A fast ground moving target focusing method based on first-order discrete polynomial-phase transform

A new ground moving target focusing method for airborne synthetic aperture radar (SAR) is introduced in this paper. Firstly, first-order discrete polynomial-phase transform (DPT) is used to reduce the target phase order. Secondly, Keystone transform (KT) is applied to correct the residual range walk, and then the target second-order motion parameter can be estimated after performing the azimuth fast Fourier transform (FFT). Finally, the target first-order motion parameter can be estimated after the Doppler frequency migration (DFM) compensation and a well-focused result of a moving target can be obtained. Compared with the conventional SAR imaging methods, the proposed method can eliminate the effects of Doppler ambiguity and azimuth spectrum split. In addition, the proposed method is computationally efficient since the target motion parameter searching procedure is avoided, which can satisfy the target real-time imaging requirements. Real data processing results are provided to validate the effectiveness of the proposed algorithm.