152 / 2024-08-28 16:30:41

Spaceborne ISAR Imaging for On-Orbit Satellite Targets with High-order Motion Estimation and Compensation Method

inverse synthetic aperture radar (ISAR) imaging,high-order motion compensation,spatial-variant phase error (SVPE) compensation

In this paper, we introduce JTFA techniques and the concept of instantaneous frequency (IF) into high-resolution imaging of spaceborne ISAR. By utilizing the spatially variable phase characteristics of scattering points on the target, we propose a high-order motion compensation method using time-frequency curve and high-order motion information inversion. Firstly, the received target echo is subjected to translational compensation and KT. At this time, the high-order residual MTRC and SVPE of the scattering points will cause image defocusing. Secondly, the energy of the defocused strong scattering points is extracted using the adaptive blocking method. Then, the doppler curve of the strong scattering points is obtained based on the time-frequency ridge extraction method. Thirdly, the high-order relative motion parameters of the target are estimated by using the higher-order motion inversion method based on the Levenberg-Marquardt algorithm (LMA). Then, the MTRC correction function and SVPE compensation function are obtained. After interpolation and residual phase compensation, local focusing is performed on the local defocusing image area. The core of the proposed method is to estimate the higher-order relative motion of target using the doppler curve of the defocused scattering points.