A flow velocity measuring device, method, control device, and medium

Abstract

The present invention discloses a flow velocity measuring device, method, control device and medium. The device includes: an ultrasonic transmitting probe for transmitting ultrasonic signals; an ultrasonic receiving probe for receiving echo signals; at least two mixers, where different mixers have different reference frequencies, and each is used to output the absolute value of the frequency difference between the echo signal and the corresponding reference frequency. The difference between any two reference frequencies is greater than twice the preset minimum frequency and less than the difference between the preset maximum frequency and the preset minimum frequency; a control device for obtaining all the absolute values of the frequency differences, determining the magnitude relationship between the frequency to be measured of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences, and calculating the frequency to be measured based on the magnitude relationship, the target absolute value of the frequency difference, and the reference frequency corresponding to the target absolute value of the frequency difference. The target absolute value of the frequency difference is one that is greater than the preset minimum frequency and less than the preset maximum frequency among all the absolute values of the frequency differences. The present invention can improve the frequency measurement accuracy and reduce the time consumption.

Description

Technical Field

[0001] The present invention relates to the technical field related to flow velocity measurement, and in particular, to a flow velocity measurement device, method, control device, and medium. Background Art

[0002] The existing method for measuring water flow velocity is to emit ultrasonic waves through ultrasonic probe A. After the ultrasonic waves encounter substances in water, reflected waves are formed, and the reflected waves are received by ultrasonic probe B. The flow velocity of water is calculated through the frequencies of the transmitted wave and the reflected wave. However, considering cost performance, the embedded chips we generally use are mid - to - low - end embedded chips. The frequency measurement of existing mid - to - low - end embedded chips can only be accurate to the microsecond level, and can only distinguish between 1MHz and 1.000001MHz, but cannot distinguish to 1.0000001MHz, so the measurement accuracy is insufficient. At the same time, if accurate measurement is required, it takes 1 second to measure accurately, which is time - consuming. If the Fast Fourier Transform (FFT) method is used, the waveform needs to be sampled by an analog - to - digital conversion module and then Fourier - transformed to obtain a frequency value. Similarly, 1 second of sampling time is required to be accurate to 1Hz, and the calculation process is relatively complex and time - consuming. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, the present invention provides a flow velocity measurement device that can improve the frequency measurement accuracy and reduce the time consumption.

[0004] The present invention also provides a flow velocity measurement method, a control device for executing the above - mentioned flow velocity measurement method, and a computer - readable storage medium.

[0005] According to the flow velocity measurement device of the first - aspect embodiment of the present invention, the device includes:

[0006] An ultrasonic transmitting probe for transmitting ultrasonic signals;

[0007] An ultrasonic receiving probe for receiving the echo signals generated after the ultrasonic signals are reflected by obstacles in water;

[0008] At least two mixers, the input ends of which are respectively electrically connected to the ultrasonic receiving probe. Different mixers have different reference frequencies, and each mixer is used to output the absolute value of the frequency difference between the echo signal and the corresponding reference frequency. Among them, the difference between any two reference frequencies is greater than twice the preset minimum frequency and less than the difference between the preset maximum frequency and the preset minimum frequency;

[0009] A control device is connected to the output ends of all mixers respectively. The control device is used to obtain all absolute frequency differences, determine the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all the absolute frequency differences, and calculate the frequency to be measured based on the magnitude relationship, the target absolute frequency difference, and the reference frequency corresponding to the target absolute frequency difference. Wherein, the target absolute frequency difference is one of all the absolute frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency.

[0010] The flow velocity measurement device according to the embodiment of the present invention has at least the following beneficial effects:

[0011] By mixing the echo signal with at least two mixers, at least two absolute frequency differences between the frequency to be measured of the echo signal and the corresponding reference frequencies can be obtained. However, since the values obtained by the mixers are absolute values, the frequency to be measured cannot be directly calculated. According to all the absolute frequency differences, the magnitude relationship between the frequency to be measured and all the reference frequencies can be determined, so that the frequency to be measured can be calculated based on the target absolute frequency difference and the reference frequency corresponding to the target absolute frequency difference. Since the reliability of the measured value will be discounted when the output value of the mixer is less than the preset minimum frequency or greater than the preset maximum frequency, selecting one of all the absolute frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency for calculation can ensure the reliability of the calculation result. The frequency after mixing can be accurate to 1 Hz, which improves the frequency measurement accuracy compared with the existing frequency measurement of embedded chips, and there is no need to perform FFT analysis, saving time and calculation amount. The flow velocity measurement device according to the embodiment of the present invention can improve the frequency measurement accuracy and reduce the time consumption.

[0012] According to some embodiments of the present invention, the number of mixers is three.

[0013] According to some embodiments of the present invention, the echo signal is within a preset frequency range, the preset frequency range is equally divided into four frequency intervals, and the three reference frequencies corresponding to the three mixers are the right boundary values of the first three frequency intervals respectively.

[0014] According to some embodiments of the present invention, a signal amplification and filtering circuit is further provided between the ultrasonic receiving probe and each mixer, and a filtering circuit is further provided between each mixer and the control device.

[0015] The flow velocity measurement method according to the second aspect embodiment of the present invention is applied to the flow velocity measurement device as described in the first aspect embodiment above. The method includes:

[0016] Obtain all absolute frequency differences;

[0017] Determine the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all the absolute frequency differences;

[0018] The measured frequency is calculated based on the size relationship, the absolute value of the target frequency difference, and the reference frequency corresponding to the absolute value of the target frequency difference, where the absolute value of the target frequency difference is one that is greater than the preset minimum frequency and less than the preset maximum frequency among all the absolute values of the frequency differences.

[0019] The flow velocity measurement method according to the embodiment of the present invention has at least the following beneficial effects:

[0020] By mixing at least two mixers with the echo signal, the absolute values of the frequency differences between the measured frequencies of at least two echo signals and the corresponding reference frequencies can be obtained. However, since the values obtained by the mixer are absolute values, the measured frequency cannot be directly calculated. According to all the absolute values of the frequency differences, the size relationship between the measured frequency and all the reference frequencies can be determined, so that the measured frequency can be calculated based on the absolute value of the target frequency difference and the reference frequency corresponding to the absolute value of the target frequency difference. Since the reliability of the measured value will be discounted when the output value of the mixer is less than the preset minimum frequency or greater than the preset maximum frequency, selecting one that is greater than the preset minimum frequency and less than the preset maximum frequency among all the absolute values of the frequency differences for calculation can ensure the reliability of the calculation result. The frequency after mixing can be accurate to 1 Hz, which improves the frequency measurement accuracy compared with the existing frequency measurement of embedded chips, and there is no need to perform FFT analysis, saving time and computational complexity. The flow velocity measurement method according to the embodiment of the present invention can improve the frequency measurement accuracy and reduce the time consumption.

[0021] According to some embodiments of the present invention, the number of mixers is two, the two corresponding reference frequencies are respectively denoted as the first reference frequency and the second reference frequency, and the first reference frequency is less than the second reference frequency. The two corresponding absolute values of the frequency differences are respectively denoted as the first absolute value of the frequency difference and the second absolute value of the frequency difference;

[0022] Determining the size relationship between the measured frequency of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences includes:

[0023] If the sum of the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, it is determined that the size relationship is that the measured frequency is greater than the first reference frequency and less than the second reference frequency;

[0024] If the difference between the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the first absolute value of the frequency difference is less than the second absolute value of the frequency difference, it is determined that the size relationship is that the measured frequency is less than the first reference frequency;

[0025] If the difference between the absolute value of the first frequency difference and the absolute value of the second frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the absolute value of the first frequency difference is greater than the absolute value of the second frequency difference, determine that the magnitude relationship is that the frequency to be measured is greater than the second reference frequency.

[0026] According to some embodiments of the present invention, calculating the frequency to be measured based on the magnitude relationship, the absolute value of the target frequency difference, and the reference frequency corresponding to the absolute value of the target frequency difference includes:

[0027] If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured;

[0028] If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured;

[0029] If the magnitude relationship is that the frequency to be measured is less than the first reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the first frequency difference from the first reference frequency to obtain the frequency to be measured;

[0030] If the magnitude relationship is that the frequency to be measured is less than the first reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured;

[0031] If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured;

[0032] If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the second frequency difference to the second reference frequency to obtain the frequency to be measured.

[0033] According to some embodiments of the present invention, the number of mixers is three. The three corresponding reference frequencies are respectively denoted as the first reference frequency, the second reference frequency, and the third reference frequency, and the first reference frequency is less than the second reference frequency, and the second reference frequency is less than the third reference frequency. The absolute values of the three corresponding frequency differences are respectively denoted as the first absolute frequency difference, the second absolute frequency difference, and the third absolute frequency difference. The echo signal is within a preset frequency range, and the preset frequency range is equally divided into four frequency intervals. The first reference frequency, the second reference frequency, and the third reference frequency are respectively the right boundary values of the first three frequency intervals;

[0034] Determining the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all the absolute values of the frequency differences includes:

[0035] Determine half of the difference between the first reference frequency and the second reference frequency, and denote it as the set minimum frequency;

[0036] Select any two of the first absolute frequency difference, the second absolute frequency difference, and the third absolute frequency difference that are both greater than the set minimum frequency, and denote them as the first comparison absolute frequency difference and the second comparison absolute frequency difference. Among them, the reference frequency corresponding to the first comparison absolute frequency difference is denoted as the first comparison reference frequency, and the reference frequency corresponding to the second comparison absolute frequency difference is denoted as the second comparison reference frequency;

[0037] According to the first comparison absolute frequency difference and the second comparison absolute frequency difference, determine the magnitude relationship between the frequency to be measured and the first comparison reference frequency and the second comparison reference frequency.

[0038] According to the control device of the third aspect embodiment of the present invention, it includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the flow rate measurement method as described in the second aspect embodiment above. Since the control device adopts all the technical solutions of the flow rate measurement method of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0039] According to the computer-readable storage medium of the fourth aspect embodiment of the present invention, it stores computer-executable instructions, and the computer-executable instructions are used to execute the flow rate measurement method as described in the second aspect embodiment above. Since the computer-readable storage medium adopts all the technical solutions of the flow rate measurement method of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0040] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will become apparent from the specification, or will be understood by implementing the present invention. Description of the Drawings

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, wherein:

[0042] Figure 1 is a schematic diagram of a flow rate measuring device according to an embodiment of the present invention;

[0043] Figure 2 is a schematic diagram of the selection of three reference frequencies of three mixers according to an embodiment of the present invention;

[0044] Figure 3 is a schematic diagram of the magnitude relationship between a frequency to be measured and three reference frequencies according to an embodiment of the present invention;

[0045] Figure 4 is a schematic diagram of the selection of two reference frequencies of two mixers according to an embodiment of the present invention;

[0046] Figure 5 is a flowchart of a flow rate measuring method according to an embodiment of the present invention.

[0047] Reference Signs:

[0048] Ultrasonic transmitting probe 100;

[0049] Ultrasonic receiving probe 200;

[0050] Mixer 300;

[0051] Control device 400;

[0052] Signal amplification and filtering circuit 500;

[0053] Filter 600. Detailed Embodiments

[0054] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0055] In the description of the present invention, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence of the indicated technical features.

[0056] In the description of the present invention, it should be understood that the orientation descriptions involved, such as up, down, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0057] In the description of the present invention, it should be noted that unless otherwise clearly defined, words such as setting, installation, connection, etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0058] The following will combine Figures 1 to 4 to clearly and completely describe the flow rate measuring device according to the embodiments of the present invention. Obviously, the following described embodiments are some embodiments of the present invention, not all embodiments.

[0059] Reference Figures 1 to 4 , Figure 1 is a schematic diagram of a flow rate measuring device according to an embodiment of the present invention; Figure 2 is a schematic diagram of the selection of three reference frequencies of three mixers 300 according to an embodiment of the present invention; Figure 3 is a schematic diagram of the magnitude relationship between the frequency to be measured and the three reference frequencies according to an embodiment of the present invention; Figure 4 is a schematic diagram of the selection of two reference frequencies of two mixers 300 according to an embodiment of the present invention.

[0060] The flow rate measuring device according to the first aspect embodiment of the present invention includes an ultrasonic transmitting probe 100, an ultrasonic receiving probe 200, a control device 400, and at least two mixers 300.

[0061] The ultrasonic transmitting probe 100 is used to transmit ultrasonic signals;

[0062] The ultrasonic receiving probe 200 is used to receive the echo signal generated after the ultrasonic signal is reflected by the obstacle in the water;

[0063] At least two mixers 300, the input ends of which are respectively electrically connected to the ultrasonic receiving probe 200. Different mixers 300 have different reference frequencies. Each mixer 300 is used to output the absolute value of the frequency difference between the echo signal and the corresponding reference frequency. Among them, the difference between any two reference frequencies is greater than twice the preset minimum frequency and less than the difference between the preset maximum frequency and the preset minimum frequency;

[0064] The control device 400 is respectively connected to the output ends of all the mixers 300. The control device 400 is used to obtain all the absolute values of the frequency differences, determine the magnitude relationship between the frequency to be measured of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences, and calculate the frequency to be measured based on the magnitude relationship, the target absolute value of the frequency difference, and the reference frequency corresponding to the target absolute value of the frequency difference. Among them, the target absolute value of the frequency difference is one of all the absolute values of the frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency.

[0065] In some embodiments, refer to Figure 1 , the ultrasonic transmitting probe 100 emits an ultrasonic signal of 1 MHz (the reason for using 1 MHz is that ultrasonic waves in this frequency band are more easily transmitted in water). After the ultrasonic waves encounter substances in water (point Q), a reflected wave (i.e., the echo signal) is formed, and the echo signal is received by the ultrasonic receiving probe 200. The constraint formula for the water flow velocity is:

[0066] ;

[0067] Among them, is the water flow velocity, is the frequency difference generated during the process from the transmission to the reception of the ultrasonic signal, is the propagation speed of ultrasonic waves in the fluid, is the frequency of the ultrasonic signal, is the angle between the ultrasonic propagation direction and the fluid flow direction (approximately equal to 0).

[0068] As can be seen from the above formula, actually the physical quantity to be measured is changed from velocity to frequency.

[0069] During the process of measuring the frequency, the target measurement accuracy is 1 Hz. However, considering the cost performance, the embedded chips we generally use are mid - to - low - end embedded chips. The frequency measurement of existing mid - to - low - end embedded chips can only be accurate to the microsecond level, and can only distinguish between 1 MHz and 1.000001 MHz, but cannot distinguish to 1.0000001 MHz. At the same time, if accurate measurement is required, it takes 1 second to measure accurately. If only 0.1 second is measured, then the measured value should be 0.1 MHz or 0.100001 MHz (the last digit is determined by the microsecond level, which can be understood as a resolution problem). After multiplying by 10, the obtained frequency is 1 MHz or 1.00001 MHz, and the resolution becomes 10 Hz instead of 1 Hz. If the FFT method (which is also the method used by many devices now) is adopted, the waveform needs to be sampled by the analog - to - digital conversion module and then Fourier - transformed to obtain a frequency value. Similarly, 1 second of sampling time is required to be accurate to 1 Hz, and there is also a complex calculation process.

[0070] In addition, it should be noted that the flow rate measuring device of the present invention is battery-powered, and the sampling time of 0.1 second is set considering energy consumption under the condition of battery power supply. The advantage of the present invention is that it can complete the measurement task in a shorter time, reduce energy consumption, and lower the measurement cost.

[0071] It can be understood that the mixer 300 is used to output the absolute value of the frequency difference between the echo signal and the corresponding reference frequency. That is to say, only one mixer 300 cannot determine the frequency to be measured of the echo signal. Taking a reference point of 1 MHz as an example, the values obtained by mixing 0.99 MHz with it and 1.01 MHz with it are the same. Therefore, at least two mixers 300 are required to determine the magnitude relationship between the frequency to be measured of the echo signal and the two reference frequencies through the corresponding two absolute values of the frequency differences. Then, the frequency to be measured can be calculated based on the magnitude relationship, the target absolute value of the frequency difference, and the reference frequency corresponding to the target absolute value of the frequency difference. And since the reliability of the measured value will be discounted when the output value of the mixer 300 is less than the preset minimum frequency or greater than the preset maximum frequency, the difference between any two reference frequencies should be greater than twice the preset minimum frequency and less than the difference between the preset maximum frequency and the preset minimum frequency to ensure that the output result of at least one mixer 300 is valid. Then, select one of all the absolute values of the frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency for calculation to ensure the reliability of the calculation result.

[0072] In some embodiments of the present invention, referring to Figures 1 to 4 , the number of mixers 300 is two. The two corresponding reference frequencies are respectively denoted as the first reference frequency and the second reference frequency, and the first reference frequency is less than the second reference frequency. The two corresponding absolute values of the frequency differences are respectively denoted as the first absolute value of the frequency difference and the second absolute value of the frequency difference;

[0073] Determining the magnitude relationship between the frequency to be measured of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences includes:

[0074] If the sum of the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, determine that the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency;

[0075] If the difference between the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the first absolute value of the frequency difference is less than the second absolute value of the frequency difference, determine that the magnitude relationship is that the frequency to be measured is less than the first reference frequency;

[0076] If the difference between the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the first absolute value of the frequency difference is greater than the second absolute value of the frequency difference, determine that the magnitude relationship is that the frequency to be measured is greater than the second reference frequency.

[0077] In some embodiments of the present invention, with reference to Figures 1 to 4 , the frequency to be measured is calculated based on the magnitude relationship, the absolute value of the target frequency difference, and the reference frequency corresponding to the absolute value of the target frequency difference, including:

[0078] If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured;

[0079] If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured;

[0080] If the magnitude relationship is that the frequency to be measured is less than the first reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the first frequency difference from the first reference frequency to obtain the frequency to be measured;

[0081] If the magnitude relationship is that the frequency to be measured is less than the first reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured;

[0082] If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured;

[0083] If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the second frequency difference to the second reference frequency to obtain the frequency to be measured.

[0084] Next, a specific embodiment is used to illustrate the calculation process. In this embodiment, the preset minimum frequency is 2KHz (i.e., 0.002MHz), the preset maximum frequency is 50KHz (i.e., 0.05MHz), with reference to Figure 3 , two reference frequencies, reference 1 (0.9925MHz) and reference 2 (1MHz), are selected.

[0085] The absolute value of the frequency difference between the frequency to be measured and reference 1 is 0.0025 MHz, denoted as f1. The absolute value of the frequency difference between the frequency to be measured and reference 2 is 0.01 MHz, denoted as f2. f2 - f1 = 0.0075 MHz = 1 MHz - 0.9925 MHz. Then the frequency to be measured is outside reference 1 (0.9925 MHz) and reference 2 (1 MHz), and the absolute value of the first frequency difference (0.0025 MHz) is less than the absolute value of the second frequency difference (0.01 MHz). So the frequency to be measured is closer to reference 1 (0.9925 MHz). Therefore, the frequency to be measured is on the left of reference 1 (0.9925 MHz), and both the absolute value of the first frequency difference (0.0025 MHz) and the absolute value of the second frequency difference (0.01 MHz) are greater than 0.002 MHz and less than 0.05 MHz. Thus, either one can be chosen for calculation, that is, 0.9925 MHz - 0.0025 MHz = 0.99 MHz, or 1 MHz - 0.01 MHz = 0.99 MHz. The frequency to be measured is 0.99 MHz.

[0086] In some embodiments, during the circuit design process, problems may occur in the cooperation between the MCU processor and the circuit. When using two mixers 300, it is possible that the reference frequency of one of them is exactly equal to the frequency to be measured. Then the output result of this mixer 300 has no calculation significance, which is equivalent to the data here being ambiguous, and many additional cases need to be considered in the program. Since the water flow rate is generally within plus or minus 10 meters per second, the received frequency range is generally: 0.985 MHz to 1.015 MHz. The two reference frequencies can be set outside this range, that is Figure 4 reference 4 (0.983 MHz) and reference 5 (1.017 MHz) in [reference], then it can be ensured that generally the frequency to be measured will not be the same as the reference frequency of the mixer 300. There is also a frequency difference greater than 2 KHz and less than 50 KHz between the frequency to be measured and reference 4 (0.983 MHz) and reference 5 (1.017 MHz). Relatively speaking, the data will be more accurate.

[0087] It should be noted that since the frequency to be measured is not necessarily within the range of 0.985 MHz to 1.015 MHz in actual situations, two mixers 300 are still needed to determine the value of the frequency to be measured.

[0088] According to the flow velocity measuring device of the embodiments of the present invention, by mixing with at least two mixers 300 and an echo signal, the absolute value of the frequency difference between the measured frequency of at least two echo signals and the corresponding reference frequencies can be obtained. However, since what the mixer 300 obtains is an absolute value, the measured frequency cannot be directly calculated. According to all the absolute values of the frequency differences, the magnitude relationship between the measured frequency and all the reference frequencies can be determined. Thus, the measured frequency can be calculated through the target absolute value of the frequency difference and the reference frequency corresponding to the target absolute value of the frequency difference. Since the reliability of the measured value will be discounted when the output value of the mixer 300 is less than the preset minimum frequency or greater than the preset maximum frequency, selecting one of all the absolute values of the frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency for calculation can ensure the reliability of the calculation result. The frequency after mixing can be accurate to 1 Hz, which improves the frequency measurement accuracy compared with the existing frequency measurement of embedded chips, and there is no need to perform FFT analysis, saving time and calculation amount. The flow velocity measuring device of the embodiments of the present invention can improve the frequency measurement accuracy and reduce the time consumption.

[0089] In some embodiments of the present invention, referring to Figures 1 to 3 , the number of mixers 300 is three. With two mixers 300, it can be determined that at least one of the measurement results of the mixers 300 is accurate. By determining the magnitude relationship between the measured frequency and the reference frequency of this mixer 300, and the output value of this mixer 300 and the corresponding reference frequency, the value of the measured frequency can be accurately calculated. With three mixers 300, there are more reference quantities, which can make the calculation result more accurate and can avoid the situation where two mixers 300 are used, but the reference frequency of one of the mixers 300 is exactly equal to the measured frequency and cannot be calculated.

[0090] It should be noted that the number of mixers 300 can be more, which cannot be regarded as a limitation of the present invention.

[0091] In some embodiments of the present invention, referring to Figures 1 to 3 , the echo signal is within a preset frequency range, the preset frequency range is equally divided into four frequency intervals, and the three reference frequencies corresponding to the three mixers 300 are respectively the right boundary values of the first three frequency intervals.

[0092] The three corresponding reference frequencies are respectively denoted as the first reference frequency, the second reference frequency, and the third reference frequency, and the first reference frequency is less than the second reference frequency, and the second reference frequency is less than the third reference frequency. The three corresponding absolute values of the frequency differences are respectively denoted as the first absolute value of the frequency difference, the second absolute value of the frequency difference, and the third absolute value of the frequency difference. The echo signal is within a preset frequency range, the preset frequency range is equally divided into four frequency intervals, and the first reference frequency, the second reference frequency, and the third reference frequency are respectively the right boundary values of the first three frequency intervals;

[0093] Determine the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all absolute frequency differences, including:

[0094] Determine half of the difference between the first reference frequency and the second reference frequency, and denote it as the set minimum frequency;

[0095] Select any two of the first absolute frequency difference, the second absolute frequency difference, and the third absolute frequency difference that are both greater than the set minimum frequency, and denote them as the first comparison absolute frequency difference and the second comparison absolute frequency difference. Among them, the reference frequency corresponding to the first comparison absolute frequency difference is denoted as the first comparison reference frequency, and the reference frequency corresponding to the second comparison absolute frequency difference is denoted as the second comparison reference frequency;

[0096] Determine the magnitude relationship between the frequency to be measured and the first comparison reference frequency and the second comparison reference frequency according to the first comparison absolute frequency difference and the second comparison absolute frequency difference.

[0097] In some embodiments, since the water flow velocity is generally within plus or minus 10 meters per second, the received frequency range should be: 0.985 MHz to 1.015 MHz (i.e., the preset frequency range). Then the three reference frequencies corresponding to the three mixers 300 are respectively reference 1 (0.9925 MHz), reference 2 (1 MHz), and reference 3 (1.0075 MHz).

[0098] Half of the difference between any two of reference 1 (0.9925 MHz), reference 2 (1 MHz), and reference 3 (1.0075 MHz) is equal to 0.00375 MHz, which is the set minimum frequency. The function of the set minimum frequency is to screen out the one closest to the frequency to be measured from the three reference frequencies and perform calculations with the other two effective reference frequencies. Reference Figure 2 , the first absolute frequency difference, the second absolute frequency difference, and the third absolute frequency difference corresponding to the frequency to be measured and reference 1 (0.9925 MHz), reference 2 (1 MHz), and reference 3 (1.0075 MHz) are respectively denoted as f1, f2, and f3. C, D, E, and F are respectively the midpoints of the four frequency intervals.

[0099] For point B, f1 > 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Any 2 references can be taken, that is, f1, f2, or f3 are all acceptable.

[0100] For point C, f1 = 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Any 2 references can be taken, that is, f1, f2, or f3 are all acceptable.

[0101] For the points between C and D: f1 < 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Take reference 2 and reference 3, that is, f2 and f3.

[0102] For point D, f1 = 0.00375 MHz, f2 = 0.00375 MHz, f3 > 0.00375 MHz. Arbitrarily select 2 references, that is, f1, f2, or f3 is acceptable.

[0103] For the points between D and E: f1 > 0.00375 MHz, f2 < 0.00375 MHz, f3 > 0.00375 MHz. Take reference 1 and reference 3, that is, f1 and f3.

[0104] For point E, f1 > 0.00375 MHz, f2 = 0.00375 MHz, f3 = 0.00375 MHz. Arbitrarily select 2 references, that is, f1, f2, or f3 is acceptable.

[0105] For the points between E and F: f1 > 0.00375 MHz, f2 > 0.00375 MHz, f3 < 0.00375 MHz. Take reference 1 and reference 2, that is, f1 and f2.

[0106] For point F and the points after it: f1 > 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Arbitrarily select 2 references, that is, f1, f2, or f3 is acceptable.

[0107] The smallest frequency available for calculation is 3.75 KHz, and the largest frequency is the frequency from the left endpoint to reference 3 or from the right endpoint to reference 1, which is 22.5 KHz. For high frequencies around 1 MHz, 1 Hz is 1 microsecond, which is the limit of the chip. However, for the mixed frequencies, the highest frequency is 22.5 KHz, and 1 Hz is at least 44 μS. So we can be accurate to 0.025 Hz. Considering that we only use a measurement time of 0.1 second, we need to multiply by 10 at this accuracy, so the accuracy is 0.25 Hz, and thus we can be accurate to 1 Hz.

[0108] Next, a specific embodiment is used to illustrate the calculation process. In this embodiment, the preset minimum frequency is 2 KHz (i.e., 0.002 MHz), and the preset maximum frequency is 50 KHz (i.e., 0.05 MHz).

[0109] Reference Figure 3, the absolute values of the first frequency difference, the second frequency difference, and the third frequency difference corresponding to the frequency to be measured and reference 1 (0.9925 MHz), reference 2 (1 MHz), and reference 3 (1.0075 MHz) are 0.0025 MHz, 0.01 MHz, and 0.0175 MHz respectively, denoted as f1, f2, and f3. Since 0.0025 MHz < 0.00375 MHz, 0.01 MHz and 0.0175 MHz are taken for calculation. 0.01 MHz - 0.0175 MHz = 0.0075 MHz = 1 MHz - 1.0075 MHz. Therefore, the frequency to be measured is outside of reference 2 (1 MHz) and reference 3 (1.0075 MHz). Also, since the frequency to be measured is closest to reference 1 (0.9925 MHz), the frequency to be measured is on the left side of reference 2 (1 MHz). Both 0.01 MHz and 0.0175 MHz are greater than 0.002 MHz and less than 0.05 MHz. Therefore, either one can be selected for calculation, that is, the frequency to be measured is 1 MHz - 0.01 MHz = 0.99 MHz, or 1.0075 MHz - 0.0175 MHz = 0.99 MHz.

[0110] It should be noted that it is simpler from a programming perspective that reference 1, reference 3, and reference 3 divide the preset frequency range equally. Reference 1, reference 3, and reference 3 may also not divide the preset frequency range equally, and it can still be implemented. It's just that the program will be more complex, and it cannot be regarded as a limitation to the present invention.

[0111] In some embodiments of the present invention, reference Figure 1 , a signal amplification and filtering circuit 500 is further provided between the ultrasonic receiving probe 200 and each mixer 300, and a filtering circuit is further provided between each mixer 300 and the control device 400. In some embodiments, there are three mixers 300, and the filtering circuit includes three filters 600. The three filters 600 are connected to the output ends of the three mixers 300 in one-to-one correspondence.

[0112] It should be noted that the functions and principles of the signal amplification and filtering circuit 500 and the filtering circuit are prior arts known to those skilled in the art, and will not be elaborated here.

[0113] Next, the flow rate measurement method of the embodiments of the present invention will be clearly and completely described. Obviously, the following described embodiments are some embodiments of the present invention, not all embodiments. Figures 1 to 5 Reference

[0114] Reference Figures 1 to 5 , Figure 1 is a schematic diagram of a flow rate measurement device according to an embodiment of the present invention; Figure 2 is a schematic diagram of the selection of three reference frequencies of three mixers 300 according to an embodiment of the present invention; Figure 3It is a schematic diagram showing the magnitude relationship between the frequency to be measured and three reference frequencies in an embodiment of the present invention; Figure 4 It is a schematic diagram showing the selection of two reference frequencies of two mixers 300 in an embodiment of the present invention; Figure 5 It is a flowchart of a flow velocity measurement method in an embodiment of the present invention.

[0115] The flow velocity measurement method according to the second aspect embodiment of the present invention is applied to the flow velocity measurement device as described in the first aspect embodiment above. The method includes:

[0116] Obtain all absolute frequency differences;

[0117] Determine the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all absolute frequency differences;

[0118] Calculate the frequency to be measured based on the magnitude relationship, the target absolute frequency difference, and the reference frequency corresponding to the target absolute frequency difference, where the target absolute frequency difference is one of all absolute frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency.

[0119] It can be understood that the mixer 300 is used to output the absolute value of the frequency difference between the echo signal and the corresponding reference frequency. That is to say, it is impossible to determine the frequency to be measured of the echo signal with only one mixer 300. Taking a reference point of 1 MHz as an example, the values obtained by mixing 0.99 MHz with it and 1.01 MHz with it are the same. Therefore, at least two mixers 300 are required to determine the magnitude relationship between the frequency to be measured of the echo signal and two reference frequencies through the corresponding two absolute frequency differences, and then the frequency to be measured can be calculated based on the magnitude relationship, the target absolute frequency difference, and the reference frequency corresponding to the target absolute frequency difference. And since the reliability of the measured value will be discounted when the output value of the mixer 300 is less than the preset minimum frequency or greater than the preset maximum frequency, the difference between any two reference frequencies should be greater than twice the preset minimum frequency and less than the difference between the preset maximum frequency and the preset minimum frequency to ensure that the output result of at least one mixer 300 is valid, and then select one of all absolute frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency for calculation to ensure the reliability of the calculation result.

[0120] According to the flow rate measurement method of the embodiments of the present invention, by mixing at least two mixers 300 with the echo signal, the absolute value of the frequency difference between the measured frequency of at least two echo signals and the corresponding reference frequencies can be obtained. However, since the values obtained by the mixers 300 are absolute values, the measured frequency cannot be directly calculated. According to all the absolute values of the frequency differences, the magnitude relationship between the measured frequency and all the reference frequencies can be determined. Thus, the measured frequency can be calculated through the target absolute value of the frequency difference and the reference frequency corresponding to the target absolute value of the frequency difference. Since the reliability of the measured value will be discounted when the output value of the mixer 300 is less than the preset minimum frequency or greater than the preset maximum frequency, selecting one of all the absolute values of the frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency for calculation can ensure the reliability of the calculation result. The frequency after mixing can be accurate to 1 Hz, which improves the frequency measurement accuracy compared with the existing frequency measurement of embedded chips, and there is no need to perform FFT analysis, saving time and computational complexity. The flow rate measurement method of the embodiments of the present invention can improve the frequency measurement accuracy and reduce the time consumption.

[0121] In some embodiments of the present invention, referring to Figures 1 to 4 , the number of mixers 300 is two. The two corresponding reference frequencies are respectively denoted as the first reference frequency and the second reference frequency, and the first reference frequency is less than the second reference frequency. The two corresponding absolute values of the frequency differences are respectively denoted as the first absolute value of the frequency difference and the second absolute value of the frequency difference;

[0122] Determining the magnitude relationship between the measured frequency of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences includes:

[0123] If the sum of the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, it is determined that the magnitude relationship is that the measured frequency is greater than the first reference frequency and less than the second reference frequency;

[0124] If the difference between the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the first absolute value of the frequency difference is less than the second absolute value of the frequency difference, it is determined that the magnitude relationship is that the measured frequency is less than the first reference frequency;

[0125] If the difference between the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the first absolute value of the frequency difference is greater than the second absolute value of the frequency difference, it is determined that the magnitude relationship is that the measured frequency is greater than the second reference frequency.

[0126] In some embodiments of the present invention, referring to Figures 1 to 4 , calculating the measured frequency according to the magnitude relationship, the target absolute value of the frequency difference, and the reference frequency corresponding to the target absolute value of the frequency difference includes:

[0127] If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency, less than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured;

[0128] If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency, less than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured;

[0129] If the magnitude relationship is that the frequency to be measured is less than the first reference frequency and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the first frequency difference from the first reference frequency to obtain the frequency to be measured;

[0130] If the magnitude relationship is that the frequency to be measured is less than the first reference frequency and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured;

[0131] If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured;

[0132] If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the second frequency difference to the second reference frequency to obtain the frequency to be measured.

[0133] Next, a specific embodiment is used to illustrate the calculation process. In this embodiment, the preset minimum frequency is 2 KHz (i.e., 0.002 MHz), and the preset maximum frequency is 50 KHz (i.e., 0.05 MHz). Refer to Figure 3 , and select two reference frequencies, reference 1 (0.9925 MHz) and reference 2 (1 MHz).

[0134] The absolute value of the frequency difference between the frequency to be measured and Reference 1 is 0.0025 MHz, denoted as f1. The absolute value of the frequency difference between the frequency to be measured and Reference 2 is 0.01 MHz, denoted as f2. f2 - f1 = 0.0075 MHz = 1 MHz - 0.9925 MHz. Then the frequency to be measured is outside of Reference 1 (0.9925 MHz) and Reference 2 (1 MHz), and the absolute value of the first frequency difference (0.0025 MHz) is less than the absolute value of the second frequency difference (0.01 MHz). So the frequency to be measured is closer to Reference 1 (0.9925 MHz). Therefore, the frequency to be measured is on the left side of Reference 1 (0.9925 MHz), and both the absolute value of the first frequency difference (0.0025 MHz) and the absolute value of the second frequency difference (0.01 MHz) are greater than 0.002 MHz and less than 0.05 MHz. Thus, either one can be chosen for calculation, that is, 0.9925 MHz - 0.0025 MHz = 0.99 MHz, or 1 MHz - 0.01 MHz = 0.99 MHz. The frequency to be measured is 0.99 MHz.

[0135] In some embodiments, during the circuit design process, problems may be encountered in the cooperation between the MCU processor and the circuit. When two mixers 300 are used, it is possible that the reference frequency of one of them is exactly equal to the frequency to be measured. Then the output result of this mixer 300 has no calculation significance, which is equivalent to the data here being ambiguous, and many supplementary measures for unexpected situations need to be taken in the program. Since the water flow velocity is generally within plus or minus 10 meters per second, the generally received frequency range is: 0.985 MHz to 1.015 MHz. The two reference frequencies can be set outside this range, that is Figure 4 Reference 4 (0.983 MHz) and Reference 5 (1.017 MHz) in [reference content], then it can be ensured that generally the frequency to be measured will not be the same as the reference frequency of the mixer 300, and there is also a frequency difference greater than 2 KHz and less than 50 KHz between the frequency to be measured and Reference 4 (0.983 MHz) and Reference 5 (1.017 MHz). Relatively speaking, the data will be more accurate.

[0136] It should be noted that since the frequency to be measured is not necessarily within the range of 0.985 MHz to 1.015 MHz in actual situations, two mixers 300 are still needed to determine the value of the frequency to be measured.

[0137] In some embodiments of the present invention, reference Figures 1 to 3, the number of mixers 300 is three. The three corresponding reference frequencies are respectively denoted as the first reference frequency, the second reference frequency, and the third reference frequency, and the first reference frequency is less than the second reference frequency, and the second reference frequency is less than the third reference frequency. The absolute values of the three corresponding frequency differences are respectively denoted as the first absolute frequency difference, the second absolute frequency difference, and the third absolute frequency difference. The echo signal is within a preset frequency range, and the preset frequency range is equally divided into four frequency intervals. The first reference frequency, the second reference frequency, and the third reference frequency are respectively the right boundary values of the first three frequency intervals;

[0138] Determine the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all the absolute values of the frequency differences, including:

[0139] Determine half of the difference between the first reference frequency and the second reference frequency, and denote it as the set minimum frequency;

[0140] Select any two of the first absolute frequency difference, the second absolute frequency difference, and the third absolute frequency difference that are both greater than the set minimum frequency, and denote them as the first comparative absolute frequency difference and the second comparative absolute frequency difference. Among them, the reference frequency corresponding to the first comparative absolute frequency difference is denoted as the first comparative reference frequency, and the reference frequency corresponding to the second comparative absolute frequency difference is denoted as the second comparative reference frequency;

[0141] Determine the magnitude relationship between the frequency to be measured and the first comparative reference frequency and the second comparative reference frequency according to the first comparative absolute frequency difference and the second comparative absolute frequency difference.

[0142] Using two mixers 300, it can be determined that at least one measurement result of the mixer 300 is accurate. By determining the magnitude relationship between the frequency to be measured and the reference frequency of this mixer 300, as well as the output value of this mixer 300 and the corresponding reference frequency, the value of the frequency to be measured can be accurately calculated. Using three mixers 300, there are more reference quantities, which can make the calculation result more accurate, and can avoid the situation where two mixers 300 are used, but the reference frequency of one of the mixers 300 is exactly equal to the frequency to be measured and cannot be calculated.

[0143] It should be noted that the number of mixers 300 can be more, which cannot be regarded as a limitation of the present invention.

[0144] In some embodiments, since the water flow velocity is generally within plus or minus 10 meters per second, the received frequency range should be: 0.985 MHz to 1.015 MHz (i.e., the preset frequency range). Then the three reference frequencies corresponding to the three mixers 300 are respectively Reference 1 (0.9925 MHz), Reference 2 (1 MHz), and Reference 3 (1.0075 MHz).

[0145] Half of the difference between any two of Reference 1 (0.9925 MHz), Reference 2 (1 MHz), and Reference 3 (1.0075 MHz) is equal to 0.00375 MHz, which is the set minimum frequency. The role of the set minimum frequency is to screen out the reference frequency closest to the frequency to be measured from the three reference frequencies and perform calculations using the other two valid reference frequencies. Reference Figure 2 , the absolute values of the first frequency difference, the second frequency difference, and the third frequency difference corresponding to the frequency to be measured and Reference 1 (0.9925 MHz), Reference 2 (1 MHz), and Reference 3 (1.0075 MHz) are respectively denoted as f1, f2, and f3, and C, D, E, and F are the midpoints of the four frequency intervals.

[0146] For point B, f1 > 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Arbitrarily select 2 references, that is, any of f1, f2, f3 is acceptable.

[0147] For point C, f1 = 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Arbitrarily select 2 references, that is, any of f1, f2, f3 is acceptable.

[0148] For points between C and D: f1 < 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Select Reference 2 and Reference 3, that is, f2 and f3.

[0149] For point D, f1 = 0.00375 MHz, f2 = 0.00375 MHz, f3 > 0.00375 MHz. Arbitrarily select 2 references, that is, any of f1, f2, f3 is acceptable.

[0150] For points between D and E, f1 > 0.00375 MHz, f2 < 0.00375 MHz, f3 > 0.00375 MHz. Select Reference 1 and Reference 3, that is, f1 and f3.

[0151] For point E, f1 > 0.00375 MHz, f2 = 0.00375 MHz, f3 = 0.00375 MHz. Arbitrarily select 2 references, that is, any of f1, f2, f3 is acceptable.

[0152] For points between E and F, f1 > 0.00375 MHz, f2 > 0.00375 MHz, f3 < 0.00375 MHz. Select Reference 1 and Reference 2, that is, f1 and f2.

[0153] For point F and subsequent points, f1 > 0.00375 MHz, f2 > 0.00375 MHz, f3 > 0.00375 MHz. Arbitrarily select 2 references, that is, any of f1, f2, f3 is acceptable.

[0154] The smallest frequency available for calculation is 3.75 KHz, and the largest frequency is the frequency from the left endpoint to reference 3 or from the right endpoint to reference 1, which is 22.5 KHz. For high frequencies around 1 MHz, 1 Hz is 1 microsecond, which is the limit of the chip. However, for the mixed frequencies, the highest frequency is 22.5 KHz, and 1 Hz is at least 44 μS. Therefore, we can be accurate to 0.025 Hz. Considering that we only use a measurement time of 0.1 second, we need to multiply by 10 at this accuracy, so the accuracy is 0.25 Hz, and thus we can be accurate to 1 Hz.

[0155] Next, a specific embodiment is used to illustrate the calculation process. In this embodiment, the preset minimum frequency is 2 KHz (i.e., 0.002 MHz), and the preset maximum frequency is 50 KHz (i.e., 0.05 MHz).

[0156] Reference Figure 3 , the absolute values of the first frequency difference, the second frequency difference, and the third frequency difference between the frequency to be measured and reference 1 (0.9925 MHz), reference 2 (1 MHz), and reference 3 (1.0075 MHz) are 0.0025 MHz, 0.01 MHz, and 0.0175 MHz respectively, denoted as f1, f2, and f3. Since 0.0025 MHz < 0.00375 MHz, we take 0.01 MHz and 0.0175 MHz for calculation. 0.01 MHz - 0.0175 MHz = 0.0075 MHz = 1 MHz - 1.0075 MHz. Therefore, the frequency to be measured is outside of reference 2 (1 MHz) and reference 3 (1.0075 MHz). Also, since the frequency to be measured is closest to reference 1 (0.9925 MHz), the frequency to be measured is on the left side of reference 2 (1 MHz). Both 0.01 MHz and 0.0175 MHz are greater than 0.002 MHz and less than 0.05 MHz. Therefore, we can choose either one for calculation, that is, the frequency to be measured is 1 MHz - 0.01 MHz = 0.99 MHz, or 1.0075 MHz - 0.0175 MHz = 0.99 MHz.

[0157] It should be noted that it is simpler from a programming perspective to divide the preset frequency range equally among reference 1, reference 3, and reference 3. Reference 1, reference 3, and reference 3 can also not divide the preset frequency range equally, and it can still be achieved, but the program will be more complex, and it cannot be regarded as a limitation of the present invention.

[0158] In addition, an embodiment of the present invention also provides a control device 400, which includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor and the memory can be connected through a bus or other means.

[0159] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely located relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0160] The non-transitory software programs and instructions required to implement the flow rate measurement method of the above embodiments are stored in the memory, and when executed by the processor, the flow rate measurement method in the above embodiments is executed.

[0161] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0162] In addition, an embodiment of the present invention also provides a computer-readable storage medium storing computer-executable instructions, which when executed by a processor or a controller, such as the processor in the above embodiment, can cause the above processor to execute the flow rate measurement method in the above embodiment.

[0163] Those of ordinary skill in the art will understand that all or some of the steps and systems disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include a computer storage medium (or non-transitory medium) and a communication medium (or transitory medium). As is well known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information, such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disks (DVDs) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and that can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically includes computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transmission mechanism, and can include any information delivery media.

[0164] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art to which the present invention pertains, various changes can be made without departing from the gist of the present invention.

Claims

1. A flow velocity measuring device, characterized in that, The device includes: An ultrasonic transmitting probe for transmitting ultrasonic signals; An ultrasonic receiving probe for receiving the echo signals generated after the ultrasonic signals are reflected by obstacles in water; At least two mixers, the input ends of which are respectively electrically connected to the ultrasonic receiving probe. Different mixers have different reference frequencies. Each mixer is used to output the absolute value of the frequency difference between the echo signal and the corresponding reference frequency. Among them, the difference between any two reference frequencies is greater than twice the preset minimum frequency and less than the difference between the preset maximum frequency and the preset minimum frequency; A control device, which is respectively connected to the output ends of all mixers. The control device is used to obtain all the absolute values of the frequency differences, determine the magnitude relationship between the measured frequency of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences, and calculate the measured frequency according to the magnitude relationship, the target absolute value of the frequency difference, and the reference frequency corresponding to the target absolute value of the frequency difference. Among them, the target absolute value of the frequency difference is one of all the absolute values of the frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency.

2. The flow velocity measuring device according to claim 1, characterized in that The number of mixers is three.

3. The flow rate measuring device according to claim 2, characterized in that, The echo signal is within a preset frequency range. The preset frequency range is equally divided into four frequency intervals. The three reference frequencies corresponding to the three mixers are respectively the right boundary values of the first three frequency intervals.

4. The flow rate measuring device according to claim 1, wherein A signal amplification and filtering circuit is further provided between the ultrasonic receiving probe and each mixer, and a filtering circuit is further provided between each mixer and the control device.

5. A flow velocity measurement method, characterized in that, Applied to the flow velocity measuring device as described in any one of claims 1 to 4, the method includes: Obtaining all the absolute values of the frequency differences; Determining the magnitude relationship between the measured frequency of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences; Calculating the measured frequency according to the magnitude relationship, the target absolute value of the frequency difference, and the reference frequency corresponding to the target absolute value of the frequency difference. Among them, the target absolute value of the frequency difference is one of all the absolute values of the frequency differences that is greater than the preset minimum frequency and less than the preset maximum frequency.

6. The flow velocity measurement method according to claim 5, characterized in that, The number of mixers is two. The two corresponding reference frequencies are respectively denoted as the first reference frequency and the second reference frequency, and the first reference frequency is less than the second reference frequency. The two corresponding absolute values of the frequency differences are respectively denoted as the first absolute value of the frequency difference and the second absolute value of the frequency difference; The determining the magnitude relationship between the measured frequency of the echo signal and all the reference frequencies according to all the absolute values of the frequency differences includes: If the sum of the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, determining that the magnitude relationship is that the measured frequency is greater than the first reference frequency and less than the second reference frequency; If the difference between the first absolute value of the frequency difference and the second absolute value of the frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the first absolute value of the frequency difference is less than the second absolute value of the frequency difference, determining that the magnitude relationship is that the measured frequency is less than the first reference frequency; If the difference between the absolute value of the first frequency difference and the absolute value of the second frequency difference is equal to the difference between the first reference frequency and the second reference frequency, and the absolute value of the first frequency difference is greater than the absolute value of the second frequency difference, determine that the magnitude relationship is that the frequency to be measured is greater than the second reference frequency.

7. The flow rate measurement method according to claim 6, wherein Calculating the frequency to be measured according to the magnitude relationship, the absolute value of the target frequency difference, and the reference frequency corresponding to the absolute value of the target frequency difference includes: If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured; If the magnitude relationship is that the frequency to be measured is greater than the first reference frequency and less than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured; If the magnitude relationship is that the frequency to be measured is less than the first reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the first frequency difference from the first reference frequency to obtain the frequency to be measured; If the magnitude relationship is that the frequency to be measured is less than the first reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, subtract the absolute value of the second frequency difference from the second reference frequency to obtain the frequency to be measured; If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency, and the absolute value of the first frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the first frequency difference to the first reference frequency to obtain the frequency to be measured; If the magnitude relationship is that the frequency to be measured is greater than the second reference frequency, and the absolute value of the second frequency difference is greater than the preset minimum frequency and less than the preset maximum frequency, add the absolute value of the second frequency difference to the second reference frequency to obtain the frequency to be measured.

8. The flow rate measurement method according to claim 5, characterized in that The number of mixers is three. The three corresponding reference frequencies are respectively denoted as the first reference frequency, the second reference frequency, and the third reference frequency, and the first reference frequency is less than the second reference frequency, and the second reference frequency is less than the third reference frequency. The absolute values of the three corresponding frequency differences are respectively denoted as the first absolute value of the frequency difference, the second absolute value of the frequency difference, and the third absolute value of the frequency difference. The echo signal is within a preset frequency range, and the preset frequency range is equally divided into four frequency intervals. The first reference frequency, the second reference frequency, and the third reference frequency are respectively the right boundary values of the first three frequency intervals; Determining the magnitude relationship between the frequency to be measured of the echo signal and all reference frequencies according to all absolute values of the frequency differences includes: Determine half of the difference between the first reference frequency and the second reference frequency, and denote it as the set minimum frequency; Among the absolute values of the first frequency difference, the absolute value of the second frequency difference, and the absolute value of the third frequency difference, any two that are greater than the set minimum frequency are denoted as the first comparative absolute value of the frequency difference and the second comparative absolute value of the frequency difference. Among them, the reference frequency corresponding to the first comparative absolute value of the frequency difference is denoted as the first comparative reference frequency, and the reference frequency corresponding to the second comparative absolute value of the frequency difference is denoted as the second comparative reference frequency; Based on the first comparative absolute value of the frequency difference and the second comparative absolute value of the frequency difference, determine the magnitude relationship between the frequency to be measured, the first comparative reference frequency, and the second comparative reference frequency.

9. A control device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the flow velocity measurement method according to any one of claims 5 to 8.

10. A computer-readable storage medium storing computer-executable instructions, characterized in that, The computer-executable instructions are used to execute the flow velocity measurement method according to any one of claims 5 to 8.

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