|Abstract: ||Because of the medical technology advance cause the domestic population’s life growth continuously.Due to deepen social industrialization the people who move to work outside increas gradually.Causing the social problem of the elder population who live alone that can't ignore nowadays also becomes the heavy burden for medical system.So the construction daily life at home environment physiology information monitoring system to monitor the elders’ physiology message realtime,when detect abnormal physiology signal then notify the medical organization immediately to provide emergency medical service in order to reduce the dead and injured also save the medical resources.|
Survey the domestic and international academics’ research of homecare physiology information monitor system for electrocardiogram,heartbeat,blood pressure etc,at the daily life.All have already put into the related realm to carry on the research and have many best solution.However the clinical experience of the basis medical science：the elder dies abruptly in the case blame on breath terminated,so monitor the elder’ breathe signal to the daily life at home care become the worth research item.Try to combine the breath signal detect circuit and the wireless LAN communication system constructing a wireless breath monitoring system to save the medical resource,avoiding not necessary dead and injured.
The research can be divided into three parts,（Ⅰ）the breath signal detect and filter circuit:place stethoscope on the neck exterior or chest to capture breath sound signal through electric condenser microphone take the faintly signal input to convert become the electronic signal,then process by the bandpass filter(cutoff frequence 50,1000 Hz) that constituted by highpass and lowpass filter,isolate unuseful noise from the lung sound signal effectively.（Ⅱ）analog to digital signal conversion and processing:the microcontroller that design by Texas Instrument company ( Microcontroller Unit,MCU) MSP430 F449 response analog to digital signal conversion (A/D Converter) and signal level process,this type of microcontroller is one of the ultra low power microcontrollers that develop by Texas Instrument CO. in 1996,its biggest advantage is the ultralow consumption,and low power supply range 2.2-3.6Ｖ,it fit use for protable device.（Ⅲ）wireless transceiver:This part adopts the WLAN transceiver module in 2.4 GHz frequency band to transmit and receive wireless signal, along with wireless LAN technology keep on the progress can extend the related device to apply the application effectively,and its transmit distance about 100 meters is good enough to daily life at home environment,but have to measure interference effect of floor,metal or any other articals etc, to do the further study research.
The result of research ,there are three capture points for breath soung signal of the breath system from lung to nose. Respectively is chest, neck,and both sides among nose then the best with the neck. The wireless transmission attenuation effect by the floor that per floor reduces about 30%,and when the signal reduces range reach to 50% above,then packets loss rate increase then disconnection will taking place , along with the wireless technique,believe soon a new generation cellular phone will developed in the future should be able to improve effectively.That reach to develop a wireless protable monitor device which can connect anywhere.