The Research Correlation Ultrasonic Flowmeter

Using ultrasonic to measure fluid flow is one of the earliest applied technologies in theultrasonic industrial test. Compare with other flow meter, firstly, ultrasonic flow meter is freefrom pipe shape and size, the structure is very sample, and do not produce pressure loss to fluid;secondly, it can measure velocity online, fast response for the change of velocity, with largemeasure range and good system stability, especially it have particular advantages to super largepipe; at last, ultrasonic is free from fluid physical and chemical property, such as viscosity,conductivity and corrosivity of fluid.This design subject proposed of STM8as system microprocessor, designed and realized thehardware circuit which is around the microprocessor as the core. The system hardware circuitincluding sending and receiving circuit of ultrasonic, high-speed A/D transforms, and introducedthe power circuit, A/D keyboard circuit, LCD12864interface circuit, memory circuit andcommunication interface circuit of system buffer circuit. The core work circuit of this subject isultrasonic sending and receiving circuit, the radiating circuit is made up of LM555device, andcontrolled by field-effect tube; ultrasonic sending and receiving circuit including echo receivingcircuit, primary amplitude limit amplification, band pass and low pass filter circuit.As the traditional method of phase difference is detection count when the signal is zero, it’svery strict on circuit and very easy be disturb, to propose add related law principle andinterpolation theory on the basis of traditional method of phase difference. To add theinterpolation algorithm before using related principles, the proper use of the interpolationalgorithm not only makes the system to achieve higher sampling frequency effect and improvethe measurement accuracy. After adding the correlation method and interpolation, it couldsimplify measurement circuit, save cost and improve the measurement accuracy.