Design Of Radio-Frequency Sensor Netwok Monitoring System Based On GPRS

Monitoring system is essential in some important places such as bank, oilfield, power, traffic, security-monitoring, environmental monitoring. In this paper, radio frequency (RF) communication technology, ARM embedded technology and GPRS communication technology are incorporated to develop one remote wireless monitoring system,which has the features automation, large amounts data acquisition, real-time, lower costs.Based on lots of references, key technologies involved are in-depth studyed and discussed, which include design of the RF network and protocol, GPRS and network accessing technologies, development based on embedded platform.According to the functional requirements of the system, the paper proposes three-tier communication structure:acquisition node network, centralized control devices(base station),remote monitoring center. Acquisition node network is responsible for collecting information and then transmitting to base station by RF. Base station is responsible for transmitting date information to the remote monitoring center by GPRS, so that monitors can get the information on the distance easily.This paper focuses on hardware and software design of the monitoring system. About hardware : Acquisition node is composed of STC89C52 MCU and nRF905 RF module;Base station is mainly composed of ARM7-S3C44BOX controller, GPRS module, nRF905 module, LCD module; Monitoring center is PC with mainstream configurations.Besides, factors and issues that may affect the communication reliability of the system are discussed in depth and put forward practical solutions. About radio network : multiple access conflict is resolved by CSMA / CA, hidden node problem is resolved by handshake mechanism, the structure of the frame is made, design of data retransmission and frequency hopping mechanism are completed; About GPRS network connection : fixed static IP-network program is determined, network status monitoring and re-connected solution is proposed for GPRS dropping. At the end of the system design, experiments are carried out, the results show that wireless monitoring function of the system is realized,and requirements of project are met.