Accurate phase demodulation is critical for vital sign detection using millimeter-wave radar. However, in complex environments, time-varying DC offsets and phase imbalances can severely degrade demodulation performance. To address this, we propose a novel DC offset calibration method alongside a Hilbert and Differential Cross-Multiply (HADCM) demodulation algorithm. The approach estimates time-varying DC offsets from neighboring signal peaks and valleys, then employs both differential forms and Hilbert transforms of the I/Q channel signals to extract vital sign information. Simulation and experimental results demonstrate that the proposed method maintains robust performance under low signal-to-noise ratios. Compared to existing demodulation techniques, it offers more accurate signal recovery in challenging scenarios and effectively suppresses noise interference.
@article{arxiv.2505.08366,
title = {Non-contact Vital Signs Detection in Dynamic Environments},
author = {Shuai Sun and Chong-Xi Liang and Chengwei Ye and Huanzhen Zhang and Kangsheng Wang},
journal= {arXiv preprint arXiv:2505.08366},
year = {2025}
}