Micro‐Doppler effect removal for ISAR imaging based on bivariate variational mode decomposition

Abstract

Micro-Doppler (m-D) effect is caused by vibrations and/or rotations of mechanical components of moving targets. The m-D signatures corresponding to such micro-motions (m-Ms) may significantly degrade the usefulness of synthetic aperture radar/inverse synthetic aperture radar (ISAR) imagery. The strong echo of the main body of a target can make the m-D parameter estimation of the vibrating or rotating parts more difficult. The removal of m-D effect from target's ISAR image is thus very important for realising high-resolution imaging of a complex target involving m-M parts. To treat this problem, the bivariate variational mode decomposition (BVMD) is proposed to get rid of the m-D effect from the image of target's main body. The BVMD method first decomposes the radar echoes of range cells into a series of complex-valued mode functions according to which m-D signatures can be distinguished and removed from common Doppler responses. Finally, a refined ISAR image of the main body is produced using conventional range-Doppler imaging algorithms. Both simulated and real measured data are processed to show the effectiveness of the proposed method.