Design Of Ultrasonic Short-Range Flow Measurement In Small Channels

In the area of industrial production and agricultural irrigation, the flow detection is a key technology. Using this technology could improve the efficiency of production, promote environmental protection and save the water resources. The traditional methods have an obvious drawback which is need make contact with the measured liquid. But in some special occasions such as: have lots of impurities, corrosive, or to ensure the purity of the measured fluid contamination in the fluid under test. These problems make the flow of the application by the constraints. In order to solve this practical problem, the ultrasonic flowmeter is thriving in recent years. Ultrasonic flowmeter is the most important feature of the fluid under test can be carried out without exposure to flow measurements, which can be widely used in various occasions. Because of its unique advantages, this technology has broad application prospects.This article is for flow measurement of small channels, which refers the width of that water is less than five meters and the flow rate is not fast. For example, irrigation canals, industrial waste water drainage, and the production of juice drinks flow detection and so on. In order to facilitate the installation and the measurement of instruments, we selected the ultrasonic flowmeter.According to design requiements, we examined a large number of domestic and international dates about ultrasonic flowmeter. And to analyzed and summarized the current research of this technology. Based on the studies of several common methods of measurement, proposed the overall idea of design about ultrasonic flowmeter:using the FPGA (Field Programmable Gate Array) chip as a data processing core, the AVR microcontroller as the control, and the Doppler effect for the flow measuring method of the ultrasonic flowmeter.This paper made a hardware circuit and the corresponding part of the design software. Among them, the hardware components selected the Atmegal28 chip of AVR and FLEX10K20 chip of FPGA, designed for simulating the part of the ultrasonic transmitter and ultrasonic receiver processing circuit (including the signal reception, amplification, filtering, mixing, sampling and so on), digital part of the FPGA, FIFO data buffer and control circuit of AVR backend services (including the data storage, data display and data communication sections). Software component completed the preparation of the main program and the preparation of the various modules and debugging routines. Through the above two parts of the hardware and software design, this implements the integrity of the whole system.During the circuit design at the same time, use the software of MultisimlO to simulate the hardware circuit, which verify hardware able to meet the design requirements; Software build environment chosen AVR Studio and QuartusⅡ, with these two software compile the program and verify the feasibility of the program. Finally, use the Protel99Se draw the system schematic, and design the printed circuit board of system.The results show that the whole system could completed the ultrasonic signal launch, acquisition and processing. At the same time this system could get the desired design requirement.