Research And Implementation Of Non-contact Vital Signs Monitoring Radar

Vital signs are a reflection of the health of a living body,and cardiopulmonary activity is an important indicator of vital signs.Traditional contact vital signs monitoring devices have problems such as skin contact,cable limitation,and passive measurement,and the application scenario is limited.The electromagnetic pulse transmitted by the ultra-wideband radar has strong penetration,and is less affected by external environment such as weather,temperature,cotton yarn,etc.It can realize non-contact measurement,and has unique advantages in the monitoring of vital signs.From the aspect of cost and practicability,this paper studies an ultra-wideband vital sign monitoring radar based on discrete components.The details are as follows:1.Two methods of generating Gauss pulse source is studied.Firstly,a monopole negative Gaussian pulse is designed and fabricated based on avalanche triode.On this basis,a bipolar Gauss pulse with higher spectrum energy is obtained by adding a microstrip short line coupling structure.Then,the monopole positive Gauss pulse is designed and fabricated based on the step recovery diode,and a bipolar Gauss pulse without DC spectrum is obtained through RC differential network.2.The advantages and disadvantages of the four time domain equivalent sampling gate circuits is analyzed.A double-tube balanced sampling integral circuit is selected for simulation and physical production.An equivalent test method for sampling and holding circuits is proposed to verify the sampling result of the circuit.3.A simple square wave source composed of a relaxation oscillator is designed,and a timing control unit with a high precision of time combining a varactor diode is made,which is used to control the delay time of sampling pulse in the time domain equivalent sampling receiver;Then an active band-pass filter is designed to filter out low frequency clutter at the output of the receiver signal.4.A rapid scanning and sampling method for acquiring information for human respiratory and heartbeat is presented,and an appropriate antenna is selected to verify that the radar can accomplish the work for human respiratory and heartbeat monitoring within a certain range.