Ultrasonic wave transit time measuring circuit by secondary reflection waves

Abstract

The invention relates to an ultrasonic wave transit time measuring circuit by secondary reflection waves. The ultrasonic wave transit time measuring circuit is used on an ultrasonic flowmeter and used for measuring the ultrasonic wave transit time between two sensors through the waveform similarity between primary received ultrasonic waves and secondary reflected ultrasonic waves. The ultrasonic wave transit time measuring circuit comprises a multi-path gating device (5), a programmable amplifier (6), waveform characteristic judging electrical systems (7-13), wherein the multi-path gating device (5) is used for ensuring that excitation signals, the primary received signals and the secondary reflected waves can accurately enter a subsequent circuit; the programmable amplifier (6) is used for processing different magnification time requirements of the primary received signals and the secondary reflected signals; the waveform characteristic judging electrical systems (7-13) are used for controlling the starting up / shutting down of a time counter (14) according to judgment results so as to complete the measurement of the transit time. According to the ultrasonic wave transit time measuring circuit, the energy source of the primary received ultrasonic waves is the same as that of the secondary reflected ultrasonic waves, so that a super-high similarity relation exists between the primary received ultrasonic waves and the secondary reflected ultrasonic waves. Thus, the problem that corresponding waveform characteristics are misjudged is avoided.

Description

technical field [0001] The invention relates to a circuit for measuring ultrasonic transit time by using secondary reflected waves, which is mainly used in time-difference ultrasonic flowmeters to measure the transit time of sound waves between two opposing ultrasonic sensors. Background technique [0002] The transit-time ultrasonic flowmeter relies on detecting the modulation effect of the flowing medium on the ultrasonic signal, and obtains the transit time of the sound wave on the fixed-length channel, thereby deriving the flow velocity data of the medium. At present, ultrasonic flowmeters usually judge the transit time by identifying specific mark points on the waveform, so the judgment of specific mark points on the waveform has become the key technology of time difference ultrasonic flowmeters. [0003] In the prior art, when sending out ultrasonic signals, the main methods adopted include: [0004] 1. Use square wave sequence excitation and set the threshold value. ...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to solve the problems in the prior art that the error rate of ultrasonic zero-crossing judgment is relatively large and the algorithm is complex, and the transit time is judged by using the waveform height similarity between the primary received wave and the secondary reflected wave that has a causal relationship

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