| By monitoring some physiological information of human body,multi-physiological health monitoring can provide early prediction and diagnosis of diseases or data records during patients’ rehabilitation.At present,the portable physiological parameter monitoring mostly uses wireless technology.The disadvantage of wireless technology is that each device is powered separately,the battery needs to be replaced frequently or the device needs to be charged separately,and the wireless communication technology is complex and the cost is high,the transmission of information between multiple nodes is prone to frequency interference,and the communication quality is difficult to be guaranteed.In this paper,data transmission is realized based on DC power line communication technology,which can supply power to multiple devices uniformly so that the single device does not need its own power supply.And only two power lines are needed to realize communication,which reduces the communication cost and avoid the refluence of the frequency interference of wireless technology.Wearable sensor applications where wireless communication monitors the human body,where power can be provided locally via small batteries connected to the sensor,are useful.But for more power-hungry,or long-term monitoring applications,power must be supplied via cables from the battery unit conveniently placed somewhere in the body.The multi-physiological monitoring system designed in this paper is divided into host receiving terminal,slave collecting terminal and DC power line communication module.After receiving the command from the host end,multiple slave collecting terminals collect the physiological data of the target position of the human body,such as temperature,humidity,heart rate,blood oxygen and so on.Referring to relevant protocols,formulate a user-defined communication protocol frame structure,encapsulate the collected data,and send it to the DC power line communication module for processing.The host receiving node adopts the polling working mode to control the whole system,sends commands to the slave acquisition terminal,receives the data processed by the DC power line communication module,analyzes the data according to the protocol,displays the data on the display screen,and sends it to the host computer through Bluetooth device for real-time waveform display and data storage.The core part of this paper is the DC power line communication module,which receives the command frame from the host or the data frame from the slave,performs ASK modulation on the frame to obtain the modulated signal,and processes the modulated signal by using power amplification circuit and various filter circuits to make the modulated signal meet the transmission requirements on the DC power line,The modulated signal is coupled to the power line through the coupler of the DC power line communication module.The coupler adopts the combination form based on differential mode inductance and resistance capacitance coupling,and transmits the signal on the power line.The coupler of the DC carrier communication module at the receiving terminal receives the signal on the power line,and demodulates the received signal after filtering,then send to target node.This paper also analyzes and solves the impedance matching problem in DC power line communication. |
