The two-step motion compensation combined squint wavenumber domain algorithm based on fractional Fourier transform

Gewei Tan, Wei Lin

School of information science and engineering, Huaqiao University, Xiamen, China

Fractional Fourier transform (FrFT) is a kind of generalized Fourier transform, which processes signals in the unified time-frequency domain and the linear frequency modulation signal can be well focused after FrFT. Motion error is an important factor affecting the SAR resolution, conventional wavenumber domain (CWD) algorithm  is an ideal solution of SAR focusing problem as long as nominal straight flight track is given, especially in the case of high squint angles and long synthetic apertures, but it has certain limitation in processing airborne SAR data affected by motion error, so extended wavenumber domain algorithm (EWD) is presented. Pointing to the problem that the effect of error elimination is not obvious in processing non-stationary motion error using EWD algorithm, FrFT based the two-step motion compensation combined squint wavenumber domain algorithm is put forward in this paper, which is expected to eliminate the influence of motion error more effectively, so as to obtain high quality SAR images. The simulation results and the imaging results of real SAR data show that the proposed algorithm can eliminate the influence of motion error effectively. (the real SAR data provided by Institute of Electronics, Chinese Academy of Sciences).