Research On Life Signal Detection Technology Based On FMCW Millimeter Wave Radar

Radar-based vital signal detection technology uses radar to realize remote non-contact detection,which has broad application prospects in medical monitoring,disaster rescue and other fields.At present,the radar systems commonly used in the field of radar vital signal detection are mainly CW radar,UWB radar and FMCW radar.The application of CW radar in the field of life signal detection has the advantages of simple structure and easy implementation,but it does not have the ability of ranging and is vulnerable to interference;UWB radar can achieve high-precision ranging and strong anti-jamming ability,but the circuit of UWB radar is complex and requires high sampling rate;the FMCW radar has both the stability of CW radar and the ranging capability of UWB radar.,it has multi-target detection capability and strong anti-interference ability.Therefore,this paper chooses FMCW radar to realize non-contact vital signal detection.This paper first deals with the noise interference in radar life signals and the interference of respiratory harmonics on heartbeat signals,proposes a radar vital signal processing algorithm based on ICEEMDAN.The proposed algorithm first decomposes the radar vital signal into multiple IMF by ICEEMDAN,then calculate the correlation coefficient between each IMF component and the original radar vital signal,finally,according to the correlation coefficient,the IMF component is selected to reconstruct the respiratory and heartbeat signals,so as to separate and extract the respiratory and heartbeat signals.According to the data analysis measured by 10 volunteers at a distance of 0.3 m,0.5 m and 1 m,compared to the EMD algorithm,the SNR of respiratory and heartbeat signals extracted by vital signal processing algorithm based on ICEMDAN is is increased by 1.25 dB and 5.10 dB.Compared with the reference heartbeat signal,the error of the extracted heartbeat frequency is very small,within a reasonable error range.Then study the radar vital signal processing algorithm based on adaptive algorithm.The computation of radar vital signal processing algorithm based on ICEEMDAN is too large,which is not conducive to real-time signal processing.Therefore,based on the adaptive noise cancellation structure,this paper proposes a vital signal processing algorithm based on adaptive algorithm.Firstly,the respiratory frequency is estimated by window-finding method,and then the reconstructed signal is used as the noise reference signal to separate the respiratory and heartbeat signals.The reference signal contains both respiratory and respiratory harmonic frequencies,which can reduce the influence of respiratory harmonic on the extraction of heartbeat signals while separating respiratory and heartbeat signals.Finally,the feasibility of the algorithm is proved by simulation and measured data.Finally,the vital signal detection system based on FMCW millimeter wave radar is realized.The system mainly includes three main parts: radar front end,signal processing and display interface.The radar front end and the signal processing module are integrated in the IWR1443,and the data collection is completed by the RF subsystem and the radio processing subsystem of the module,and the signal processing process in the detection system is completed by the ARM and the hardware accelerator in the module,and the final detection results are transmitted to the computer through serial port.The display interface is implemented on the computer,the test results uploaded by are received and analyzed by MATLAB and displayed in the GUI interface.