An Improved Wigner-Hough Transform Based Method for Moving Target Imaging in Spaceborne SAR

During the synthetic aperture radar (SAR) imaging process, target motion introduces additional Doppler center frequency and Doppler chirp rate. Using mismatched Doppler parameters for imaging will result in defocused and shifted imaging results. To address this issue, this paper proposes an improved joint algorithm based on Wigner-Ville Distribution (WVD) and Hough Transform for more accurate Doppler parameter estimation, thereby achieving moving target imaging. The algorithm workflow is as follows: Firstly, the echo data undergoes range compression, azimuth Fourier transform, and range walk correction. Then, the proposed method is used to obtain and optimize the time-frequency linear relationship. Subsequently, the slope and intercept information of the time-frequency lines are extracted to estimate the Doppler center frequency and Doppler chirp rate. Finally, simulations are conducted for a single point target and an arranged dot-matrix target, and the estimated parameters are used to complete the imaging of the moving targets.