| Water is not only the lifeblood of agriculture, but also the key of social development and human survival. In irrigation, water resource should be distributed reasonably, since precision agriculture is becoming the inevitable choice for sustainable development. In order to overcome the deficiencies of the existing system used for soil moisture measurement, a new system is designed. It is based on the characteristics of electromagnetic wave propagation in the medium and combined with wireless sensor networks.Firstly, the overall program is designed to realize the function of measuring soil moisture content. Soil dielectric technology and electromagnetic transmission principle are studied. Factors affecting on soil permittivity are also analyzed. Then the transmission line is designed, and its model is built to demonstrate the program. Besides a new method is showed to measure the permittivity, which measuring the frequency instead of the original delay. More importantly, Fourier frequency measurement algorithm is adopted in order to avoid external interference and ensure the accuracy. Secondly, the hardware of the system is designed based on the technology of wireless sensor network, especially ZigBee and GPRS technology. And then, software system is developed on the basis of hardware platform, including software functions of the sensor nodes, network master node and PC used as a remote monitoring. Finally, some experiments are taken to test and verify the Function of each module, such as test of data acquisition and communications.The soil moisture measuring system was showed in detail in this article. ZigBee and GPRS technology are also applied in the system. It can monitor for a wide range of farmland at the same time, which makes it have significant meaning in precision agriculture and Intelligent irrigation. |
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