The work uses the characteristic that the propagation speed of ultrasonic waves in the medium changes with temperature, and designs a new type of precision ultrasonic thermometer that has both low cost and high precision. The special software subdivision algorithm is used to process the collected data, combined with the FPGA-based high-speed data acquisition control system, so that the ultrasonic measurement reaches the ns level. As a result, the temperature measurement resolution of the ultrasonic thermometer is better than 0.001°C. At the same time, because ultrasound is a high-frequency mechanical wave, it has the characteristics of fast, accurate, and strong anti-interference ability. The lowest temperature can reach -200℃ and the highest temperature can reach 2000℃.
Ultrasonic thermometer, as a new type of temperature sensor, has become a new and promising temperature measurement method. With the development of ultrasonic sensors, people began to explore the application of this new type of ultrasonic temperature measurement technology in industry, and a series of results have been achieved in theoretical research and practical applications, and have been applied in industrial and medical fields. This work is based on the characteristics that the propagation speed of ultrasonic waves in the medium changes with temperature, and takes advantage of the fast and anti-interference characteristics of ultrasonic waves. It is aimed at the contact temperature sensor that cannot guarantee a stable height in a wide measurement range. For the difficult problem of accuracy, a new type of precision ultrasonic thermometer is proposed. There are two main innovations in this work. First, it uses the characteristics of high frequency, strong anti-interference ability, and sensitivity to temperature changes to make temperature measurement fast and stable. The lowest measurement temperature can reach -200°C. , The highest temperature can reach 2000 ℃. The second is to use FPGA chips for high-speed and accurate data acquisition and control of signals, and use subdivision algorithms to process the signals, so that the works can accurately excite and collect the signals, and realize nanosecond ultrasonic propagation. Time measurement. The work indirectly measures the ambient temperature of the ultrasonic wave by measuring the propagation time of the ultrasonic wave at a specific distance. Because the change of the environment temperature will more sensitively affect the change of the ultrasonic propagation speed, the measurement hardware of the ultrasonic propagation time of nanosecond level can measure the temperature with a resolution better than 0.001℃.