A High-precision Multi-target Vital Signs Detection Method Based on FMCW Radar

At present, most of the radar-based vital signs detection algorithms focus on single-target vital signs measurement, and there are few studies on multi-target vital signs detection. In the detection of multi-target vital signs, the positioning of multiple human targets and the extraction of respiration and heartbeat signals are the difficulties of research. In this paper, a non-contact multiple targets vital signs detection method based on frequency modulated continuous wave (FMCW) radar is proposed for simultaneous detection of the respiration rate and heart rate of multiple people. In this proposed method, the multiple input multiple output (MIMO) mode of radar is utilized to collect vital signs signals of multiple human targets. Then, the minimum variance distortionless response (MVDR) beamforming algorithm is used to enhance the echo signal in the desired direction and suppress the interference signal in other directions, so as to obtain the angle information of the target. By jointly estimating the distance and angle of each target, multiple targets are separated and the phase information of different targets can be extracted. Finally, the variational mode decomposition (VMD) algorithm is utilized to separate and reconstruct the respiration and heartbeat signals from the phase information of different targets, while avoiding the interference of the high-order harmonic components of the respiration signal on the heartbeat signal. The experimental results show that this method is effective in distinguishing multiple targets and realizing accurate respiration rate and heart rate estimation both when the targets are located at different angles at different distances and different angles at the same distance.