Development of Frequency Measurement Circuit for Soil Moisture Content and Electric Conductivity Measurement System with Detection of Soil Transient Response Characteristics for On-Site Measurement

被引：0
作者：
Takimoto S. [1 ]
Shigemasu R. [1 ]
Fujisono M. [1 ]
Ota S. [2 ]
Futagawa M. [2 ,3 ]
机构：
[1] Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1, Johoku, Naka-ku, Shizuoka, Hamamatsu
[2] College of Engineering, Academic Institute, Shizuoka University, 3-5-1, Johoku, Naka-ku, Shizuoka, Hamamatsu
[3] Graduate School of Science and Technology, Shizuoka University, 3-5-1, Johoku, Naka-ku, Shizuoka, Hamamatsu
来源：
IEEJ Transactions on Sensors and Micromachines | 2023年 / 143卷 / 05期
关键词：
frequency counter; ion concentration; precision agriculture; soil sensor; soil transient response characteristics; water content;
D O I：
10.1541/IEEJSMAS.143.89
中图分类号：
学科分类号：
摘要：
In agricultural field, compact sensors that can measure both water content and electric conductivity are needed. Focusing on the fact that water content and conductivity depend on soil impedance, our group has been developing a new compact and noise-resistant driving circuit that measured soil impedance by detecting transient characteristics of the voltage obtained by injecting current through the soil and converting it to frequency information. In order to realize agricultural field measurements with sensors using this new driving circuit, it had been necessary to miniaturize the part that detected the output from the driving circuit, but it hadn’t been achieved in our previous work. In this research, a microcomputer-based frequency counter was developed to downsize the system for on-site measurement. In general, there are two methods of frequency measurement: direct counting and reciprocal. The direct-counting method is suited for high-frequency measurements, while the reciprocal method is suited for low-frequency measurements. The developed frequency counter could measure with an error of 0.005% over the assumed frequency range by switching between those two measurement methods according to the measured frequency. Using this driving circuit and frequency counter, we measured the model soil and succeeded in capturing changes in water content as changes in impedance. © 2023 The Institute of Electrical Engineers of Japan.
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页码：89 / 95
页数：6
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