Vertical Synchrosqueezing for High-Resolution Radar Imaging

This article presents a novel approach to inverse synthetic aperture radar (ISAR) image enhancement using time-frequency (TF) vertical synchrosqueezing (VSS). The authors proposed adding the signal extraction block to the ISAR image processing path. Since the VSS technique does not change the signal amplitude-phase dependencies but only performs its decomposition and denoising, the proposed method is noninvasive. It was shown that denoising the signal by the VSS in the TF domain reduces the sidelobe level of the ISAR image and enables its denoising. For imaging purposes, the authors derived four novel TF signal parameter estimators in the TF domain that are practically investigated in a radar application. The proposed technique was extensively tested through simulation studies and on data obtained from measurements using high-resolution wideband frequency-modulated continuous wave (FMCW) radar. The usefulness of the proposed technique is shown using simulated and real-life results.