基于蓝牙与PDA的便携式土壤电导率测试仪开发  

Development of portable soil EC meter with Bluetooth and PDA

作　　者：李民赞[1] 孔德秀[1] 张俊宁[1] 隋伟[1] 邹奇章[1] 

机构地区：[1]中国农业大学现代精细农业系统集成研究教育部重点实验室,北京100083

出　　处：《江苏大学学报（自然科学版）》2008年第2期93-96,共4页Journal of Jiangsu University：Natural Science Edition

基　　金：国家"863"计划项目(2006AA10A301)

摘　　要：开发了一种具有无线通讯功能的便携式土壤电导率测试仪.测试仪采用"电流-电压四端法"设计方案,包括传感器电极、控制电路和基于蓝牙与PDA的无线通讯系统3部分.传感器电极由4个不锈钢探针组成,外侧电极用于向土壤中输入交流恒流激励信号,内侧电极用于检测与土壤电导率密切相关的电压降.控制电路采用AT89S52单片机作为主控芯片,包括作为输入激励的交流恒流源电路和信号采集与处理电路,交流恒流源电路可以输出10μA^1 mA电流,电流变化幅度小于1.5%;信号采集与处理电路具有将检测到的信号整流放大后进行A/D转换、计算、显示的功能,以及接收GPS数据和U盘存储等功能.无线通讯系统将数据通过蓝牙传给PDA,在PDA上可实现数据的接收与显示、文本文件存储和测量结果的实时图形化显示等.室内及室外试验结果表明,在保持土壤质量含水量在15%左右条件下仪器输出可以有效地反映土壤电导率水平.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%.

关 键 词：土壤电导率 四端法 蓝牙 PDA 无线通讯 

分 类 号：S24[农业科学—农业电气化与自动化]