Research On Respiration Signal Processing Method Based On Doppler Radar

Respiration and heartbeat are important vital signs of human beings.Monitoring vital signs based on continuous wave Doppler radar is a research hotspot of non-contact vital signs monitoring.In order to solve the problem that the baseline signals of breathing and heartbeat signs are difficult to obtain during the research process,using a step motor level motion simulation chest motion is designed to test the performance of the method of extracting vital signs of Doppler radar.Software and hardware design of chest motion simulation system and K-band 24 GHz continuous wave Doppler radar signal acquisition module,and use vital signal extraction methods such as complex signal demodulation,arctangent demodulation,and parameterization method to test collect radar data were performed and experimental results show that the simulation system can effectively evaluate the performance of the above methods.Aiming at the research of Doppler radar based respiratory signal processing method,this thesis mainly includes the following:(1)A chest motion simulation system is designed to simulate human chest movement simulation system,including embedded microcontroller,chest movement simulation module,sensor and data acquisition module,power supply module and host computer software.This system paves the way for subsequent data acquisition and algorithm research.(2)In order to solve the problem of arctangent demodulation of the two-channel signal imbalance,a signal orthogonalization method based on ellipse rotation matrix is proposed to solve the problem of radar I / Q two-channel signal imbalance.(3)In order to solve the frequency resolution problem of the fast Fourier transform,a signal frequency extraction method based on first-order Fourier series fitting is proposed,which can obtain accurate respiration rate in the signal of 8 seconds Frequency characteristics.(4)In order to solve the problem of obtaining respiration and heartbeat features at the same time,a method based on particle swarm optimization algorithm is proposed to extract respiration and heartbeat features of the chest displacement signal,which can simultaneously obtain respiration and heartbeat features and solve the frequency resolution problem of the fast Fourier transform.In this thesis,the designed chest motion simulation system is used to collect the radar data for experimental verification.The experimental results show that can accurately extract respiratory frequency and amplitude features,Therefore,it is a practical significance to design and complete the research of Doppler radar respiratory monitoring system.