Method for detecting flight time, ultrasonic flowmeter and optical device

Abstract

The embodiments of the present application relate to the technical field of optical equipment, and disclose a method for detecting flight time, an ultrasonic flowmeter, and an optical device. The above method includes: sending a first electrical signal at a transmitting end, the first electrical signal includes at least two continuous characteristic electrical signal sequences, the characteristic electrical signal sequence has a first pulse signal and a constant level signal, and the characteristic electrical signal sequence has a characteristic period; receiving a second electrical signal at a receiving end; based on the time domain waveform of the second electrical signal, obtaining a characteristic time point, the characteristic time point is a time point corresponding to the intersection of adjacent waveform areas with a characteristic period in the time domain waveform; based on the characteristic time point, obtaining the first wave position; based on the first wave position, obtaining the flight time. The method for detecting flight time provided in the embodiments of the present application solves the problem of errors in the detection of flight time caused by deviations in the first wave position.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of optical devices, and in particular to a method for detecting time of flight, an ultrasonic flow meter, and an optical device. Background Art

[0002] The measurement of flight time is often used to measure distance and fluid velocity. Generally, a pair of transducers are placed between two points to convert the excitation electrical signal (usually a continuous pulse signal in the form of multiple square waves) into an ultrasonic signal that propagates in the medium. After a period of time, it is received by the transducer at the other end and converted back into an electrical signal. Then, by measuring the flight time, the distance between the two points or the flow rate of the medium fluid itself can be calculated.

[0003] Ultrasonic flowmeter measurement is to measure the flow rate through gas or liquid media. The measurement principle depends on the flight time of the ultrasonic signal in the medium. The flight time is the time difference between the uplink flight time (Tup) and the downlink flight time (Tdn). The flow velocity can be calculated by the time difference, and then the flow value can be obtained. At present, ultrasonic flight time measurement is mainly carried out by performing first wave detection on the transducer receiving end, and judging the end point of the flight time by several zero-crossing detection waveforms after the first wave, obtaining the flight time, and then calculating the speed or flight distance of the fluid in the medium. The first wave detection generally sets an open time window and finds a judgment level with a large threshold range to minimize the possibility of misjudgment. However, the first wave detection often deviates from the first wave position as the fluid temperature changes, and the occasional impurities, bubbles, etc. in the fluid, resulting in a wrong wave phenomenon, which in turn brings a large measurement error to the flight time detection and affects the measurement accuracy. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method for detecting flight time, an ultrasonic flowmeter and an optical device to solve the problem of error in flight time detection caused by deviation in the first wave position.

[0005] To solve the above technical problems, an embodiment of the present application provides a method for detecting flight time, comprising the following steps: sending a first electrical signal at a transmitting end, the first electrical signal comprising at least two continuous characteristic electrical signal sequences, the characteristic electrical signal sequence having a first pulse signal and a constant level signal, and the characteristic electrical signal sequence having a characteristic period; receiving a second electrical signal at a receiving end, the second electrical signal being formed by converting the first electrical signal into an acoustic wave signal and then transmitting it in a medium to undergo acoustic-to-electric conversion; obtaining a characteristic time point based on a time domain waveform of the second electrical signal, the characteristic time point being a time point corresponding to a boundary point of adjacent waveform regions in the time domain waveform having the characteristic period; obtaining a first wave position based on the characteristic time point; and obtaining the flight time based on the first wave position.

[0006] In addition, the first electrical signal also includes a second pulse signal; adjacent characteristic electrical signal sequences are spliced ​​to form a spliced ​​sequence, and the spliced ​​sequence is spliced ​​with the second pulse signal.

[0007] In addition, the first electrical signal is:

[0008]

[0009] Wherein, λ1 is a full cycle of the first pulse signal, λ2 is a full cycle of the second pulse signal, γ is a 1 / n cycle of the constant level signal, M1 is the number of cycles of the first pulse signal, M2 is the number of cycles of the second pulse signal, and N is the number of 1 / n cycle of the constant level signal. For sequence splicing, is the characteristic electrical signal sequence, k is the number of characteristic electrical signal sequences, n≥1, k≥2.

[0010] In addition, the first electrical signal also includes a third pulse signal; the first end of the splicing sequence is spliced ​​with the third pulse signal, and the tail end of the splicing sequence is spliced ​​with the second pulse signal.

[0011] In addition, the first electrical signal is:

[0012]

[0013] Wherein, λ1 is a first pulse signal of a whole cycle, λ2 is a second pulse signal of a whole cycle, λ3 is a third pulse signal of a whole cycle, γ is a constant level signal of a 1 / n cycle, n≥1, M1 is the number of cycles of the first pulse signal, M2 is the number of cycles of the second pulse signal, L is the number of cycles of the third pulse signal, and N is the number of constant level signals of a 1 / n cycle. For sequence splicing, is the characteristic electrical signal sequence, k is the number of characteristic electrical signal sequences, n≥1, k≥2.

[0014] In addition, the first pulse signal, the second pulse signal, and the third pulse signal are all square wave pulse signals; and the constant level signal is a high level constant signal or a low level constant signal.

[0015] In addition, obtaining the characteristic time point based on the time domain waveform of the second electrical signal includes: obtaining the envelope wave curve of the time domain waveform of the second electrical signal based on the envelope wave amplitude detection method; and obtaining the characteristic time point based on the envelope wave curve.

[0016] In addition, the method of obtaining the characteristic time point based on the time domain waveform of the second electrical signal includes: obtaining the period time of the sine wave in the second electrical signal by a zero-crossing detection method based on a preset reference level; and obtaining the characteristic time point based on the period time of the sine wave in the electrical signal.

[0017] An embodiment of the present application also provides an ultrasonic flow meter, comprising: at least one ultrasonic transducer and a processor connected to the ultrasonic transducer; a memory connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for detecting flight time described in any of the above embodiments.

[0018] An embodiment of the present application further provides an optical device, comprising a time-of-flight converter and the above-mentioned ultrasonic flow meter.

[0019] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0020] The method for detecting the flight time provided in the embodiment of the present application is to send a first electrical signal having a characteristic electrical signal sequence at the transmitting end, and the characteristic electrical signal sequence has a characteristic period, and then receive a second electrical signal at the receiving end, and based on the time domain waveform of the second electrical signal, obtain the time point corresponding to the intersection point of the waveform area adjacent to each other and having a characteristic period in the time domain waveform, that is, the characteristic time point; then obtain the first wave position based on the characteristic time point, and then obtain the flight time based on the first wave position. Because the electrical signal is converted into a Lamb wave with an envelope shape and a diffusion trend after being converted by the transducer, it will affect the detection of the first wave position. The embodiment of the present application sends a characteristic electrical signal sequence with a characteristic period at the transmitting end, and then obtains the time point corresponding to the intersection point of the waveform area of ​​the characteristic period in the time domain waveform of the second electrical signal to obtain the first wave position. The amplitude of the envelope wave in the time domain waveform received by the receiving end of the embodiment of the present application changes periodically, and its period is consistent with the period of the characteristic electrical signal sequence emitted by the transmitting end, so that the first wave position can be accurately obtained. Therefore, the method for detecting the flight time in the embodiment of the present application can reduce the detection deviation of the first wave position, so that the flight time can be measured more accurately, and the measurement accuracy and measurement precision can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments.

[0022] Figure 1 is a schematic diagram of phase insertion of the related art;

[0023] Figure 2 is a flow chart of a method for detecting flight time according to an embodiment of the present application;

[0024] Figure 3 is a schematic diagram of a first electrical signal according to an embodiment of the present application;

[0025] Figure 4 is a schematic diagram of a first electrical signal according to another embodiment of the present application;

[0026] Figure 5 is a schematic diagram of a time domain waveform of a second electrical signal in an embodiment of the present application;

[0027] Figure 6 is a schematic diagram of a first electrical signal of yet another embodiment of the present application;

[0028] Figure 7 It is a schematic diagram of the structure of an optical device according to an embodiment of the present application. DETAILED DESCRIPTION

[0029] As can be seen from the background technology, there is currently a problem that the deviation of the first wave position easily leads to errors in the detection of the flight time.

[0030] The first wave, also known as the head wave, is the beginning of an effective signal in the field of ultrasonic and other types of signal pulse detection. The reliable detection and accurate positioning of the first wave play a key role in the accuracy of such measurements. The biggest difficulty in detecting the first wave position is that the amplitude of the first wave is generally very small, which is very easy to be confused with the system noise. The presence of noise has a great impact on the accuracy of the first wave position measurement. In addition, the amplitude of the first wave usually decays rapidly as the signal frequency increases. Therefore, in high-frequency measurements, the detection of the first wave position is more difficult and is very prone to deviations, resulting in poor measurement accuracy.

[0031] In order to reduce the deviation of the first wave position, the related technology proposes a phase insertion method, such as Figure 1 As shown, by inserting a phase into the excitation electrical signal sent from the transmitter, usually the number of inserted phases is an integer multiple of one quarter of a square wave pulse period; by changing the phase of the time domain waveform of the excitation electrical signal sent from the transmitter, so as to find a characteristic waveform in the time domain waveform of the electrical signal at the receiving end, the corresponding relationship between the signals at the transmitting end and the receiving end is determined, the deviation of the first wave position detection is reduced, and the purpose of improving the detection accuracy is achieved.

[0032] However, optical and ultrasonic systems are extremely susceptible to external interference, such as temperature, bubbles, flow rate, fluid pressure or fluid mixtures. Ultrasonic transducers have high stability in the time domain, but their physical quantities such as voltage level, that is, the amplitude of the received electrical signal, are easily affected by various physical parameters in the system. Due to the characteristics of transducer energy conversion, the excitation electrical signal at the transmitting end is in the form of a square wave pulse. The excitation electrical signal in the form of a square wave pulse is converted into a Lamb wave after passing through the transducer, and presents an envelope shape in the time domain. In the related technology, when inserting a phase in the excitation electrical signal, the time domain waveform of the electrical signal formed after the acoustic-to-electric conversion usually has a tendency to diffuse. In practice, it is difficult to accurately locate the position corresponding to the inserted phase point, which will also cause misalignment of the first wave position detection or the characteristic wave detection, resulting in a large measurement error of the flight time. Therefore, it is impossible to solve the problem of errors in the flight time detection caused by the deviation of the first wave position.

[0033] In order to solve this technical problem, Figure 2 As shown, the embodiment of the present application provides a method for detecting flight time, comprising the following steps:

[0034] Step S101: sending a first electrical signal at a transmitting end, the first electrical signal comprising at least two consecutive characteristic electrical signal sequences, the characteristic electrical signal sequence comprising a first pulse signal and a constant level signal, and the characteristic electrical signal sequence having a characteristic period;

[0035] Step S102, receiving a second electrical signal at a receiving end, the second electrical signal being formed by converting the first electrical signal into an acoustic wave signal and then transmitting the first electrical signal in a medium and then performing acoustic-electric conversion;

[0036] Step S103, based on the time domain waveform of the second electrical signal, obtaining a characteristic time point, where the characteristic time point is a time point corresponding to a junction point of waveform regions that are adjacent and have a characteristic period in the time domain waveform;

[0037] Step S104, obtaining the first wave position based on the characteristic time point;

[0038] Step S105: Obtain the flight time based on the first wave position.

[0039] The embodiments of the present application are applied to the measurement of ultrasonic flow rate by measuring the transmission time or flight time. Measuring the flight time can be used to measure various parameters, such as the flow velocity, flow rate and heat flow of liquids and gases. Ultrasonic flow meters based on flight time have various applications in industrial and legal measurement, for example, safety detection such as ultrasound. In addition, the measurement of flight time can also be used for optical applications, such as distance measurement and 3D imaging. Usually in the measurement of ultrasonic flow meters, it is necessary to measure the flight time to measure parameters such as flow velocity and distance.

[0040] In some embodiments, the method for detecting the flight time provided by the embodiments of the present application, the first electrical signal is converted into an ultrasonic signal by an ultrasonic transducer, and then the ultrasonic signal is transmitted in the medium, and reaches the receiving end and is converted into a second electrical signal by the ultrasonic transducer again. The ultrasonic transducer can be, for example, a piezoelectric crystal, and one ultrasonic transducer can be used as a transceiver, that is, transmitting the first electrical signal and receiving the second electrical signal, or two ultrasonic transducers can be used as transducers at the transmitting end and the receiving end respectively. The output signal of the flight time converter is usually used to alternately excite the ultrasonic transducer, and the ultrasonic pulse signal is alternately sent to the channel filled with the flowing medium to be measured to measure the flight time.

[0041] like Figure 3As shown, the embodiment of the present application first sends a first electrical signal at the transmitting end, and the first electrical signal includes at least two consecutive first electrical signals of characteristic electrical signal sequences, and the characteristic electrical signal sequence has a characteristic period, which helps to obtain the time point corresponding to the intersection of adjacent waveform areas with characteristic periods in the time domain waveform of the second electrical signal received at the receiving end, that is, to obtain the characteristic time point; then use the time-to-digital conversion (Time Digital Converter, TDC) to generate the signal at the characteristic time point into a digital timestamp. The digital timestamp is used to obtain the first wave position in the time domain waveform, thereby obtaining the uplink flight time (Tup) and the downlink flight time (Tdn), and then the flight time is obtained. The flight time is the time difference between the uplink flight time and the downlink flight time. The flow velocity of the medium is calculated by the flight time, as shown in the following formula:

[0042]

[0043] Wherein, Δt is the time difference between the uplink flight time and the downlink flight time, c is the sound velocity of the ultrasonic signal in the medium, and L is the flight distance.

[0044] After the electrical signal is converted by the transducer, it is converted into a Lamb wave with an envelope shape and a diffusion tendency, which will affect the detection of the first wave position. The embodiment of the present application obtains the first wave position by sending a characteristic electrical signal sequence with a characteristic period at the transmitting end, and then obtaining the time point corresponding to the intersection of the waveform area of ​​the characteristic period in the time domain waveform of the second electrical signal. The envelope wave amplitude in the time domain waveform of the second electrical signal received by the receiving end of the embodiment of the present application shows periodic changes, and its period is consistent with the period of the characteristic electrical signal sequence emitted by the transmitting end, so that the first wave position can be accurately obtained. Therefore, the method for detecting the flight time of the embodiment of the present application can reduce the detection deviation of the first wave position, so that the flight time can be measured more accurately, and the measurement accuracy and measurement precision can be improved.

[0045] In some embodiments, the first electrical signal further includes a second pulse signal, adjacent characteristic electrical signal sequences are spliced ​​to form a spliced ​​sequence, and the spliced ​​sequence is spliced ​​with the second pulse signal.

[0046] In some embodiments, please continue to see Figure 3 The two characteristic electrical signal sequences are spliced ​​head to tail to form a spliced ​​sequence, and the tail of the spliced ​​sequence is spliced ​​with the second pulse signal. The characteristic electrical signal sequence includes a spliced ​​sequence of a first pulse signal and a constant level signal, the first pulse signal and the second pulse signal can be, for example, square wave pulse signals, and the constant level signal can be, for example, a high level constant signal or a low level constant signal. Figure 3The example of splicing three square wave pulse signals and a low level constant signal to form a characteristic electrical signal sequence, and splicing two characteristic electrical signal sequences with two second pulse signals is used for illustration. The embodiment of the present application uses the second pulse signal sequence as a stable oscillation sequence, splicing the characteristic electrical signal sequence with the second pulse signal sequence, and plays a role in reducing interference.

[0047] In some embodiments, the first electrical signal is:

[0048]

[0049] Wherein, λ1 is a full cycle of the first pulse signal, λ2 is a full cycle of the second pulse signal, γ is a 1 / n cycle of the constant level signal, M1 is the number of cycles of the first pulse signal, M2 is the number of cycles of the second pulse signal, and N is the number of 1 / n cycle of the constant level signal. For sequence splicing, is the characteristic electrical signal sequence, k is the number of characteristic electrical signal sequences, n≥1, k≥2.

[0050] See also Figure 4 , taking the first pulse signal and the second pulse signal as square wave pulse signals, the constant level signal as a low level constant signal, M1=3, N=3, k=3, M2=3, n=4 as an example for illustration, the three characteristic electrical signal sequences are spliced ​​head to tail to form a spliced ​​sequence, and the tail end of the spliced ​​sequence is spliced ​​with the three second pulse signals.

[0051] It is understandable that M1, N, M2, and n can be other values ​​greater than 1.

[0052] Please continue to see Figure 4 , taking the period of a square wave pulse signal as one period, and the inserted low-level constant signal as 0.75 periods (0.75T), then the characteristic period of the characteristic electrical signal sequence is three square wave pulse signals plus the inserted low-level constant signal. When obtaining the first wave position, the characteristic time point corresponding to the intersection of the adjacent waveform area with the above characteristic period is found in the time domain waveform diagram of the second electrical signal received at the receiving end, and the characteristic time point corresponding to the characteristic period is obtained; because in the time domain waveform of the second electrical signal received at the receiving end, the amplitude of the envelope wave changes periodically, and the period of the envelope wave is consistent with the period of the characteristic electrical signal sequence inserted in the first electrical signal sent from the transmitting end. Figure 5 As shown, if the envelope amplitude detection method is used in the time domain waveform of the second electrical signal received at the receiving end, a periodically changing envelope wave consistent with the period of the characteristic electrical signal sequence can be obtained, the characteristic time point can be easily found, and the real first wave position can be accurately located to obtain the flight time.

[0053] In some embodiments, the first electrical signal further includes a third pulse signal, the first end of the splicing sequence is spliced ​​with the third pulse signal, and the tail end of the splicing sequence is spliced ​​with the second pulse signal.

[0054] In some embodiments, see Figure 6 The three characteristic electrical signal sequences are spliced ​​head to tail to form a spliced ​​sequence, the head end of the spliced ​​sequence is spliced ​​with the third pulse signal, and the tail end of the spliced ​​sequence is spliced ​​with the second pulse signal. The characteristic electrical signal sequence includes a spliced ​​sequence of a first pulse signal and a constant level signal, the first pulse signal and the second pulse signal can be, for example, square wave pulse signals, and the constant level signal can be, for example, a high level constant signal or a low level constant signal. Figure 6 The characteristic electrical signal sequence is formed by splicing three square wave pulse signals with a low-level constant signal. After the three characteristic electrical signal sequences are spliced, the head end is spliced ​​with two third pulse signals, and the tail end is spliced ​​with three second pulse signals. As the Q value of some transducers is relatively low, the initial oscillation process may require more excitation electrical signals of the first pulse signals to achieve a stable oscillation state. The number of cycles of the first pulse signal is generally small, so the transducer cannot be fully enabled. Therefore, it is necessary to design a longer stable oscillation sequence to meet high-precision measurement, so as to accurately measure the cycle time value under the stable oscillation state. Therefore, the embodiment of the present application splices the third pulse signal sequence at the head end of the splicing sequence before the splicing sequence of the characteristic electrical signal sequence as a stable oscillation sequence to reduce interference and minimize interference.

[0055] In some embodiments, the first electrical signal is:

[0056]

[0057] Wherein, λ1 is a first pulse signal of a whole cycle, λ2 is a second pulse signal of a whole cycle, λ3 is a third pulse signal of a whole cycle, γ is a constant level signal of a 1 / n cycle, n≥1, M1 is the number of cycles of the first pulse signal, M2 is the number of cycles of the second pulse signal, L is the number of cycles of the third pulse signal, and N is the number of constant level signals of a 1 / n cycle. For sequence splicing, is the characteristic electrical signal sequence, k is the number of characteristic electrical signal sequences, n≥1, k≥2.

[0058] See also Figure 6 , the first pulse signal, the second pulse signal, and the third pulse signal are all square wave pulse signals, the constant level signal is a low level constant signal, L=2, M1=3, N=3, k=3, M2=3, n=4 are used as an example for illustration.

[0059] It can be understood that L, M1, N, M2, and n can be other values ​​greater than 1.

[0060] Please continue to see Figure 6 , the three characteristic electrical signal sequences are spliced ​​head to tail to form a spliced ​​sequence, the head end of the spliced ​​sequence is spliced ​​with the two third pulse signals, and the tail end of the spliced ​​sequence is spliced ​​with the three second pulse signals. Taking the period of a square wave pulse signal as one period, and the inserted low-level constant signal as 0.75 periods (0.75T), the characteristic period of the characteristic electrical signal sequence is three square wave pulse signals plus the inserted low-level constant signal. When obtaining the first wave position, the characteristic time point corresponding to the characteristic period is obtained by finding the time point corresponding to the intersection of the adjacent waveform area with the above-mentioned characteristic period in the time domain waveform diagram of the second electrical signal received at the receiving end; as mentioned above, because in the time domain waveform of the second electrical signal received at the receiving end, the amplitude of the envelope wave changes periodically, the period of the envelope wave is consistent with the period of the characteristic electrical signal sequence inserted in the first electrical signal sent from the transmitting end. By using the envelope amplitude detection method, a periodically changing envelope wave that is consistent with the period of the characteristic electrical signal sequence can be obtained in the time domain waveform of the second electrical signal, so that the characteristic time point can be easily found, and then the real first wave position can be accurately located to obtain the flight time.

[0061] In some embodiments, the first pulse signal, the second pulse signal, and the third pulse signal are all square wave pulse signals; and the constant level signal is a high level constant signal or a low level constant signal.

[0062] In some embodiments, obtaining the characteristic time point based on the time domain waveform of the second electrical signal includes: obtaining the envelope wave curve of the time domain waveform of the second electrical signal based on an envelope wave amplitude detection method; and obtaining the characteristic time point based on the envelope wave curve.

[0063] See also Figure 5 , is the time domain waveform of the second electrical signal. Figure 5 It can be seen that the time domain waveform of the second electrical signal includes multiple sinusoidal waveform periods. Usually, the first electrical signal emitted by the transmitting end with a continuous pulse excitation pulse is converted into an ultrasonic signal by the transducer and changes when transmitted in the medium. The first electrical signal of the embodiment of the present invention includes a characteristic electrical signal sequence with a characteristic period. Then, in the time domain waveform of the second electrical signal received by the receiving end, the peak value of each sinusoidal wave is connected to obtain an envelope curve, such as Figure 5 As shown in FIG. 1 , the characteristic time point can be found by searching for the time point corresponding to the intersection of the adjacent waveform regions having the above characteristic period on the envelope curve. Figure 4In the form of a first electrical signal, the first electrical signal includes three continuous characteristic electrical signal sequences, then the characteristic time points corresponding to the three continuous characteristic electrical signal sequences can be found on the time domain waveform of the second electrical signal, and the first wave position can be accurately located. The embodiment of the present application greatly reduces the detection deviation of the first wave position by sending a characteristic electrical signal sequence with a characteristic period at the transmitting end, and then obtaining the time point corresponding to the intersection of the waveform area of ​​the characteristic period in the time domain waveform of the second electrical signal, thereby more accurately measuring the flight time and improving the measurement accuracy and precision.

[0064] In some embodiments, the method of obtaining the characteristic time point based on the time domain waveform of the second electrical signal includes: obtaining the period time of the sine wave in the second electrical signal by a zero-crossing detection method based on a preset reference level; and obtaining the characteristic time point based on the period time of the sine wave in the electrical signal.

[0065] In some embodiments, in the time domain waveform of the second electrical signal received at the receiving end, as Figure 5 As shown, by setting a reference level (generally set to the level of the center position of the envelope wave), and through the zero-crossing detection method, the signal at the characteristic time point is generated as a digital timestamp using time-to-digital conversion (TDC), and the first wave position is obtained in the time domain waveform through the digital timestamp, thereby obtaining the flight time. Experiments have proved that, through the embodiment of the present application, in the time domain waveform of the second electrical signal received at the receiving end, a periodic envelope wave can be obtained, and the period time of each sine wave also shows a periodic change feature. According to the characteristic period of the inserted characteristic electrical signal sequence, the time point corresponding to the intersection point of the adjacent waveform area with the characteristic period is found in the time domain waveform, and the characteristic time point is found, so as to accurately locate the real first wave position and obtain the flight time.

[0066] The method for detecting the flight time provided by the embodiment of the present application is to send a first electrical signal with a characteristic electrical signal sequence at the transmitting end, and the characteristic electrical signal sequence has a characteristic period, and then receive a second electrical signal at the receiving end, and based on the time domain waveform of the second electrical signal, obtain the time point corresponding to the intersection point of the waveform area adjacent to each other and having a characteristic period in the time domain waveform, that is, the characteristic time point; then obtain the first wave position based on the characteristic time point, and then obtain the flight time based on the first wave position. Because the electrical signal is converted into a Lamb wave with an envelope shape and a diffusion trend after being converted by the transducer, it will affect the detection of the first wave position. The embodiment of the present application sends a characteristic electrical signal sequence with a characteristic period at the transmitting end, and then obtains the time point corresponding to the intersection point of the waveform area of ​​the characteristic period in the time domain waveform of the second electrical signal to obtain the first wave position. The envelope wave amplitude in the time domain waveform of the second electrical signal received by the receiving end of the embodiment of the present application changes periodically, and its period is consistent with the period of the characteristic electrical signal sequence emitted by the transmitting end, so that the first wave position can be accurately obtained. Therefore, the method for detecting the flight time of the embodiment of the present application can reduce the detection deviation of the first wave position, so that the flight time can be measured more accurately, and the measurement accuracy and measurement precision can be improved.

[0067] An embodiment of the present application also provides an ultrasonic flow meter, comprising: at least one ultrasonic transducer 10 and a processor 11 connected to the ultrasonic transducer 10; a memory 12 connected to the at least one processor 11; wherein the memory 12 stores instructions executable by the at least one processor 11, and the instructions are executed by the at least one processor 11 so that the at least one processor 11 can execute the method for detecting flight time described in any of the above embodiments.

[0068] In some embodiments, the memory 12 and the processor 11 are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 11 and the memory 12 together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor 11 is transmitted on a wireless medium through an antenna, and further, the antenna also receives data and transmits the data to the processor 11.

[0069] In some embodiments, the processor 11 is responsible for managing the bus and general processing, and may also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The memory 12 may be used to store data used by the processor 11 when performing operations.

[0070] An embodiment of the present application further provides an optical device, comprising a time-of-flight converter and the above-mentioned ultrasonic flow meter.

[0071] The optical device provided in the embodiments of the present application includes an infrared optical device, a visible light optical device or an ultraviolet UV radiation optical device, including a flight time converter and the above-mentioned ultrasonic flow meter, and its processor 11 can execute the method for detecting the flight time described in any of the above embodiments.

[0072] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A method for detecting flight time, characterized in that: The following steps are involved: Sending a first electrical signal at a transmitting end, wherein the first electrical signal includes at least two continuous characteristic electrical signal sequences, wherein the characteristic electrical signal sequence has a first pulse signal and a constant level signal, and the characteristic electrical signal sequence has a characteristic period; Receiving a second electrical signal at a receiving end, the second electrical signal being formed by converting the first electrical signal into an acoustic wave signal and then transmitting the first electrical signal in a medium and then performing an acoustic-to-electric conversion; Based on the time domain waveform of the second electrical signal, a characteristic time point is obtained, where the characteristic time point is a time point corresponding to a junction point of adjacent waveform regions having the characteristic period in the time domain waveform; Based on the characteristic time point, obtaining the first wave position; Based on the first wave position, the flight time is obtained.

2. The method for detecting flight time according to claim 1, characterized in that: The first electrical signal further includes: A second pulse signal; Adjacent characteristic electrical signal sequences are spliced ​​to form a spliced ​​sequence, and the spliced ​​sequence is spliced ​​with the second pulse signal.

3. The method for detecting flight time according to claim 2, characterized in that: The first electrical signal is: {M1λ1⊕Nγ}k⊕M2λ2(1) Among them, λ1 is a whole cycle of the first pulse signal, λ2 is a whole cycle of the second pulse signal, γ is a constant level signal of the first pulse signal of 1 / n cycle, M1 is the number of cycles of the first pulse signal, M2 is the number of cycles of the second pulse signal, N is the number of constant level signals of 1 / n cycle, ⊕ is the splicing of the sequence, M1λ1⊕Nγ is the characteristic electrical signal sequence, k is the number of characteristic electrical signal sequences, n≥1, k≥2.

4. The method for detecting flight time according to claim 2, characterized in that: The first electrical signal further includes: The third pulse signal; The head end of the splicing sequence is spliced ​​with the third pulse signal, and the tail end of the splicing sequence is spliced ​​with the second pulse signal.

5. The method for detecting flight time according to claim 4, characterized in that: The first electrical signal is: Lλ3⊕{M1λ1⊕Nγ}k⊕M2λ2(2) Among them, λ1 is a first pulse signal of an entire cycle, λ2 is a second pulse signal of an entire cycle, λ3 is a third pulse signal of an entire cycle, γ is a constant level signal of the first pulse signal of a 1 / n cycle, n≥1, M1 is the number of cycles of the first pulse signal, M2 is the number of cycles of the second pulse signal, L is the number of cycles of the third pulse signal, N is the number of constant level signals of a 1 / n cycle, ⊕ is the splicing of the sequence, M1λ1⊕Nγ is the characteristic electrical signal sequence, k is the number of characteristic electrical signal sequences, n≥1, k≥2.

6. The method for detecting flight time according to claim 4, characterized in that: The first pulse signal, the second pulse signal, and the third pulse signal are all square wave pulse signals; The constant level signal is a high level constant signal or a low level constant signal.

7. The method for detecting flight time according to any one of claims 1 to 6, characterized in that: The acquiring of the characteristic time point based on the time domain waveform of the second electrical signal comprises: Based on the envelope wave amplitude detection method, obtaining the envelope wave curve of the time domain waveform of the second electrical signal; Based on the envelope wave curve, characteristic time points are acquired.

8. The method for detecting flight time according to any one of claims 1 to 6, characterized in that: The acquiring of the characteristic time point based on the time domain waveform of the second electrical signal comprises: Based on a preset reference level, obtaining a period time of a sine wave in the second electrical signal by a zero-crossing detection method; A characteristic time point is obtained based on the period time of the sine wave in the electrical signal.

9. An ultrasonic flow meter, characterized in that: include: at least one ultrasonic transducer and a processor connected to the ultrasonic transducer; A memory connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for detecting flight time as claimed in any one of claims 1 to 8.

10. An optical device, characterized in that: The ultrasonic flow meter comprises a time-of-flight converter and the ultrasonic flow meter as claimed in claim 9.

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