基于无线传感器网络的水产养殖水质监测系统开发与试验

为解决目前水产养殖水质自动监测系统存在布线困难、灵活性差和成本高等问题,该文构建了基于无线传感器网络的水产养殖水质监测系统。该系统的传感器节点负责水质数据采集功能,并通过无线传感器网络将数据发送给汇聚节点,汇聚节点通过RS232串口将数据传送给监测中心。传感器节点的处理器模块采用MSP430F149单片机,无线通信模块由nRF905射频芯片及其外围电路组成,传感器模块以PHG-96FS型pH复合电极和DOG-96DS型溶解氧电极为感知元件,电源模块以LT1129-3.3、LT1129-5和Max660组成的电路提供3.3和±5V。设计了传感器输出信号的调理电路,将测量电极输出的微弱信号放大,满足A/D转换的要求。节点软件以IAR Embedded Workbench为开发环境,采用单片机C语言开发,实现节点数据采集与处理、无线传输和串口通信等功能。监测中心软件采用VB6.0开发,为用户提供形象直观的实时数据监测平台。对系统的性能进行了测试,网络平均丢包率为0.77%,pH值、温度和溶解氧的平均相对误差分别为1.40%、0.27%和1.69%,满足水产养殖水质监测的应用要求,并可对大范围水域实现水质环境参数的实时监测。

Development and test of aquacultural water quality monitoring system based on wireless sensor network

Some problems of aquaculture water quality monitoring systems, such as wiring difficulties, low performance-price ratio and short of flexibility, still exist. This paper analyzes the limitations of the existing aquaculture water quality monitoring systems and the new aquaculture water quality monitoring systems based on wireless sensor networks. The proposed system uses sensor nodes to obtain data of water temperature, pH value and dissolved oxygen concentration; a sink node is used to collect data from the sensor nodes through a wireless sensor network and monitoring center to process data downloaded from the sink node through RS232 serial port, and present to users. The hardware platform of the sensor node is composed of a processing module, a sensor module, wireless communication and a power module. The processing module uses a MSP430F149 as the processing core. The sensor module uses PHG-96FS pH combination electrodes and DOG-96DS dissolved oxygen electrodes to measure water quality parameters. Since sensor output signals are weak and noisy, a signal conditioning circuit is designed to amplify and filter the weak signals so as to meet the requirement of input range of the A/D converter. The wireless communication module uses an RF905 RF chip and its periphery circuits to receive and send data. The power module uses an LT1129-3.3 chip, an LT1129-5 chip, a Max660 chip and their periphery circuits to supply 3.3 V and ±5 V voltage for the processing module, wireless communication and the sensor module. The system software consists of two parts, the node software and monitoring software. The node software, which is compiled using C Language in IAR Embedded Workbench, can complete data acquisition and processing, wireless transmission, and serial communication. The monitoring software, which is compiled using vb6.0, can provide users with a visual image of real-time data monitoring platform. Furthermore, the correction and reliability of system are verified. The results demonstrate that the average packet loss rate is 0.77%, and the relative errors of pH value, temperature and dissolved oxygen are less than 1.40%, 0.27% and 1.69%, respectively. Our study showed that the system with characteristics of higher acquisition frequency, smaller size, lower cost, and good flexibility, can implement real-time monitoring of water quality parameters in a wide range of water types.