Sound wave flying time measuring device

Abstract

The invention discloses a sound wave flying time measuring device, and belongs to the field of sound wave measurement. The sound wave flying time measuring device comprises a control module, a pulse generation unit, a transducer assembly, a wave crest feature detection unit, a flying time measuring unit and a comparator assembly. The flying time measuring unit, the wave crest characteristic detecting unit and the pulse generating unit are electrically connected with the control module; the pulse generating unit is electrically connected with the transducer assembly, the comparator assembly and the flying time measuring unit, and the transducer assembly is electrically connected with the comparator assembly; the wave crest characteristic detection unit comprises a wave crest amplitude detection circuit, the wave crest amplitude detection circuit is electrically connected with the transducer assembly, the comparator assembly is electrically connected with the wave crest amplitude detection circuit and the flight time measurement unit, and the wave crest amplitude detection circuit is electrically connected with the flight time measurement unit and the control module; and the wave crest amplitude detection circuit can be reset.

Description

Technical Field

[0001] The present application belongs to the field of sound wave measurement, and specifically relates to a device for measuring the flight time of sound waves. Background Art

[0002] With the development of science and technology, the application of measurement by sound waves (including infrasound, sound waves with audible frequencies to human ears, and ultrasound) is becoming more and more widespread. Take the measurement of ultrasonic flight time as an example. Specifically, the ultrasonic wave is transmitted in the measuring tube, and the transmission time is affected by the fluid type and flow rate of the fluid in the measuring tube. Therefore, the parameter values ​​of the flow rate, flow rate, and other parameters of the fluid in the measuring tube can be determined by measuring the time of ultrasonic wave propagation and flight in the measuring tube, combined with the propagation speed of ultrasonic wave in the fluid. Among them, one or more groups of transducers are set at both ends of the measuring tube. When one end is used as an excitation transducer, the other end is used as a response transducer. After the excitation transducer is excited, an ultrasonic wave is generated. The ultrasonic wave propagates in the fluid in the measuring tube, and then the ultrasonic wave propagates to the response transducer. The time for the ultrasonic wave to propagate in the fluid in the measuring tube is regarded as the time interval from the excitation transducer generating the ultrasonic wave to the response transducer receiving the ultrasonic wave. The time for the ultrasonic wave to propagate in the fluid in the measuring tube is also called the flight time of the ultrasonic wave. By setting the position and direction of the transducer assembly, the acoustic wave flight time measurement technology can be used for ultrasonic ranging. However, in the related art, the method for measuring the flight time of ultrasonic flight cannot accurately determine the measurement result, especially in the case of noise interference, the measurement result will be inaccurate, resulting in inaccurate other parameters determined based on the flight time of ultrasonic flight. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a device for measuring the acoustic wave flight time, which at least solves the problem that the results of ultrasonic wave flight time measurement are inaccurate, resulting in inaccurate other parameters determined based on the ultrasonic wave flight time.

[0004] The embodiment of the present application provides a device for measuring the acoustic wave transit time, the device comprising: a control module, a pulse generating unit, a transducer component, a wave peak feature detecting unit, a transit time measuring unit and a comparator component;

[0005] The flight time measurement unit, the wave peak feature detection unit, and the pulse generation unit are all electrically connected to the control module; the pulse generation unit is electrically connected to the transducer assembly, the comparator assembly, and the flight time measurement unit, respectively, and the transducer assembly is electrically connected to the comparator assembly;

[0006] The peak feature detection unit includes a peak amplitude detection circuit, the peak amplitude detection circuit is electrically connected to the transducer assembly, the comparator assembly is electrically connected to the peak amplitude detection circuit and the flight time measurement unit, respectively, and the peak amplitude detection circuit is electrically connected to the flight time measurement unit and the control module, respectively;

[0007] The peak amplitude detection circuit is resettable; the peak amplitude detection circuit is used to detect and store the peak amplitude of the response voltage wave generated by the transducer assembly, and send the detection result to the control module, the control module determines whether the peak amplitude of the response voltage wave is attenuated; or the peak feature detection unit determines whether the peak amplitude of the response voltage wave is attenuated;

[0008] When it is determined that the peak amplitude of the response voltage wave has attenuated, the flight time measurement unit stops the measurement of the wave group and determines the stop time of the acoustic wave flight. The flight time measurement unit or the control module determines the acoustic wave flight time of the acoustic wave group based on the start time and stop time of the acoustic wave flight.

[0009] Optionally, the peak feature detection unit further includes a hysteresis comparison circuit, and the number of the peak amplitude detection circuits is two;

[0010] The two peak amplitude detection circuits are both electrically connected to the transducer assembly, and the two peak amplitude detection circuits are both electrically connected to the hysteresis comparison circuit;

[0011] One of the peak amplitude detection circuits is used to continuously detect and record the maximum value of the peak amplitude of the response voltage wave in the response voltage wave group transmitted from the transducer assembly, and transmit the detected and recorded maximum value of the peak amplitude of the response voltage wave to the hysteresis comparison circuit, and the other of the peak amplitude detection circuits is used to periodically detect and record the current peak amplitude of the response voltage wave according to the period of the response voltage wave, and transmit the detected and recorded current peak amplitude of the response voltage wave to the hysteresis comparison circuit, and the hysteresis comparison circuit is used to compare the maximum value of the peak amplitude of the transmitted response voltage wave and the current peak amplitude of the transmitted response voltage wave to determine whether the peak amplitude of the response voltage wave group is attenuated;

[0012] Wherein, the hysteresis ratio circuit is electrically connected to the control module.

[0013] Optionally, the peak amplitude detection circuit includes a first operational amplifier, a first diode, a first capacitor, a second diode, a third diode, a second capacitor and a second operational amplifier;

[0014] The positive connection end of the first operational amplifier is electrically connected to the transducer component and the comparator component, the first diode is connected in parallel to the first capacitor, and the first end of the first diode and the first end of the first capacitor are both electrically connected to the negative connection end of the first operational amplifier, the output end of the first operational amplifier is electrically connected to the second end of the first diode, the second end of the first capacitor and the first end of the second diode respectively, the second end of the second diode is electrically connected to the first end of the third diode, the second end of the third diode is electrically connected to the first end of the second capacitor, the second end of the second capacitor is grounded, the first end of the second capacitor is electrically connected to the positive connection end of the second operational amplifier, the negative connection end of the second operational amplifier is electrically connected to the output end of the second operational amplifier, the negative connection end of the second operational amplifier is electrically connected to the negative connection end of the first operational amplifier, and the output end of the second operational amplifier is electrically connected to the control module;

[0015] The second capacitor is used to store the electric energy corresponding to the peak amplitude of the response voltage wave.

[0016] Optionally, the peak amplitude detection circuit further includes a first switch tube;

[0017] The first end of the first switch tube is electrically connected to the first end of the second capacitor, the second end of the first switch is grounded, and the third end of the first switch tube is electrically connected to the control module;

[0018] When the first end of the first switch tube and the second end of the first switch tube are turned on, the electric energy on the second capacitor becomes zero, so that the second capacitor is reset.

[0019] Optionally, the peak amplitude detection circuit further includes a first resistor, a second resistor and a third resistor;

[0020] The first end of the first resistor is electrically connected to the transducer component and the comparator component, the second end of the first resistor is electrically connected to the positive connection terminal of the first operational amplifier, the first end of the second resistor is electrically connected to the negative connection terminal of the first operational amplifier, the second end of the second resistor is electrically connected to the first end of the third resistor, the first end of the third resistor is electrically connected to the negative connection terminal of the second operational amplifier, and the second end of the third resistor is electrically connected to the second end of the second diode.

[0021] Optionally, the peak amplitude detection circuit further includes a fourth resistor;

[0022] The first end of the fourth resistor is electrically connected to the third end of the first switch tube, and the second end of the fourth resistor is electrically connected to the control module, so that the third end of the first switch tube is electrically connected to the control module.

[0023] Optionally, the peak feature detection unit further includes an analog-to-digital converter;

[0024] The output end of the second operational amplifier is electrically connected to the analog input end of the analog-to-digital converter, and the digital interface end of the analog-to-digital converter is electrically connected to the control module.

[0025] Optionally, the hysteresis comparison circuit includes a threshold adjustment circuit, a difference comparison circuit, and a loopback comparator;

[0026] The threshold adjustment circuit is used to adjust the comparison threshold of the loopback comparator. The threshold adjustment circuit includes a first adjustment resistor, a second adjustment resistor, an adjustable resistor, a first adjustment capacitor, a third operational amplifier, and a programmable potentiometer. The first end of the first adjustment resistor is connected to a power supply, the second end of the first adjustment resistor is electrically connected to the first end of the second adjustment resistor, the second end of the second adjustment resistor is electrically connected to the first end of the adjustable resistor, the second end of the adjustable resistor is grounded, the first end of the first adjustment capacitor is electrically connected to the first end of the second adjustment resistor, the second end of the first adjustment capacitor is electrically connected to the second end of the adjustable resistor, the first end of the second adjustment resistor is electrically connected to the positive connection end of the third operational amplifier, the negative connection end of the third operational amplifier is electrically connected to the output end of the third operational amplifier, the output end of the third operational amplifier is electrically connected to the programmable potentiometer, and the programmable potentiometer is electrically connected to the positive connection end of the loopback comparator;

[0027] The difference comparison circuit comprises a difference comparator, a negative connection terminal of the difference comparator is electrically connected to one of the peak amplitude detection circuits, a positive connection terminal of the difference comparator is electrically connected to another of the peak amplitude detection circuits, and an output terminal of the difference comparator is electrically connected to a negative connection terminal of the loopback comparator;

[0028] The output end of the loopback comparator is electrically connected to the positive connection end of the loopback comparator through a fifth adjustment resistor, and the output end of the loopback comparator is electrically connected to the control module and / or the flight time measurement unit.

[0029] Optionally, the difference comparison circuit further includes a sixth adjustment resistor, a seventh adjustment resistor, an eighth adjustment resistor and a ninth adjustment resistor;

[0030] The first end of the sixth adjustment resistor is electrically connected to an output end of the peak amplitude detection circuit, the second end of the sixth adjustment resistor is electrically connected to the positive connection end of the difference comparator, the first end of the seventh adjustment resistor is connected to a voltage source, and the second end of the seventh adjustment resistor is electrically connected to the second end of the sixth adjustment resistor;

[0031] The first end of the eighth adjustment resistor is electrically connected to another of the peak amplitude detection circuits, the second end of the eighth adjustment resistor is electrically connected to the negative connection end of the difference comparator, the first end of the ninth adjustment resistor is electrically connected to the second end of the eighth adjustment resistor, and the second end of the ninth adjustment resistor is electrically connected to the output end of the difference comparator.

[0032] Optionally, the hysteresis comparison circuit further includes an inverter;

[0033] The first end of the inverter is electrically connected to the output end of the loopback comparator, and the second end of the inverter is electrically connected to the control module and / or the flight time measurement unit.

[0034] Optionally, the hysteresis comparison circuit further includes: a tenth adjustment resistor, an eleventh adjustment resistor, an adjustment diode and a second adjustment capacitor;

[0035] A first end of the tenth adjustment resistor is electrically connected to the output end of the loopback comparator, a second end of the tenth adjustment resistor is electrically connected to a first end of the adjustment diode, a second end of the adjustment diode is electrically connected to a first end of the inverter, a first end of the eleventh adjustment resistor is electrically connected to a first end of the tenth adjustment resistor, a second end of the eleventh adjustment resistor is electrically connected to a first end of the second adjustment capacitor, a first end of the second adjustment capacitor is also electrically connected to a second end of the adjustment diode, and a second end of the second adjustment capacitor is grounded.

[0036] In an embodiment of the present application, a peak feature detection unit and a control module are provided so that whether the peak amplitude is attenuated can be determined by the peak feature detection unit or the control module. Once it is determined that the peak amplitude begins to attenuate, the flight time measurement unit stops the measurement of the current wave group. The flight time measurement unit determines the stop time of the acoustic wave flight. This stop time is an accurate time, and the start time of the acoustic wave flight is certain. Therefore, based on the determined start time and the accurate stop time, the acoustic wave flight time can be accurately determined, and then the corresponding other parameters can be more accurately determined according to the acoustic wave flight time. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram showing a device for measuring acoustic wave transit time provided in an embodiment of the present application;

[0038] Figure 2 One of the schematic diagrams showing a peak feature detection unit provided in an embodiment of the present application;

[0039] Figure 3 A schematic diagram showing an application circuit of an analog-to-digital converter provided in an embodiment of the present application;

[0040] Figure 4 A schematic diagram showing a resettable peak value detection circuit provided in an embodiment of the present application;

[0041] Figure 5 A schematic diagram showing a comparator with adjustable hysteresis voltage provided in an embodiment of the present application;

[0042] Figure 6 A second schematic diagram showing a peak feature detection unit provided in an embodiment of the present application;

[0043] Figure 7 A third schematic diagram showing a peak feature detection unit provided in an embodiment of the present application.

[0044] Reference numerals:

[0045] 001: power supply; 002: voltage source; 10: control module; 20: pulse generating unit; 30: transducer assembly; 40: peak characteristic detection unit; 41: peak amplitude detection circuit; 411: first operational amplifier; 412: first diode; 413: first capacitor; 414: second diode; 415: third diode; 416: second capacitor; 417: second operational amplifier; 418: first switch tube; 419: first resistor; 4191: second resistor; 4192: third resistor; 4193: fourth resistor; 4194: fifth resistor; 42: hysteresis comparison circuit; 421: threshold adjustment circuit; 4211: first adjustment resistor; 4212: third resistor; 4213: fourth resistor; 4214: fifth resistor; 4215: fifth resistor; 4216: fifth resistor; 4217: fifth resistor; 4218: fifth resistor; 4219: fifth resistor; 42 ... The second adjustment resistor; 4213: adjustable resistor; 4214: first adjustment capacitor; 4215: third operational amplifier; 4216: programmable potentiometer; 422: difference comparison circuit; 4221: difference comparator; 4222: sixth adjustment resistor; 4223: seventh adjustment resistor; 4224: eighth adjustment resistor; 4225: ninth adjustment resistor; 423: loopback comparator; 4231: fifth adjustment resistor; 424: inverter; 425: tenth adjustment resistor; 426: eleventh adjustment resistor; 427: adjustment diode; 428: second adjustment capacitor; 429: inverting resistor; 43: analog-to-digital converter; 50: flight time measurement unit; 60: comparator component. DETAILED DESCRIPTION

[0046] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0047] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0048] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] like Figures 1 to 7 As shown, the acoustic wave flight time measuring device includes: a control module 10, a pulse generating unit 20, a transducer assembly 30, a wave peak feature detecting unit 40, a flight time measuring unit 50 and a comparator assembly 60;

[0050] The flight time measurement unit 50, the peak feature detection unit 40, and the pulse generation unit 20 are all electrically connected to the control module 10; the pulse generation unit 20 is electrically connected to the transducer assembly 30, the comparator assembly 60 and the flight time measurement unit 50, and the transducer assembly 30 is electrically connected to the comparator assembly 60; the peak feature detection unit 40 includes a peak amplitude detection circuit 41, the peak amplitude detection circuit 41 is electrically connected to the transducer assembly 30, the comparator assembly 60 is electrically connected to the peak amplitude detection circuit 41 and the flight time measurement unit 50, and the peak amplitude detection circuit 41 is electrically connected to the flight time measurement unit 50 and the control module 10 Connect; the peak amplitude detection circuit 41 can be reset; the peak amplitude detection circuit 41 is used to detect and store the peak amplitude of the response voltage wave generated by the transducer assembly 30, and send the detection result to the control module 10, the control module 10 determines whether the peak amplitude of the response voltage wave is attenuated; or, the peak feature detection unit 40 determines whether the peak amplitude of the response voltage wave is attenuated; when it is determined that the peak amplitude of the response voltage wave is attenuated, the flight time measurement unit 50 stops the current wave group measurement and determines the stop time of the sound wave flight. The flight time measurement unit 50 or the control module 10 determines the sound wave flight time of the sound wave group according to the start time and stop time of the sound wave flight.

[0051] It should be noted that the initial pulse group generated by the pulse generating unit 20 is usually a periodic square wave or rectangular wave pulse. Of course, the initial pulse group generated by the pulse generating unit 20 can also be a periodic triangle wave. The specific type of the initial pulse group generated by the pulse generating unit 20 is not limited in the embodiment of the present application. For the sake of convenience, the embodiment of the present application takes the initial pulse group generated by the pulse generating unit 20 as a periodic square wave to illustrate the principle of the invention. Correspondingly, the ultrasonic group and the response voltage wave are quasi-sine waves.

[0052] When the peak amplitude of the response voltage wave in the response voltage wave group is detected by the peak feature detection unit 40, the peak feature detection unit 40 sends the detected peak amplitude to the control module 10, and the control module 10 determines whether the peak amplitude is attenuated. Once the control module 10 determines that the peak amplitude is attenuated, the control module 10 controls the flight time measurement unit 50 to stop the current wave group measurement; or, when the peak peak value of the response voltage wave is detected by the peak feature detection unit 40, and it is determined whether the peak amplitude is attenuated, once the peak feature detection unit 40 determines that the peak amplitude is attenuated, the peak feature detection unit 40 sends an attenuation flag signal to the flight time measurement unit 50, and the attenuation flag signal includes a peak amplitude attenuation flag signal. When the flight time measurement unit 50 receives the attenuation flag signal, it stops the current wave group measurement.

[0053] In the embodiment of the present application, since the flight time measurement unit 50, the peak feature detection unit 40, and the pulse generation unit 20 are all electrically connected to the control module 10, the flight time measurement unit 50, the peak feature detection unit 40, and the pulse generation unit 20 can be controlled by the control module 10, or send signals to the control module 10, or the control module 10 can collect required data from the flight time measurement unit 50 and the peak feature detection unit 40. Since the pulse generation unit 20 is electrically connected to the transducer assembly 30, the comparator assembly 60, and the flight time measurement unit 50, respectively, once the pulse generation unit 20 generates an initial pulse group, the initial pulse group can be transmitted to the flight time measurement unit 50, the comparator assembly 60, and the transducer assembly 30. After the initial pulse group is transmitted to the comparator assembly 60, the comparator assembly 60 can continue to transmit the initial pulse group to the flight time measurement unit 50, so that the flight time measurement unit 50 can use the time of receiving the initial pulse group as the start time of the acoustic wave flight. After receiving the initial pulse group, the transducer assembly 30 can be excited so that the transducer assembly 30 generates and emits an acoustic wave group, and the transducer assembly 30 generates a response voltage wave group when receiving the acoustic wave group. Since the transducer assembly 30 is electrically connected to the comparator assembly 60, the comparator assembly 60 is electrically connected to the peak feature detection unit 40, and the peak feature detection unit 40 is electrically connected to the transducer assembly 30, the flight time measurement unit 50 and the control module 10, once the transducer assembly 30 generates a response voltage wave group, the response voltage wave group can be transmitted to the peak feature detection unit 40 and the comparator assembly 60. After receiving the response voltage wave group, the comparator assembly 60 can compare and output a comparison pulse to the flight time measurement unit 50. The essence of the comparison pulse is to convert the quasi-sine wave of the response voltage wave group into a rectangular pulse that can be measured by flight, and transmit it to the flight time measurement unit 50 for flight time measurement, and the peak feature detection unit 40 can perform real-time detection on the response voltage wave group. The peak feature detection unit 40 detects the peak amplitude of the response voltage wave group and determines whether the peak amplitude is attenuated, or the peak feature detection unit 40 detects the peak amplitude and sends the detected peak amplitude to the control module 10, and the control module 10 determines whether the peak amplitude is attenuated. Once it is determined that the waveform amplitude is attenuated, the flight time measurement unit 50 immediately stops the current wave group measurement, and uses the target time point of the response voltage wave of the target cycle before the time point at which the peak feature detection unit 40 detects the peak amplitude of the response voltage wave group attenuation as the stop time of the acoustic wave flight. After determining the start time and stop time for the flight time measurement, the acoustic wave flight time of the acoustic wave group can be determined.In addition, the peak amplitude detection circuit 41 can be reset, so that the peak amplitude detection circuit 41 can be reset within the period of the response voltage wave, thereby realizing the detection of the response voltage wave of each period to determine whether the response voltage wave is attenuated. Once the peak amplitude of the response voltage wave is attenuated, it can be quickly determined, that is, it can be quickly determined whether the peak amplitude is attenuated.

[0054] That is, in the embodiment of the present application, by setting up the peak feature detection unit 40 and the control module 10, it is possible to determine whether the peak amplitude is attenuated through the peak feature detection unit 40 or the control module 10. Once it is determined that the peak amplitude begins to attenuate, the flight time measurement unit 50 stops the current wave group measurement. The flight time measurement unit 50 determines the stop time of the sound wave flight. This stop time is an accurate time, and the start time of the sound wave flight is determined. Therefore, based on the determined start time and the accurate stop time, the sound wave flight time can be accurately determined, and then the corresponding other parameters can be more accurately determined according to the sound wave flight time.

[0055] It should be noted that after the pulse generating unit 20 generates the initial pulse group, the initial pulse group is transmitted to the transducer assembly 30, which can stimulate the transducer assembly 30 to generate and emit a sound wave group. The transducer assembly 30 that is not driven by the pulse generating unit 20 generates a response voltage wave group after receiving the sound wave group. Since the initial pulse group is a periodic pulse, the response wave in the response voltage wave group is a quasi-sine wave. When the response wave reaches resonance, the response wave at this time is also periodic, and the response period is the same as the period of the initial pulse group. In this process, the initial pulse group is transmitted to the transducer assembly 30, the transducer assembly 30 generates and emits a sound wave group, and the sound wave group is transmitted to the transducer assembly 30, so that the transducer assembly 30 that is not driven by the pulse generating unit 20 generates a response voltage wave group, which is equivalent to the initial pulse group continuously exciting the transducer assembly 30 to generate and emit a sound wave group. The sound wave group is a mechanical wave. The receiving transducer assembly 30 generates a response voltage wave group under the excitation of the received sound wave group. With the continuous excitation of the sound wave group, the peak amplitude of the response voltage wave group must gradually increase until the receiving transducer assembly 30 reaches a resonant state with the same period as the initial pulse group. At this time, the peak amplitude of the response voltage wave in the response voltage wave group remains unchanged, and the peak amplitude reaches the maximum value. Once the pulse generating unit 20 stops generating the initial pulse group, it is equivalent to stopping the energy output to the transmitting transducer assembly 30, and the transmitting transducer assembly 30 immediately stops generating and transmitting the acoustic wave group. Since the acoustic wave group stops exciting the receiving transducer, the response voltage wave in the response voltage wave group generated by the receiving transducer assembly 30 will inevitably begin to decay, that is, the peak amplitude of the response voltage wave will inevitably begin to decay. When the peak feature detection unit 40 detects that the peak amplitude of the response voltage wave begins to decay, it sends an attenuation mark signal to the control module 10 and the flight time measurement unit 50, and the flight time measurement unit 50 immediately stops measuring and determines the stop time; or the peak feature detection unit 40 sends the detected peak amplitude to the control module 10, and when the control module 10 detects that the peak amplitude of the response voltage wave begins to decay, the control module 10 notifies the flight time measurement unit 50 to immediately stop measuring and determine the stop time. The stop time can be the target time point of the response voltage wave of the target cycle before the peak amplitude of the response voltage wave begins to decay. For example, when the receiving transducer generates a response voltage wave group, if the response voltage wave starts to decay, the target time of the response voltage wave in the previous response cycle adjacent to the decay start time before the decay starts can be used as the stop time.

[0056] Since the peak amplitude of the response voltage wave will inevitably decay after the initial pulse group is emitted, the event of the peak amplitude of the response voltage wave decaying is a deterministic event, and the attenuated first wave can be accurately detected. Therefore, the flight time measurement unit 50 can accurately determine the stop time of the sound wave flight, and the time when the flight time measurement unit 50 receives the initial pulse group is certain and accurate, that is, the start time determined by the flight time measurement unit 50 is accurate, so based on the accurate start time and the accurate stop time, the sound wave flight time can be accurately determined.

[0057] It should be noted that, in the embodiment of the present application, the transducer assembly 30 is an energy conversion device that can work bidirectionally, and can both emit sound waves and receive sound waves. That is, after the transducer assembly 30 driven by the pulse generating unit 20 receives the initial pulse group, the transducer assembly 30 can be excited to generate and emit a sound wave group, and the transducer assembly 30 not driven by the pulse generating unit 20 will be excited to generate a response voltage wave group when receiving the sound wave group.

[0058] In addition, in some embodiments, Figure 2 As shown, the peak amplitude detection circuit 41 may include a first operational amplifier 411, a first diode 412, a first capacitor 413, a second diode 414, a third diode 415, a second capacitor 416 and a second operational amplifier 417; the positive connection end of the first operational amplifier 411 is electrically connected to the transducer component 30 and the comparator component 60, the first diode 412 is connected in parallel with the first capacitor 413, and the first end of the first diode 412 and the first end of the first capacitor 413 are both electrically connected to the negative connection end of the first operational amplifier 411, and the output end of the first operational amplifier 411 is respectively connected to the second end of the first diode 412, the second end of the first capacitor 413 and the second diode 414. The first end of the second diode 414 is electrically connected to the first end of the third diode 415, the second end of the third diode 415 is electrically connected to the first end of the second capacitor 416, the second end of the second capacitor 416 is grounded, the first end of the second capacitor 416 is electrically connected to the positive connection end of the second operational amplifier 417, the negative connection end of the second operational amplifier 417 is electrically connected to the output end of the second operational amplifier 417, the negative connection end of the second operational amplifier 417 is electrically connected to the negative connection end of the first operational amplifier 411, and the output end of the second operational amplifier 417 is electrically connected to the control module 10; wherein the second capacitor 416 is used to store the electric energy corresponding to the peak amplitude of the response voltage wave.

[0059] Through such a setting, the voltage on the second capacitor 416 is equivalent to the voltage on the positive connection terminal of the second operational amplifier 417, the voltage on the negative connection terminal of the second operational amplifier 417 and the voltage on the output terminal of the second operational amplifier 417, and the analog signal of the response voltage wave output from the comparator component 60 can be input to the positive connection terminal of the first operational amplifier 411. At this time, within a response cycle of the propagation of the response voltage wave, once the voltage on the second capacitor 416 is less than the voltage of the response voltage wave, the first diode 412 is reverse biased, and the first operational amplifier 411 is equivalent to an amplifier with a large gain, so that the first operational amplifier 411 outputs a high level and charges the second capacitor 416 through the second diode 414 and the third diode 415 until the voltage of the second capacitor 416 is equal to the voltage of the peak value of the response voltage wave, so that the second capacitor 416 stores the voltage of the peak value; once the voltage of the response voltage wave decreases, that is, when the response voltage wave moves from the peak to the trough, the positive connection terminal of the first operational amplifier 411 The voltage at the end is less than the voltage of the second capacitor 416, and the first operational amplifier 411 outputs a low level, so that the first diode 412 is forward biased. At this time, the first operational amplifier 411 is equivalent to a follower, so that the output end of the first operational amplifier 411 will not be negatively saturated, and the second diode 414 and the third diode 415 are reverse biased and will not be charged, that is, the charge of the second capacitor 416 is prevented from being released through the second diode 414 and the third diode 415, ensuring that the charge and voltage on the second capacitor 416 are maintained, so that the second capacitor 416 stores the voltage corresponding to the peak amplitude of the response voltage wave, and then the second operational amplifier 417 can transmit the voltage corresponding to the peak amplitude to the control module 10, so that the control module 10 can obtain the voltage value corresponding to the peak amplitude of each response cycle of the response voltage wave. When the response voltage wave is attenuated, the control module 10 can determine that the peak amplitude of the response voltage wave begins to attenuate; or, the peak feature detection unit determines whether the peak amplitude of the response voltage wave is attenuated.

[0060] For example, in the three response cycles of the response voltage wave, in the first response cycle, the voltage corresponding to the peak amplitude stored in the second capacitor 416 is 2V, in the second response cycle, the voltage corresponding to the peak amplitude stored in the second capacitor 416 is 3V, and in the third response cycle, the voltage corresponding to the peak amplitude stored in the second capacitor 416 is 2.4V. After the control module 10 obtains the voltage of the peak amplitude in each response cycle of the three response cycles of the response voltage wave, it can be determined that the peak amplitude of the response voltage wave begins to attenuate from the second response cycle.

[0061] In addition, in some embodiments, Figure 2As shown, the peak amplitude detection circuit 41 also includes a first switch tube 418; the first end of the first switch tube 418 is electrically connected to the first end of the second capacitor 416, the second end of the first switch is grounded, and the third end of the first switch tube 418 is electrically connected to the control module 10; when the first end of the first switch tube 418 and the second end of the first switch tube 418 are turned on, the electric energy on the second capacitor 416 becomes zero to reset the second capacitor 416.

[0062] Through such a setting, once the peak amplitude of the response voltage wave is sampled by the second capacitor 416 within a response cycle of the response voltage wave, that is, within a response cycle, the second capacitor 416 has stored the voltage corresponding to the peak amplitude of the response voltage wave in the current response cycle, and the second operational amplifier 417 can transmit the peak amplitude of the response voltage wave stored in the second capacitor 416 to the control module 10 in the form of a digital signal, so that the control module 10 stores the voltage value corresponding to the peak amplitude of the response voltage wave in the current response cycle. In the next response cycle, once the first end of the first switch tube 418 and the second end of the first switch tube 418 are controlled to be turned on, the first end of the second capacitor 416 can be turned on to the ground, so that the charge on the second capacitor 416 is released to the ground, and the voltage on the second capacitor 416 becomes 0, so that the second capacitor 416 can continue to store the voltage corresponding to the peak amplitude of the response voltage wave in the next propagation cycle in the next response cycle.

[0063] In addition, the leakage of the third diode 415 can be effectively reduced by providing the second diode 414 .

[0064] In addition, in some embodiments, Figure 2 As shown, the peak amplitude detection circuit 41 also includes a first resistor 419, a second resistor 4191 and a third resistor 4192; the first end of the first resistor 419 is electrically connected to the transducer component 30 and the comparator component 60, the second end of the first resistor 419 is electrically connected to the positive connection terminal of the first operational amplifier 411, the first end of the second resistor 4191 is electrically connected to the negative connection terminal of the first operational amplifier 411, the first end of the second resistor 4191 is electrically connected to the first end of the third resistor 4192, the first end of the third resistor 4192 is electrically connected to the negative connection terminal of the second operational amplifier 417, and the second end of the third resistor 4192 is electrically connected to the second end of the second diode 414.

[0065] Among them, the resistance value of the second resistor 4191 can be greater than the forward resistance of the first diode 412 when the first diode 412 is forward biased, and the resistance value of the second resistor 4191 can be less than the reverse resistance of the first diode 412 when the first diode 412 is reverse biased. In addition, by setting the second resistor 4191, the second resistor 4191 can make the first operational amplifier 411 play the role of amplification of the operational amplifier, that is, when the voltage of the positive connection terminal of the first operational amplifier 411 is greater than the voltage of the negative connection terminal, the first operational amplifier 411 plays an amplification role, and can also make the first operational amplifier 411 play a following role, that is, when the voltage of the positive connection terminal of the first operational amplifier 411 is less than the voltage of the negative connection terminal, the first operational amplifier 411 plays a following role. In addition, by setting the second resistor 4191, a bias current will be input to the negative connection terminal of the first operational amplifier 411, and by setting the first resistor 419, the first resistor 419 can offset the influence of the bias current input to the first operational amplifier 411 caused by the second resistor 4191. In addition, by setting the third resistor 4192, a reverse bias current can be provided to the second diode 414 through the third resistor 4192, that is, the third resistor 4192 provides a very small bias current to the reverse leakage of the second diode 414, so that the voltage drop on the third resistor 4192 is very small, and thus the voltage difference between the two ends of the third diode 415 is very small, thereby reducing the leakage current of the third diode 415, so that the charge and voltage of the second capacitor 416 remain stable within a sampling period.

[0066] In addition, in the embodiments of the present application, Figure 2 As shown, the peak amplitude detection circuit 41 also includes a fourth resistor 4193; the first end of the fourth resistor 4193 is electrically connected to the third end of the first switch tube 418, and the second end of the fourth resistor 4193 is electrically connected to the control module 10, so that the third end of the first switch tube 418 is electrically connected to the control module 10, so that the control module 10 or other control circuits can control the first switch tube 418 to switch between the two states of being conductive or non-conductive to the ground, thereby controlling the power of the second capacitor 416 to be maintained or discharged, thereby realizing the detection and reset of the peak amplitude detection circuit. And through such a setting, when the first switch tube 418 is a triode, the triode has a base current, and the base current of the triode can be limited by the fourth resistor 4193 to ensure that the triode is controlled by the control module 10 to achieve conduction.

[0067] In addition, in the embodiments of the present application, Figure 2As shown, the peak amplitude detection circuit 41 may further include a fifth resistor 4194, a first end of the fifth resistor 4194 is electrically connected to the output end of the second operational amplifier 417, and a second end of the fifth resistor 4194 is electrically connected to the analog-to-digital converter 43. Thus, the fifth resistor 4194 can form a low-pass filter with the capacitor at the input end of the analog-to-digital converter 43 to avoid conversion errors caused by noise input to the analog-to-digital converter 43, thereby affecting the correct operation of the analog-to-digital converter 43.

[0068] In addition, in the embodiment of the present application, when the first switch tube 418 is a MOS tube or an analog switch chip, the fourth resistor 4193 may not be provided.

[0069] In addition, in some embodiments, Figure 4 As shown, the peak feature detection unit 40 further includes an analog-to-digital converter 43; the output end of the second operational amplifier 417 is electrically connected to the analog-to-digital converter 43, and the analog-to-digital converter 43 is electrically connected to the control module 10. Through such a configuration, the analog signal flowing out of the peak amplitude detection circuit 41 can be converted into a digital signal by the analog-to-digital converter 43, so that the type-converted signal can be acquired and identified by the control module 10, thereby facilitating the control module 10 to subsequently determine whether the peak amplitude of the response voltage wave is attenuated.

[0070] In addition, in some embodiments, Figure 6 As shown, the peak feature detection unit 40 may also include a hysteresis comparison circuit 42, and the number of the peak amplitude detection circuits 41 is two; the two peak amplitude detection circuits 41 are both electrically connected to the transducer assembly 30, and the two peak amplitude detection circuits 41 are both electrically connected to the hysteresis comparison circuit 42; one peak amplitude detection circuit 41 is used to continuously detect and record the maximum value of the peak amplitude of the response voltage wave in the response voltage wave group generated by the excitation of the receiving transducer assembly 30, and transmit the detected and recorded maximum value of the peak amplitude of the response voltage wave group to A hysteresis comparison circuit 42 and another peak amplitude detection circuit 41 are used to periodically detect and record the peak amplitude of the current response voltage wave according to the response period of the response voltage wave, and transmit the detected and recorded peak amplitude of the current response voltage wave to the hysteresis comparison circuit 42. The hysteresis comparison circuit 42 is used to compare the maximum value of the peak amplitude of the transmitted response voltage wave group and the peak amplitude of the transmitted current response voltage wave to determine whether the peak amplitude of the response voltage wave group is attenuated; wherein, the hysteresis ratio circuit is electrically connected to the control module 10.

[0071] By setting up the hysteresis comparison circuit 42, it is equivalent to determining whether the peak amplitude of the response voltage wave is attenuated through the hysteresis comparison circuit 42, thereby avoiding determining whether the peak amplitude of the response voltage wave is attenuated through the control module 10, so that the peak feature detection unit 40 itself can determine whether the peak amplitude of the response voltage wave is attenuated, that is, avoiding the signal from flowing to the control module 10, so as to determine whether the peak amplitude of the response voltage wave is attenuated, thereby effectively improving the response time of the measurement device of the acoustic wave flight time.

[0072] In addition, in some embodiments, Figure 5 As shown, the hysteresis comparison circuit 42 includes a threshold adjustment circuit 421, a difference comparison circuit 422, and a loopback comparator 423; the threshold adjustment circuit 421 is used to adjust the comparison threshold of the loopback comparator 423, and the threshold adjustment circuit 421 includes a first adjustment resistor 4211, a second adjustment resistor 4212, an adjustable resistor 4213, a first adjustment capacitor 4214, a third operational amplifier 4215, and a programmable potentiometer 4216. The first end of the first adjustment resistor 4211 is connected to the power supply 001, the second end of the first adjustment resistor 4211 is electrically connected to the first end of the second adjustment resistor 4212, the second end of the second adjustment resistor 4212 is electrically connected to the first end of the adjustable resistor 4213, the second end of the adjustable resistor 4213 is grounded, the first end of the first adjustment capacitor 4214 is electrically connected to the first end of the second adjustment resistor 4212, the second end of the first adjustment capacitor 4214 is electrically connected to the second end of the adjustable resistor 4213, and the first end of the second adjustment resistor 4212 is electrically connected to the third operational amplifier. The positive connection terminal of the third operational amplifier 4215 is electrically connected to the positive connection terminal of the loopback comparator 423; the negative connection terminal of the third operational amplifier 4215 is electrically connected to the output terminal of the third operational amplifier 4215 through the programmable potentiometer 4216 and the fifth adjustment resistor 4231; the output terminal of the third operational amplifier 4215 is electrically connected to the programmable potentiometer 4216; the programmable potentiometer 4216 is electrically connected to the positive connection terminal of the loopback comparator 423; the difference comparison circuit 422 includes a difference comparator 4221, and the negative connection terminal of the difference comparator 4221 is electrically connected to the output terminal of the third operational amplifier 4215 through the programmable potentiometer 4216 and the fifth adjustment resistor 4231. The positive connection end of the difference comparator 4221 is electrically connected to a peak amplitude detection circuit 41, the positive connection end of the difference comparator 4221 is electrically connected to another peak amplitude detection circuit 41, and the output end of the difference comparator 4221 is electrically connected to the negative connection end of the loopback comparator 423; the output end of the loopback comparator 423 is electrically connected to the positive connection end of the loopback comparator 423 through the fifth adjustment resistor 4231, and the output end of the loopback comparator 423 is electrically connected to the control module 10 and / or the flight time measurement unit 50.

[0073] The voltage transmitted by the power supply 001 is divided by the adjustable resistor 4213, the first adjustment resistor 4211, and the second adjustment resistor 4212. The divided voltage can be used as the lowest voltage threshold of the loopback comparator 423. The loopback value of the loopback comparator 423 can be configured by the programmable potentiometer 4216, so that the highest voltage threshold of the loopback comparator 423 can be determined, that is, the sum of the lowest voltage threshold and the loopback value is used as the highest voltage threshold of the loopback comparator 423.

[0074] For example, the lowest voltage threshold of the loopback comparator 423 is VIL, the loopback value is Vhb, and the highest voltage threshold of the loopback comparator 423 is VIH, VIH=Vhb+VIL.

[0075] In addition, by determining the highest voltage threshold and the lowest voltage threshold of the loopback comparator 423, the loopback comparator 423 can effectively filter out noise, that is, once the voltage value of the signal input to the loopback comparator 423 is between the lowest voltage threshold and the highest voltage threshold, it indicates that the signal is a noise signal. Only when the voltage value of the signal input to the loopback comparator 423 is less than the lowest voltage threshold, or the voltage value of the signal input to the loopback comparator 423 is greater than the highest voltage threshold, the loopback comparator 423 will compare and output a valid signal.

[0076] In addition, once the positive connection terminal and the negative connection terminal of the difference comparator 4221 input a signal, the difference comparator 4221 can perform addition and subtraction operations in real time. The difference comparator 4221 makes a difference between the voltage of the signal input at the positive connection terminal and the voltage of the signal input at the negative connection terminal, and outputs it through the output terminal, which is connected to the negative connection terminal of the loopback comparator 423, so that the loopback comparator 423 determines whether the peak amplitude of the response voltage wave is attenuated. That is, the signal input to the positive connection terminal of the difference comparator 4221 is the superposition of the signal output by a peak amplitude detection circuit 41 and the signal transmitted by the voltage source 002, and the signal input to the negative connection terminal of the difference comparator 4221 is the signal output by another peak amplitude detection circuit 41. Among them, one peak amplitude detection circuit 41 continuously detects and records the maximum value of the peak amplitude of the response voltage wave in the response voltage wave group transmitted from the transducer component, and transmits the maximum value of the peak amplitude to the positive connection end of the difference comparator 4221, and another peak amplitude detection circuit 41 detects and records the peak amplitude of the current response voltage wave according to the period of the response voltage wave, and transmits the detected and recorded peak amplitude of the current response voltage wave to the negative connection end of the difference comparator 4221. The difference comparator 4221 can perform calculations in real time and transmit the calculation results to the loopback comparator 423.

[0077] In addition, by providing the loopback comparator 423 , the loopback comparator 423 can filter out noise, so that the hysteresis comparison circuit 42 can accurately determine whether the peak amplitude of the response voltage wave is attenuated.

[0078] It should be noted that the voltage of the power supply 001 may be 3.3V. Of course, the voltage of the power supply 001 may also be other values, which is not limited in the embodiment of the present application.

[0079] In addition, the function of the voltage source 002 is to ensure that the output of the difference comparator 4221 is a positive voltage; the voltage of the voltage source 002 can be 100mv. Of course, the voltage of the voltage source 002 can also be other values, which is not limited in this embodiment of the present application.

[0080] In addition, in some embodiments, Figure 5 As shown, the difference comparison circuit 422 may also include a sixth adjustment resistor 4222, a seventh adjustment resistor 4223, an eighth adjustment resistor 4224 and a ninth adjustment resistor 4225; a first end of the sixth adjustment resistor 4222 is electrically connected to the output end of a peak amplitude detection circuit 41, a second end of the sixth adjustment resistor 4222 is electrically connected to the positive connection end of the difference comparator 4221, a first end of the seventh adjustment resistor 4223 is connected to the voltage source 002, and a second end of the seventh adjustment resistor 4223 is electrically connected to the second end of the sixth adjustment resistor 4222; a first end of the eighth adjustment resistor 4224 is electrically connected to the output end of another peak amplitude detection circuit 41, a second end of the eighth adjustment resistor 4224 is electrically connected to the negative connection end of the difference comparator 4221, a first end of the ninth adjustment resistor 4225 is electrically connected to the second end of the eighth adjustment resistor 4224, and a second end of the ninth adjustment resistor 4225 is electrically connected to the output end of the difference comparator 4221.

[0081] Among them, through the sixth adjustment resistor 4222, the seventh adjustment resistor 4223, the eighth adjustment resistor 4224 and the ninth adjustment resistor 4225, the sixth adjustment resistor 4222, the seventh adjustment resistor 4223, the eighth adjustment resistor 4224 and the ninth adjustment resistor 4225 can cooperate with the difference comparator 4221 to perform addition and subtraction operations, so that the difference comparator 4221 can perform operations in real time and make the operation of the difference comparator 4221 more accurate.

[0082] In addition, in some embodiments, Figure 5 As shown, the hysteresis comparison circuit 42 further includes an inverter 424 ; a first end of the inverter 424 is electrically connected to the output end of the loopback comparator 423 , and a second end of the inverter 424 is electrically connected to the control module 10 and / or the flight time measurement unit 50 .

[0083] Among them, the inverter 424 is usually a Schmidt type inverter. By setting the inverter 424, the input and output of the inverter 424 are both digital signals. The inverter 424 can reverse the high-level input signal to a low-level signal output, and reverse the low-level signal to a high-level signal output, and can properly filter the signal jitter and burrs in the level conversion process of the input signal, so that the signal output from the inverter 424 can be easily recognized by the control module 10 and / or the flight time measurement unit 50. In addition, the inverter 424 can obtain a stable level after inversion, and the stable voltage can be transmitted to the control module 10 and / or the flight time measurement unit 50, which is convenient for the stable operation of the acoustic wave flight time measurement device.

[0084] In addition, in the embodiment of the present application, the second end of the inverter 424 may be connected to an inverting resistor 429, the first end of the inverting resistor 429 is electrically connected to the second end of the inverter 424, and the second end of the inverting resistor 429 is electrically connected to the control module 10 and / or the flight time measurement unit 50. By providing the inverting resistor 429, a series impedance matching function is achieved to avoid a large voltage overshoot transmitted to the control module 10 and / or the flight time measurement unit 50, which affects the correct operation of the control module 10 and / or the flight time measurement unit 50.

[0085] In addition, in some embodiments, Figure 5 As shown, the hysteresis comparison circuit 42 also includes: a tenth adjustment resistor 425, an eleventh adjustment resistor 426, an adjustment diode 427 and a second adjustment capacitor 428; the first end of the tenth adjustment resistor 425 is electrically connected to the output end of the loop comparator 423, the second end of the tenth adjustment resistor 425 is electrically connected to the first end of the adjustment diode 427, the second end of the adjustment diode 427 is electrically connected to the first end of the inverter 424, the first end of the eleventh adjustment resistor 426 is electrically connected to the first end of the tenth adjustment resistor 425, the second end of the eleventh adjustment resistor 426 is electrically connected to the first end of the second adjustment capacitor 428, the first end of the second adjustment capacitor 428 is also electrically connected to the second end of the adjustment diode 427, and the second end of the second adjustment capacitor 428 is grounded.

[0086] Among them, the second adjustment capacitor 428 can cooperate with the tenth adjustment resistor 425, the eleventh adjustment resistor 426 and the adjustment diode 427, so that when the loopback comparator 423 outputs a high level, the second adjustment capacitor 428 is quickly charged, and when the loopback comparator 423 outputs a low level, the second adjustment capacitor 428 is slowly discharged. In addition, by setting the tenth adjustment resistor 425, the eleventh adjustment resistor 426, the adjustment diode 427 and the second adjustment capacitor 428, the pulse output by the loopback comparator 423 can also be shaped into a stable level, which is convenient for the inverter 424 to invert the stable level, so that the inverter 424 outputs a correct level signal.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0088] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A device for measuring the acoustic wave transit time, characterized in that: The acoustic wave flight time measuring device comprises: a control module, a pulse generating unit, a transducer component, a wave peak feature detecting unit, a flight time measuring unit and a comparator component; The flight time measurement unit, the wave peak feature detection unit, and the pulse generation unit are all electrically connected to the control module; the pulse generation unit is electrically connected to the transducer assembly, the comparator assembly, and the flight time measurement unit, respectively, and the transducer assembly is electrically connected to the comparator assembly; The peak feature detection unit includes a peak amplitude detection circuit, the peak amplitude detection circuit is electrically connected to the transducer assembly, the comparator assembly is electrically connected to the peak amplitude detection circuit and the flight time measurement unit, respectively, and the peak amplitude detection circuit is electrically connected to the flight time measurement unit and the control module, respectively; The peak amplitude detection circuit is resettable; the peak amplitude detection circuit is used to detect and store the peak amplitude of the response voltage wave generated by the transducer assembly, and send the detection result to the control module, the control module determines whether the peak amplitude of the response voltage wave is attenuated; or the peak feature detection unit determines whether the peak amplitude of the response voltage wave is attenuated; When it is determined that the peak amplitude of the response voltage wave has attenuated, the flight time measurement unit stops the measurement of the wave group and determines the stop time of the acoustic wave flight. The flight time measurement unit or the control module determines the acoustic wave flight time of the acoustic wave group based on the start time and stop time of the acoustic wave flight.

2. The device for measuring the acoustic wave transit time according to claim 1, characterized in that: The peak feature detection unit further includes a hysteresis comparison circuit, and the number of the peak amplitude detection circuits is two; The two peak amplitude detection circuits are both electrically connected to the transducer assembly, and the two peak amplitude detection circuits are both electrically connected to the hysteresis comparison circuit; One of the peak amplitude detection circuits is used to continuously detect and record the maximum value of the peak amplitude of the response voltage wave in the response voltage wave group transmitted from the transducer assembly, and transmit the detected and recorded maximum value of the peak amplitude of the response voltage wave to the hysteresis comparison circuit, and the other of the peak amplitude detection circuits is used to periodically detect and record the current peak amplitude of the response voltage wave according to the response period of the response voltage wave, and transmit the detected and recorded current peak amplitude of the response voltage wave to the hysteresis comparison circuit, and the hysteresis comparison circuit is used to compare the maximum value of the peak amplitude of the transmitted response voltage wave and the current peak amplitude of the transmitted response voltage wave to determine whether the peak amplitude of the response voltage wave group is attenuated; Wherein, the hysteresis ratio circuit is electrically connected to the control module.

3. The device for measuring the acoustic wave transit time according to claim 1, characterized in that: The peak amplitude detection circuit includes a first operational amplifier, a first diode, a first capacitor, a second diode, a third diode, a second capacitor and a second operational amplifier; The positive connection end of the first operational amplifier is electrically connected to the transducer component and the comparator component, the first diode is connected in parallel to the first capacitor, and the first end of the first diode and the first end of the first capacitor are both electrically connected to the negative connection end of the first operational amplifier, the output end of the first operational amplifier is electrically connected to the second end of the first diode, the second end of the first capacitor and the first end of the second diode respectively, the second end of the second diode is electrically connected to the first end of the third diode, the second end of the third diode is electrically connected to the first end of the second capacitor, the second end of the second capacitor is grounded, the first end of the second capacitor is electrically connected to the positive connection end of the second operational amplifier, the negative connection end of the second operational amplifier is electrically connected to the output end of the second operational amplifier, the negative connection end of the second operational amplifier is electrically connected to the negative connection end of the first operational amplifier, and the output end of the second operational amplifier is electrically connected to the control module; The second capacitor is used to store the electric energy corresponding to the peak amplitude of the response voltage wave.

4. The device for measuring the acoustic wave transit time according to claim 3, characterized in that: The peak amplitude detection circuit also includes a first switch tube; The first end of the first switch tube is electrically connected to the first end of the second capacitor, the second end of the first switch is grounded, and the third end of the first switch tube is electrically connected to the control module; When the first end of the first switch tube and the second end of the first switch tube are turned on, the electric energy on the second capacitor becomes zero, so that the second capacitor is reset.

5. The device for measuring the acoustic wave transit time according to claim 3, characterized in that: The peak amplitude detection circuit also includes a first resistor, a second resistor and a third resistor; The first end of the first resistor is electrically connected to the transducer component and the comparator component, the second end of the first resistor is electrically connected to the positive connection terminal of the first operational amplifier, the first end of the second resistor is electrically connected to the negative connection terminal of the first operational amplifier, the second end of the second resistor is electrically connected to the first end of the third resistor, the first end of the third resistor is electrically connected to the negative connection terminal of the second operational amplifier, and the second end of the third resistor is electrically connected to the second end of the second diode.

6. The device for measuring the acoustic wave transit time according to claim 4, characterized in that: The peak amplitude detection circuit further includes a fourth resistor; The first end of the fourth resistor is electrically connected to the third end of the first switch tube, and the second end of the fourth resistor is electrically connected to the control module, so that the third end of the first switch tube is electrically connected to the control module.

7. The device for measuring the acoustic wave transit time according to claim 3, characterized in that: The peak feature detection unit also includes an analog-to-digital converter; The output end of the second operational amplifier is electrically connected to the analog input end of the analog-to-digital converter, and the digital interface end of the analog-to-digital converter is electrically connected to the control module.

8. The device for measuring the acoustic wave transit time according to claim 2, characterized in that: The hysteresis comparison circuit includes a threshold adjustment circuit, a difference comparison circuit, and a loopback comparator; The threshold adjustment circuit is used to adjust the comparison threshold of the loopback comparator. The threshold adjustment circuit includes a first adjustment resistor, a second adjustment resistor, an adjustable resistor, a first adjustment capacitor, a third operational amplifier, and a programmable potentiometer. The first end of the first adjustment resistor is connected to a power supply, the second end of the first adjustment resistor is electrically connected to the first end of the second adjustment resistor, the second end of the second adjustment resistor is electrically connected to the first end of the adjustable resistor, the second end of the adjustable resistor is grounded, the first end of the first adjustment capacitor is electrically connected to the first end of the second adjustment resistor, the second end of the first adjustment capacitor is electrically connected to the second end of the adjustable resistor, the first end of the second adjustment resistor is electrically connected to the positive connection end of the third operational amplifier, the negative connection end of the third operational amplifier is electrically connected to the output end of the third operational amplifier, the output end of the third operational amplifier is electrically connected to the programmable potentiometer, and the programmable potentiometer is electrically connected to the positive connection end of the loopback comparator; The difference comparison circuit comprises a difference comparator, a negative connection terminal of the difference comparator is electrically connected to one of the peak amplitude detection circuits, a positive connection terminal of the difference comparator is electrically connected to another of the peak amplitude detection circuits, and an output terminal of the difference comparator is electrically connected to a negative connection terminal of the loopback comparator; The output end of the loopback comparator is electrically connected to the positive connection end of the loopback comparator through a fifth adjustment resistor, and the output end of the loopback comparator is electrically connected to the control module and / or the flight time measurement unit.

9. The device for measuring the acoustic wave transit time according to claim 8, characterized in that: The difference comparison circuit further includes a sixth adjustment resistor, a seventh adjustment resistor, an eighth adjustment resistor and a ninth adjustment resistor; The first end of the sixth adjustment resistor is electrically connected to an output end of the peak amplitude detection circuit, the second end of the sixth adjustment resistor is electrically connected to the positive connection end of the difference comparator, the first end of the seventh adjustment resistor is connected to a voltage source, and the second end of the seventh adjustment resistor is electrically connected to the second end of the sixth adjustment resistor; The first end of the eighth adjustment resistor is electrically connected to another of the peak amplitude detection circuits, the second end of the eighth adjustment resistor is electrically connected to the negative connection end of the difference comparator, the first end of the ninth adjustment resistor is electrically connected to the second end of the eighth adjustment resistor, and the second end of the ninth adjustment resistor is electrically connected to the output end of the difference comparator.

10. The device for measuring the acoustic wave transit time according to claim 8, characterized in that: The hysteresis comparison circuit also includes an inverter; The first end of the inverter is electrically connected to the output end of the loopback comparator, and the second end of the inverter is electrically connected to the control module and / or the flight time measurement unit.

11. The device for measuring the acoustic wave transit time according to claim 10, characterized in that: The hysteresis comparison circuit further includes: a tenth adjustment resistor, an eleventh adjustment resistor, an adjustment diode and a second adjustment capacitor; A first end of the tenth adjustment resistor is electrically connected to the output end of the loopback comparator, a second end of the tenth adjustment resistor is electrically connected to a first end of the adjustment diode, a second end of the adjustment diode is electrically connected to a first end of the inverter, a first end of the eleventh adjustment resistor is electrically connected to a first end of the tenth adjustment resistor, a second end of the eleventh adjustment resistor is electrically connected to a first end of the second adjustment capacitor, a first end of the second adjustment capacitor is also electrically connected to a second end of the adjustment diode, and a second end of the second adjustment capacitor is grounded.

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