Research And Application Of Environmental Monitoring System Based On Wireless Sensor Network

Wireless sensor network is consisted of plenty of sensor nodes which are deployed in the monitored area and connected with each other through radio. These nodes form a network by self-organize. The data acquired by node may pass through other nodes by multi-hop routing with wireless communication and came to the base station. The data will be processed and fused during the transmission. Finally they will be transmitted to the monitoring center via Ethernet or a satellite.At present, the wireless sensor network in environmental monitoring plays a more and more important role. Compared with the traditional method of monitoring environment, the environmental monitoring system based on wireless sensor network can work in the field of bad circumstances without special field substation, and has large data collection capacity, high accuracy, deploy convenience etc.Based on understanding deeply the researching status of wireless sensot network both at home and abroad, and according to the needs of wild environmental monitoring, this thesis introduces the research scheme of environmental monitoring system based on wireless sensor network. The system uses a number of different sensors, respectively acquiring atmospheric pressure, atmospheric temperature, humidity, wind direction, wind speed, water depth and rainfall etc, using ZigBee wireless communication technology through multi-hop self-organizing network, and transmits the data acquired by those sensors to the environmental monitoring center. The monitoring center analyzes and processes the data came from the network, and realize some functions inchuding displaying data graphically, quering historical data, network topology and sending some command to manage the whole system, such as sleep, awakening and changing sampling frequency.Firstly, this thesis discusses the status and development trend of wireless sensor network and environmental monitoring and analyzes the advantages in environmental monitoring based on wireless sensor network. This thesis also introduce detailly the system composition of wireless sensor network. And this paper compares several short-range wireless communication technology, and select the ZigBee wireless communication technology as this sensor network's communication technology.Secondly, the thesis discusses the design and realization of the hardware and software of wireless sensor network node. The node's hardware consist of wireless communication module and data acquisition module, which wireless communication module take ATmega1281 and AT86RF230 radio chip as the components and data acquisition module uses SHT11 temperature and humidity sensor, MS5534B pressure sensor, EC9-1 measuring wind sensor, LVYLC-02 rainfall sensor and CR-20 series inputting types of level transmeter. Node software design is implemented on TinyOS operating system, using nesC language programming wireless communication module driver, the data acquisition module driver and node application's program.Thirdly, this thesis introduces the monitoring software of environmental monitoring system which developed by LabVIEW. This software uses the standard data interface provided by XServe middleware server, which will transform the entire sensor network's data received by base station into a XML format data stream output to the monitoring software. Then, the softwore will read and analyze the XML data stream to fulfill monitoring software visualized and convenient for the user to observe dataFinally, the performance of the wireless sensor network environment monitoring system is tested, including the node's communication range, the maximum radius of monitoring, temperature, humidity, atmospheric pressure, wind direction, wind speed, rainfall and water depth. Test results show that the system has low power consumption, node communication distance adjustable programming, effective communication distance is more than 150m. The data acquisition module and wireless communication module photogenic in the physical separation, support for multiple signal acquisition. The wireless sensor network platform is with ad hoc networks, network strength highly, and can provide continuous, real-time environmental information and the characteristics of high stability and sensitivity.