Wide-Angle Vital Signs Measurements by Adaptive FMCW Radar

This paper demonstrates the use of a people tracking algorithm and beamforming technique in monitoring vital signs for smart home applications. A person's location and velocity are detected. When the person remains stationary within a specific area (distance and angle), the radar beam is steered towards the target, and vital signs are measured. The advantage of this approach is not only the physiological parameters can be monitored in different positions by steering the transmitted signals towards the target's location, but also the target's range bin can be recognized clearly from other clutter according to its amplitude. To extract vital signs, the received signals from two receiver channels are combined. An algorithm based on continuous wavelet transform (CWT) with different mother wavelets is applied to the phase of the combined signal. The experimental results demonstrate that the proposed algorithm can monitor breathing and heart rate with a maximum error of 10.7% and 11.51%, respectively, within a range of 1 to 2 meters and an angle from −40 to 40 degrees.