CN113504389A - Circuit and method for measuring ultrasonic wave propagation time - Google Patents

Circuit and method for measuring ultrasonic wave propagation time Download PDF

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Publication number
CN113504389A
CN113504389A CN202110847861.3A CN202110847861A CN113504389A CN 113504389 A CN113504389 A CN 113504389A CN 202110847861 A CN202110847861 A CN 202110847861A CN 113504389 A CN113504389 A CN 113504389A
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CN
China
Prior art keywords
circuit
signal
ultrasonic
time
echo
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Pending
Application number
CN202110847861.3A
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Chinese (zh)
Inventor
王中洲
田鹏
韩豪
潘桢宇
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Mezolen Instrument Changzhou Co ltd
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Mezolen Instrument Changzhou Co ltd
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Priority to CN202110847861.3A priority Critical patent/CN113504389A/en
Publication of CN113504389A publication Critical patent/CN113504389A/en
Priority to NL2032091A priority patent/NL2032091B1/en
Pending legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/662—Constructional details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/24—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting acoustical wave
    • G01P5/245—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting acoustical wave by measuring transit time of acoustical waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/667—Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters

Abstract

The invention discloses a circuit and a method for measuring ultrasonic wave propagation time, wherein a high-speed timer module is used in cooperation with a filter circuit, a peak value holding circuit, a threshold value comparison circuit and a zero crossing point comparison circuit to finally convert an echo signal of an ultrasonic wave into a pulse signal of a zero crossing point, and the interval time of two pulses is calculated to be the propagation time of the ultrasonic wave by counting the time interval of the two pulse signals, so that the influence of the sampling frequency of an ADC (analog to digital converter) and the FIFO (first in first out) of a main controller on measurement is avoided, and the accurate measurement of the propagation time of the ultrasonic wave in forward and reverse flows is realized.

Description

Circuit and method for measuring ultrasonic wave propagation time
Technical Field
The invention belongs to the field of ultrasonic sensors, and particularly relates to a circuit and a method for measuring ultrasonic wave propagation time.
Background
The common ultrasonic flowmeter technologies on the market at present are two types: time transfer methods and doppler methods. Although the time transmission method starts late, the time transmission method is widely applied and has high accuracy. Time-of-flight determines the pipe fluid flow rate by measuring the time between the forward and reverse flow of ultrasonic pulses to and from the two transducers. The flow rate of the fluid inside the pipeline is as follows: v = C2×ΔT/2×L，Wherein C is the speed of ultrasonic movement from the transmitter to the receiver in the static liquid, Δ T is the time difference between the downstream and upstream of the probe in the flowing liquid, and L is the distance between the two probes, so it can be known as the accurate fluid flow rate inside the measurement pipe, and the time values Tdu and Tud of the upstream and downstream of the measurement probe need to be accurately measured.
Disclosure of Invention
In order to solve the above problems in the existing technology for measuring ultrasonic propagation time, the present invention provides a circuit for measuring ultrasonic propagation time, which comprises: the device comprises an MCU unit, a driving module, a timer module, a biasing circuit, a filter circuit, a VGA gain adjusting circuit, a peak value holding discharge circuit, a threshold comparison circuit and a zero crossing point comparison circuit; the driving module is connected with the timer module, and the biasing circuit, the filter circuit, the VGA gain adjusting circuit, the peak value holding discharge circuit, the threshold value comparison circuit, the zero crossing point comparison circuit and the timer module are sequentially connected; the MCU unit is used for setting a driving module and triggering the timer module.
Preferably, the driving module includes an ultrasonic driving circuit, the ultrasonic driving circuit includes a dual-channel gate driver, and a multi-channel signal switching circuit formed by a plurality of analog switches, and the upstream and downstream ultrasonic sensors can be controlled to be in a driving and receiving mode by controlling a switching logic of the analog switches.
Preferably, the VGA GAIN adjustment circuit comprises a variable GAIN amplifier with a GAIN range of 80dB, amplifies the weak signal into an echo signal with an amplitude of 500-100mV based on VCC _ OFFSET bias, and can dynamically adjust the amplitude of the output waveform through the GAIN pin.
Preferably, the PEAK holding discharge circuit is connected to the diode through the output of the operational amplifier, and charges the two capacitors in a unidirectional manner, and the ADC _ PEAK network is labeled with the PEAK voltage signal of the echo signal.
Preferably, after the EN _ START pin is enabled, the timer module records a count value from the START signal to the STOP signal, the START signal is triggered when the driving pulse is sent, when the acoustic wave passes through the pipe medium and is transmitted to the downstream probe, the echo signal passes through the bias circuit, the filter circuit and the VGA gain amplification and adjustment circuit, the zero pulse signal is generated after the threshold comparison and the zero crossing comparison and is output to the STOP pin of the timer module, the timer module records the count value between the START signal and the STOP signal, and finally calculates the propagation time between the START signal and the STOP signal.
Furthermore, a method for measuring the propagation time of ultrasonic waves is proposed, comprising the following steps:
s1, driving pulses are carried out on an ultrasonic sensor arranged at the upstream/downstream;
s2, adjusting the analog signal of the echo to be a pulse signal with a time characteristic at the lower/upper ultrasonic sensor;
and S3, calculating the counting value of the pulse signals from the START of driving to the echo by using a timer module, and converting the counting value into TIME, wherein the calculation formula is TIME =1/Fs x CNT, wherein Fs is the timing frequency of the timer module, and CNT is the counting value of the timer between the START signal and the STOP signal.
Preferably, the step S2 of adjusting the analog signal of the echo to be a pulse signal having a time characteristic is realized by integrating the piezoelectric bias, filtering, amplification, peak hold, threshold comparison, and zero-crossing point comparison of the ultrasonic echo.
Preferably, in step S2, the above-mentioned circuit for measuring the propagation time of the ultrasonic wave is used to implement the procedure of processing the report signal.
The invention uses the mode of driving pulse to an ultrasonic sensor of the ultrasonic flowmeter, and integrates the piezoelectric of the ultrasonic echo with bias, filtering, amplification, peak value holding, threshold value comparison circuit and zero crossing point comparison circuit to adjust the analog signal of the echo into the pulse signal with the embodied time characteristic, and uses the counter circuit to calculate the count value of the pulse signal from the beginning of driving to the echo and finally convert the count value into time, thereby replacing the time difference of the traditional software and leading the measured propagation time data to be more accurate.
Drawings
Fig. 1 is a schematic diagram of the overall framework of the circuit according to the present invention.
Fig. 2 is a circuit diagram of an ultrasonic drive circuit.
Fig. 3 is a bias circuit diagram.
Fig. 4 is a VGA gain adjustment circuit diagram.
Fig. 5 is a circuit diagram of a peak hold discharge.
Fig. 6 is a diagram of a threshold comparison circuit and a zero-crossing point comparison circuit.
Fig. 7 is a circuit diagram of a timer.
Fig. 8 is a waveform diagram of a driving wave.
Fig. 9 is a diagram of echo signals.
Fig. 10 is a graph of a peak sample voltage waveform.
Fig. 11 is a diagram of STOP pulse signals.
Detailed Description
Example 1
One embodiment of the circuit for measuring the propagation time of ultrasonic waves comprises: the device comprises an MCU unit, a driving module, a timer module, a biasing circuit, a filter circuit, a VGA gain adjusting circuit, a peak value holding discharge circuit, a threshold comparison circuit and a zero crossing point comparison circuit; the driving module is connected with the timer module, and the biasing circuit, the filter circuit, the VGA gain adjusting circuit, the peak value holding discharge circuit, the threshold value comparison circuit, the zero crossing point comparison circuit and the timer module are sequentially connected; the MCU unit is used for setting a driving module and triggering the timer module.
Fig. 2 is a circuit diagram of an ultrasonic driving circuit, which includes a dual-channel gate driver U11, and a multi-channel signal switching circuit composed of analog switches U9, U10, U12, and U13, and can control the driving and receiving modes of the upstream and downstream ultrasonic sensors by controlling the switching logic of the analog switches.
Fig. 3 is a bias circuit diagram, a bias circuit is composed of U1B and U3A, R6, R9, the bias voltage is VCC _ OFFSET, and the preliminary amplification of the ultrasonic echo signal is realized by the differential amplification circuit implemented by U1A.
FIG. 4 is a VGA gain adjustment circuit diagram, which is a variable gain amplifier with a gain range of 80dB, for amplifying the weak signal output from FIG. 3 into an echo signal with an amplitude of 500-100mV based on VCC _ OFFSET bias. And the amplitude of the output waveform can be dynamically adjusted through the GAIN pin of U2.
FIG. 5 is a circuit diagram of a PEAK hold discharge circuit, in which the output of the operational amplifier U7A is connected to a diode D3 to charge the capacitors C22 and C23 in one direction, and the reference sign of the ADC _ PEAK network is the PEAK voltage signal of the echo signal; when the peak sampling in this direction is completed, the peak voltage can be discharged through the 10 Ω resistor of R59 by the analog switch of U8.
FIG. 6 is a diagram of a THRESHOLD comparison circuit and a zero-crossing comparison circuit, U6 is a comparator, and the RC1 echo signal is compared with THRESHOLD comparison voltage generated by the DAC of the MCU. Because a lower THRESHOLD comparison is used, when the voltage value of RC1 is lower than THRESHOLD, the OUT _ CLK output signal is set to 1, OUT _ CLK will enable the rising edge flip-flop with clear and preset functions of U5, when EN _ CMP outputs a high level.
U4 is a single power supply comparator, EM _ CMP will enable this comparator, zero as described herein is the reference voltage of VCC _ OFFSET, when RC1 is less than VCC _ OFFSET, the output Q of U4 will be high, when Q will output a pulse voltage at the zero crossing point at the lower threshold.
Fig. 7 shows a timer module, when the EN _ START pin is enabled, the timer U14 records a count value between the START signal and the STOP signal, the START signal is triggered when the driving pulse is sent, when the acoustic wave passes through the pipe medium and is transmitted to the downstream probe, the echo signal passes through the bias circuit, the filter circuit and the gain amplifier, the zero pulse signal is generated after the threshold comparison and the zero crossing comparison and is output to the STOP pin of the timer module, the timer module records the count value between the START signal and the STOP signal, and finally calculates the propagation time between the START signal and the STOP signal.
The ultrasonic transmission pulse can be configured according to MCU human-computer interaction, and the number of the driving waves and the driving frequency are set according to the pipe diameter and the field working condition of the medium. Before transmitting the driving wave, the MCU enables a START _ EN pin of the timer module, after the TTL signal is transmitted to the driving circuit, the TTL signal is adjusted to be a driving voltage of +/-15V, and the TTL signal is connected to the START pin of the timer module to trigger the starting signal. The driving wave waveform is shown in fig. 8.
The ultrasonic signal of the driving wave excitation probe A is received by the probe B after passing through a pipeline fluid medium, the voltage reference of the signal received by the probe B is VCC _ OFFSET after passing through a bias circuit, and after filtering and gain amplification, the echo signal is as shown in a channel 2 of fig. 9.
To obtain the peak voltage of the echo signal, it is constructed by a peak sampling and discharging circuit, and the peak sampling voltage waveform is as channel 1 in fig. 10.
After the echo signals are compared by the threshold value and compared by the zero crossing point, STOP pulse signals of the zero crossing point are output, as shown in fig. 11.
The timer module counts FS and CNT between START and STOP signals, and the time between the transmission of the ultrasound to the reception of the echo can be calculated by the following algorithm: TIME =1/Fs × CNT.
Example 2
One embodiment of the method for measuring the propagation time of ultrasonic waves of the present invention comprises the following steps:
s1, driving pulse is carried out on an ultrasonic sensor arranged at the upstream;
s2, adjusting the analog signal of the echo to be a pulse signal with a time characteristic in a downstream ultrasonic sensor;
and S3, calculating the counting value of the pulse signals from the START of driving to the echo by using a timer module, and converting the counting value into TIME, wherein the calculation formula is TIME =1/Fs x CNT, wherein Fs is the timing frequency of the timer module, and CNT is the counting value of the timer between the START signal and the STOP signal.
More specifically, the adjustment of the analog signal of the echo to the pulse signal having the time characteristic in step S2 is realized by integrating the piezoelectric of the ultrasonic echo through the processes of bias, filtering, amplification, peak hold, threshold comparison, and zero-crossing point comparison.
More specifically, in step S2, the above-mentioned circuit for measuring the propagation time of the ultrasonic wave is used to implement the rewarding signal processing procedure.
The invention uses a high-speed timer module, and a filter circuit, a peak value holding circuit, a threshold value comparison circuit and a zero crossing point comparison circuit are matched to finally convert the echo signal of the ultrasonic wave into a pulse signal of a zero crossing point, realize the counting of the time interval of two pulse signals and calculate the interval time of two pulses, namely the propagation time of the ultrasonic wave.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (8)

1. A circuit for measuring ultrasonic transit time, comprising: the method comprises the following steps: the device comprises an MCU unit, a driving module, a timer module, a biasing circuit, a filter circuit, a VGA gain adjusting circuit, a peak value holding discharge circuit, a threshold comparison circuit and a zero crossing point comparison circuit; the driving module is connected with the timer module, and the biasing circuit, the filter circuit, the VGA gain adjusting circuit, the peak value holding discharge circuit, the threshold value comparison circuit, the zero crossing point comparison circuit and the timer module are sequentially connected; the MCU unit is used for setting a driving module and triggering the timer module.
2. The circuit and method for measuring ultrasonic wave propagation time according to claim 1, wherein: the drive module comprises an ultrasonic drive circuit, the ultrasonic drive circuit comprises a dual-channel gate driver and a multi-channel signal switching circuit formed by a plurality of analog switching switches, and the upstream and downstream ultrasonic sensors can be controlled to be in a driving and receiving mode by controlling the switching logic of the analog switching switches.
3. The circuit for measuring ultrasonic transit time of claim 2, wherein: the VGA GAIN adjustment circuit comprises a variable GAIN amplifier with a GAIN range of 80dB, amplifies a weak signal into an echo signal with the amplitude of 500-100mV on the basis of VCC _ OFFSET bias, and can dynamically adjust the amplitude of an output waveform through a GAIN pin.
4. The circuit for measuring ultrasonic transit time of claim 3, wherein: the PEAK value holding discharge circuit is connected to the diode through the output of the operational amplifier, two capacitors are charged in a single direction, and the ADC _ PEAK network label is the PEAK voltage signal of the echo signal.
5. A circuit for measuring ultrasonic travel time according to any of claims 1 to 4, wherein: the timer module is used for recording a count value from a START signal to a STOP signal after enabling an EN _ START pin, triggering the START signal when a driving pulse is sent, generating a zero pulse signal after an acoustic wave passes through a pipeline medium and transmitting the zero pulse signal to a downstream probe after the acoustic wave passes through a pipeline medium and outputting the zero pulse signal to the STOP pin of the timer module after a VGA gain amplification adjusting circuit, comparing a threshold value and a zero crossing point, recording the count value between the START signal and the STOP signal, and finally calculating the propagation time between the START signal and the STOP signal.
6. A method of measuring ultrasonic transit time, comprising: the method comprises the following steps:
s1, driving pulses are carried out on an ultrasonic sensor arranged at the upstream/downstream;
s2, adjusting the analog signal of the echo to a pulse signal with time characteristics at the ultrasonic sensor at the lower/upper stream;
and S3, calculating the counting value of the pulse signals from the START of driving to the echo by using a timer module, and converting the counting value into TIME, wherein the calculation formula is TIME =1/Fs x CNT, wherein Fs is the timing frequency of the timer module, and CNT is the counting value of the timer between the START signal and the STOP signal.
7. The method of measuring ultrasonic transit time of claim 6, wherein: the adjustment of the analog signal of the echo to the pulse signal having the time characteristic in step S2 is achieved by integrating the piezoelectric of the ultrasonic echo through the processes of biasing, filtering, amplification, peak holding, threshold comparison, and zero-crossing point comparison.
8. The method of measuring ultrasonic transit time of claim 7, wherein: the step S2 is to implement a report signal processing procedure by using the circuit for measuring the propagation time of ultrasonic wave according to claim 1.
CN202110847861.3A 2021-07-27 2021-07-27 Circuit and method for measuring ultrasonic wave propagation time Pending CN113504389A (en)

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CN202110847861.3A CN113504389A (en) 2021-07-27 2021-07-27 Circuit and method for measuring ultrasonic wave propagation time
NL2032091A NL2032091B1 (en) 2021-07-27 2022-06-07 Circuit and method for measuring ultrasonic wave propagation time

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110847861.3A CN113504389A (en) 2021-07-27 2021-07-27 Circuit and method for measuring ultrasonic wave propagation time

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Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ243293A (en) * 1991-06-25 1995-03-28 Commw Scient Ind Res Org Fluid flow meter: time of travel of acoustic wave packet through fluid
US5277070A (en) * 1991-08-01 1994-01-11 Xecutek Corporation Ultrasonic gas flow measurement method and apparatus
CN1204397A (en) * 1995-10-19 1999-01-06 联邦科学及工业研究组织 Digital speed determination in ultrasonic flow measurements
SE517922C2 (en) * 2000-11-15 2002-08-06 Aake Stroemberg Method and apparatus for determining the velocity of a fluid
TWI258137B (en) * 2003-04-10 2006-07-11 Via Optical Solution Inc Method and related optical disk accessing apparatus for calibrating optical disk tilt servo system according to non-constant relation between locations and tilt angles of optical disk
US11326917B2 (en) * 2018-08-22 2022-05-10 Rohm Co., Ltd. Semiconductor integrated circuit device
CN110207771B (en) * 2019-06-14 2020-08-04 浙江启尔机电技术有限公司 Single-channel continuous multi-ultrasonic-signal synchronous timing circuit and timing method thereof

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NL2032091B1 (en) 2023-12-14

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