CN118129849A - Time difference method flowmeter testing method using orthogonal code measuring signal and application thereof - Google Patents
Time difference method flowmeter testing method using orthogonal code measuring signal and application thereof Download PDFInfo
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- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
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- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
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Abstract
The application provides a time difference method flowmeter testing method using orthogonal code measuring signals and application thereof. In the process of synchronous transmission and receiving twice, the transit time from the left bank to the right bank and from the right bank to the left bank is respectively determined through sliding correlation operation, and the flow velocity of each acoustic path is calculated by combining the sound velocity, so that the interference problem of simultaneous measurement of multiple paths of signals is effectively solved, and the measurement period is obviously shortened.
Description
Technical Field
The application relates to the technical field of flow measurement, in particular to the cross fields of fluid mechanics metering technology, ultrasonic detection technology and signal processing technology, and particularly relates to a time difference method flowmeter testing method applying orthogonal code measurement signals and application thereof.
Background
With the continuous rise of the requirements of modern water resource management and environmental protection, the non-contact fluid flow measurement technology plays an increasingly important role in river and open channel flow monitoring. The existing time difference flow measurement technology is particularly suitable for precisely measuring the flow of a large-scale open flow system, and the basic principle of the existing time difference flow measurement technology depends on the characteristic that the propagation speed of ultrasonic waves in fluid is influenced by the flow velocity. Such flowmeters are typically configured with a multi-channel structure with channels deployed at different depths across the cross section of a river or open channel to enable independent measurement of the flow rate at each depth layer to integrate and calculate the average flow rate across the entire two-dimensional cross section.
In the prior art, each channel is provided with two transducers which are respectively arranged on the left and right sides of a river channel and are used for transmitting and receiving ultrasonic signals. Different methods of time-of-flight measurement are used for different signal formats, such as Continuous Wave (CW) signals, chirp signals, and pseudo-random encoded signals. For example, for a CW signal, the arrival time of the signal can be determined by setting a threshold value using its easily identifiable characteristics; for the chirp signal and the pseudo-random code signal with complex characteristics, the measurement accuracy is improved by a correlation function matching technology.
However, the time difference flow meters currently on the market present significant technical challenges in terms of multi-channel synchronous measurements. In the conventional operation mode, since only one sound path can be activated for measurement at the same time, other sound paths must wait in turn, and this process may result in an excessively long time required for the whole system to complete one-time overall measurement, especially in the case of a large number of channels. A further problem is that if all the acoustic paths are tried to operate simultaneously to shorten the measurement period, the signal detection difficulty is increased due to crosstalk between signals, and even accurate measurement of signal reception and transit time cannot be effectively completed.
Therefore, although the time difference flow meter has made an important progress in open water flow measurement, how to optimize multi-channel parallel operation, reduce measurement period, avoid signal interference, ensure that there is still a technical gap in high-precision measurement, and it is highly desirable to develop more advanced signal processing algorithms and technical means to meet the requirements of efficient real-time flow monitoring.
Disclosure of Invention
The embodiment of the application provides a time difference method flowmeter testing method applying orthogonal code measuring signals and application thereof, aiming at the problems of low measuring efficiency and the like in the prior art.
The core technology of the invention mainly utilizes orthogonal code signals to realize synchronous measurement of the multichannel time difference flowmeter, transmits and receives code signals with the characteristics of non-zero auto-correlation and zero cross-correlation through each acoustic path, and cooperates with phase modulation and sliding correlation operation, thereby solving the crosstalk problem during simultaneous measurement of multiple paths of signals, effectively improving the measurement efficiency, completing complete data acquisition of the whole system by only one-time bidirectional measurement, and greatly shortening the measurement time.
In a first aspect, the present application provides a method of time difference flow meter testing using quadrature encoded measurement signals, the method comprising the steps of:
S00, selecting at least two groups of orthogonal coded signals, wherein each group of orthogonal coded signals has a non-zero autocorrelation function value and a zero cross correlation function value, and multi-order Walsh codes are adopted as the orthogonal coded signals;
S10, carrying out phase modulation on a code sequence formed by the selected orthogonal coded signals, wherein a positive value corresponds to a 0-degree phase, and a negative value corresponds to a 180-degree phase;
S20, arranging multiple transmission and receiving transducer pairs on two sides, wherein the transmission transducer in each pair transmits a measurement coded signal subjected to phase modulation according to a selected orthogonal coded signal;
S30, in a first measurement stage, a plurality of transmitting transducers positioned on one side of the fluid channel simultaneously transmit coded signals, a plurality of receiving transducers positioned on the opposite side simultaneously receive the signals, and sliding correlation operation is carried out on each path of received signals by applying corresponding orthogonal coded signals;
Acquiring the transit time of the acoustic path transmitting signal through an autocorrelation function, wherein the maximum value of the autocorrelation function corresponds to the most accurate transit time point at the moment, and the cross-correlation function value among different acoustic paths is smaller than the maximum value of the autocorrelation function;
s40, exchanging transmitting and receiving positions in a second measuring stage, transmitting a coded signal from the other side and measuring the transit time from the right bank to the left bank;
S50, calculating the average flow velocity of the depth of each acoustic path based on the transit time from the left bank to the right bank and from the right bank to the left bank, which are respectively measured by each acoustic path, by combining a preset sound velocity value.
Further, in the step S00, a fourth order Walsh code is used, including:
Wh(1)：{1，1，1，1}
Wh(2)：{1，1，-1，-1}
Wh(3)：{1，-1，1，-1}
Wh(4)：{1，-1，-1，1}；
Wherein, the maximum value of the autocorrelation function of each group of walsh codes is 4, and the maximum value of the cross correlation function is 2.
Further, in step S10, the specific implementation of the phase modulation is: code 1 in the quadrature encoded signal is mapped to an ultrasonic signal of 0 ° phase, and code-1 is mapped to an ultrasonic signal of 180 ° phase.
Further, in step S20, three transmitting transducers are set on the left side, three receiving transducers are set on the right side, and 3 groups of data are randomly selected from 4 groups of Walsh codes.
Further, in step S20, the signal carrier frequency of the transmitting transducer is 200kHz.
Further, each walsh encoded symbol occupies ten carrier periods.
Further, in step S50, a specific formula for calculating the average flow velocity of the depth of each acoustic path is:
Average flow = (sound velocity× (right-to-left-to-right-to-time)),/(2 x sound path).
In a second aspect, the present application provides a jet lag flow meter testing device using quadrature encoded measurement signals, comprising:
A plurality of sets of orthogonal code signal generating modules for generating at least two sets of orthogonal code signals with auto-correlation functions being non-zero and cross-correlation functions being zero, the orthogonal code signals being capable of being mapped into phase modulation signals, wherein one set of orthogonal code signals comprises multi-order Walsh codes;
The multi-channel transmitting and receiving transducer pairs are respectively arranged at two sides of the fluid channel, each transducer pair comprises at least three transmitting transducers and at least three corresponding receiving transducers, and each transmitting transducer is configured with a group of orthogonal code signals to form corresponding measurement code signals after phase modulation;
the correlation operation processing unit is connected with the receiving transducer and is used for receiving the coded signals after fluid propagation and carrying out sliding correlation operation according to the orthogonal coded signals corresponding to each path of received signals, wherein the maximum value obtained when the transmitting and receiving signals of the same acoustic path carry out autocorrelation operation is the maximum value of the autocorrelation function of the orthogonal coded signals, and the maximum value obtained when the signals of different acoustic paths carry out cross correlation operation is smaller than the maximum value of the autocorrelation function;
The transit time determining module is used for simultaneously transmitting the coded signals according to the left transmitting transducer and judging the maximum value moment of the autocorrelation operation of each acoustic path through the correlation operation processing unit after the right receiving transducer receives the signals in the first measuring stage so as to measure the transit time from the left bank to the right bank; in the second measuring stage, the encoding signals are simultaneously transmitted according to the right transmitting transducer, the maximum value time of the autocorrelation operation of each acoustic path is judged through the correlation operation processing unit after the left receiving transducer receives the signals, and the transit time from the right bank to the left bank is measured;
And the flow velocity calculation module is used for calculating the average flow velocity of the depth of the corresponding acoustic path according to the left and right bank bidirectional transit time of each acoustic path and the known sound velocity value.
In a third aspect, the application provides an electronic device comprising a memory in which a computer program is stored and a processor arranged to run the computer program to perform the above-described time difference flow meter testing method using quadrature encoded measurement signals.
In a fourth aspect, the application provides a readable storage medium having stored thereon a computer program comprising program code for controlling a process to execute a process comprising a time difference flow meter test method according to the above, using quadrature encoded measurement signals.
The main contributions and innovation points of the invention are as follows: 1. compared with the prior art, the invention introduces orthogonal code signals (such as multi-order Walsh codes) to replace traditional Continuous Wave (CW), linear frequency modulation signals or pseudo-random code signals, and is used for ultrasonic measurement of a time difference flow meter. The orthogonal coded signals have non-zero autocorrelation function values and zero cross-correlation function values, so that each acoustic path is ensured to be highly sensitive to the coded signals of the acoustic paths, and has a remarkable suppression effect on the interference of other acoustic path coded signals. The method solves the detection problem caused by signal crosstalk when the multichannel parallel operation is performed in the prior art, and improves the measurement accuracy.
2. Compared with the prior art, the method solves the problems of overlong measurement period and reduced precision caused by signal crosstalk in multichannel synchronous measurement of the traditional time difference flow meter by combining quadrature coding and phase modulation. The new method realizes the parallel operation of all acoustic paths, greatly shortens the time required by overall measurement, improves the real-time monitoring capability of the flowmeter, and meets the requirements of modern water resource management and environmental protection on efficient flow monitoring.
3. Compared with the prior art, the invention also provides a time difference method flowmeter testing device applying the orthogonal code measuring signals, which comprises an orthogonal code signal generating module, a plurality of transmitting and receiving transducer pairs, a correlation operation processing unit, a transit time determining module and a flow velocity calculating module. The modules work cooperatively to convert the theoretical advantages of the orthogonal code signals into actual equipment functions, so that the generation, the transmission, the reception, the correlation operation processing and the final flow velocity calculation of the orthogonal code signals are realized, and a complete solution for testing the flow meter by the orthogonal code time difference method is formed.
The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below to provide a more thorough understanding of the other features, objects, and advantages of the application.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
FIG. 1 is a flow chart of a method of time difference flow meter testing employing quadrature encoded measurement signals in accordance with an embodiment of the present application;
FIG. 2 is a diagram showing the waveform comparison of the whole right bank received signal transmitted by the multi-channel simultaneous transmission and the single-channel single transmission in the prior art;
FIG. 3 is an enlarged waveform comparison of details of a right bank received signal of a multi-channel simultaneous transmission and a mono single transmission of the conventional art;
FIG. 4 is a graph of the overall output of a prior art multichannel receive transducer after matched filtering using a transmit pulse signal waveform;
FIG. 5 is an enlarged detailed output plot of a prior art multichannel receive transducer after matched filtering using a transmit pulse signal waveform;
FIG. 6 is a diagram showing the overall waveform comparison of a right bank received signal for simultaneous multi-channel transmission and single-channel transmission in accordance with an embodiment of the present application;
FIG. 7 is an enlarged waveform comparison of details of a right bank received signal for simultaneous multi-channel transmission and single-channel transmission in accordance with an embodiment of the present application;
FIG. 8 is a graph of overall output of a multichannel receive transducer using matched filtering of respective transmit pulse signal waveforms in accordance with an embodiment of the present application;
FIG. 9 is an enlarged detail output plot of a multichannel receive transducer using matched filtering of the respective transmit pulse signal waveforms in accordance with an embodiment of the present application;
fig. 10 is a schematic diagram of a hardware structure of an electronic device according to an embodiment of the present application.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with one or more embodiments of the present specification. Rather, they are merely examples of apparatus and methods consistent with aspects of one or more embodiments of the present description as detailed in the accompanying claims.
It should be noted that: in other embodiments, the steps of the corresponding method are not necessarily performed in the order shown and described in this specification. In some other embodiments, the method may include more or fewer steps than described in this specification. Furthermore, individual steps described in this specification, in other embodiments, may be described as being split into multiple steps; while various steps described in this specification may be combined into a single step in other embodiments.
Example 1
The application aims to provide a time difference method flowmeter testing method applying orthogonal code measuring signals, and by distributing each channel of sound path to use different orthogonal codes, the effect that each channel of sound path is only sensitive to the code signals of the sound path and simultaneously greatly inhibits the interference of the code signals of other sound paths can be achieved, and concretely, referring to fig. 1, the method comprises the following steps:
S00, selecting at least two groups of orthogonal coded signals, wherein each group of orthogonal coded signals has a non-zero autocorrelation function value and a zero cross correlation function value, and multi-order Walsh codes are adopted as the orthogonal coded signals;
In this embodiment, for example, for a 4-order Walsh orthogonal coded signal:
Wh(1)：{1，1，1，1}
Wh(2)：{1，1，-1，-1}
Wh(3)：{1，-1，1，-1}
Wh(4)：{1，-1，-1，1}
The autocorrelation function maximum for each set of walsh codes is 4 and the cross correlation function maximum is 2 (0 when the starting instants are perfectly aligned, perfectly orthogonal).
S10, carrying out phase modulation on a code sequence formed by the selected orthogonal coded signals, wherein a positive value corresponds to a 0-degree phase, and a negative value corresponds to a 180-degree phase;
In this embodiment, the code sequence is phase modulated, code 1 corresponds to a 0 ° phase, and code-1 corresponds to a 180 ° phase.
The orthogonal code signal is a special digital signal coding technology and is characterized in that a series of signals generated by coding have mathematical orthogonality. In particular, orthogonally encoded signals are typically composed of a set or series of base signals that satisfy a particular orthogonal relationship with respect to each other, i.e., they have an integral (or average) product of zero between any two at a common reference period or frequency. The property enables the orthogonal code signal to be easily separated from each independent signal component by a specific decoding algorithm at the receiving end without being influenced by other signal components, and can maintain higher decoding accuracy and anti-interference capability even in the presence of noise or interference.
The specific implementation modes of the orthogonal coded signals are various, and the selected Walsh codes (or called Walsh functions and Hadamard matrix codes) are binary code sequences constructed based on mathematical Walsh functions, and each Walsh code has strict orthogonality, namely the dot multiplication (bitwise exclusive OR and summation) result of any two different code words is zero. Walsh codes are commonly used in communication and radar systems for spread spectrum communication, code Division Multiple Access (CDMA), and other scenarios to achieve orthogonal separation and interference suppression of multi-user signals.
S20, arranging multiple transmission and receiving transducer pairs on two sides, wherein the transmission transducer in each pair transmits a measurement coded signal subjected to phase modulation according to a selected orthogonal coded signal;
in this embodiment, for example, for a 3-channel time difference flow meter, 3 groups of codes are randomly selected from 4 groups of codes, the 1 st channel is coded with Wh (1), the 2 nd channel is coded with Wh (2), and the 3 rd channel is coded with Wh (4).
The time difference flowmeter adopts Wh (1), wh (2) and Wh (4) codes to respectively correspond to three sound paths, so that the characteristics of orthogonal codes are utilized to realize effective separation of multi-channel signals, crosstalk is reduced, and meanwhile, the accuracy of signal identification is enhanced and the signal processing process is simplified by utilizing the difference of codewords with different lengths. Such a design helps to improve the accuracy and stability of the flow meter measurement, especially in complex flow fields or environments where external disturbances are present.
S30, in a first measurement stage, a plurality of transmitting transducers positioned on one side of the fluid channel simultaneously transmit coded signals, a plurality of receiving transducers positioned on the opposite side simultaneously receive the signals, and sliding correlation operation is carried out on each path of received signals by applying corresponding orthogonal coded signals;
Acquiring the transit time of the acoustic path transmitting signal through an autocorrelation function, wherein the maximum value of the autocorrelation function corresponds to the most accurate transit time point at the moment, and the cross-correlation function value among different acoustic paths is smaller than the maximum value of the autocorrelation function;
In this embodiment, in the first measurement phase, the 3 transmitting transducers located on the left side transmit measurement coded signals at the same time, and the 3 receiving transducers located on the right side start receiving at the same time. The processor of each acoustic path carries out sliding correlation operation on the received signal by using the coded signal appointed by the acoustic path, the maximum value of an autocorrelation function is 4 for the coded signal sent by the acoustic path, and the maximum value of the autocorrelation function is 2 for the coded signals sent by other acoustic paths, so that the time of flight time measurement from the left bank to the right bank can be carried out by judging the maximum value moment of the correlation operation.
Among them, sliding correlation operation is an important technology in the field of signal processing, and is mainly used for detecting whether a specific similarity or correlation exists between signal sequences, especially in the case of a time offset. In the context of a jet lag flow meter, sliding correlation operations are used to identify and accurately measure the transit time of an ultrasonic signal, i.e., the time interval between the sending of a signal from a transmitting transducer and the receiving of the same signal by a receiving transducer. The following is the basic concept and specific operational steps of the sliding correlation operation:
Basic concept: sliding correlation operations typically involve two signal sequences: one is called the reference signal (or template) and the other is called the signal under test (or input signal). In this example, the reference signal is a known, encoded ultrasonic transmit signal and the signal to be measured is the actual signal received from the receiving transducer. The basic idea of sliding correlation is to "slide" the reference signal over the signal under test (i.e. time-point by time-point or sample-wise alignment) and calculate the cross-correlation value of the two signals at each slide position.
The specific operation steps are as follows:
1. Signal preparation: a known, orthogonally encoded ultrasonic transmit signal is acquired as a reference signal (e.g., wh (1), wh (2), or Wh (4) encoded signal), and the actual ultrasonic echo signal received from the receiving transducer is taken as the signal to be measured.
2. Sliding window: a sliding window with the same length as the reference signal is set and is placed at the initial position of the signal to be detected.
3. And (3) cross-correlation calculation: and carrying out cross-correlation operation on the reference signal and the part in the window of the signal to be detected at each position in the sliding window. The cross-correlation operation typically takes the conjugate form of a discrete convolution, namely:
Wherein:
R [ i ] is the cross-correlation value at the sliding position i.
And rj is the jth sample of the reference signal.
X [ i+j ] is the jth sample of the signal under test relative to position i within the sliding window.
N is the length of the reference signal.
∗ Denotes complex conjugate operations, which may be omitted for real signals.
4. Sliding update: and (3) moving the sliding window forward by one sample (or selecting a proper step length according to the sampling rate and the resolution requirement), repeating the step (3), and calculating the cross-correlation value of the next position.
5. Maximum value positioning: and continuously sliding and calculating the cross-correlation value until the whole effective length of the signal to be detected is traversed. Recording all the cross-correlation values, and finding out the maximum value and the corresponding sliding position.
6. And (3) determination of the transit time: the sliding position corresponding to the maximum cross-correlation value is the optimal alignment point of the reference signal and the actual echo signal, and the time difference calculated by the position is the transit time of the ultrasonic signal. This time difference reflects the actual time that the ultrasonic wave propagates in the fluid and can be used to further calculate the flow rate.
7. Multichannel processing: for a multi-channel flowmeter, different orthogonal codes are used for the transmitting signals of each channel, and the receiving end correspondingly uses the codes to perform sliding correlation operation. Because the codes of the channels are orthogonal, the cross-correlation operation can effectively separate the signals of each channel, and the interference among different channels is avoided.
S40, exchanging transmitting and receiving positions in a second measuring stage, transmitting a coded signal from the other side and measuring the transit time from the right bank to the left bank;
In this embodiment, in the second measurement phase, the 3 transmitting transducers located on the right side transmit measurement coded signals at the same time, and the 3 receiving transducers located on the left side start receiving at the same time. The processor of each acoustic path carries out sliding correlation operation on the received signal by using the coded signal appointed by the acoustic path, the maximum value of an autocorrelation function is 4 for the coded signal sent by the acoustic path, and the maximum value of the autocorrelation function is 2 for the coded signals sent by other acoustic paths, so that the transit time measurement from right bank to left bank can be carried out by judging the maximum value moment of the correlation operation.
S50, calculating the average flow velocity of the depth of each acoustic path based on the transit time from the left bank to the right bank and from the right bank to the left bank, which are respectively measured by each acoustic path, by combining a preset sound velocity value.
In this embodiment, each acoustic path combines the left-to-right transit time, the right-to-left transit time, and the underwater acoustic velocity value, and can calculate the average flow velocity corresponding to the depth of the acoustic path. The specific formula of the average flow rate is:
Average flow = (sound velocity× (right-to-left-to-right-to-time)),/(2 x sound path).
In order to verify the technical effect of the invention, the following is tested in comparison with the conventional signal scheme:
Assuming that transducers of 3 channels are installed on the left and right sides of the river channel, left side transducers of 3 channels (channels) simultaneously transmit measurement pulse signals. The time for the 1 st sound path to reach the right bank is 1.000 seconds, the time for the 2 nd sound path to reach the right bank is 1.002 seconds, and the time for the 3 rd sound path to reach the right bank is 1.003 seconds.
1. Description of conventional Signal schemes
In the conventional signal scheme, the transmitted signal is typically a Linear Frequency Modulation (LFM) signal, in this example, the center frequency of the pulse signal is 200kHz, the signal bandwidth is 20kHz, and the time length is 4ms.
Fig. 2 shows, from top to bottom, the overall waveforms of 3 channels simultaneously transmitting right-bank received signals, 1 st channel separately transmitting right-bank received signals, 2 nd channel separately transmitting right-bank received signals, and 3 rd channel separately transmitting right-bank received signals, respectively.
Fig. 3 shows waveforms of 3 channels simultaneously transmitting right-bank received signals, 1 st channel separately transmitting right-bank received signals, 2 nd channel separately transmitting right-bank received signals, and 3 rd channel separately transmitting right-bank received signals, respectively, from top to bottom, after detail amplification on a time axis.
Fig. 4 shows, from top to bottom, the signal output overall waveforms of the 3-channel right-bank receiving transducer after matched filtering using the transmit pulse signal waveforms.
Fig. 5 shows waveforms of the signal output of the right-bank receiving transducers of 3 channels after the matched filtering processing by using the waveforms of the transmitted pulse signals from top to bottom, which are amplified in detail on a time axis, so that the processing outputs of the three channels are consistent, and the transit time of each channel cannot be distinguished.
2. Orthogonal Signal scheme description
In the orthogonal signal scheme, the transmitting signal is a Walsh code, each Walsh code group has 4 symbols, the 1 st channel is encoded with Wh (1), the 2 nd channel is encoded with Wh (2), and the 3 rd channel is encoded with Wh (4). The signal carrier frequency is 200khz,1 walsh symbol occupies 10 carrier periods, and 4 walsh symbols occupy 40 carrier periods in total.
Fig. 6 shows, from top to bottom, the overall waveforms of 3 channels simultaneously transmitting right-bank received signals, 1 st channel separately transmitting right-bank received signals, 2 nd channel separately transmitting right-bank received signals, and 3 rd channel separately transmitting right-bank received signals, respectively.
Fig. 7 shows waveforms of 3 channels simultaneously transmitting right-bank received signals, 1 st channel separately transmitting right-bank received signals, 2 nd channel separately transmitting right-bank received signals, and 3 rd channel separately transmitting right-bank received signals, respectively, from top to bottom, after detail amplification on a time axis.
Fig. 8 shows, from top to bottom, the signal output overall waveforms of the 3-channel right-bank receiving transducers after matched filtering processing using the transmit pulse signal waveforms of the respective channels.
Fig. 9 shows waveforms of the signal output of the right-bank receiving transducers of 3 channels after the matched filtering processing using the waveforms of the transmitted pulse signals from top to bottom, in which the waveform of the signal output is amplified in detail on the time axis, it can be seen that the processing output of the first channel has a maximum value of 1.000 seconds, the processing output of the second channel has a maximum value of 1.002 seconds, and the processing output of the third channel has a maximum value of 1.003 seconds, which has the capability of distinguishing the transit time of each channel.
Example two
Based on the same conception, the application also provides a time difference method flowmeter testing device applying the orthogonal code measuring signals, which comprises the following steps:
A plurality of sets of orthogonal code signal generating modules for generating at least two sets of orthogonal code signals with auto-correlation functions being non-zero and cross-correlation functions being zero, the orthogonal code signals being capable of being mapped into phase modulation signals, wherein one set of orthogonal code signals comprises multi-order Walsh codes;
The multi-channel transmitting and receiving transducer pairs are respectively arranged at two sides of the fluid channel, each transducer pair comprises at least three transmitting transducers and at least three corresponding receiving transducers, and each transmitting transducer is configured with a group of orthogonal code signals to form corresponding measurement code signals after phase modulation;
the correlation operation processing unit is connected with the receiving transducer and is used for receiving the coded signals after fluid propagation and carrying out sliding correlation operation according to the orthogonal coded signals corresponding to each path of received signals, wherein the maximum value obtained when the transmitting and receiving signals of the same acoustic path carry out autocorrelation operation is the maximum value of the autocorrelation function of the orthogonal coded signals, and the maximum value obtained when the signals of different acoustic paths carry out cross correlation operation is smaller than the maximum value of the autocorrelation function;
The transit time determining module is used for simultaneously transmitting the coded signals according to the left transmitting transducer and judging the maximum value moment of the autocorrelation operation of each acoustic path through the correlation operation processing unit after the right receiving transducer receives the signals in the first measuring stage so as to measure the transit time from the left bank to the right bank; in the second measuring stage, the encoding signals are simultaneously transmitted according to the right transmitting transducer, the maximum value time of the autocorrelation operation of each acoustic path is judged through the correlation operation processing unit after the left receiving transducer receives the signals, and the transit time from the right bank to the left bank is measured;
And the flow velocity calculation module is used for calculating the average flow velocity of the depth of the corresponding acoustic path according to the left and right bank bidirectional transit time of each acoustic path and the known sound velocity value.
Example III
This embodiment also provides an electronic device, referring to fig. 10, comprising a memory 404 and a processor 402, the memory 404 having stored therein a computer program, the processor 402 being arranged to run the computer program to perform the steps of any of the method embodiments described above.
In particular, the processor 402 may include a Central Processing Unit (CPU), or an application specific integrated circuit (ApplicationSpecificIntegratedCircuit, abbreviated as ASIC), or may be configured as one or more integrated circuits that implement embodiments of the present application.
The memory 404 may include, among other things, mass storage 404 for data or instructions. By way of example, and not limitation, memory 404 may comprise a hard disk drive (HARDDISKDRIVE, abbreviated HDD), a floppy disk drive, a solid state drive (SolidStateDrive, abbreviated SSD), flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. Memory 404 may include removable or non-removable (or fixed) media, where appropriate. Memory 404 may be internal or external to the data processing apparatus, where appropriate. In a particular embodiment, the memory 404 is a Non-Volatile (Non-Volatile) memory. In particular embodiments, memory 404 includes Read-only memory (ROM) and Random Access Memory (RAM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable ROM (ProgrammableRead-only memory, abbreviated PROM), an erasable PROM (ErasableProgrammableRead-only memory, abbreviated EPROM), an electrically erasable PROM (ElectricallyErasableProgrammableRead-only memory, abbreviated EEPROM), an electrically rewritable ROM (ElectricallyAlterableRead-only memory, abbreviated EAROM) or a FLASH memory (FLASH), or a combination of two or more of these. The RAM may be a static random access memory (StaticRandom-access memory, abbreviated SRAM) or a dynamic random access memory (DynamicRandomAccessMemory, abbreviated DRAM) where the DRAM may be a fast page mode dynamic random access memory 404 (FastPageModeDynamicRandomAccessMemory, abbreviated FPMDRAM), an extended data output dynamic random access memory (ExtendedDateOutDynamicRandomAccessMemory, abbreviated EDODRAM), a synchronous dynamic random access memory (SynchronousDynamicRandom-access memory, abbreviated SDRAM), or the like, where appropriate.
Memory 404 may be used to store or cache various data files that need to be processed and/or used for communication, as well as possible computer program instructions for execution by processor 402.
Processor 402 reads and executes computer program instructions stored in memory 404 to implement any of the jet lag flow meter testing methods of the above embodiments that employ quadrature encoded measurement signals.
Optionally, the electronic apparatus may further include a transmission device 406 and an input/output device 408, where the transmission device 406 is connected to the processor 402 and the input/output device 408 is connected to the processor 402.
The transmission device 406 may be used to receive or transmit data via a network. Specific examples of the network described above may include a wired or wireless network provided by a communication provider of the electronic device. In one example, the transmission device includes a network adapter (Network Interface Controller, simply referred to as a NIC) that can connect to other network devices through the base station to communicate with the internet. In one example, the transmission device 406 may be a Radio Frequency (RF) module, which is configured to communicate with the internet wirelessly.
The input-output device 408 is used to input or output information.
Example IV
The present embodiment also provides a readable storage medium having stored therein a computer program comprising program code for controlling a process to execute the process, the process comprising the time difference flow meter test method according to the first embodiment applying the quadrature encoded measurement signal.
It should be noted that, specific examples in this embodiment may refer to examples described in the foregoing embodiments and alternative implementations, and this embodiment is not repeated herein.
In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
Embodiments of the invention may be implemented by computer software executable by a data processor of a mobile device, such as in a processor entity, or by hardware, or by a combination of software and hardware. Computer software or programs (also referred to as program products) including software routines, applets, and/or macros can be stored in any apparatus-readable data storage medium and they include program instructions for performing particular tasks. The computer program product may include one or more computer-executable components configured to perform embodiments when the program is run. The one or more computer-executable components may be at least one software code or a portion thereof. In addition, in this regard, it should be noted that any blocks of the logic flows as illustrated may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on physical media such as memory chips or memory blocks implemented within the processor, magnetic media such as hard or floppy disks, and optical media such as, for example, DVDs and data variants thereof, CDs, etc. The physical medium is a non-transitory medium.
It should be understood by those skilled in the art that the technical features of the above embodiments may be combined in any manner, and for brevity, all of the possible combinations of the technical features of the above embodiments are not described, however, they should be considered as being within the scope of the description provided herein, as long as there is no contradiction between the combinations of the technical features.
The foregoing examples illustrate only a few embodiments of the application, which are described in greater detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit of the application, which are within the scope of the application. Accordingly, the scope of the application should be assessed as that of the appended claims.
Claims (10)
1. The time difference method flowmeter testing method using orthogonal code measuring signal is characterized by comprising the following steps:
S00, selecting at least two groups of orthogonal coded signals, wherein each group of orthogonal coded signals has a non-zero autocorrelation function value and a zero cross correlation function value, and multi-order Walsh codes are adopted as the orthogonal coded signals;
S10, carrying out phase modulation on a code sequence formed by the selected orthogonal coded signals, wherein a positive value corresponds to a 0-degree phase, and a negative value corresponds to a 180-degree phase;
S20, arranging multiple transmission and receiving transducer pairs on two sides, wherein the transmission transducer in each pair transmits a measurement coded signal subjected to phase modulation according to a selected orthogonal coded signal;
S30, in a first measurement stage, a plurality of transmitting transducers positioned on one side of the fluid channel simultaneously transmit coded signals, a plurality of receiving transducers positioned on the opposite side simultaneously receive the signals, and sliding correlation operation is carried out on each path of received signals by applying corresponding orthogonal coded signals;
Acquiring the transit time of the acoustic path transmitting signal through an autocorrelation function, wherein the maximum value of the autocorrelation function corresponds to the most accurate transit time point at the moment, and the cross-correlation function value among different acoustic paths is smaller than the maximum value of the autocorrelation function;
s40, exchanging transmitting and receiving positions in a second measuring stage, transmitting a coded signal from the other side and measuring the transit time from the right bank to the left bank;
S50, calculating the average flow velocity of the depth of each acoustic path based on the transit time from the left bank to the right bank and from the right bank to the left bank, which are respectively measured by each acoustic path, by combining a preset sound velocity value.
2. The method for testing a time difference flow meter using orthogonally encoded measurement signals of claim 1, wherein in step S00, a fourth order Walsh code is used, comprising:
Wh(1)：{1，1，1，1}
Wh(2)：{1，1，-1，-1}
Wh(3)：{1，-1，1，-1}
Wh(4)：{1，-1，-1，1}；
Wherein, the maximum value of the autocorrelation function of each group of walsh codes is 4, and the maximum value of the cross correlation function is 2.
3. The method for testing a time difference flow meter using quadrature code measurement signals according to claim 2, wherein in step S10, the phase modulation is specifically implemented as follows: code 1 in the quadrature encoded signal is mapped to an ultrasonic signal of 0 ° phase, and code-1 is mapped to an ultrasonic signal of 180 ° phase.
4. The method for testing a time difference flow meter using orthogonally encoded measurement signals as claimed in claim 3, wherein in step S20, three transmitting transducers are provided on the left side, three receiving transducers are provided on the right side, and 3 sets of Walsh codes are randomly selected from the 4 sets of Walsh codes.
5. The method of time difference flow meter testing using quadrature encoded measurement signals of claim 4, wherein in step S20, the signal carrier frequency of the transmitting transducer is 200kHz.
6. The method for time-difference flow meter testing using orthogonally encoded measurement signals of claim 5, wherein each walsh encoded symbol occupies ten carrier cycles.
7. The method for testing a flow meter using time difference method of orthogonal coded measurement signals according to any one of claims 1-6, wherein in step S50, the specific formula for calculating the average flow velocity of the depth of each acoustic path is:
Average flow = (sound velocity× (right-to-left-to-right-to-time)),/(2 x sound path).
8. A time difference flow meter testing device using quadrature code measurement signals, comprising:
a plurality of sets of orthogonal coded signal generating modules for generating at least two sets of orthogonal coded signals with auto-correlation functions being non-zero and cross-correlation functions being zero, the orthogonal coded signals being capable of being mapped to phase modulated signals, wherein one set of orthogonal coded signals comprises a multi-order Walsh code;
the multi-channel transmitting and receiving transducer pairs are respectively arranged at two sides of the fluid channel, each transducer pair comprises at least three transmitting transducers and at least three corresponding receiving transducers, and each transmitting transducer is configured with a group of orthogonal coded signals to form corresponding measurement coded signals after phase modulation;
The correlation operation processing unit is connected with the receiving transducer and is used for receiving the coded signals after fluid propagation and carrying out sliding correlation operation according to the orthogonal coded signals corresponding to each path of received signals, wherein the maximum value obtained when the transmitting and receiving signals of the same acoustic path carry out autocorrelation operation is the maximum value of the autocorrelation function of the orthogonal coded signals, and the maximum value obtained when the signals of different acoustic paths carry out cross correlation operation is smaller than the maximum value of the autocorrelation function;
The transit time determining module is used for simultaneously transmitting the coded signals according to the left transmitting transducer and judging the maximum value moment of the autocorrelation operation of each acoustic path through the correlation operation processing unit after the right receiving transducer receives the signals in the first measuring stage so as to measure the transit time from the left bank to the right bank; in the second measuring stage, the encoding signals are simultaneously transmitted according to the right transmitting transducer, the maximum value time of the autocorrelation operation of each acoustic path is judged through the correlation operation processing unit after the left receiving transducer receives the signals, and the transit time from the right bank to the left bank is measured;
And the flow velocity calculation module is used for calculating the average flow velocity of the depth of the corresponding acoustic path according to the left and right bank bidirectional transit time of each acoustic path and the known sound velocity value.
9. An electronic device comprising a memory and a processor, wherein the memory has stored therein a computer program, the processor being arranged to run the computer program to perform the time difference flow meter testing method of any of claims 1 to 7 using quadrature encoded measurement signals.
10. A readable storage medium, characterized in that the readable storage medium has stored therein a computer program comprising program code for controlling a process to execute a process comprising the time difference flow meter testing method according to any of claims 1 to 7 applying quadrature encoded measurement signals.
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