A dual-threshold detection circuit and detection method for ultrasonic signal propagation time

Abstract

The present invention relates to a dual-threshold detection circuit and detection method for ultrasonic signal propagation time. The detection circuit includes a first comparator, a second comparator, a first NOR gate, an AND gate, a NOT gate and a second NOR gate; The first threshold signal is 0.2~0.5V; the second threshold signal is 0~20mV; the first external control signal is turned to low level after 80~100μs of the emission pulse; the second external control signal is 80~100μs after the emission pulse After flipping to low or high level. It avoids the error caused by the influence of fluid temperature and viscosity on the ultrasonic waves in the fluid propagation, making the propagation time measurement more accurate; the invention can cut out the NOT gate U5 and the NOR gate U6, and lead the Latch of the first comparator U2 The pin is connected to GND, which can also realize the detection processing and generate multiple stop timing enable functions, which can further simplify the circuit and improve reliability.

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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