FPGA-based Study Of Acoustic Processing In Ultrasonic Gas Flowmeter

With the non-contact measurement mode, high accuracy, wide measurement range,data accuracy,stable and easy to maintain, the ultrasonic gas flowmeter has been considered ideal flowmeter in the natural energy and other areas.Propagation velocity in fluid of ultrasonic wave is susceptible to velocity of fluid.Though the collection and analysis of the affected acoustic signal,velocity information of fluid can be obtained.Generating,receiving and processing of ultrasonic acoustic signal is the key technology of the ultrasonic flowmeter.This article use high-speed sampling and the related algorithm of digital signal to ultrasonic signal,has overcome the dependence on the key level of ultrasonic threshold detection in analog circuit,simplified the complexity of circuit and improved the anti-interference ability and stability of the system.In this article,by useing of digital signal processing and the transit-time method to calculate the flow rate of fluid.The processing schemes are as follows:Using the low-cost Cylone IV FPGA family to achieve the AD conversion data control,data caching and controlling coordinated operation of the circuit system.Using the high-performance TMS320VC5509 DSP to digital filtering de-noising for the collected acoustic signal,and using fast correlation algorithm to calculate transit time of ultrasonic downstream and upstream signal.The hardware part is based on the idea of modular design,including power module,transmitter drive circuit module,the receiving end amplifying and filtering module, ultrasonic sensor switching circuit and high-speed signal acquisition module.Algotithms involved in this paper by the Matlab simulation,FPGA module and the circuit has passed the test.The experiment proved that the theory in this design is feasible,and has certain actual application value,provides the certain theory instruction for the research of ultrasonic gas flowmeter that based on digital signal processing method.