A Non-Linearly Moving Ship Autofocus Method Under Hybrid Coordinate System

Due to the influence of waves, the fluctuations of each part of the ship are heterogeneous, which makes the motion error is two-dimensional space-variant and the phase error is hard to be compensated uniformly. This phenomenon causes the moving ship target SAR imaging always contains blurs. In this paper, an autofocus method for non-linearly moving ship targets is proposed. By the backprojection (BP) imaging in the hybrid coordinate (HC) grid, multiple scattering regions are selected and local phase error estimation is performed. Then the phase errors of all pixels in the scene are obtained by polynomial regression. Finally, the image will be compensated precisely. Simulation experiments verify the effectiveness of the proposed method.