Research For Ultrasonic Flowmeter Flow Detection Method Based On Amplitude-marked

In modern industrial field, flow, pressure and temperature are known as the three mostimportant industrial inspection parameters. As the most important detection tool in the fluid flowfield, flowmeter is more and more widespread used in modern industry. With a wide rangeapplications of ultrasonic technology in gas flow measurement, the characteristic of non-contactmeasurement, measurement accuracy and good stability of ultrasonic testing get more attention,and now has become the third largest class standard measurement instruments natural gasmeasure.Now the international market of large-caliber gas ultrasonic flowmeter is occupied bymanufacturers such as ABB, the method is mainly the external power technology based ondigital processing technology, domestic gas ultrasonic flowmeter can only be competed withtraditional turbine, root type flowmeters etc. about small and medium caliber application. Thegas flowmeters of small and medium size in the market are generally battery-powered, gasultrasonic flowmeter must compensate for the lack of low-power design to get the kind ofcompetitive advantage of these flowmeters, so that it is necessary to replace the transit timemeasurement technology based on big computing with electrical work. Japan’s AICHI batteriesgas ultrasonic flowmeter illustrates the feasibility that low power technology implementation inthe field of gas measurement. In this paper, zero-crossing detection method based on thehardware is used in ultrasonic transit time measurement process, that reduce the need for highprecision AD in the signal process, and greatly reduce the chip computing power required, laidthe foundation of the low-power designed next.The ultrasonic measurement of gas is same as basic principles of the liquid, but for theinstability and susceptible to interference and other characteristics of the gas flow, the liquidultrasonic measurement technique of transit time which has matured, such as the phase method,can not be applied directly in the gas measurement field. It needs a lot of work to resolve theseconfounding factors, by using some engineering skills, not pursuing the capacity oflarge computation, furthermore improve the accuracy of ultrasound measurements of gas as much as possible.As an attempt of new engineering method, the main mission of the project is study thefeasibility about low computation scheme which is applicable to the gas ultrasonic flowmeter.The design use a TI’s TMS320F2812DSP chip as the core, the voltage amplitude excitationsignal generating transducer excitation work to improve the reliability of the received signalcharacteristic point judging system, which has completed the ultrasonic flow study based on themagnitude marker, in which the feature point is determined by solutions of using hardware tomake the zero-crossing detection. The main contents include the following sections: introductionand analysis of works of the gas ultrasonic measurements; analysis of the main factors affectingthe accuracy, and the corresponding improvement measures; designing primarily timing circuits,including ultrasound excitation circuit, receiving circuit, and gas-related circuits, focusing on thefeature point determination method based on the magnitude marker; through the meter prototypemeasurement results analysis to determine the effectiveness and feasibility of the method.