Design And Implementation Of Wireless Grain Situation Measuring And Controlling System For Xuzhou State Grain Depot

Food security is the basis of sustainable development of national economy. Because temperature, humidity, pest density and other factors in granary make an impact on food quality, the annual crop damage of our country could reach ten-million tones. Therefore, the establishment of modern grain situation measuring and controlling system is the need to safeguard the food security. At present, grain situation measuring and controlling system in our country mostly use wired communication mode. Wired grain situation measuring and controlling system has its inherent shortcomings. For example, easy to introduce interference, could make wiring difficult, easily struck by lightning and so on. However, Wireless grain situation measuring and controlling system is very efficient to solve the above problems. Wireless sensor network has two main characteristics:1. low-power dissipation;2.flexible in net building. These features make it very suitable to be used in the field of measuring and controlling grain situation. In recent years, as wireless sensor network technology is gradually applied to the field of measuring and controlling grain situation, it has developed wireless grain situation measuring and controlling system based on the IEEE802.14.2technical standard and the ZigBee wireless protocol stack. The communication distance of the above-mentioned wireless system is limited, which can not meet the development needs of the modern large-scale grain depot.The goal of this thesis is to design a low-power wireless grain situation measuring and controlling system to meet the development needs of the modern large-scale grain depot. Firstly, the thesis introduced the background, the significance, and the research status of grain situation measuring and controlling system, and the basic concept of wireless sensor network. Secondly, through the analysis of application environment of grain situation measuring and controling system and the choice of communication mode, the thesis determined the overall structure of wireless grain situation measuring and controlling system. Thirdly, the thesis introduced the hardware and software design of Wireless sensor network node. Finally, the thesis completed the testing and the overall evaluation of wireless grain situation monitoring and control system.In terms of hardware design, the thesis selected Si1000chip system produced U.S. Silicon labs, inc. as the main control chip. The Si1000integrates the high-performance, ultra-low power dissipation,8bit CIP-51core microcontroller C8051F9XX, and the240-960MHz EZRadioPRO Series RF transceiver. Its barrier-free transmission distance reaches2.2km and its ultra-low power consumption(the node which can be powered by two batteries could work for4-5years), which make it meet the design requirement of low-power wireless grain situation measuring and controlling system for large-scale grain depot. In addition, the thesis also completed the development of pest sensor, which fills the blank of domestic grain situation measuring and controling system in the field of monitoring pests.In terms of software design, the system uses a cross-layer optimization communication protocol-EZMAC Improved. EZMAC Improved is based on the EZMAC Pro, which is a wireless communication software module offered by the Silicon labs, inc. The structure of this communication protocol is very simple. The link budget of this communication protocol reaches141DB which is the biggest link budget in the industry. The sensor node in the bottom can pass the collected information to management node on the top only by three jump, which reduces the chance that the external environment interferences with signal transmission.In terms of test, this thesis completed the whole network testing of wireless grain situation measuring and controlling system and the performance test of node. Node performance testing includes transmission distance test, power consumption test, signal strength test and data accuracy test.The system has been put into operation in Xuzhou state grain depot. So far, the system has been put into operation for more than a year. The system is running stably, and the collected data of the system is very accurate. In addition, the battery consumption of the system is very low. So the system reaches the system design requirements.