR), a geosynchronous (GEO) SAR can have a shorter revisit period and vaster coverage. However, relative motion between this SAR and targets is more complicated, which makes range cell migration (RCM) spatially variant along both range and azimuth. As a result, efficient and precise imaging becomes difficult. This paper analyzes and models spatial variance for GEO SAR in the time and frequency domains. A novel algorithm for GEO SAR imaging with a resolution of 2 m in both the ground cross-range and range directions is proposed, which is composed of five steps. The first is to eliminate linear azimuth variance through the first azimuth time scaling. The second is to achieve RCM correction and range compression. The third is to correct residual azimuth variance by the second azimuth time-frequency scaling. The fourth and final steps are to accomplish azimuth focusing and correct geometric distortion. The most important innovation of this algorithm is implementation of the time-frequency scaling to correct high-order azimuth variance. As demonstrated by simulation results, this algorithm can accomplish GEO SAR imaging with good and uniform imaging quality over the entire swath.
authors.affiliation: School of Electronics and Information Engineering, Beihang University, Beijing 100191, China. yz613@buaa.edu.cn.
authors.forename: Ze
authors.initials: Z
authors.lastname: Yu
authors.affiliation: School of Electronics and Information Engineering, Beihang University, Beijing 100191, China. linpeng@buaa.edu.cn.
authors.forename: Peng
authors.initials: P
authors.lastname: Lin
authors.affiliation: School of Electronics and Information Engineering, Beihang University, Beijing 100191, China. xiaopeng_email1984@163.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Xiao
authors.affiliation: Beijing Institute of Remote Sensing Information, Beijing 100192, China. gregrs@126.com.
authors.forename: Lihong
authors.initials: L
authors.lastname: Kang
authors.affiliation: School of Electronics and Information Engineering, Beihang University, Beijing 100191, China. lichunsheng@buaa.edu.cn.
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Li
keywords: geosynchronous synthetic aperture radar; imaging; spatial variance correction; time-frequency scaling