Method Of Enhancing Of Detecting Precision Of The PH Value

The protection of the environment is a basic national policy. As the modern industrial and agricultural development, water pollution has become the prominent face of China's environmental problems. The use of advanced technological means to achieve the water quality of real-time, accurate, continuous, automated monitoring,for environmental protection departments to provide water quality data. The protection of the increasing scarcity of environmental resources, improve people's living environment and improve people's quality of life, are the great significance .Based on the experience and the development tendency of water environmental monitoring at home and abroad, automated monitoring system of water quality pH is established as a Changchun City Scientific enterprise technology innovation fund program--Environmental pollution network platform . The system composed a comprehensive automatic monitoring system by using sensor technology, automatic measurement technology, automatic control technology and communications technology. The system mainly realized the automatic monitoring of pH of the water quality environmental and compensated the impact of temperature measurement and achieved automatic cleaning of the pH sensor electrode.In the course of design, the use of the environmental pH of the water quality testing device is TI's low-power MSP430F149 MCU. The selection of pH sensors which measure the water quality pH value; the selection Pt 100 platinum resistances which measure the temperature of the water; the selection the United States'the 16 AD-?ΣA / D converter AD7705 through MSP430F149 MCU signal and the pH value temperature signal A / D conversion and data acquisition. The system is designed seven buttons to finish the detection device's setting and control. In addition, In order to facilitate the testing system, the system has added LCD1602 LCD module, which used to display the collected water pH and temperature.The main issue of the pH of the water quality environmental testing is temperature which impact on the pH value. By understanding the principium of pH value sensors and temperature on the principle of measuring the pH value, we have found a way to solve this problem. Through software programming approach , the system realized the temperature compensation of water pH value .the paper analyzed measurement results on condition that with temperature compensation and no temperature compensation .we can conclude that the temperature compensation of pH value improved measurement accuracy and reduce measurement error.Because when the pH value of the sensor electrode test environmental water , pollutants will be attached to the glass electrode which impact their sensitivity and accuracy .so we must regular or irregular conduct cleansing. In order to save manpower, the paper designed automatic cleaning device to enable the system to carry out continuous monitoring. So we have adopted the method of liquid water jet cleaning automatically.In order to satisfy different needs of the voltage requests of each module, the power source administration module which outputted the voltage of 1.8V, 3.3V and 5V had specially been designed.After the work of hardware design and software programming, the entire system debugging and test were carried on. The test results indicate that the design has satisfied the requests of the system and achieves the anticipated goals.