Design Of Ultrasonic Doppler Flowmeter Based On DSP

Our life cannot leave flow measurement.With people study flow measurement more and more depth, the type of flowmeter becomes more and more. Ultrasonic Doppler flowmeter has two advantages:no contact with measured medium and applying to two-phase flow, so it has been continuously studied and applied in many fields, and it played a huge role.This paper analyzes the current several mainstream design methods of ultrasonic flowmeter, and has selected Doppler method as the design plan. Doppler method is based on acoustic Doppler effect. It uses ultrasonic to measure frequency shift, then calculates the flow rate according to the flow formula and find the fluid flow at last. By analyzing some mature ultrasonic flowmeters, this paper makes some improvements in the design. This paper uses DSP as the core of the system which is used to achieve significant control and signal processing, and uses AVR to control the keyboard settings and LCD display. TMS320F2812 is a chip of DSP. It does not only have powerful digital signal processing, but also incorporates a wealth of peripherals and have a strong ability to control. AVR, as the auxiliary of DSP, help DSP calculate flow, display information, thereby it reduces the burden of DSP. This paper mostly has done several aspects of the work:First, this paper describes the working principle of the Doppler flowmeter, analyses its flow equation and determines its operating frequency, and describes FIR digital filter and FFT algorithms. Secondly, this paper designs the transmitter module and the receiver mixing module, and implements transmit and receive signals; This paper designs Control and processing module and describes the design of DSP and its peripheral device specifically, and introduces and Uses DSP interface, such as SPI, SCI, XINTF etc, and has completed their hardware design. Thirdly, this paper has completed software design of the DSP and the AVR module, and has implemented the communication between DSP and AVR. Finally, this paper simulates FIR digital filter and FFT algorithm, and has proved the feasibility of the program.System hardware includes ultrasonic transducer, DDS circuit, filter circuit, mixer circuit, power/signal amplification circuit, DSP/AVR and their peripheral devices. System software includes three modules, they are the DSP module,the AVR module and the communication between DSP and AVR. Simulation includes FIR digital filter and FFT algorithm.After verification, the system can meet requirements of the design basically, but it has a certain gap with envision in terms of accuracy and stability. Finally, this paper gives advice and prospects on the system.