Development of portable soil EC meter with Bluetooth and PDA
Key Laboratory of Modern Precision Agriculture System Integration Research, Ministry of Education, China Agricultural University, Beijing 100083, China)
Abstract:A portable soil EC meter with Bluetooth and PDA has been developed. The meter adopts four-electrode method and consists of three parts: sensing unit, control circuit and wireless communication system based on Bluetooth and PDA. The sensing unit has four metal probes. The two outside ones inject constant alternating current into soil and the two inside ones detect the voltage drop in the soil. The control circuit uses a micro-processor AT89S52 as MCU which includes two sections: the constant alternating current section and the signal acquiring and processing section. The constant alternating current section can produce 10 μA - 1 mA current with less than 1.5% of fluctuation. The signal acquiring and processing section has the functions of adjusting and amplifying the signal, executing A/D conversion, changing the voltage drop into soil EC, displaying soil EC in LCD, and recording the EC data in flash disk together with GPS data. The wireless communication system transmits data to a PDA via Bluetooth to recode and display the data in a real-time figure in the PDA. The result of experiments revealed that the developed meter is practical to measure the soil EC when the soil moisture content is kept in about 15%.
李民赞, 孔德秀, 张俊宁, 隋伟, 邹奇章 . 基于蓝牙与PDA的便携式土壤电导率测试仪开发[J]. 江苏大学学报(自然科学版), 2008, 29(2): 93-96.
Li Minzan, Kong Dexiu, Zhang Junning, Sui Wei, Zou Qizhang- . Development of portable soil EC meter with Bluetooth and PDA[J]. Journal of Jiangsu University(Natural Science Eidtion)
, 2008, 29(2): 93-96.