CN116772908A - Signal data processing method applied to distributed optical fiber acoustic wave sensing system - Google Patents
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Abstract
The invention provides a signal data processing method applied to a distributed optical fiber acoustic wave sensing system on the basis of not changing the coherent detection structure of the traditional distributed optical fiber acoustic wave sensing system, which aims to solve the problems of low system response speed, low signal-to-noise ratio, poor demodulation precision and the like caused by adopting a fixed and lower data transmission rate in the signal processing process of the traditional distributed optical fiber acoustic wave sensing system. The method adopts a method combining two modes of light intensity amplitude differential demodulation and phase demodulation, so that effective data are rapidly and accurately extracted, and the data processing speed is increased; according to the existence or non-existence of the sound wave vibration event or the vibration frequency in the sampling process, the data transmission rate of the data acquisition module is automatically adjusted, the redundancy of original data is avoided, and the response speed of the system is improved; in the phase demodulation process, the steps of eliminating the initial phase and removing the substrate are added, the signal to noise ratio of the system is improved, and the frequency demodulation precision of the system is optimized.
Description
Technical Field
The invention belongs to the technical field of optical fiber sensing, and particularly relates to a signal data processing method applied to a distributed optical fiber acoustic wave sensing system.
Background
The distributed optical fiber acoustic wave sensing system is based on the principle of scattering of light and phase sensitive optical time domain reflection (phi-OTDR). Light propagates in the optical fiber to generate Rayleigh scattering, which belongs to elastic scattering, and when a certain point of the optical fiber is stressed, the scattering property of the point changes, and information reversely transmitted along the optical fiber from backward Rayleigh scattering light also changes correspondingly. The method is characterized in that the method comprises the steps of taking an ultra-narrow linewidth laser as a light source, injecting strong coherent light into an optical fiber, and determining the frequency and the relative amplitude of sound wave generation by using the ultra-narrow linewidth laser as a light source, wherein an output signal is a coherent interference result of backward Rayleigh scattered light within a pulse range, and the specific position of sound wave generation can be positioned according to the coherent interference result.
In a distributed fiber acoustic wave sensing system, each point in the optical fiber may act as a separate sensing unit. However, with the increase of the length of the optical fiber and the frequency of the acoustic wave signal, the transmission and calculation of mass data in a short time become difficult, and the response speed of the system is seriously affected.
The traditional signal processing method of the distributed optical fiber acoustic wave sensing system has the problems of low signal-to-noise ratio, poor demodulation precision and the like, and the patent name of China patent CN105606196A is: a phase sensitive optical time domain reflection system based on self-mixing technology provides a method for utilizing self-mixing of signals to convert the signals to baseband, so that the required data sampling rate can be reduced, and the real-time performance of the system is improved. However, the demodulation signal of the scheme is affected by the optical amplitude, the external disturbance magnitude and the demodulation signal of the scheme cannot be in accurate linear relation with each other, the application range of the phi-OTDR optical fiber sensing system is limited, and meanwhile, the scheme increases the complexity of an optical path and devices.
In order to solve the problem of large signal data volume, chinese patent CN109540280a, patent name: a signal processing method for improving efficiency of phase sensitive optical time domain reflection system, wherein a fixed window width is selected, intermediate frequency signals are divided into end-to-end intervals on a distance axis, the phase relation of Rayleigh scattered light of optical fibers at different positions is analyzed, and the specific position where disturbance occurs is positioned by utilizing a phase comparison method, so that the process of high-efficiency signal processing of a phi-OTDR system is realized. However, the scheme adopts a fixed data transmission rate and a direct demodulation phase, which causes massive data redundancy, reduces the data transmission rate and prolongs the response time of the system.
Disclosure of Invention
In order to solve the problems of slow system response speed, low signal-to-noise ratio, poor demodulation precision and the like caused by adopting a fixed and lower data transmission rate in the signal processing process of the traditional distributed optical fiber acoustic wave sensing system, the invention provides a signal data processing method applied to the distributed optical fiber acoustic wave sensing system on the basis of not changing the coherent detection structure of the traditional distributed optical fiber acoustic wave sensing system.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a signal data processing method applied to a distributed optical fiber acoustic wave sensing system is characterized in that the applied distributed optical fiber acoustic wave sensing system is a coherent detection sensing system and comprises an ultra-narrow linewidth laser module, a first coupling module, an optical modulation module, an optical amplification module, an optical circulator, a second coupling module, a photoelectric detection module, a data acquisition module, a signal demodulation module and a single-mode optical fiber;
the continuous laser emitted by the ultra-narrow linewidth laser module is divided into two paths through the first coupling module, one path enters the second coupling module, the other path enters the optical modulation module to be modulated into a pulse-form optical signal, the optical modulation module outputs a trigger signal through the data acquisition module, the pulse-form optical signal is amplified through the optical amplification module and then enters the second coupling module after being combined with the single-mode optical fiber through the optical circulator, and the two paths of light are combined in the second coupling module; the combined wave signal output by the second coupling module is converted into an analog signal through the photoelectric detection module and enters the data acquisition module, the analog signal is acquired and converted into a digital signal through the data acquisition module, and the digital signal is transmitted to the signal demodulation module for data processing;
the modulation module is used for modulating laser into pulse light, and simultaneously, the laser pulse obtains frequency shift of fixed frequency, and the maximum modulation frequency is AKHz; the sampling rate of the data acquisition card in the data acquisition module is BMHz;
the method is characterized in that:
the method comprises the following steps:
step 1), setting the transmission frequency, the data acquisition time interval and the number of sampling data groups of signals of an initial data acquisition module;
designating the signal transmission frequency f of the data acquisition module, wherein the data acquisition time interval is tau, and the number of the sampled data sets is tau/f;
step 2), setting an initial original data sampling length according to the spatial sampling resolution of the system, and starting to acquire original data G (N) in a set range of a single-mode fiber;
defining the length of the optical fiber as L, and according to the sampling rate fs=250 MHz of the data acquisition module and the propagation speed c=2×10 of light in the optical fiber 8 m/s, to obtain the spatial sampling resolution of the system Δl=c/(2×fs), Δl=0.4 m;
since L/Δl=2.5l, the initial original data sampling length is set to 2.5L, and the original data is denoted as G (N), n=1, 2,3, …;
step 3), judging whether the sampled data is full-section optical fiber data or not according to the effective data length of the original data;
according to the data image acquired by the data acquisition system, calculating the effective data length M of the sampling data, and comparing the effective data length M with the sampling length of the sampling data;
if M is less than 2.5L, invalid data exists in the sampling data, and the step 4) is entered;
if m=2.5l, the sampled data are valid data, and the original data are phase-demodulated, and step 9 is entered;
step 4), calculating the light intensity amplitude difference H of the sampled data i (N)；
Step 5), according to the light intensity amplitude difference value H of different sampling data sets i (N) judging whether an acoustic vibration event occurs in the acquisition process;
when the difference value of the light intensity amplitude is larger than or equal to the set threshold value of the vibration event, judging that the sound wave vibration event occurs, and entering the step 6);
when the light intensity amplitude difference value is smaller than the vibration event set threshold value, judging that no sound wave vibration event occurs, and entering step 16);
step 6), obtaining the positioning z of the sound wave vibration according to the waveform diagram of the light intensity amplitude difference j ；
The positioning z of the sound wave vibration can be obtained from the waveform diagram of the light intensity amplitude difference j J is the acoustic vibration point number, j=1, 2,3, &..r;
step 7), adjusting a sampling data acquisition range according to the position of the acoustic vibration;
select z 1 The position of the x-th sampling point on the left side is taken as the data acquisition starting position, z R The position of the x-th sampling point on the right side is used as a data acquisition end position;
the acquisition range of the full-section optical fiber data in the default state is adjusted to be (z) from 0L to 2.5L 1 -x)～(z R +x), the sampled data is G (N), n= (z) 1 -x)，...，(z R +x)；
Step 8), adjusting and setting the signal transmission frequency of the data acquisition module and the number of the sampled data sets at the data acquisition time interval;
setting the signal transmission frequency f of the data acquisition module to be the maximum value f max The sampling group number is set as C groups, and the data sampling time interval is C/f max Returning to the step 2);
step 9), carrying out phase demodulation on the sampled data, and calculating to obtain an output phase difference value array delta phi j (N)；
Step 10), according to the output phase difference value array delta phi j (N) judging whether an acoustic vibration event occurs in the acquisition process;
when the phase difference score is larger than or equal to the vibration event set threshold, judging that an acoustic vibration event occurs, and entering step 11);
when the phase difference score is smaller than the vibration event set threshold, judging that a sound wave-free vibration event occurs, and entering step 15);
step 11), obtaining the vibration frequency F of each sound wave vibration position according to a frequency spectrum demodulation method 1 ，F 2 ，F 3 ，...，F R ；
Step 12), calculating the maximum vibration frequency F of the acoustic vibration max
F max ＝max(F 1 ，F 2 ，F 3 ，...，F R )；
Step 13), according to the nyquist sampling theorem, it can be known that the effective spectrogram can be obtained by analyzing the data acquisition module with the signal transmission frequency F being more than 2 times of the maximum vibration frequency, so that F is compared max And f max Judging whether the data transmission frequency needs to be adjusted or not;
if 2F max ≤f max ≤5F max Step 16) is entered;
if f max ≥5F max Then, go to step 14);
step 14), adjusting the signal transmission frequency F of the data acquisition module to meet 2F max ≤f≤5F max ；
Step 15), setting the initial original data sampling length to be 2.5L;
step 16), judging whether the system stops running, if yes, ending, otherwise, returning to the step 2).
Further, the step 4) specifically includes:
4.1, mixing, filtering and demodulating the sampled data to obtain two paths of signals I (N) and Q (N);
4.2 calculating the intensity amplitude S of different sampled data sets i (N)，
The intensity amplitude of the different sampled data sets is denoted as S i (N), i is the number of sampled data sets, i=1, 2, 3;
4.3 calculating the light intensity amplitude Difference H of different sampled data sets i (N)，
H i (N)＝|S i+1 (N)-S i (N)|。
Further, the step 9) specifically includes:
9.1 Mixing, filtering and demodulating the sampled data G (N) to obtain two paths of signals I (N) and Q (N);
9.2 Arctangent and sum range expansion are carried out on two paths of signals I (N) and Q (N) to obtain the output phase of the signals
Where i represents different sampled data sets, j represents acoustic vibration point number, i=1, 2,3.
Then z 1 The phase value array at the position is
z 2 The phase value array at the position is......；
z R The phase value array at the position is
9.3 Eliminating the initial phase to obtain an eliminated phase value
9.4 Further removing the phase substrate to obtain a phase value after removing the phase substrate;
phase value after removing phase substrate at k time
Continuously sampled kth group data, namely continuously operated k time;
9.5 Calculating a phase difference score)
9.6 Outputting the phase difference value array delta phi) j (N)，
Further, in step 1), the signal transmission frequency is 0.3Hz < f < 5Hz, and the data acquisition time interval τ=10s.
Further, the maximum modulation frequency A of the modulation (3) of the optical modulation module is 20KHz; the sampling rate B of the data acquisition card in the data acquisition module (8) is 250MHz.
Further, in step 7), x=10.
Further, in step 8), c=100.
Further, in step 1), f=1 Hz.
Compared with the prior art, the invention has the following beneficial technical effects:
1. the invention is applied to the signal data processing method of the distributed optical fiber acoustic wave sensing system, and automatically adjusts the data transmission rate of the data acquisition module according to the existence of an acoustic wave vibration event or the vibration frequency, thereby avoiding the redundancy of massive original data and improving the response speed of the system.
2. The invention is applied to a signal data processing method of a distributed optical fiber acoustic wave sensing system, and adopts a method combining two modes of light intensity amplitude differential demodulation and phase demodulation, thereby rapidly and accurately extracting effective data, accelerating data processing speed and further improving system response time.
3. The method is applied to the phase demodulation processing process in the signal data processing method of the distributed optical fiber acoustic wave sensing system, and the steps of eliminating the initial phase and removing the substrate are added, so that the signal-to-noise ratio of the system can be effectively improved, and the frequency demodulation precision of the system is optimized.
Drawings
FIG. 1 is a schematic diagram of a distributed optical fiber acoustic wave sensing system according to the present invention;
FIG. 2 is a flow chart of a signal data processing method applied to a distributed optical fiber acoustic wave sensing system according to the present invention;
FIG. 3 is a schematic diagram of the effective length of the original data in the embodiment of the present invention;
FIG. 4 is a schematic diagram of light intensity amplitude differences in an embodiment of the present invention;
FIG. 5 is a schematic view of an adjusted raw data acquisition range according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a phase demodulation process according to an embodiment of the present invention;
FIG. 7 is a diagram showing the phase difference score waveform output results according to an embodiment of the present invention; wherein the graph (a) is the vibration point z 1 A phase difference score waveform at the position (b) is a vibration point z 2 A phase difference score waveform at the position (c) is a vibration point z R Phase difference score waveform diagram at;
reference numerals:
the device comprises a 1-ultra-narrow linewidth laser module, a 2-first coupling module, a 3-light modulation module, a 4-light amplification module, a 5-light circulator, a 6-second coupling module, a 7-photoelectric detection module, an 8-data acquisition module, a 9-signal demodulation module and a 10-single mode fiber.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following describes in further detail a signal data processing method applied to a distributed optical fiber acoustic wave sensor system according to the present invention with reference to the accompanying drawings and detailed description. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention.
As shown in fig. 1, the distributed optical fiber acoustic wave sensing system according to the embodiment of the present invention is based on a coherent detection structure of a conventional distributed optical fiber acoustic wave sensing system, and includes an ultra-narrow linewidth laser module 1, a first coupling module 2, an optical modulation module 3, an optical amplification module 4, an optical circulator 5, a second coupling module 6, a photoelectric detection module 7, a data acquisition module 8, a signal demodulation module 9, and a single-mode optical fiber 10.
The continuous laser emitted by the ultra-narrow linewidth laser module 1 is divided into two paths through the first coupling module 2, one path enters the second coupling module 6, the other path enters the optical modulation module 3 to be modulated into a pulse-form optical signal, the optical modulation module 3 outputs a trigger signal through the data acquisition module 8, the pulse-form optical signal is amplified through the optical amplification module 4, and then enters the second coupling module 6 after being combined with the single-mode optical fiber 10 through the optical circulator 5, and the two paths of light are combined in the second coupling module 6. The combined wave signal output by the second coupling module 6 is converted into an analog signal through the photoelectric detection module 7 and enters the data acquisition module 8, and then the analog signal is acquired and converted into a digital signal through the data acquisition module 8 and is transmitted to the signal demodulation module 9 for data processing.
The key indexes of the system are as follows: the modulation 3 of the optical modulation module is used for modulating the laser into pulse light, and meanwhile, the laser pulse obtains the frequency shift of fixed frequency, and the maximum modulation frequency is 20KHz. The sampling rate of the data acquisition card in the data acquisition module 8 is 250MHz.
As shown in fig. 2, the signal data processing method applied to the distributed optical fiber acoustic wave sensing system of the present invention includes the following steps:
step 1), setting the transmission frequency, the data acquisition time interval and the number of sampling data groups of signals of an initial data acquisition module;
in general, no sound wave vibration is generated, the larger the transmission frequency set by the data acquisition module is, the more data will be generated by the system, the system operation amount is increased, and the system response time is prolonged, so that the data acquisition module needs to set reasonable signal transmission frequency.
Designating the signal transmission frequency f of the data acquisition module, wherein the data acquisition time interval is tau, the signal transmission frequency f of the data acquisition module is usually 0.3-5 Hz when no sound wave vibration occurs, in the embodiment, the value is f=1 Hz, tau=10s, and the number of the sampled data sets is 10 in a default state.
Step 2), setting an initial original data sampling length according to the spatial sampling resolution of the system, and starting to acquire original data G (N) within a set range of the single-mode fiber 10;
defining the length of the optical fiber as L, and according to the sampling rate fs=250 MHz of the data acquisition module and the propagation speed c=2×10 of light in the optical fiber 8 m/s, to obtain the spatial sampling resolution of the system Δl=c/(2×fs), Δl=0.4 m;
since L/Δl=2.5L, the initial original data sample length is set to 2.5L, the original data is denoted as G (N), n=1, 2,3.
Step 3), judging whether the sampled data is full-section optical fiber data or not according to the effective data length of the original data;
as shown in fig. 3, according to the data image acquired by the data acquisition system, calculating the effective data length M of the sampled data, and comparing the effective data length M with the sampling length of the sampled data;
if M is less than 2.5L, invalid data exists in the sampling data, and the step 4) is entered;
if m=2.5l, the sampled data are valid data, and the original data are phase-demodulated, and step 9 is entered;
if M is more than 2.5L, the effective data length is more than the set data sampling length, which indicates that the system has faults.
Step 4), calculating the light intensity amplitude difference H of the sampled data i (N)
4.1, mixing, filtering and demodulating the sampled data to obtain two paths of signals I (N) and Q (N);
4.2 calculating the intensity amplitude S of different sampled data sets i (N)
The intensity amplitude of the different sampled data sets is denoted as S i (N), i is the number of sampled data sets, i=1, 2, 3..10;
4.3 calculating the light intensity amplitude Difference H of different sampled data sets i (N)
H i (N)＝|S i+1 (N)-S i (N)|。
Step 5), according to the light intensity amplitude difference value H of different sampling data sets i (N) judging whether an acoustic vibration event occurs in the acquisition process;
when the difference value of the light intensity and the amplitude is larger than or equal to the set threshold value of the vibration event, judging that the sound wave vibration event occurs, and further demodulating the vibration frequency and the amplitude to enter the step 6);
when the light intensity amplitude difference value is smaller than the vibration event setting threshold value, judging that no sound wave vibration event occurs, and entering step 16.
Step 6), obtaining the positioning z of the sound wave vibration according to the waveform diagram of the light intensity amplitude difference j ；
As shown in FIG. 4, the location z of the acoustic vibrations can be obtained from the waveform of the light intensity amplitude difference j J is the acoustic vibration point number, j=1, 2,3,..r.
Step 7), adjusting a sampling data acquisition range according to the position of the acoustic vibration;
select z 1 The position of the x-th sampling point on the left side is taken as the data acquisition starting position, z R The position of the x-th sampling point on the right side is taken as a data acquisition end position, and generally x is taken as 10;
as shown in FIG. 5, the full-length optical fiber data acquisition range in the default state is adjusted to (z) from 0L to 2.5L 1 -10)～(z R +10), then the sampled data is G (N), n= (z) 1 -10)，...，(z R +10)。
Step 8), adjusting and setting the signal transmission frequency of the data acquisition module and the number of the sampled data sets at the data acquisition time interval;
setting the signal transmission frequency f of the data acquisition module to be the maximum value f max The number of sampling groups is set to 100 groups, and the data sampling time interval is 100/f max Returning to step 2).
Step 9), as shown in fig. 6, the sampled data is phase-demodulated, and an output phase difference value array delta phi is calculated j (N)；
9.1 Mixing, filtering and demodulating the sampled data G (N) to obtain two paths of signals I (N) and Q (N);
9.2 Arctangent and sum range expansion are carried out on two paths of signals I (N) and Q (N) to obtain the output phase of the signals
Where i represents the different sampled data sets, j represents the acoustic wave vibration point sequence number, i=1, 2,3., 100, j=1, 2,3,;
then the array of phase values at z1 is
The array of phase values at z2 is......；
z R The phase value array at the position is
9.3 Eliminating the initial phase to obtain an eliminated phase value
9.4 Further removing the phase substrate to obtain a phase value after removing the phase substrate;
phase value after removing phase substrate at k time
Continuously sampled kth group data, namely continuously operated k time;
9.5 Calculating a phase difference score)
9.6 As shown in fig. 7), a phase difference score array ΔΦ is output j (N)
Wherein the graph (a) is the vibration point z 1 Phase difference score ΔΦ at 1 (N) waveform diagrams; FIG. b shows the vibration point z 2 Phase difference score ΔΦ at 2 (N) waveform diagrams; FIG. (c) shows the vibration point z R Phase difference score ΔΦ at R Waveform diagram of (N).
The waveform diagram in fig. 7 shows phase difference time-domain diagrams of the vibration points in parallel relation to each other.
Step 10), according to the output phase array delta phi j (N) judging whether an acoustic vibration event occurs in the acquisition process;
when the phase difference score is larger than or equal to the vibration event set threshold, judging that an acoustic vibration event occurs, and entering step 11);
when the phase difference score is smaller than the vibration event setting threshold, it is determined that a no-sound-wave vibration event occurs, and the process proceeds to step 15).
Step 11), obtaining the vibration frequency F of each sound wave vibration position according to a frequency spectrum demodulation method 1 ，F 2 ，F 3 ，...，F R 。
Step 12), calculating the maximum vibration frequency F of the acoustic vibration max
F max ＝max(F 1 ，F 2 ，F 3 ，...，F R )。
Step 13), according to the nyquist sampling theorem, it can be known that the effective spectrogram can be obtained by analyzing the data acquisition module with the signal transmission frequency F being more than 2 times of the maximum vibration frequency, so that F is compared max And f max Judging whether the data transmission frequency needs to be adjusted or not;
if 2F max ≤f max ≤5F max Step 16) is carried out without adjusting the signal transmission frequency of the data acquisition module;
if f max ≥5F max Then, step 14) is entered.
Step 14), adjusting the signal transmission frequency F of the data acquisition module to meet 2F max ≤f≤5F max 。
Step 15), setting the initial original data sampling length to be 2.5L.
Step 16), judging whether the system stops running, if so, ending, otherwise, returning to the step 2);
whether to stop depends on the software operator, who stops the system to shut down and does not stop the system to continue operation.
When the steps are used for processing the signal data of the distributed optical fiber acoustic wave sensing system, the method combining two modes of light intensity amplitude differential demodulation and phase demodulation is adopted, so that effective data are rapidly and accurately extracted, and the data processing speed is increased; according to the existence of sound wave vibration events or the vibration frequency in the sampling process, the data transmission rate of the data acquisition module is automatically adjusted, the redundancy of massive original data is avoided, and the response speed of the system is improved. Meanwhile, in the phase demodulation processing process, the steps of eliminating the initial phase and removing the substrate are added, so that the signal-to-noise ratio of the system can be effectively improved, and the frequency demodulation precision of the system can be optimized.
The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention without requiring creative effort by one of ordinary skill in the art. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.
Claims (8)
1. A signal data processing method applied to a distributed optical fiber acoustic wave sensing system is characterized in that the applied distributed optical fiber acoustic wave sensing system is a coherent detection sensing system and comprises an ultra-narrow linewidth laser module (1), a first coupling module (2), an optical modulation module (3), an optical amplification module (4), an optical circulator (5), a second coupling module (6), an optical detection module (7), a data acquisition module (8), a signal demodulation module (9) and a single-mode optical fiber (10);
the continuous laser emitted by the ultra-narrow linewidth laser module (1) is divided into two paths through the first coupling module (2), one path enters the second coupling module (6), the other path enters the optical modulation module (3) to be modulated into a pulse-form optical signal, the optical modulation module (3) outputs a trigger signal through the data acquisition module (8), the pulse-form optical signal is amplified through the optical amplification module (4), and then enters the second coupling module (6) after being combined with the single-mode optical fiber (10) through the optical circulator (5), and the two paths of light are combined in the second coupling module (6); the combined wave signal output by the second coupling module (6) is converted into an analog signal through the photoelectric detection module (7) and enters the data acquisition module (8), and then the analog signal is acquired and converted into a digital signal through the data acquisition module (8) and transmitted to the signal demodulation module (9) for data processing;
the modulation (3) of the optical modulation module is used for modulating laser into pulse light, and meanwhile, the laser pulse obtains frequency shift of fixed frequency, and the maximum modulation frequency is AKHz; the sampling rate of the data acquisition card in the data acquisition module (8) is BMHz;
the method is characterized in that:
the method comprises the following steps:
step 1), setting the transmission frequency, the data acquisition time interval and the number of sampling data groups of signals of an initial data acquisition module;
designating the signal transmission frequency f of the data acquisition module, wherein the data acquisition time interval is tau, and the number of the sampled data sets is tau/f;
step 2), setting an initial original data sampling length according to the spatial sampling resolution of the system, and starting to acquire original data G (N) within a set range of a single-mode fiber (10);
defining the length of the optical fiber as L, and according to the sampling rate fs=250 MHz of the data acquisition module and the propagation speed c=2×10 of light in the optical fiber 8 m/s, to obtain the spatial sampling resolution of the system Δl=c/(2×fs), Δl=0.4 m;
since L/Δl=2.5l, the initial original data sampling length is set to 2.5L, and the original data is denoted as G (N), n=1, 2,3, …;
step 3), judging whether the sampled data is full-section optical fiber data or not according to the effective data length of the original data;
according to the data image acquired by the data acquisition system, calculating the effective data length M of the sampling data, and comparing the effective data length M with the sampling length of the sampling data;
if M is less than 2.5L, invalid data exists in the sampling data, and the step 4) is entered;
if m=2.5l, the sampled data are valid data, and the original data are phase-demodulated, and step 9 is entered;
step 4), calculating the light intensity amplitude difference H of the sampled data i (N)；
Step 5), according to the light intensity amplitude difference value H of different sampling data sets i (N) judging whether an acoustic vibration event occurs in the acquisition process;
when the difference value of the light intensity amplitude is larger than or equal to the set threshold value of the vibration event, judging that the sound wave vibration event occurs, and entering the step 6);
when the light intensity amplitude difference value is smaller than the vibration event set threshold value, judging that no sound wave vibration event occurs, and entering step 16);
step 6), obtaining the positioning z of the sound wave vibration according to the waveform diagram of the light intensity amplitude difference j ；
The positioning z of the sound wave vibration can be obtained from the waveform diagram of the light intensity amplitude difference j J is the acoustic vibration point number, j=1, 2,3, &..r;
step 7), adjusting a sampling data acquisition range according to the position of the acoustic vibration;
select z 1 The position of the x-th sampling point on the left side is taken as the data acquisition starting position, z R The position of the x-th sampling point on the right side is used as a data acquisition end position;
the acquisition range of the full-section optical fiber data in the default state is adjusted to be (z) from 0L to 2.5L 1 -x)～(z R +x), the sampled data is G (N), n= (z) 1 -x)，...，(z R +x)；
Step 8), adjusting and setting the signal transmission frequency of the data acquisition module and the number of the sampled data sets at the data acquisition time interval;
setting the signal transmission frequency f of the data acquisition module to be the maximum value f max The sampling group number is set as C groups, and the data sampling time interval is C/f max Returning to the step 2);
step 9), carrying out phase demodulation on the sampled data, and calculating to obtain an output phase difference value array delta phi j (N)；
Step 10), according to the output phase difference value array delta phi j (N) judging whether an acoustic vibration event occurs in the acquisition process;
when the phase difference score is larger than or equal to the vibration event set threshold, judging that an acoustic vibration event occurs, and entering step 11);
when the phase difference score is smaller than the vibration event set threshold, judging that a sound wave-free vibration event occurs, and entering step 15);
step 11), obtaining the vibration frequency F of each sound wave vibration position according to a frequency spectrum demodulation method 1 ，F 2 ，F 3 ，...，F R ；
Step 12), calculating the maximum vibration frequency F of the acoustic vibration max
F max ＝max(F 1 ，F 2 ，F 3 ，...，F R )；
Step 13), according to the Nyquist sampling theorem, the data acquisition module signal transmission is knownThe frequency F is more than 2 times of the maximum vibration frequency, and the effective spectrogram can be obtained by analysis, so F is compared max And f max Judging whether the data transmission frequency needs to be adjusted or not;
if 2F max ≤f max ≤5F max Step 16) is entered;
if f max ≥5F max Then, go to step 14);
step 14), adjusting the signal transmission frequency F of the data acquisition module to meet 2F max ≤f≤5F max ；
Step 15), setting the initial original data sampling length to be 2.5L;
step 16), judging whether the system stops running, if yes, ending, otherwise, returning to the step 2).
2. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 1, wherein: the step 4) is specifically as follows:
4.1, mixing, filtering and demodulating the sampled data to obtain two paths of signals I (N) and Q (N);
4.2 calculating the intensity amplitude S of different sampled data sets i (N)，
The intensity amplitude of the different sampled data sets is denoted as S i (N), i is the number of sampled data sets, i=1, 2, 3;
4.3 calculating the light intensity amplitude Difference H of different sampled data sets i (N)，
H i (N)＝|S i+1 (N)-S i (N)|。
3. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 2, wherein: the step 9) is specifically as follows:
9.1 Mixing, filtering and demodulating the sampled data G (N) to obtain two paths of signals I (N) and Q (N);
9.2 Arctangent and sum range expansion are carried out on two paths of signals I (N) and Q (N) to obtain the output phase of the signals
Where i represents different sampled data sets, j represents acoustic vibration point number, i=1, 2,3.
Then z 1 The phase value array at the position is
z 2 The phase value array at the position is
z R The phase value array at the position is
9.3 Eliminating the initial phase to obtain an eliminated phase value
9.4 Further removing the phase substrate to obtain a phase value after removing the phase substrate;
phase value after removing phase substrate at k time
Continuously sampled kth group data, namely continuously operated k time;
9.5 Calculating a phase difference score)
9.6 Outputting the phase difference value array delta phi) j (N)，
4. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 1, wherein:
in step 1), the signal transmission frequency is 0.3Hz < f < 5Hz, and the data acquisition time interval tau=10s.
5. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 4, wherein:
the maximum modulation frequency A of the modulation (3) of the optical modulation module is 20KHz; the sampling rate B of the data acquisition card in the data acquisition module (8) is 250MHz.
6. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 1, wherein:
in step 7), x=10.
7. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 6, wherein:
in step 8), c=100.
8. The signal data processing method applied to the distributed optical fiber acoustic wave sensing system according to claim 4, wherein:
in step 1), f=1 Hz.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118013401A (en) * | 2024-04-10 | 2024-05-10 | 宁波联河光子技术有限公司 | DAS-based belt conveyor vibration false alarm suppression method |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103954348A (en) * | 2014-05-12 | 2014-07-30 | 重庆大学 | Distributed optical fiber vibration sensing system based on differential pulse sequence |
| US20180080812A1 (en) * | 2017-07-25 | 2018-03-22 | University Of Electronic Science And Technology Of China | Distributed optical fiber sensing signal processing method for safety monitoring of underground pipe network |
| WO2018076551A1 (en) * | 2016-10-25 | 2018-05-03 | 北京大学 | Distributed optical fibre sensing system capable of realizing all-phase demodulation, and measuring method therefor |
| CN109557035A (en) * | 2018-12-11 | 2019-04-02 | 华侨大学 | A kind of Doppler's optimal imaging method of sinusoidal phase differential ference spiral |
| US20200182685A1 (en) * | 2016-08-25 | 2020-06-11 | Shanghai Jiaotong University | Distributed fibre sensing system and vibration detection and positioning method therefor |
| CN113566858A (en) * | 2021-06-11 | 2021-10-29 | 太原理工大学 | Phase sensitive optical time domain reflection system for dual-wavelength frequency diversity |
| CN113624363A (en) * | 2021-08-02 | 2021-11-09 | 太原理工大学 | Optical fiber temperature monitoring device |
| US20210384987A1 (en) * | 2020-06-09 | 2021-12-09 | Wuhan University Of Technology | Method for Correcting Phase Jump Caused by Polarization-Induced Fading in Optical Fiber Phase Demodulation |
-
2021
- 2021-12-28 CN CN202111626064.9A patent/CN116772908A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103954348A (en) * | 2014-05-12 | 2014-07-30 | 重庆大学 | Distributed optical fiber vibration sensing system based on differential pulse sequence |
| US20200182685A1 (en) * | 2016-08-25 | 2020-06-11 | Shanghai Jiaotong University | Distributed fibre sensing system and vibration detection and positioning method therefor |
| WO2018076551A1 (en) * | 2016-10-25 | 2018-05-03 | 北京大学 | Distributed optical fibre sensing system capable of realizing all-phase demodulation, and measuring method therefor |
| US20180080812A1 (en) * | 2017-07-25 | 2018-03-22 | University Of Electronic Science And Technology Of China | Distributed optical fiber sensing signal processing method for safety monitoring of underground pipe network |
| CN109557035A (en) * | 2018-12-11 | 2019-04-02 | 华侨大学 | A kind of Doppler's optimal imaging method of sinusoidal phase differential ference spiral |
| US20210384987A1 (en) * | 2020-06-09 | 2021-12-09 | Wuhan University Of Technology | Method for Correcting Phase Jump Caused by Polarization-Induced Fading in Optical Fiber Phase Demodulation |
| CN113566858A (en) * | 2021-06-11 | 2021-10-29 | 太原理工大学 | Phase sensitive optical time domain reflection system for dual-wavelength frequency diversity |
| CN113624363A (en) * | 2021-08-02 | 2021-11-09 | 太原理工大学 | Optical fiber temperature monitoring device |
Non-Patent Citations (1)
| Title |
|---|
| 蒋鹏: "基于瑞利散射的分布式光纤振动传感技术研究", 基于瑞利散射的分布式光纤振动传感技术研究, pages 1 - 35 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118013401A (en) * | 2024-04-10 | 2024-05-10 | 宁波联河光子技术有限公司 | DAS-based belt conveyor vibration false alarm suppression method |
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