Papers by Author: Xing Hong Zhang

Abstract: Because the high precision ultrasonic flowmeter has shortcomings of expensive, the A/D conversion circuit based on ARM for the time-difference method ultrasonic flowmeter is designed. On the basis of time-difference method ultrasonic flowmeter theory and the domestic and overseas advanced technology, a cost-effective low-power 12-bit ADC12DL040 chip and ARM processor LPC2138 are chosen for the design. According to the data acquisition system issues of the time- difference method ultrasonic flowmeter, the two-channel 12-bit low-power monolithic CMOS analog-digital conversion chip is adopted to design the nanosecond-level high-resolution data acquisition system. In this paper, the A/D chip peripheral pin circuit design is given, hardware structure diagram and software flowchart are also given. The input frequency of ultrasonic signal is 400 kHz and the sampling frequency is 8MHz.The experimental results indicated that the designed A/D conversion circuit is able to accomplish the high-speed and high-resolution ultrasonic echo signal sampling; the minimum resolution time of A/D conversion circuit is 0.305ns. The physical map of A/D conversion circuit for the time-difference method ultrasonic flowmeter is presented. The design of A/D conversion circuit for time-difference method ultrasonic flowmeter not only lower the production cost, but also lays a solid foundation for the research of low-cost and high-precision time-difference method ultrasonic flowmeter.

Abstract: A new type of temperature measurement apparatus is designed by utilizing the characteristic that the velocity of the ultrasonic wave varies with the temperature through the medium, with both merits low cost and high precision. This paper introduces the principle of ultrasonic thermometer and puts forward the realization of hardware and software of thermometer, and details the special software subdivision algorithm which is used to measure the ultrasonic transmission time accurately. The experimental results indicate that the thermometer achieves the measure of the ultrasonic wave transmitting time with nanosecond level. The key problems are solved in the practical application of the ultrasonic temperature measuring technology, and the resolution of the temperature measurement is better than 0.001 centigrade.

Abstract: A theory of time-space coordinate transformation is presented for measuring space with time. A novel type of displacement sensor named time grating is developed, and methods of electronic rectifying, self-compensation and self-correction are proposed to intelligentize the sensor. Experiment results coming from applications conform to the validity of the proposed theory and methods. The experiment and test results show that high-precision measurement is achieved without high-precision manufacture and that angular displacement is measured very accurately without a dividing scale, which embeds the remarkable characteristics of low cost but high accuracy to the time grating sensor.

Abstract: Machining precision deficiency and installing error are very common problems for many sensors, which may result in unstable amplitude i the signal detected by the probe and further cause measurement errors of the sensors. The concept of using electronic technology to offset machinery precision deficiency is utilized. A new method of electronic rectifying is proposed. The automatic gain control (AGC) technology used in the field of wireless communication is applied for sensor signal processing. An AGC circuit consisting of a multiplier and divider AD534 is designed. A new smart time grating displacement sensor currently under development by us is used to provide experimental results for comparison with and without the AGC technology.

Abstract: For many reasons, the study of differential frequency measurement had disappeared for some years. This paper applies the differential frequency measurement previously used to measure transmission error to static differential frequency measurement. A new method called method of duality for gear and electric wave is proposed to explain the differential frequency measurement in a new way to discover its essence. A novel angular displacement sensor is designed. The composite error is ±17″ based on the static differential frequency measurement.