Ultrasonic echo duty cycle measuring circuit and method

Abstract

The invention provides an ultrasonic echo duty cycle measuring circuit and relates to an ultrasonic echo duty cycle measuring circuit and method. The circuit comprises an echo counter U0; the circuit is characterized in that an input port CLK of the echo counter U0 is connected with an external echo pulse ECHO, the echo counter U0 is connected with a ring oscillator U3, the ring oscillator U3 is connected with a falling edge detector U1, a latch U2 and a high-speed counter U4, an input port D of the falling edge detector U1 is connected with the external echo pulse ECHO, the high-speed counter U4 is connected with the latch U2 and a divider U5, and the latch U2 is connected with the divider U5. The circuit is provided with no external high-speed clock, a scheme where a high-speed clock is generated in the circuit is adopted, the measuring precision of the circuit is never affected even though the clock of the ring oscillator changes with factors such as voltage and temperature, and the circuit and the method are very suitable for implementation in integrated circuits.

Description

technical field [0001] The invention relates to the field of ultrasonic flow measurement, in particular to an ultrasonic echo duty ratio measurement circuit and a measurement method thereof. Background technique [0002] Ultrasonic flow measurement uses the principle of acoustics to measure the flow rate of fluid flowing through the pipeline: a pair of ultrasonic transducers are installed on the wall of the flow pipeline. During the flow measurement process, the components on the circuit board apply excitation signals to the transmitting transducers to generate Ultrasound, the receiving transducer converts it into an electrical signal after receiving the signal, and the measurement circuit can record the time from transmission to reception. According to the principle of the Kepler effect, the propagation speed of the ultrasonic wave will change under the condition of forward flow and reverse flow , the velocity of the fluid can be calculated by using the measured forward and...

AI Technical Summary

Problems solved by technology

In practical applications, the ultrasonic echo is not an ideal sine wave, especially the first few waveforms, after being converted into a square wave, it is not a square wave with a duty cycle of 50%, and the transducer will age, Scaling and other phenomena directly lead to the gradual weakening of the waveform amplitude. According to the experiment, discarding the unstable waveform at the front and using several waves with stable amplitude will get better measurement results, and the duty cycle of the echo It is an important basis for judging the stability of ultrasonic waves. In general heat meters, the frequency of ultrasonic echoes is 1MHz, which means that a 100Mhz clock is used for measurement to obtain a duty cycle with an accuracy of about 1%, but the actual heat meter In general, such a high-frequency clock source is not provided. In order to solve this problem, the present invention provides an ultrasonic echo duty ratio measurement circuit and its measurement method

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