Research Of Ultrasonic Flowmeter With High Precision Based On TDC-GP22 And Correlation Algorithm

The ultrasonic flowmeter as one kind of new type flowmeter,has high precision,wide range ration,no pressure,easy to install an other characters,which is widely used in daily life,commerce,industry and other fields of flow measurement.With the rapid development of automated instrumentatiom,the ultrasonic flowmeter measurement precision and stability is put forward higher requirements in all areas.A measurement method is designed based on TDC-GP22 and correlation algorithm in this article,which is to solve the problem of low precision and low stability in the ultrasonic flowmeter.The measurement precision and stability of the system is improved.The main work of the dissertation includes:(1)The history and status of ultrasonic flowmeter are reviewed,the basic theory is introduced in detail.It is proposed based on the direct time difference method and the related time difference method on the time of ultrasonic measurement.(2)The STM32F407 of an 32 bit ARM core microcontroller was used as the central controller by making full use of the hardware,software resources,low power of the microcontroller.The system is easy to control and monitoring and the power consumption of the system is reduced.(3)The hardware part adopts modular design arounding the time difference method,which includes single chip microcomputer system circuit,high precision digital timing chip TDC-GP22 circuit,ultrasonic stimulate circuit,ultrasonic receiving circuit,data storage circuit and zero crossing detection circuit.The analog and digital circuit is separated to improve the anti-interference ability of the system and easy to maintain.(4)The software part is finished with the keil MDK.The software system design flow chart and part of the subroutine flow chart are discussed.Through the correlation method of the simulation,the related time difference method is applied to the flow measurement system.The problem of threshold is solved in the direct time difference method and accuracy and stability of system is improved.(5)The system software and hardware are tested in the laboratory conditions.The method of time measuring based on TDC-GP22 and correlation algorithm is analyzed and the flow revision coefficient is studied and analyzed through the experiment data.Finally,The flow test is carried out with the ultrasonic flowmeter.The measurement precision and stability of the ultrasonic flowmeter is analyzed and the reasons of data error are analyzed.