Double-threshold detection circuit of ultrasonic wave signal propagation time, and detection method

Abstract

The invention relates to a double-threshold detection circuit of ultrasonic wave signal propagation time, and a detection method. The detection circuit comprises a first comparator, a second comparator, a first NOR gate, an AND gate, a NOT gate and a second NOR gate. First threshold signals are 0.2 to 0.5V; second threshold signals are 0 to 20mV; first external control signals are overturned into low level after emission pulses are emitted for 80 to 100[mu]s; and second external control signals are overturned into low level or high level after the emission pulses are emitted for 80 to 100[mu]s. The circuit provided by the invention has the following advantages: errors caused by influences exerted by fluid temperature and viscosity on ultrasonic waves in fluid propagation are avoided, and measurement of the propagation time is more accurate; and a NOT gate U5 and a NOR gate U6 can be omitted and the Latch pin of the first comparator U1 is connected with GND, such that detection processing and generation of multiple stop timing enabling functions can also be realized, the circuit can be further simplified, and the reliability is improved.

Description

technical field [0001] The invention relates to a double-threshold detection circuit and a detection method for ultrasonic signal propagation time, belonging to the field of flow metering instruments. Background technique [0002] Ultrasonic flowmeter is a kind of measuring instrument that uses the fluid flow to modulate the ultrasonic signal, and obtains the volume flow by detecting the propagation time of the signal. Ultrasonic flowmeter has the characteristics of simple structure, fast response, large measurement range, good stability and high precision. In addition, the ultrasonic flowmeter is also a non-contact measurement method, which will not cause pressure loss to the measurement pipeline, has no requirements for the measurement medium, and can measure the flow rate of various gases and liquid media. [0003] In the process of measuring the ultrasonic propagation time, when the excitation line starts to generate the excitation pulse, the high-precision time measure...

AI Technical Summary

Problems solved by technology

When comparing the ultrasonic signal with a single threshold, there is a change in the ultrasonic signal, which causes the ultrasonic propagation time to stop and the timing enable to change, which affects the measurement accuracy

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