Millimeter-wave radar heart rate monitoring via time-frequency fusion and composite filtering with ECG alignment
摘要
Non-contact heart rate monitoring is increasingly important in remote care and infection control. Optical methods such as remote photoplethysmography (rPPG) and infrared thermography (IRT) can estimate heart rate but are easily affected by illumination, airflow, and temperature variations. In contrast, millimeter-wave (mmWave) radar has the advantages of being immune to light interference and low cost, and can estimate heart rate from chest movements. However, further suppression and compensation are needed to reduce its susceptibility to interference from factors such as respiratory drift, reflected clutter, and phase instability. This study proposes a time–frequency fusion framework that combines composite filtering and cepstrum analysis to enhance the stability of mmWave heart rate estimation. Noise is progressively suppressed using bandpass (BP), wavelet, median, and amplification (AMP) filtering, followed by drift compensation with Peaks + Drift and electrocardiogram (ECG) alignment. Heart rate is inferred by reconstructing periodic structures through the fast Fourier transform (FFT) and cepstrum, with peak tracking constrained within physiological ranges. Experiments comparing 12 filter sequences, parameter sensitivity, and noise-stress tests show that AMP to BP yields the best performance, achieving 4.3 bpm MAE, 8.4 bpm RMSE, and 0.8 bpm bias at a 4-s window, 0.5-s hop, and