Ambiguity-Free Doppler Velocity Decomposed Imaging Method for 79-GHz Band Millimeter-Wave Radar

This article proposes an accurate Doppler velocity-associated radar imaging method for millimeter-wave (MMW) short-range radar. Doppler velocity-based data decomposition is promising in terms of enhancing the spatial resolution of radar images, especially for multiple objects with different motion velocities, e.g., human walking models. However, the traditional short-time Fourier transform (STFT) or other time-frequency analysis methods inherently suffer from inaccuracy due to a limited unambiguous velocity range or the tradeoff between temporal and frequency resolutions. To address this problem, the proposed method incorporates time-of-flight (TOF)-based Doppler velocity estimation, i.e., the weighted kernel density (WKD) method, which overcomes the limitations of unambiguous velocity range and the tradeoff between temporal and frequency resolutions in the Doppler velocity decomposed and associated radar imaging. Experimental results obtained using 79-GHz band MMW radar equipment demonstrate the effectiveness of the proposed method for two use cases, i.e., multiple rotating spheres and a human walking model.