Raw Data-Based Motion Compensation for High-Resolution Sliding Spotlight Synthetic Aperture Radar

Sensors (Basel). 2018 Mar 12;18(3):842. doi: 10.3390/s18030842.

Authors

Ning Li¹, Shilin Niu², Zhengwei Guo³, Yabo Liu⁴, Jiaqi Chen⁵

Affiliations

¹ School of Computer and Information Engineering, Henan University, Kaifeng 475004, China. hedalining@henu.edu.cn.
² School of Computer and Information Engineering, Henan University, Kaifeng 475004, China. nsl1993@foxmail.com.
³ School of Computer and Information Engineering, Henan University, Kaifeng 475004, China. henugzw@foxmail.com.
⁴ Space Microwave Remote Sensing System Department, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China. ybliu@mail.ie.ac.cn.
⁵ College of Computer and Information Engineering, Hohai University, Nanjing 210098, China. jiaqichen@hhu.edu.cn.

Abstract

For accurate motion compensation (MOCO) in airborne synthetic aperture radar (SAR) imaging, a high-precision inertial navigation system (INS) is required. However, an INS is not always precise enough or is sometimes not even included in airborne SAR systems. In this paper, a new, raw, data-based range-invariant motion compensation approach, which can effectively extract the displacements in the line-of-sight (LOS) direction, is proposed for high-resolution sliding spotlight SAR mode. In this approach, the sub-aperture radial accelerations of the airborne platform are estimated via a well-developed weighted total least square (WTLS) method considering the time-varying beam direction. The effectiveness of the proposed approach is validated by two airborne sliding spotlight C band SAR raw datasets containing different types of terrain, with a high spatial resolution of about 0.15 m in azimuth.

Keywords: Doppler rate (DR); motion compensation (MOCO); sliding spotlight; synthetic aperture radar (SAR); weighted total least square (WTLS) method.