The Designing Of Gas Thickness Detector Based On Ultrasonic Technology

This paper introduces the history and actuality of the ultrasonic correlation measurement and analyzes the digital signal processing project of the ultrasonic signal. In an attempt to measure SF6 gas thickness in air, a new technology to detect gas thickness in a binary gas mixture is investigated. The essential measurement formula and error formula of the technology are deduced and the application fields of this method are also discussed. Applying this technology, an CPLD-based SF6 gas thickness detector is invented. Comparing to the traditional technology of gas detecting, the technology of ultrasonic gas detecting is more steady and reliable. Its degree of automation is higher and it is easy to be upgraded comparing to the project that does not adopt intelligent chip. So, this technology has a good future.This paper introduces the process of the project in theory analysis, system collectivity design, system hardware circuit design and system software circuit design. There is great innovation in this system's hardware and software design. First, difference phase comparation is used to realize the accurate measurement of mixture gas and the shortages of general sound-time measurement is overcome in this paper. Second, software compensation is used to improve accurateness. Third, the relation between the temperature and the dual-ultrasonic phase difference and the relation between the gas thickness and the dual-ultrasonic phase difference are found by experiments. More the sound compensation of the two relations are realized the by soft. combination of MCU and CPLD expands the function of the system. Two patents-invention and new pattern utility have been applied at the same time.In practice testing, when the thickness of SF6 is over 1 000ppm, this detector emits sound and light signal and simultaneously displays the value of gas thickness, temperature and humidity etc in digital. Another, gas thickness-time wave, temperature-time wave and humidity-time wave etc are showed visually in computer watching software.