Remote Sensing for Vital Information Based on Spectral-Domain Harmonic Signatures

In this paper, we propose an efficient and robust non-contact heart rate estimation algorithm. The key idea is to recover the fundamental heartbeat frequency from its higher-order spectral features. Our contributions are threefold: 1) carefully review and examine possible approaches in vital signs detection with ultra-wide band (UWB) impulse radar; 2) numerically and experimentally show an important result that, in the spectral domain, the fundamental heartbeat signal is respiration-interference-limited, whereas its higher-order harmonics are noise-limited; and 3) implement an adaptive heart rate monitoring algorithm based on the proposed theory, which is feasible with continuous monitoring. To justify the proposed theory, we perform a spectral analysis of the harmonics of vital signs signal. We validate the proposed algorithm using a controlled vital sign simulator. We experimentally demonstrate the effectiveness of the harmonics-based heart rate estimation algorithm and compare it against existing methods. For completeness, we also provide a limitation analysis of the proposed algorithm.