Design Of Turbidity Detection System Based On Near Infrared Light

Water is one of the important material conditions for human survival.With the development of society and the progress of science and technology,people have put forward higher demands on the water quality of domestic water.Turbidity is an important indicator of the identification of water quality is good or bad,therefore,the detection of turbidity to determine the quality of water is one of the most simple way.Imported turbidity detection equipment,high precision and stability,but the price is expensive,poor maintenance;and domestic turbidity instrument affordable,but narrow measurement range,and stability and reliability of slightly less.Therefore,how to design a stable,reliable,inexpensive and suitable turbidity measuring instrument for the mass demand has become a hotspot in the field of water quality testing under the existing hardware condition.Based on the principle of turbidity measurement and the research status and future development trend of turbidity measuring instrument at home and abroad,a turbidity detection system based on near infrared light is designed.The design of the turbidity sensor is completed by using the near infrared light emitting diode as the light source,and the water sample tank structure is designed by the combination of the scattering method and the transmission method.The system hardware is designed with the STC12C5A60S2 microcontroller as the core,including the constant current source drive module,Relay control module,signal processing module and display circuit module;using KEIL software to program and simulate the system to complete the A/D conversion,data collection,calculation and processing;to achieve the turbidity value display,turbidity threshold setting,Alarm and other functions.Based on Labview platform to write the host computer software,set the serial communication protocol,to achieve the turbidity detection system communication function,to facilitate the transmission of data and follow-up processing.Experimental results show that::the system measurement range of 0-1000NTU;0?200NTU,the measurement accuracy of±1%FS;200?1000NTU,the measurement accuracy of ±3%FS;resolution of 0.1NTU;turbidity measurement repeatability error<5%;voltage stability ± 0.3%;the system has better linearity and stability.