Optical fiber specific frequency vibration event monitoring method and device based on variable delay line

Abstract

The present invention relates to the field of optical fiber sensing technology, and specifically provides a method and device for monitoring optical fiber specific frequency vibration events based on a variable delay line. The monitoring method includes adjusting the delay time of optical signal propagation in the variable delay line, aligning the phase of the target frequency signal, and obtaining a beam pointing signal; performing a sparse representation on the beam pointing signal to obtain an optimal sparse coefficient; reconstructing the optimal sparse coefficient to obtain an enhanced target frequency signal; if the expected signal strength and the signal strength of the target frequency signal do not match, readjusting the delay time until the expected signal strength and the signal strength match; and confirming the corresponding vibration event based on the target frequency signal. The present invention can accurately monitor vibration events at the target frequency.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to a method and device for monitoring optical fiber specific frequency vibration events based on a variable delay line. Background Art

[0002] Fiber-optic sensing technology exploits the physical properties of light as it propagates through optical fibers, converting changes in the external measured quantity into changes in the optical signal. This information is then acquired through detection and analysis of the optical signal. Due to its advantages such as high sensitivity, strong resistance to electromagnetic interference, and long-distance transmission, fiber-optic sensing technology is widely used in fields such as structural health monitoring, environmental monitoring, and mechanical fault diagnosis. However, when applying fiber-optic sensing technology to monitor vibration events of specific frequencies, existing technologies struggle to accurately monitor these signals in complex signal environments. Summary of the Invention

[0003] The method and device for monitoring optical fiber specific frequency vibration events based on a variable delay line provided in the embodiments of the present invention at least solve the problem that existing optical fiber sensing technology is not accurate enough when facing complex signal environments, and can accurately monitor vibration events of the target frequency.

[0004] In the first aspect, the present invention provides a method for monitoring optical fiber specific frequency vibration events based on a variable delay line, comprising adjusting the delay time of optical signal propagation in the variable delay line, aligning the phase of the target frequency signal, and obtaining a beam pointing signal; sparsely representing the beam pointing signal to obtain an optimal sparse coefficient; reconstructing the optimal sparse coefficient to obtain an enhanced target frequency signal; in the case where the expected signal strength and the signal strength of the target frequency signal do not match, readjusting the delay time until the expected signal strength and the signal strength match; and confirming the corresponding vibration event based on the target frequency signal.

[0005] In one embodiment of the present invention, adjusting the delay time of an optical signal propagating in a variable delay line includes: adjusting the propagation speed of the optical signal in the variable delay line to adjust the delay time; or / and adjusting the length of the variable delay line to adjust the delay time.

[0006] In one embodiment of the present invention, the variable delay line includes an optical fiber and an electro-optical modulator connected to the optical fiber; adjusting the propagation speed of the optical signal in the variable delay line to adjust the delay time includes: adjusting the voltage applied to the electro-optical modulator to cause the electro-optical modulator to deform; causing the optical fiber to deform due to the deformation generated by the electro-optical modulator to change the refractive index of the optical fiber, thereby obtaining the optical fiber with a changed refractive index; and propagating the optical signal through the optical fiber with a changed refractive index to adjust the propagation speed of the optical signal in the optical fiber, thereby adjusting the delay time.

[0007] In one embodiment of the present invention, the electro-optical modulator is configured as a piezoelectric ceramic, and a plurality of fiber Bragg gratings are provided in the core of the optical fiber, wherein the fiber Bragg gratings are provided in a one-to-one correspondence with the piezoelectric ceramics; and adjusting the voltage applied to the piezoelectric ceramics to cause the piezoelectric ceramics to deform, comprises: calculating the delay time of each fiber Bragg grating according to the equivalent pointing phase, expressed as: ,in, For the the delay time of each of the fiber Bragg gratings, is an integer and , is the total number of the fiber Bragg gratings, For the The initial phase of the signal of the fiber Bragg grating, is the equivalent pointing phase, is the frequency of the target frequency signal; according to the delay time, the target voltage of each piezoelectric ceramic is calculated, which is expressed as: ,in, For the the target voltage of each of the piezoelectric ceramics, is the speed of light in vacuum, is the effective refractive index of the optical fiber, is the piezoelectric constant of the piezoelectric ceramic; and according to the target voltage, the voltage applied to the piezoelectric ceramic is adjusted to cause the piezoelectric ceramic to deform.

[0008] In one embodiment of the present invention, adjusting the voltage applied to the piezoelectric ceramic to cause the piezoelectric ceramic to deform further includes: calculating the theoretical deformation of each piezoelectric ceramic; obtaining the actual deformation of each piezoelectric ceramic; and if the actual deformation does not match the theoretical deformation, readjusting the target voltage until the actual deformation matches the theoretical deformation.

[0009] In one embodiment of the present invention, the theoretical deformation of each piezoelectric ceramic is calculated and expressed as: ,in, For the The theoretical deformation amount produced by the piezoelectric ceramic.

[0010] In one embodiment of the present invention, performing a sparse representation on the beam steering signal to obtain an optimal sparse coefficient includes: constructing a problem model based on the beam steering signal, expressed as: ,in, is the beam pointing signal, For the dictionary, is the sparse coefficient, is noise, , is a Gaussian distribution, is the noise variance, is the identity matrix; define the sparse coefficient The prior distribution of is expressed as: , ,in, is the covariance matrix, is a diagonal function, is the hyperparameter of the sparse prior, , For the dictionary The number of atoms; define the marginal likelihood function , expressed as: , ; According to the marginal likelihood function, optimize the hyperparameters , get the optimal hyperparameters , expressed as: , ,in, To solve the hyperparameters exist The maximum value in is the number of sampling points, is a constraint condition; according to the optimal hyperparameter , calculate the optimal sparse coefficient , expressed as: .

[0011] In one embodiment of the present invention, the optimal sparse coefficients are reconstructed to obtain the enhanced target frequency signal, which is expressed as: ,in, is the enhanced target frequency signal, For time.

[0012] In the second aspect, the present invention also provides an optical fiber specific frequency vibration event monitoring device based on a variable delay line, which is applied to the optical fiber specific frequency vibration event monitoring method based on a variable delay line as described in any one of the above items, including a delay adjustment module, which is used to adjust the delay time of the optical signal propagation in the variable delay line, align the phase of the target frequency signal, and obtain a beam pointing signal; a sparse representation module, which is used to perform sparse representation on the beam pointing signal to obtain an optimal sparse coefficient; a signal reconstruction module, which is used to reconstruct the optimal sparse coefficient to obtain an enhanced target frequency signal; an intensity judgment module, which is used to judge whether the expected signal strength and the signal strength of the target frequency signal match. If the expected signal strength and the signal strength of the target frequency signal do not match, the delay time is readjusted by the delay adjustment module until the expected signal strength and the signal strength match; an event confirmation module, which is used to confirm the corresponding vibration event according to the target frequency signal.

[0013] In a third aspect, the present invention further provides an electronic device comprising: a processor, and a memory for storing a program, wherein the program comprises instructions, and when the instructions are executed by the processor, the processor executes the optical fiber specific frequency vibration event monitoring method based on a variable delay line as described in any one of the above.

[0014] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0015] The method and device for monitoring optical fiber vibration events at specific frequencies using a variable delay line, described in this invention, dynamically adjusts the optical signal delay time through the variable delay line, aligns the phase of the target frequency signal, implements beamforming, and improves the signal-to-noise ratio. Furthermore, combined with sparse representation technology, an iterative process extracts the target frequency signal, suppresses noise and other interference, and achieves a more robust and accurate signal representation. Ultimately, this method enables the detection and monitoring of vibration events at the target frequency in complex signal environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without inventive work. In the drawings:

[0017] Figure 1 It is a flow chart of a method for monitoring optical fiber specific frequency vibration events based on a variable delay line in a preferred embodiment of the present invention.

[0018] Figure 2 It is a schematic structural diagram of an optical fiber specific frequency vibration event monitoring device based on a variable delay line in a preferred embodiment of the present invention.

[0019] Figure 3 It is a schematic structural diagram of an electronic device in a preferred embodiment of the present invention.

[0020] The above drawings include the following reference numerals:

[0021] 11. Delay adjustment module; 12. Sparse representation module; 13. Signal reconstruction module; 14. Strength judgment module; 15. Event confirmation module; 21. Computing unit; 22. ROM; 23. RAM; 24. Bus; 25. I / O interface; 26. Input unit; 27. Output unit; 28. Storage unit; 29. Communication unit. DETAILED DESCRIPTION

[0022] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that fiber optic sensing technology utilizes the physical properties of light when it propagates in optical fibers, converts changes in external measurements into changes in optical signals, and obtains measured information by detecting and analyzing optical signals.

[0024] For example, using fiber optic sensing to monitor vibration events, external vibrations modulate the optical signal parameters transmitted through the fiber. These parameters include phase, wavelength, intensity, and polarization state. By detecting these modulated optical signals, relevant information about the vibration can be inferred.

[0025] However, when monitoring vibration events at specific frequencies, the signal environment is less than ideal. Faced with this complex signal environment, existing fiber optic sensing systems typically need to process mixed signals with multiple frequency components. In the presence of multi-frequency interference, traditional signal processing methods, including Fourier transforms and bandpass filtering, struggle to effectively extract the target frequency signal, making it impossible to accurately monitor vibration events.

[0026] To solve the above problems, refer to Figure 1As shown, the present invention provides a method for monitoring optical fiber specific frequency vibration events based on a variable delay line. By combining beamforming technology with sparse representation technology and using a variable delay line to dynamically adjust the phase of the target frequency signal, accurate and reliable monitoring of the target frequency signal is achieved.

[0027] The optical fiber specific frequency vibration event monitoring method based on variable delay line includes:

[0028] The delay time of the optical signal propagation in the variable delay line is adjusted to align the phase of the target frequency signal and obtain a beam pointing signal.

[0029] The beam pointing signal is sparsely represented to obtain the optimal sparse coefficient.

[0030] The optimal sparse coefficients are reconstructed to obtain the enhanced target frequency signal.

[0031] In the event that the expected signal strength does not match the signal strength of the target frequency signal, the delay time is readjusted until the expected signal strength matches the signal strength.

[0032] Identify the corresponding vibration events based on the target frequency signal.

[0033] Specifically, first, the delay time of the optical signal propagation in the variable delay line is adjusted to align the phase of the target frequency signal to obtain a beam steering signal.

[0034] A variable delay line is a device that adjusts the delay time of an optical signal propagating through an optical fiber through electronic or mechanical control. Those skilled in the art will be able to configure specific methods for adjusting the delay time of the variable delay line based on actual needs, including but not limited to adjusting the propagation speed of the optical signal or adjusting the length of the variable delay line.

[0035] After the delay time of the optical signal is adjusted, the phase of the optical signal is aligned. In the case of phase alignment, signal enhancement can be achieved.

[0036] Exemplary, to include The present invention will be described using a fiber Bragg grating (FBG) grating array as an example. It should be noted that those skilled in the art can configure other structures to replace the fiber Bragg grating according to actual needs.

[0037] Specifically, The reflected signal of a fiber Bragg grating It can be expressed as:

[0038] .

[0039] Where, For the The signal intensity of the reflected signal of a fiber Bragg grating. It can be understood that the reflected signal and the fiber Bragg grating are one-to-one corresponding. is an integer and . For the The frequency of the vibration event corresponding to a fiber Bragg grating. For time. For the The initial phase of the reflected signal of a fiber Bragg grating. For the The noise term in the reflected signal of a fiber Bragg grating.

[0040] The monitoring frequency is The vibration event, When the initial phases of the reflected signals are different, the signal strength of the independent signal is low. When the signal is interfered with by other frequencies, the signal-to-noise ratio is low, making it difficult to effectively extract the signal and unable to accurately monitor the vibration event.

[0041] To this end, in the present invention, the signal in the grating array is phase matched so that the signal phase is matched to the equivalent pointing phase In the case of phase-matched alignment, signals related to the target frequency can be coherently added after combination, while other frequency components are suppressed.

[0042] Among them, by adjusting the The delay time of a fiber Bragg grating After adjusting the delay time, the phase is aligned. The reflected signal of a fiber Bragg grating It can be expressed as:

[0043] .

[0044] Where, To adjust the delay time, The noise term in the reflected signal of a fiber Bragg grating.

[0045] Through simple transformation, we can know that after adjusting the delay time, the The phase of the reflected signal of a fiber Bragg grating becomes .

[0046] The signals are superimposed to obtain the beam pointing signal , expressed as:

[0047] .

[0048] At this time, the phases of the reflected signals are unified into the equivalent directional phase , the signals related to the target frequency can be coherently superimposed, and the signal strength can be obtained The noise is generally random and has low coherence. In the process of signal superposition, the noise contribution is relatively small, thus improving the signal-to-noise ratio. Those skilled in the art can set the equivalent pointing phase according to actual needs. .

[0049] It is worth noting that in order to make the signal strength finally obtain To achieve a multiplication of the gain, it is often necessary to adjust the delay time multiple times. Therefore, by setting a variable delay line, it is possible to adapt well to the dynamic adjustment requirements, and the phase control accuracy requirement is relatively low.

[0050] After adjusting the delay time and aligning the phase of the target frequency signal to obtain the beam pointing signal, although the signal strength of the target frequency signal is enhanced, noise interference still exists and the target frequency signal needs to be extracted.

[0051] Specifically, after obtaining the beam pointing signal, a sparse representation is performed on the beam pointing signal to obtain an optimal sparse coefficient.

[0052] Among them, sparse representation technology can extract target frequency signals in complex environments, but when used alone, its noise resistance in the face of strong interference is insufficient. However, by first aligning the phase of the target frequency signal and improving the signal-to-noise ratio, the present invention can process the beam pointing signal through sparse representation technology, realize the best advantages and avoid the worst, and obtain the optimal sparse coefficient. The optimal sparse coefficient is usually a vector. Those skilled in the art can process the beam pointing signal through the corresponding sparse representation according to actual needs.

[0053] After obtaining the optimal sparse coefficient, the optimal sparse coefficient is reconstructed to achieve denoising and obtain the enhanced target frequency signal.

[0054] When the target frequency signal is obtained after denoising and signal strength enhancement, the actual signal strength of the target frequency signal can be analyzed to determine the signal phase matching when the delay time is adjusted through the variable delay line.

[0055] It can be understood that if the phases are matched, the expected signal strength and the signal strength of the reconstructed target frequency signal are equal, or the two signal strengths are approximately equal.

[0056] In the case of being approximately equal, the signal strength of the target frequency signal can be based on the expected signal strength to achieve a certain fluctuation. Those skilled in the art can set the condition of being approximately equal according to actual needs, which will not be repeated here.

[0057] If the delay time is adjusted accurately, the phase of each signal will be matched to the equivalent directional phase. , to include Taking a fiber Bragg grating array as an example, the signal strength of the target frequency signal after phase alignment can be obtained. Correspondingly, if the signal strength of the target frequency signal obtained by sparse representation and reconstruction does not meet If the gain is multiple, then the phase of at least some of the signals is not aligned.

[0058] Therefore, when reconstructing and obtaining the enhanced target frequency signal, it is necessary to analyze the matching between the expected signal strength and the signal strength of the target frequency signal.

[0059] In the case where the expected signal strength does not match the signal strength of the target frequency signal, it is necessary to readjust the delay time and perform sparse representation, reconstruction, and strength analysis again until the expected signal strength matches the signal strength.

[0060] After repeated iterations, the expected signal strength eventually matches the target frequency signal strength. This matching not only removes noise and other interference, but also effectively enhances the target frequency signal strength, making the signal representation more robust and accurate.

[0061] Finally, the corresponding vibration event is confirmed based on the fully de-noised and enhanced target frequency signal. How to confirm the corresponding vibration event based on the target frequency signal belongs to the existing technology and will not be described in detail.

[0062] In summary, the variable delay line-based optical fiber frequency-specific vibration event monitoring method described in the present invention dynamically adjusts the optical signal delay time through the variable delay line, aligns the phase of the target frequency signal, implements beamforming, and improves the signal-to-noise ratio. Furthermore, combined with sparse representation technology, the target frequency signal is extracted, noise and other interference are suppressed during the iterative process, and the final signal representation is more robust and accurate. Ultimately, the detection and monitoring of vibration events at the target frequency in a complex signal environment is achieved.

[0063] In some embodiments of the variable delay line-based optical fiber frequency-specific vibration event monitoring method of the present invention, adjusting the delay time of an optical signal propagating in the variable delay line includes adjusting the propagation speed of the optical signal in the variable delay line to adjust the delay time. Alternatively, adjusting the length of the variable delay line to adjust the delay time may also be performed.

[0064] Specifically, in optical fiber communication, the delay time of optical signal propagation is affected by the propagation speed of the optical signal and the length of the variable delay line.

[0065] Taking adjusting the propagation speed of optical signals as an example, by adjusting the refractive index of the optical fiber, other conditions remaining unchanged, the propagation speed of the optical signal, and thus the delay time, can be adjusted. For example, the refractive index of the optical fiber can be adjusted by driving a small change in length through a driver such as a motor, or by changing environmental parameters such as the electric and magnetic fields surrounding the optical fiber. By adjusting the propagation speed of the optical signal, a fast response can be achieved, meeting the requirements of high-speed dynamic delay adjustment.

[0066] For example, adjusting the length of a variable delay line can increase or decrease the optical signal propagation time, while other conditions remain unchanged. Adjusting the length of the variable delay line allows for a wider range of delay adjustments.

[0067] Those skilled in the art can adjust the delay time by only using one of the methods or by combining the two methods according to actual needs.

[0068] Preferably, in the present invention, the propagation speed of the optical signal is adjusted only by adjusting the refractive index of the optical fiber, thereby adjusting the delay time.

[0069] Furthermore, in some embodiments of the variable delay line-based optical fiber frequency-specific vibration event monitoring method described herein, the variable delay line includes an optical fiber and an electro-optic modulator connected to the optical fiber. Those skilled in the art will be able to configure the specific connection method based on actual needs. The optical fiber is used to transmit optical signals, and the electro-optic modulator is used to deform and change the refractive index of the optical fiber.

[0070] Adjusting the propagation speed of the optical signal in the variable delay line to adjust the delay time includes:

[0071] First, the voltage applied to the electro-optic modulator is adjusted to cause the electro-optic modulator to deform.

[0072] Secondly, the deformation generated by the electro-optical modulator drives the optical fiber to deform, thereby changing the refractive index of the optical fiber, thereby obtaining an optical fiber with a changed refractive index.

[0073] Finally, the optical signal is propagated through the optical fiber with the changed refractive index to adjust the propagation speed of the optical signal in the optical fiber, thereby adjusting the delay time.

[0074] Exemplarily, the electro-optic modulator includes a piezoelectric ceramic. The piezoelectric ceramic is electrically connected to a voltage controller on one side and to an optical fiber on the other side. When the voltage controller adjusts the output voltage, the piezoelectric ceramic deforms according to the inverse piezoelectric effect.

[0075] Preferably, the piezoelectric ceramic is configured as lead zirconate titanate piezoelectric ceramic; the voltage controller controls the output voltage via a microcontroller, such as an FPGA (Field Programmable Gate Array) or a DSP (Digital Signal Processing).

[0076] When the piezoelectric ceramic deforms, the optical fiber tightly fixed to the piezoelectric ceramic deforms synchronously, and the refractive index of the optical fiber changes. Correspondingly, the propagation speed of the optical signal propagating therein also changes, thereby achieving adjustment of the delay time.

[0077] By adjusting the voltage applied to the electro-optic modulator, the electro-optic modulator is deformed and drives the optical fiber to deform, thereby changing the refractive index of the optical fiber. On the basis of fast response speed, the operation is convenient and relatively accurate.

[0078] Furthermore, in the optical fiber specific frequency vibration event monitoring method based on the variable delay line described in the present invention, in some embodiments, the electro-optical modulator is configured as a piezoelectric ceramic, and a plurality of fiber Bragg gratings are arranged in the core of the optical fiber, and the fiber Bragg gratings and the piezoelectric ceramics are arranged in a one-to-one correspondence.

[0079] Adjust the voltage applied to the piezoelectric ceramic to cause the piezoelectric ceramic to deform, including:

[0080] According to the equivalent pointing phase, the delay time of each fiber Bragg grating is calculated and expressed as:

[0081] .

[0082] Where, For the The delay time of a fiber Bragg grating, is an integer and , is the total number of fiber Bragg gratings, For the The initial phase of the fiber Bragg grating signal, is the equivalent pointing phase, is the frequency of the target frequency signal.

[0083] After obtaining the delay time, the target voltage of each piezoelectric ceramic is calculated according to the delay time, which is expressed as:

[0084] .

[0085] Where, For the The target voltage of the piezoelectric ceramic, is the speed of light in vacuum, is the effective refractive index of the optical fiber, is the piezoelectric constant of the piezoelectric ceramic, which represents the strain efficiency under the action of an electric field. Those skilled in the art can set piezoelectric ceramics with different piezoelectric constants according to actual needs to ensure that the piezoelectric ceramic can generate sufficient deformation when a voltage is applied.

[0086] It is worth noting that before calculating the delay time of each fiber Bragg grating based on the equivalent pointing phase, an initial equivalent pointing phase needs to be set. Of course, in some embodiments, the equivalent pointing phase can also be updated.

[0087] For example, when monitoring begins, an initialization operation should be performed to set an initial equivalent pointing phase according to actual needs, so that the voltage applied to the piezoelectric ceramic can be controlled according to the initial equivalent pointing phase, thereby deforming the piezoelectric ceramic and adjusting the refractive index of the optical fiber to achieve preliminary adjustment of the delay time.

[0088] Finally, according to the target voltage, the voltage applied to the piezoelectric ceramic is adjusted to cause the piezoelectric ceramic to deform.

[0089] In this way, the target voltage can be calculated quickly and conveniently to control the actual applied voltage and cause the piezoelectric ceramic to produce precise deformation.

[0090] Considering that the deformation of piezoelectric ceramics is easily affected by other factors during actual use, in order to achieve more precise deformation control, the method for monitoring optical fiber specific frequency vibration events based on a variable delay line according to the present invention, in some embodiments, adjusts the voltage applied to the piezoelectric ceramic to cause the piezoelectric ceramic to deform, and further includes:

[0091] Calculate the theoretical deformation of each piezoelectric ceramic.

[0092] Obtain the actual deformation of each piezoelectric ceramic.

[0093] In the case that the actual deformation amount does not match the theoretical deformation amount, the target voltage is readjusted until the actual deformation amount matches the theoretical deformation amount.

[0094] The theoretical deformation of each piezoelectric ceramic is calculated as follows:

[0095] .

[0096] Where, For the The theoretical deformation produced by a piezoelectric ceramic.

[0097] Exemplarily, a feedback sensor is provided to obtain the actual deformation of the piezoelectric ceramic, and to determine whether the actual deformation matches the theoretical deformation, so as to achieve real-time monitoring of the deformation of the piezoelectric ceramic.

[0098] It can be understood that the matching can be that the two are equal or approximately equal. Those skilled in the art can set the condition that the two are approximately equal according to actual needs, and will not be repeated here.

[0099] Those skilled in the art can set a feedback sensor, such as a laser interferometer or an optical encoder, according to actual needs.

[0100] If the theoretical and actual deformations of the piezoelectric ceramic do not match, the feedback sensor sends a feedback signal to the voltage controller. The voltage controller then adjusts the correction voltage to control the deformation of the piezoelectric ceramic, ultimately achieving precise adjustment of the delay time.

[0101] Therefore, after applying voltage to the piezoelectric ceramic and controlling its deformation, the theoretical deformation and actual deformation of the piezoelectric ceramic are compared. If the two do not match, the voltage is readjusted to ensure that the actual deformation of the piezoelectric ceramic matches the theoretical deformation. This enables precise adjustment of the delay time, making the final signal representation more robust and accurate.

[0102] In some embodiments of the optical fiber specific frequency vibration event monitoring method based on a variable delay line of the present invention, a sparse representation is performed on the beam pointing signal to obtain an optimal sparse coefficient, including:

[0103] First, a problem model is constructed based on the beam pointing signal. The sampled beam pointing signal is regarded as the superposition of the target frequency signal and noise, which can be expressed as:

[0104] .

[0105] Where, is the sampled beam pointing signal. is a dictionary, whose column vectors are bases (or characteristic signals) of different frequencies. Those skilled in the art can set a specific dictionary according to actual needs. is a sparse coefficient, which is usually a vector and is what we want to extract. is the noise, which is usually a vector. , represented as noise Subject to zero mean, is the noise variance, Gaussian distribution of the identity matrix .

[0106] Next, define the sparse coefficients The prior distribution of is expressed as:

[0107] ,

[0108] .

[0109] Where, is the covariance matrix. is a diagonal function. is the hyperparameter of the sparse prior, , used to control the sparsity of the sparse vector. For dictionary The number of atoms.

[0110] Then, define the marginal likelihood function , expressed as:

[0111] ,

[0112] .

[0113] Then, according to the marginal likelihood function, optimize the hyperparameters , get the optimal hyperparameters , expressed as:

[0114] ,

[0115] .

[0116] in, To solve the hyperparameters exist The maximum value in is the number of sampling points, As constraints. On this basis, the hyperparameters The optimal solution process is equivalent to solving the optimization problem of the above formula. How to solve the above formula is common knowledge among those skilled in the art and will not be described in detail.

[0117] Finally, according to the optimal hyperparameters , calculate the optimal sparse coefficient , expressed as:

[0118] .

[0119] Get the optimal sparse coefficient After that, the optimal sparse coefficients are reconstructed to obtain the enhanced target frequency signal and achieve denoising, which is expressed as:

[0120] .

[0121] in, The enhanced target frequency signal. , which can realize the confirmation of corresponding vibration events.

[0122] Reference Figure 2 The present invention also provides a variable delay line-based optical fiber specific frequency vibration event monitoring device, which is applicable to the variable delay line-based optical fiber specific frequency vibration event monitoring method described in any of the above embodiments. The variable delay line-based optical fiber specific frequency vibration event monitoring device includes a delay adjustment module 11, a sparse representation module 12, a signal reconstruction module 13, an intensity determination module 14, and an event confirmation module 15.

[0123] The sparse representation module 12 is electrically connected to the delay adjustment module 11 , the signal reconstruction module 13 is electrically connected to the sparse representation module 12 , and the strength judgment module 14 is electrically connected to the delay adjustment module 11 , the signal reconstruction module 13 and the event confirmation module 15 .

[0124] Specifically, the delay adjustment module 11 is used to adjust the delay time of the optical signal propagation in the variable delay line, align the phase of the target frequency signal, and obtain a beam steering signal.

[0125] A variable delay line is a device that adjusts the delay time of an optical signal propagating through an optical fiber through electronic or mechanical control. Those skilled in the art will be able to configure specific methods for adjusting the delay time of the variable delay line based on actual needs, including but not limited to adjusting the propagation speed of the optical signal or adjusting the length of the variable delay line.

[0126] After the delay time of the optical signal is adjusted, the phase of the optical signal is aligned. In the case of phase alignment, signal enhancement can be achieved.

[0127] Exemplary, to include The present invention will be described using a fiber Bragg grating (FBG) grating array as an example. It should be noted that those skilled in the art can configure other structures to replace the fiber Bragg grating according to actual needs.

[0128] Specifically, The reflected signal of a fiber Bragg grating It can be expressed as:

[0129] .

[0130] Where, For the The signal intensity of the reflected signal of a fiber Bragg grating. It can be understood that the reflected signal and the fiber Bragg grating are one-to-one corresponding. is an integer and . For the The frequency of the vibration event corresponding to a fiber Bragg grating. For time. For the The initial phase of the reflected signal of a fiber Bragg grating. For the The noise term in the reflected signal of a fiber Bragg grating.

[0131] The monitoring frequency is The vibration event, When the initial phases of the reflected signals are different, the signal strength of the independent signal is low. When the signal is interfered with by other frequencies, the signal-to-noise ratio is low, making it difficult to effectively extract the signal and unable to accurately monitor the vibration event.

[0132] To this end, in the present invention, the signal in the grating array is phase matched so that the signal phase is matched to the equivalent pointing phase In the case of phase-matched alignment, signals related to the target frequency can be coherently added after combination, while other frequency components are suppressed.

[0133] Among them, by adjusting the The delay time of a fiber Bragg grating After adjusting the delay time, the phase is aligned. The reflected signal of a fiber Bragg grating It can be expressed as:

[0134] .

[0135] Where, To adjust the delay time, The noise term in the reflected signal of a fiber Bragg grating.

[0136] Through simple transformation, we can know that after adjusting the delay time, the The phase of the reflected signal of a fiber Bragg grating becomes .

[0137] The signals are superimposed to obtain the beam pointing signal , expressed as:

[0138] .

[0139] At this time, the phases of the reflected signals are unified into the equivalent directional phase , the signals related to the target frequency can be coherently superimposed, and the signal strength can be obtained The noise is generally random and has low coherence. In the process of signal superposition, the noise contribution is relatively small, thus improving the signal-to-noise ratio.

[0140] It is worth noting that in order to make the signal strength finally obtain To achieve a multiplication of the gain, it is often necessary to adjust the delay time multiple times. Therefore, by setting a variable delay line, it is possible to adapt well to the dynamic adjustment requirements, and the phase control accuracy requirement is relatively low.

[0141] After adjusting the delay time and aligning the phase of the target frequency signal to obtain the beam pointing signal, although the signal strength of the target frequency signal is enhanced, noise interference still exists and the target frequency signal needs to be extracted.

[0142] Therefore, after the beam pointing signal is obtained, the beam pointing signal is input into the sparse representation module 12, and the sparse representation module 12 performs sparse representation on the beam pointing signal to obtain the optimal sparse coefficient.

[0143] Among them, sparse representation technology can extract target frequency signals in complex environments, but when used alone, its noise resistance in the face of strong interference is insufficient. However, by first aligning the phase of the target frequency signal and improving the signal-to-noise ratio, the present invention can process the beam pointing signal through sparse representation technology, realize the best advantages and avoid the worst, and obtain the optimal sparse coefficient. The optimal sparse coefficient is usually a vector. Those skilled in the art can process the beam pointing signal through the corresponding sparse representation according to actual needs.

[0144] After the optimal sparse coefficient is obtained, the optimal sparse coefficient is input to the signal reconstruction module 13, and the optimal sparse coefficient is reconstructed by the signal reconstruction module 13 to obtain an enhanced target frequency signal.

[0145] When the target frequency signal is obtained after denoising and signal strength enhancement, the actual signal strength of the target frequency signal can be analyzed to determine the signal phase matching when the delay time is adjusted through the variable delay line.

[0146] It can be understood that if the phases are matched, the expected signal strength and the signal strength of the reconstructed target frequency signal are equal, or the two signal strengths are approximately equal.

[0147] In the case of being approximately equal, the signal strength of the target frequency signal can be based on the expected signal strength to achieve a certain fluctuation. Those skilled in the art can set the condition of being approximately equal according to actual needs, which will not be repeated here.

[0148] If the delay time is adjusted accurately, the phase of each signal will be matched to the equivalent directional phase. , to include Taking a fiber Bragg grating array as an example, the signal strength of the target frequency signal after phase alignment can be obtained. Correspondingly, if the signal strength of the target frequency signal obtained by sparse representation and reconstruction does not meet If the gain is multiple, then the phase of at least some of the signals is not aligned.

[0149] Therefore, when reconstructing and obtaining the enhanced target frequency signal, it is necessary to analyze the matching between the expected signal strength and the signal strength of the target frequency signal.

[0150] Specifically, the enhanced target frequency signal is input into the strength judgment module 14, and the strength judgment module 14 determines whether the expected signal strength matches the signal strength of the target frequency signal. If the expected signal strength does not match the signal strength of the target frequency signal, the delay time is readjusted through the delay adjustment module 11, and the corresponding sparse representation and reconstruction are re-performed through the sparse representation module 12 and the signal reconstruction module 13 until the expected signal strength matches the signal strength.

[0151] After repeated iterations, the expected signal strength eventually matches the target frequency signal strength. This matching not only removes noise and other interference, but also effectively enhances the target frequency signal strength, making the signal representation more robust and accurate.

[0152] Finally, the fully denoised and enhanced target frequency signal is input to the event confirmation module 15, which confirms the corresponding vibration event based on the target frequency signal. How to confirm the corresponding vibration event based on the target frequency signal belongs to the existing technology and will not be described in detail.

[0153] In summary, the optical fiber specific frequency vibration event monitoring device based on a variable delay line described in the present invention dynamically adjusts the optical signal delay time through the variable delay line, aligns the phase of the target frequency signal, realizes beamforming, and improves the signal-to-noise ratio. On this basis, combined with sparse representation technology, the target frequency signal is extracted, noise and other interference are suppressed in the iterative process, and the final signal representation is more robust and accurate. Ultimately, the detection and monitoring of vibration events of the target frequency in a complex signal environment is achieved.

[0154] In the optical fiber specific frequency vibration event monitoring device based on a variable delay line of the present invention, in some embodiments, the delay adjustment module 11 includes a first adjustment submodule and / or a second adjustment submodule.

[0155] The first adjustment submodule is used to adjust the propagation speed of the optical signal in the variable delay line to adjust the delay time, and the second adjustment submodule is used to adjust the length of the variable delay line to adjust the delay time.

[0156] Specifically, in optical fiber communication, the delay time of optical signal propagation is affected by the propagation speed of the optical signal and the length of the variable delay line.

[0157] Taking adjusting the propagation speed of optical signals as an example, by adjusting the refractive index of the optical fiber, other conditions remaining unchanged, the propagation speed of the optical signal, and thus the delay time, can be adjusted. For example, the refractive index of the optical fiber can be adjusted by driving a small change in length through a driver such as a motor, or by changing environmental parameters such as the electric and magnetic fields surrounding the optical fiber. By adjusting the propagation speed of the optical signal, a fast response can be achieved, meeting the requirements of high-speed dynamic delay adjustment.

[0158] For example, adjusting the length of a variable delay line can increase or decrease the optical signal propagation time, while other conditions remain unchanged. Adjusting the length of the variable delay line allows for a wider range of delay adjustments.

[0159] Those skilled in the art can adjust the delay time by only using one of the methods or by combining the two methods according to actual needs.

[0160] Preferably, in the present invention, the propagation speed of the optical signal is adjusted by adjusting the refractive index of the optical fiber only through the first adjustment submodule, thereby adjusting the delay time.

[0161] Furthermore, in some embodiments of the variable delay line-based optical fiber frequency-specific vibration event monitoring device described herein, the variable delay line includes an optical fiber and an electro-optic modulator connected to the optical fiber. Those skilled in the art will be able to configure the specific connection method based on actual needs. The optical fiber is used to transmit optical signals, and the electro-optic modulator is used to deform and change the refractive index of the optical fiber.

[0162] The first adjustment submodule is configured to adjust the voltage applied to the electro-optical modulator, causing the modulator to deform. This deformation of the electro-optical modulator causes the optical fiber to deform, changing its refractive index and producing an optical fiber with a modified refractive index. The optical signal is then propagated through the optical fiber with a modified refractive index to adjust its propagation speed within the fiber, thereby adjusting the delay time.

[0163] Exemplarily, the first adjustment submodule includes a voltage controller, and the electro-optical modulator includes a piezoelectric ceramic. The piezoelectric ceramic is electrically connected to the voltage controller on one side and to the optical fiber on the other side. When the voltage controller adjusts the output voltage, the piezoelectric ceramic deforms due to the inverse piezoelectric effect.

[0164] Preferably, the piezoelectric ceramic is configured as lead zirconate titanate piezoelectric ceramic; the voltage controller controls the output voltage via a microcontroller, such as an FPGA (Field Programmable Gate Array) or a DSP (Digital Signal Processing).

[0165] When the piezoelectric ceramic deforms, the optical fiber tightly fixed to the piezoelectric ceramic deforms synchronously, and the refractive index of the optical fiber changes. Correspondingly, the propagation speed of the optical signal propagating therein also changes, thereby achieving adjustment of the delay time.

[0166] The voltage applied to the electro-optic modulator is adjusted by the first adjustment submodule to deform the electro-optic modulator and drive the optical fiber to deform, thereby changing the refractive index of the optical fiber. On the basis of fast response speed, the operation is convenient and relatively accurate.

[0167] Furthermore, in some embodiments of the variable delay line-based optical fiber frequency-specific vibration event monitoring device of the present invention, the electro-optical modulator is configured as a piezoelectric ceramic, and a plurality of fiber Bragg gratings are disposed within the core of the optical fiber, with the fiber Bragg gratings corresponding to the piezoelectric ceramics. The first adjustment submodule also includes a parameter calculator.

[0168] In one aspect, the parameter calculator is used to calculate the delay time of each fiber Bragg grating according to the equivalent pointing phase, which is expressed as:

[0169] .

[0170] Where, For the The delay time of a fiber Bragg grating, is an integer and , is the total number of fiber Bragg gratings, For the The initial phase of the fiber Bragg grating signal, is the equivalent pointing phase, is the frequency of the target frequency signal.

[0171] On the other hand, the parameter calculator is used to calculate the target voltage of each piezoelectric ceramic according to the delay time, expressed as:

[0172] .

[0173] Where, For the The target voltage of the piezoelectric ceramic, is the speed of light in vacuum, is the effective refractive index of the optical fiber, is the piezoelectric constant of the piezoelectric ceramic, which represents the strain efficiency under the action of an electric field. Those skilled in the art can set piezoelectric ceramics with different piezoelectric constants according to actual needs to ensure that the piezoelectric ceramic can generate sufficient deformation when a voltage is applied.

[0174] It is worth noting that before calculating the delay time of each fiber Bragg grating based on the equivalent pointing phase, an initial equivalent pointing phase needs to be set. Of course, in some embodiments, the equivalent pointing phase can also be updated.

[0175] For example, when monitoring begins, an initialization operation should be performed to set an initial equivalent pointing phase according to actual needs, so that the voltage applied to the piezoelectric ceramic can be controlled according to the initial equivalent pointing phase, thereby deforming the piezoelectric ceramic and adjusting the refractive index of the optical fiber to achieve preliminary adjustment of the delay time.

[0176] After calculating the relevant parameters, a voltage controller adjusts the voltage applied to the piezoelectric ceramic according to the target voltage, causing the piezoelectric ceramic to deform. This method allows for quick and convenient calculation of the target voltage, controlling the actual applied voltage and achieving precise deformation of the piezoelectric ceramic.

[0177] Considering that the deformation of piezoelectric ceramics is easily affected by other factors during actual use, in order to achieve more precise deformation control, the optical fiber specific frequency vibration event monitoring device based on a variable delay line according to the present invention, in some embodiments, the parameter calculator is also used to calculate the theoretical deformation of each piezoelectric ceramic, expressed as:

[0178] .

[0179] Where, For the The theoretical deformation produced by a piezoelectric ceramic.

[0180] The first adjustment submodule also includes a feedback sensor for obtaining the actual deformation of the piezoelectric ceramic and matching the actual deformation with the theoretical deformation to achieve real-time monitoring of the piezoelectric ceramic deformation. It will be appreciated that the matching can be achieved by ensuring that the two are equal or approximately equal. Those skilled in the art can set the condition for approximately equalization based on actual needs, and this will not be further described.

[0181] Those skilled in the art can set a feedback sensor, such as a laser interferometer or an optical encoder, according to actual needs.

[0182] If the theoretical and actual deformations of the piezoelectric ceramic do not match, the feedback sensor sends a feedback signal to the voltage controller. The voltage controller then adjusts the correction voltage to control the deformation of the piezoelectric ceramic, ultimately achieving precise adjustment of the delay time.

[0183] Therefore, after applying voltage to the piezoelectric ceramic and controlling its deformation, the theoretical deformation and actual deformation of the piezoelectric ceramic are compared. If the two do not match, the voltage is readjusted to ensure that the actual deformation of the piezoelectric ceramic matches the theoretical deformation. This enables precise adjustment of the delay time, making the final signal representation more robust and accurate.

[0184] In some embodiments of the optical fiber specific frequency vibration event monitoring method based on a variable delay line described in the present invention, the sparse representation module includes a model construction submodule, a definition submodule, an optimization submodule and a coefficient calculation submodule.

[0185] The model building submodule is used to build a problem model based on the beam pointing signal. The sampled beam pointing signal is regarded as the superposition of the target frequency signal and noise, which can be expressed as:

[0186] .

[0187] Where, is the sampled beam pointing signal. is a dictionary, whose column vectors are bases (or characteristic signals) of different frequencies. Those skilled in the art can set a specific dictionary according to actual needs. is a sparse coefficient, which is usually a vector and is what we want to extract. is the noise, which is usually a vector. , represented as noise Subject to zero mean, is the noise variance, Gaussian distribution of the identity matrix .

[0188] Define submodules for defining sparse coefficients The prior distribution of and the definition of the marginal likelihood function .

[0189] Specifically, define the sparse coefficient The prior distribution of is expressed as:

[0190] ,

[0191] .

[0192] Where, is the covariance matrix. is a diagonal function. is the hyperparameter of the sparse prior, , used to control the sparsity of the sparse vector. For dictionary The number of atoms.

[0193] Define the marginal likelihood function , expressed as:

[0194] ,

[0195] .

[0196] The optimization submodule is used to optimize hyperparameters based on the marginal likelihood function , get the optimal hyperparameters , expressed as:

[0197] ,

[0198] .

[0199] in, To solve the hyperparameters exist The maximum value in is the number of sampling points, As constraints. On this basis, the hyperparameters The optimal solution process is equivalent to solving the optimization problem of the above formula. How to solve the above formula is common knowledge among those skilled in the art and will not be described in detail.

[0200] The coefficient calculation submodule is used to calculate the optimal hyperparameters , calculate the optimal sparse coefficient , expressed as:

[0201] .

[0202] To obtain the optimal sparse coefficient After that, it is input into the signal reconstruction module 13 for reconstruction to obtain the enhanced target frequency signal and realize denoising, which is expressed as:

[0203] .

[0204] in, The enhanced target frequency signal. , which can realize the confirmation of corresponding vibration events.

[0205] The present invention also provides a non-transitory machine-readable medium storing a computer program, wherein the computer program, when executed by a processor of a computer, causes the computer to execute the method for monitoring optical fiber specific frequency vibration events based on a variable delay line as described in any one of the above embodiments.

[0206] The present invention further provides a computer program product, including a computer program, wherein when executed by a processor of a computer, the computer is configured to cause the computer to execute the optical fiber specific frequency vibration event monitoring method based on a variable delay line as described in any one of the above embodiments.

[0207] The present invention also provides an electronic device comprising at least one processor and a memory communicatively connected to the at least one processor. The memory stores a computer program executable by the at least one processor, wherein the computer program, when executed by the at least one processor, causes the electronic device to perform the method for monitoring optical fiber specific frequency vibration events based on a variable delay line as described in any of the above-described embodiments.

[0208] Reference Figure 3 As shown, a block diagram of an electronic device that can be used as a server or client of an embodiment of the present invention will now be described, which is an example of a hardware device that can be applied to various aspects of the present invention. The electronic device is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0209] The electronic device includes a computing unit 21, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 22 or a computer program loaded from a storage unit 28 into a random access memory (RAM) 23. RAM 23 may also store various programs and data required for the operation of the electronic device. The computing unit 21, ROM 22, and RAM 23 are interconnected via a bus 24. An input / output (I / O) interface 25 is also connected to the bus 24.

[0210] Multiple components in the electronic device are connected to the I / O interface 25, including: an input unit 26, an output unit 27, a storage unit 28, and a communication unit 29. The input unit 26 can be any type of device that can input information into the electronic device. The input unit 26 can receive input digital or character information and generate key signal input related to user settings and / or function control of the electronic device. The output unit 27 can be any type of device that can present information, and can include but is not limited to a display, a speaker, a video / audio output terminal, a vibrator, and / or a printer. The storage unit 28 can include but is not limited to a magnetic disk and an optical disk. The communication unit 29 allows the electronic device to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks, and can include but is not limited to a modem, a network card, an infrared communication device, and / or a wireless communication transceiver, such as a Bluetooth device, a WiFi device, a WiMax device, a cellular communication device, and / or the like.

[0211] The computing unit 21 can be various general-purpose and / or specialized processing components with processing and computing capabilities. Some examples of the computing unit 21 include, but are not limited to, a CPU, a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing units, various computing units that run machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 21 performs the various methods and processes described above. For example, in some embodiments, the method embodiments of the present invention can be implemented as a computer program that is tangibly contained in a machine-readable medium, such as a storage unit 28. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device via the ROM 22 and / or the communication unit 29. In some embodiments, the computing unit 21 can be configured to perform the above-described methods by any other appropriate means (e.g., by means of firmware).

[0212] The computer programs for implementing the methods of the embodiments of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer programs are executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer programs may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0213] In the context of embodiments of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable signal medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, or infrared system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of machine-readable storage media may include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fibers, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0214] It should be noted that the term "including" and its variations used in the embodiments of the present invention are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; and the term "some embodiments" means "at least some embodiments". The modifications of "one" and "a plurality of" mentioned in the embodiments of the present invention are illustrative and non-restrictive. Those skilled in the art should understand that unless the context clearly indicates otherwise, they should be understood as "one or more".

[0215] The various steps described in the method implementation schemes provided in the embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method implementation schemes may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0216] The term "embodiment" in this specification refers to specific features, structures, or characteristics described in conjunction with the embodiment that can be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. The various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments are referenced to each other. In particular, for the embodiments of the device, equipment, and system, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts are referred to the partial description of the method embodiment.

[0217] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for monitoring optical fiber specific frequency vibration events based on a variable delay line, characterized in that: include: Adjust the delay time of the optical signal propagation in the variable delay line to align the phase of the target frequency signal and obtain the beam pointing signal; Performing a sparse representation on the beam steering signal to obtain an optimal sparse coefficient; Reconstructing the optimal sparse coefficient to obtain the enhanced target frequency signal; If the expected signal strength does not match the signal strength of the target frequency signal, readjust the delay time until the expected signal strength matches the signal strength; A corresponding vibration event is confirmed according to the target frequency signal.

2. The optical fiber specific frequency vibration event monitoring method based on a variable delay line according to claim 1, characterized in that: Adjusting the delay time of optical signal propagation in a variable delay line, including: adjusting the propagation speed of the optical signal in the variable delay line to adjust the delay time; or / and, The length of the variable delay line is adjusted to adjust the delay time.

3. The method for monitoring optical fiber specific frequency vibration events based on a variable delay line according to claim 2, characterized in that: The variable delay line includes an optical fiber and an electro-optical modulator connected to the optical fiber; Adjusting the propagation speed of the optical signal in the variable delay line to adjust the delay time includes: adjusting the voltage applied to the electro-optical modulator to cause the electro-optical modulator to deform; The deformation generated by the electro-optical modulator drives the optical fiber to deform, thereby changing the refractive index of the optical fiber, thereby obtaining the optical fiber with a changed refractive index; The optical signal is propagated through the optical fiber with the changed refractive index to adjust the propagation speed of the optical signal in the optical fiber, thereby adjusting the delay time.

4. The method for monitoring optical fiber specific frequency vibration events based on a variable delay line according to claim 3, characterized in that: The electro-optical modulator is configured as a piezoelectric ceramic, a plurality of fiber Bragg gratings are provided in the core of the optical fiber, and the fiber Bragg gratings are arranged in a one-to-one correspondence with the piezoelectric ceramic; Adjusting the voltage applied to the piezoelectric ceramic to cause the piezoelectric ceramic to deform, comprising: According to the equivalent pointing phase, the delay time of each fiber Bragg grating is calculated and expressed as: ， in, For the the delay time of each of the fiber Bragg gratings, is an integer and , is the total number of the fiber Bragg gratings, For the The initial phase of the signal of the fiber Bragg grating, is the equivalent pointing phase, is the frequency of the target frequency signal; According to the delay time, the target voltage of each piezoelectric ceramic is calculated, which is expressed as: ， in, For the the target voltage of each of the piezoelectric ceramics, is the speed of light in vacuum, is the effective refractive index of the optical fiber, is the piezoelectric constant of the piezoelectric ceramic; According to the target voltage, the voltage applied to the piezoelectric ceramic is adjusted to cause the piezoelectric ceramic to deform.

5. The optical fiber specific frequency vibration event monitoring method based on a variable delay line according to claim 4 is characterized in that , adjusting the voltage applied to the piezoelectric ceramic to cause the piezoelectric ceramic to deform, and further comprising: Calculating the theoretical deformation of each of the piezoelectric ceramics; Obtaining the actual deformation of each of the piezoelectric ceramics; When the actual deformation amount does not match the theoretical deformation amount, the target voltage is readjusted until the actual deformation amount matches the theoretical deformation amount.

6. The optical fiber specific frequency vibration event monitoring method based on a variable delay line according to claim 5, characterized in that: The theoretical deformation of each piezoelectric ceramic is calculated as follows: ， in, For the The theoretical deformation amount produced by the piezoelectric ceramic.

7. The optical fiber specific frequency vibration event monitoring method based on a variable delay line according to claim 1, characterized in that: Performing a sparse representation on the beam steering signal to obtain an optimal sparse coefficient includes: The problem model is constructed based on the beam pointing signal and is expressed as: ， in, is the beam pointing signal, For the dictionary, is the sparse coefficient, is noise, , is a Gaussian distribution, is the noise variance, is the identity matrix; Define the sparse coefficient The prior distribution of is expressed as: ， ， in, is the covariance matrix, is a diagonal function, is the hyperparameter of the sparse prior, , For the dictionary The number of atoms; Define the marginal likelihood function , expressed as: ， ； According to the marginal likelihood function, the hyperparameters are optimized , get the optimal hyperparameters , expressed as: ， ， in, To solve the hyperparameters exist The maximum value in is the number of sampling points, is a constraint condition; According to the optimal hyperparameters , calculate the optimal sparse coefficient , expressed as: 。 8. The optical fiber specific frequency vibration event monitoring method based on a variable delay line according to claim 7, characterized in that: The optimal sparse coefficient is reconstructed to obtain the enhanced target frequency signal, which is expressed as: ， in, is the enhanced target frequency signal, For time.

9. An optical fiber specific frequency vibration event monitoring device based on a variable delay line, applied to the optical fiber specific frequency vibration event monitoring method based on a variable delay line according to any one of claims 1 to 8, characterized in that: include: The delay adjustment module is used to adjust the delay time of the optical signal propagation in the variable delay line, align the phase of the target frequency signal, and obtain the beam pointing signal; A sparse representation module, configured to perform sparse representation on the beam pointing signal to obtain an optimal sparse coefficient; A signal reconstruction module, configured to reconstruct the optimal sparse coefficients to obtain an enhanced target frequency signal; a strength judgment module, configured to judge whether the expected signal strength matches the signal strength of the target frequency signal; and if the expected signal strength does not match the signal strength of the target frequency signal, readjusting the delay time through the delay adjustment module until the expected signal strength matches the signal strength; The event confirmation module is used to confirm the corresponding vibration event according to the target frequency signal.

10. An electronic device comprising: A processor and a memory storing a program, wherein the program comprises instructions, which, when executed by the processor, cause the processor to perform the method for monitoring optical fiber specific frequency vibration events based on a variable delay line according to any one of claims 1 to 8.

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