Cross-range scaling method of inverse synthetic aperture radar image based on discrete polynomial-phase transform

Abstract

The cross-range scaling of inverse synthetic aperture radar image depends on both the radar wavelength and the rotating angle of the target relative to the radar line-of-sight. After compensating the translational motion, the second-order phase coefficients of the range echoes are a linear polynomial of the rotating angular velocity and range geometry. In this study, a novel method for estimating the rotating angular velocity of the targets with dominant scatters is proposed. The range cells where the amplitudes have smaller normalised variances are selected, and then frequency domain windowing is applied to extract echoes of dominant scatters. Based on the discrete polynomial-phase transform, the second-order phase coefficients of the strong scatter echoes are estimated, and thus the rotating angular velocity can be obtained through the least-square-error method. Simulated and real-data results have shown the effectiveness and robustness of this method.