Doppler Through-Wall Radar target localization based on Local optimum Time-Frequency Chirp Reassignment

Doppler-based Through-Wall Radar (TWR) has shown great potential for non-contact target localization. However, in scenarios involving multiple moving targets, closely spaced or intersecting instantaneous frequency (IF) components pose significant challenges to conventional time-frequency analysis (TFA), resulting in poor localization accuracy. This paper proposes a novel algorithm-Local Optimum Time-Frequency Chirp Reassignment (LPFCR)-to address this issue. The method begins with a Short-Time Fourier transform (STFT) for initial time frequency representation, followed by region segmentation based on energy concentration to extract representative local features. A chirp-based local synchronization strategy is then introduced to perform high-dimensional reassignment in both frequency and chirp-rate domains, enhancing resolution and reducing time frequency aliasing. Experimental results demonstrate that LPFCR significantly improves IF estimation and target localization accuracy compared to traditional methods.