Multi-state FMCW Radar Real-time Vital Signs Monitoring System

Aiming at the variety of states non-contact real-time vital signs monitoring system for 77GHz Frequency Modulated Continuous Wave (FMCW) radar, the hardware, software construction and experimental analysis of the real-time monitoring system are studied based on IWR1642 chip. The system workflow is as follows: radar transmitting antenna transmits the signal, the signal bounces off the object, then receiving antenna receives the echo, and the echo is mixed with the transmitted signal through the filter to obtain the intermediate frequency signal. The intermediate frequency signal is sampled by Analog to Digital Converter (ADC), and the target range-bin is obtained by performing Fast Fourier Transform (FFT) on the sampled signal; the target range-bin is phase extraction and the extracted phase is unwrapping and difference; the respiration and heartbeat waveforms are separated from the difference signal with band-pass filter; respiratory rate and heart rate are obtained by FFT and peak counting of respiratory and heartbeat waveforms. Finally, we compare the designed system with the mature equipment. Experimental results show that the system can effectively extract and display human respiratory rate and heartbeat rate for different experimental states and distances. And heart rate accuracy is about 96 %, respiratory rate accuracy is about 91 %. This paper provides a small, low power consumption, high accuracy, and high sensitivity reference scheme for non-contact real-time measurements.