Optical cable vibration detection method and system, terminal equipment and storage medium

Abstract

The invention provides an optical cable vibration detection method and system, terminal equipment and a storage medium, and the method comprises the steps: modulating a continuous optical signal to obtain pulsed light, and transmitting the pulsed light to a to-be-detected optical cable; wherein the to-be-measured optical cable comprises an optical fiber, and scattering enhancement points are distributed at preset positions of the optical fiber; acquiring a scattering signal fed back by each scattering enhancement point based on the pulsed light, and mixing the scattering signal with the continuous light signal to obtain a mixed signal; the frequency mixing signals are demodulated, phase information of each frequency mixing signal is obtained, and phase difference information between every two adjacent scattering enhancement points is calculated based on the phase information; fourier transform is carried out on the phase difference information to obtain frequency information between the scattering enhancement points, and when a frequency component exists in the frequency information, it is judged that an optical cable vibration phenomenon exists between the two adjacent scattering enhancement points. The accuracy of optical cable vibration detection can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensing and power system monitoring, and in particular to an optical cable vibration detection method, system, terminal equipment and storage medium. Background Art

[0002] Optical cable is a transmission medium composed of one or more optical fibers, mainly used to transmit optical signals, with the advantages of long transmission distance, large bandwidth, low loss, and strong anti-electromagnetic interference ability. In the power transmission system, the overhead optical fiber composite phase line (Optical Phase Conductor, hereinafter referred to as OPPC) optical cable not only has the traditional conductive function, but also can realize the communication function at the same time, so it has been widely used in long-distance transmission lines. OPPC optical cable integrates power transmission and communication transmission, significantly improving the operating efficiency and safety of power lines. However, since OPPC optical cable is exposed to outdoor environment for a long time, it is easily affected by natural environment such as wind, rain, snow, and ice. For example, strong winds can cause the optical cable to vibrate, and long-term vibration will gradually damage the sheath and internal optical fiber of the optical cable; ice and snow will increase the load of the optical cable, which may cause the optical cable to sag or break; temperature changes will cause thermal expansion and contraction of the optical cable material, resulting in stress concentration in the optical cable, which will cause mechanical damage. These mechanical damages will not only affect the communication performance of the optical cable, but may also cause optical cable breakage or transmission line failure, threatening the safe operation of the power system and may even cause large-scale power outages, causing serious impacts on the social economy and people's lives.

[0003] Most of the existing technologies use fiber optic sensing technology, especially distributed acoustic sensing (DAS) technology, to detect the vibration of optical cables. DAS technology uses the Rayleigh scattering effect in optical fibers to achieve vibration monitoring of optical cables by emitting pulsed light and receiving scattered light signals. However, the Rayleigh scattering signal of ordinary single-mode optical fibers is weak and has a random interference effect. This interference effect can cause coherent fading of the signal, that is, the scattered signals in certain areas cancel each other out, forming a detection blind spot. In addition, interference between pulses can also cause instability in the equivalent scattering position in the optical fiber, affecting the temporal consistency of the demodulated signal, thereby reducing the detection accuracy of the system. These problems make the DAS system face challenges in high-fidelity and high-resolution vibration monitoring, limiting its application effect in complex vibration analysis and acoustic wave tracking. Summary of the invention

[0004] The present invention aims to provide an optical cable vibration detection method, system, terminal equipment and storage medium to solve the above technical problems and improve the accuracy of optical cable vibration detection.

[0005] In order to solve the above technical problems, the present invention provides a method for detecting optical cable vibration, comprising:

[0006] Modulating a continuous optical signal to obtain pulsed light, and sending the pulsed light to an optical cable to be tested; wherein the optical cable to be tested includes an optical fiber with a scattering enhancement point arranged at a preset position;

[0007] Acquire a scattering signal of each scattering enhancement point based on the pulse light feedback, and mix the scattering signal with the continuous light signal to obtain a mixed signal;

[0008] Demodulating the mixing signal, obtaining phase information of each mixing signal, and calculating phase difference information between each two adjacent scattering enhancement points based on the phase information;

[0009] The phase difference information is subjected to Fourier transformation to obtain frequency information between the scattering enhancement points. When a frequency component exists in the frequency information, it is determined that there is an optical cable vibration phenomenon between the two adjacent scattering enhancement points.

[0010] In the above scheme, scattering enhancement points are arranged in the optical cable to be tested. The arrangement of the scattering enhancement points makes the source position of the scattered signal more fixed, reduces the interference effect between pulses, ensures the time consistency of the demodulated signal, and can also enhance the intensity of the Rayleigh scattering signal, thereby improving the detection accuracy. The design of the scattering enhancement point reduces the coherent fading of the signal, thereby reducing the detection blind area and improving the overall coverage and reliability of vibration detection. The continuous optical signal is modulated to generate pulsed light, which is convenient for propagation in the optical fiber and obtaining the scattered signal. The scattered signal is then mixed with the continuous optical signal, and the obtained mixed signal can convert the frequency of the scattered signal to a lower intermediate frequency range, which is convenient for subsequent processing and analysis. And the mixing process retains the phase information of the scattered signal and will not affect subsequent detection.

[0011] In one implementation, the step of modulating a continuous optical signal to obtain pulsed light and sending the pulsed light to the optical cable to be tested specifically includes:

[0012] Acquire a continuous light signal output by a laser, and input the continuous light signal into an acousto-optic modulator to obtain an optical pulse signal;

[0013] The optical pulse signal is input into an electro-optical modulator for linear frequency sweep modulation to obtain a chirped pulse light, and the chirped pulse light is sent to the optical cable to be tested.

[0014] In the above scheme, the continuous optical signal is converted into a series of temporally discrete pulsed light, which is convenient for transmission in the optical fiber and generates scattered signals for vibration detection. Through linear frequency sweep modulation, each pulse of light has a linearly changing frequency when it is transmitted, forming a chirped pulse. This helps to achieve higher time resolution and better signal-to-noise ratio through correlation processing at the receiving end. The optical pulse carrying the time code is injected into the optical cable to be tested so that it interacts with the scattering enhancement point when propagating in the optical cable to generate a detectable scattered signal.

[0015] In one implementation, the obtaining of the scattered signal of each of the scattering enhancement points based on the pulse light feedback, and mixing the scattered signal with the continuous light signal to obtain a mixed signal specifically includes:

[0016] An initial scattering signal fed back by each of the scattering enhancement points;

[0017] Performing echo amplification and noise filtering on the initial scattered signal to obtain the scattered signal;

[0018] The scattered signal and the continuous optical signal are input into a coupler for mixing to obtain the mixed signal.

[0019] In the above scheme, scattered light generated by the Rayleigh scattering effect in the optical fiber is collected to provide basic vibration information. The noise component in the initial scattered signal is removed by filtering operation, useful vibration information is retained, and the interference of noise on vibration detection is reduced. Through mixing operation, the medium and high frequency components of the scattered signal are converted into easy-to-process intermediate frequency signals, which are convenient for subsequent signal demodulation and analysis.

[0020] In one implementation, the demodulating the mixed signals to obtain phase information of each mixed signal specifically includes:

[0021] Inputting the mixing signal into the first mixer and the second mixer in sequence to obtain a first mixing signal; wherein the phase difference between the first mixer and the second mixer is 90 degrees;

[0022] The first mixing signal is input into a filter for filtering, an in-phase component and a quadrature component of the first mixing signal are extracted, and the phase information is obtained based on the in-phase component and the quadrature component; wherein the expression of the phase information is:

[0023]

[0024] Where φ is the wrapping phase value, Q is the quadrature component, and I is the in-phase component.

[0025] The phase difference information between each two adjacent scattering enhancement points is calculated based on the adjacent point difference method, wherein the expression of the phase difference information is:

[0026] Δφ(n)=φ wrap (n)-φ wrap (n-1);

[0027] Where Δφ(n) is the phase difference; φ wrap (n) is the wrapping phase value of the nth scattering enhancement point; φ wrap (n-1) is the wrapping phase value of the (n-1)th scattering enhancement point.

[0028] In the above scheme, two mixers with a phase difference of 90 degrees are used to achieve orthogonal decomposition of the mixed signal, preparing for the subsequent extraction of the in-phase component and the orthogonal component. The high-frequency noise and unnecessary components in the signal are removed by the filter, and the pure in-phase component and the orthogonal component are extracted to provide accurate data for phase calculation. By calculating the phase difference of adjacent points, the phase change caused by vibration can be effectively extracted, reducing the impact of the overall phase drift of the system and improving the accuracy of vibration detection.

[0029] In one implementation, after calculating the phase difference information between every two adjacent scattering enhancement points based on the phase information, the method further includes performing phase unwrapping based on the phase difference information to obtain continuous phase information;

[0030] When the phase difference is greater than π, it is determined that a phase jump occurs between two adjacent scattering enhancement points, and the wrapped phase value is adjusted based on the first phase expansion formula; wherein the expression of the first phase expansion formula is:

[0031] φ unwrap (n) = φ wrap (n) -2π×k;

[0032] In the formula, φ unwrap is the unfolded phase value of the nth scattering enhancement point; k is the number of jumps;

[0033] When the phase difference is less than -π, it is determined that a phase jump occurs between two adjacent scattering enhancement points, and the wrapped phase value is adjusted based on the second phase unwrapping formula; wherein the expression of the second phase unwrapping formula is:

[0034] φ unwrap (n) = φ wrap (n)-2π×k.

[0035] In the above scheme, phase unwrapping is used to eliminate phase jumps in the wrapped phase value and restore continuous phase information. According to the size and direction of the phase difference, it is determined whether a phase jump has occurred, providing a basis for phase unwrapping. The wrapped phase value is adjusted using the phase unwrapping formula to eliminate phase jumps and ensure the continuity and accuracy of the phase information.

[0036] In a second aspect, the present application also provides an optical cable vibration detection system for performing the optical cable vibration detection method as described above, comprising: a laser, an optical fiber coupler, an acousto-optic modulator, an electro-optic modulator, a first erbium-doped optical fiber amplifier, a circulator, a second erbium-doped optical fiber amplifier, a dense wavelength division multiplexer, a four-port optical fiber coupler, a balanced detector, a data acquisition card, a radio frequency signal source, and a direct current source;

[0037] The optical signal output end of the laser is connected to the optical signal input end of the optical fiber coupler; wherein the laser is used to output a continuous optical signal;

[0038] The first optical signal output end of the optical fiber coupler is connected to the optical signal input end of the acousto-optic modulator; wherein the acousto-optic modulator is used to modulate the continuous optical signal into an optical pulse signal;

[0039] The optical signal output end of the acousto-optic modulator is connected to the optical signal input end of the electro-optic modulator; wherein the electro-optic modulator is used to modulate the optical pulse signal into a chirped pulse light;

[0040] The optical signal output end of the electro-optic modulator is connected to the input end of the first erbium-doped fiber amplifier; wherein the first erbium-doped fiber amplifier is used to amplify the optical power of the chirped pulse light;

[0041] The output end of the first erbium-doped fiber amplifier is connected to the first port of the circulator, and is connected to the optical cable to be tested through the second port of the circulator;

[0042] The third port of the circulator is connected to the input end of the second erbium-doped fiber amplifier; wherein the third port of the circulator is used to capture the scattered signal fed back by the optical cable to be tested and send the scattered signal to the second erbium-doped fiber amplifier; the second erbium-doped fiber amplifier is used to perform echo amplification on the scattered signal;

[0043] The output end of the second erbium-doped fiber amplifier is connected to the input end of a dense wavelength division multiplexer; the dense wavelength division multiplexer is used to filter out broadband noise;

[0044] The output end of the dense wavelength division multiplexer is connected to the first input end of the four-port optical fiber coupler;

[0045] The second optical signal output end of the optical fiber coupler is connected to the second input end of the four-port optical fiber coupler; wherein the four-port optical fiber coupler is used to mix the continuous optical signal and the scattered signal;

[0046] The third port and the fourth port of the four-port optical fiber coupler are connected to the first input end and the second input end of the balanced detector;

[0047] The output end of the balanced detector is connected to the electrical signal input end of the data acquisition card;

[0048] The radio frequency signal source is used to drive the acousto-optic modulator;

[0049] The radio frequency signal source and the direct current source jointly drive the electro-optic modulator.

[0050] In the above scheme, the modular design realizes the accurate detection from continuous optical signal to vibration signal. The system includes laser, modulator, amplifier, circulator, filter, mixer, detector and data acquisition module. Through the precise signal processing process, it ensures the accurate extraction and high-sensitivity detection of optical cable vibration information. The overall effect is to achieve high-precision detection and analysis of optical cable vibration through the combination of optical and electronic technologies.

[0051] In one implementation, the output power of the laser is in the range of 20 mW-30 mW, and the wavelength is in the range of 1549-1551 nm.

[0052] In one implementation, the dense wavelength division multiplexer is a narrowband filter; and the detection bandwidth range of the balanced detector is 0 MHz-1 GHz.

[0053] In a third aspect, the present application also provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the method as described above when executing the computer program.

[0054] In a fourth aspect, the present application further provides a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A schematic flow chart of a method for detecting optical cable vibration provided in one embodiment of the present invention;

[0056] Figure 2 The present invention is a schematic structural diagram of an optical cable vibration detection system provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0057] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0058] The terms "first" and "second" and the like in the specification, claims and drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0059] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0060] Example 1

[0061] See also Figure 1 , Figure 1 The present invention provides a method for detecting optical cable vibration, including steps 101 to 103, each of which is as follows:

[0062] Step 101: modulate a continuous optical signal to obtain pulsed light, and send the pulsed light to an optical cable to be tested; wherein the optical cable to be tested includes an optical fiber with a scattering enhancement point arranged at a preset position.

[0063] In one embodiment, the step of modulating a continuous optical signal to obtain pulsed light and sending the pulsed light to the optical cable to be tested specifically includes: obtaining a continuous optical signal output by a laser, inputting the continuous optical signal into an acousto-optic modulator to obtain an optical pulse signal; inputting the optical pulse signal into an electro-optic modulator for linear frequency sweep modulation to obtain chirped pulsed light, and sending the chirped pulsed light to the optical cable to be tested.

[0064] In technologies such as fiber optic sensing, optical time domain reflection, and coherent optical time domain reflection, it is usually necessary to modulate a continuous optical signal into a pulsed light in order to accurately detect scattering points or preset positions in the optical fiber. In an embodiment of the present invention, a laser is used to emit a continuous single-frequency optical signal. The output light of the laser has a stable wavelength and phase, and a narrow spectrum, which is suitable for high-precision fiber optic sensing applications. The continuous optical signal output by the laser is input into an acousto-optic modulator. By applying a radio frequency signal to the acousto-optic modulator, the modulator will perform frequency shift or amplitude modulation on the optical signal. Within a specific time window, the amplitude modulation of the radio frequency signal can cut the continuous optical signal into a short pulse form to form an optical pulse signal. Then, the optical pulse signal output by the acousto-optic modulator is input into an electro-optic modulator. By applying a linearly changing voltage signal (such as a sawtooth wave or a triangle wave) to the electro-optic modulator, the modulator will perform linear frequency sweep modulation on the frequency of the optical pulse. This modulation causes the frequency of the optical pulse to change linearly in time, that is, to form a chirped pulse light. Preferably, in the embodiment of the present invention, the formed chirped pulse light is optically amplified by an erbium-doped fiber amplifier, and the amplified chirped pulse light is input into the optical cable to be tested through a circulator.

[0065] In an embodiment of the present invention, a scattering enhancement point is arranged at preset intervals in the optical fiber, and the positions of these scattering points are precisely controllable, and the positions of the scattering enhancement points in the optical fiber can be adjusted according to actual monitoring needs. The enhancement points are prepared by micro-nanostructure processing technology (such as micro-optical structure, grating or special coating) to form a series of tiny evenly distributed scattering centers. These structures will form regular refractive index modulation in the core of the optical fiber, significantly improving the intensity of the scattering signal. The optical fiber with scattering enhancement points and ordinary single-mode optical fiber are placed in the OPPC optical cable to form an integrated optical unit. The enhanced scattering signal makes it easier for the DAS system to identify and process useful signals in a noisy background, improving the detection sensitivity and reliability of the system.

[0066] Step 102: Obtain a scattering signal of each scattering enhancement point based on the pulse light feedback, and mix the scattering signal with the continuous light signal to obtain a mixed signal.

[0067] In one embodiment, the step of obtaining a scattering signal based on the pulse light feedback from each scattering enhancement point and mixing the scattering signal with the continuous light signal to obtain a mixed signal specifically includes: collecting an initial scattering signal fed back from each scattering enhancement point; performing echo amplification and noise filtering on the initial scattering signal to obtain the scattering signal; and inputting the scattering signal and the continuous light signal into a coupler for mixing to obtain the mixed signal.

[0068] In an embodiment of the present invention, the scattered light signal returned from the scattering enhancement point is captured to provide raw data for subsequent signal processing. Then, a high-gain low-noise amplifier (such as an erbium-doped fiber amplifier) ​​is used to amplify the initial scattered signal. It should be noted that the amplifier needs to have sufficient gain bandwidth to cover the spectrum range of the scattered signal. Then, a filter is used to remove unnecessary frequency components, and digital signal processing technology (such as FFT filtering) can also be used to further suppress noise. Then, the collected ide scattered signal and the continuous light signal output by the laser are input into the coupler. In the coupler, the scattered signal and the continuous light signal interfere with each other to produce a mixing effect. By mixing the scattered signal with the continuous light signal, a difference frequency component, i.e., an intermediate frequency signal, is generated. The frequency of the scattered signal can be converted to a lower intermediate frequency range to facilitate subsequent processing and analysis. In addition, the mixing process retains the phase information of the scattered signal and will not affect subsequent detection.

[0069] Step 103: demodulate the mixing signal, obtain phase information of each mixing signal, and calculate phase difference information between every two adjacent scattering enhancement points based on the phase information.

[0070] In one embodiment, the demodulating the mixing signal to obtain the phase information of each mixing signal specifically includes: inputting the mixing signal to a first mixer and a second mixer in sequence to obtain a first mixing signal; wherein the phase difference between the first mixer and the second mixer is 90 degrees; inputting the first mixing signal to a filter for filtering, extracting the in-phase component and the orthogonal component of the first mixing signal, and obtaining the phase information based on the in-phase component and the orthogonal component; wherein the expression of the phase information is:

[0071]

[0072] Where φ is the wrapping phase value, Q is the quadrature component, and I is the in-phase component.

[0073] The phase difference information between each two adjacent scattering enhancement points is calculated based on the adjacent point difference method, wherein the expression of the phase difference information is:

[0074] Δφ(n)=φ wrap (n)-φ wrap (n-1);

[0075] Where Δφ(n) is the phase difference; φ wrap (n) is the wrapping phase value of the nth scattering enhancement point; φ wrap (n-1) is the wrapping phase value of the (n-1)th scattering enhancement point.

[0076] In the implementation of the present invention, two mixers (such as electric mixers) are used to process the first mixing signal respectively. The phase difference between the local oscillation signals of the first mixer and the second mixer is 90 degrees. The output signals of the first mixer and the second mixer correspond to the in-phase component (I) and the quadrature component (Q) of the first mixing signal respectively. Then, a low-pass filter or a band-pass filter is used to filter the second mixing signal. The design of the filter needs to consider the spectrum range and noise characteristics of the signal to ensure the effective extraction of the in-phase component (I) and the quadrature component (Q). Through the filter, the in-phase component (I) and the quadrature component (Q) are extracted respectively. The filter can remove high-frequency noise and unnecessary frequency components to improve the signal quality. The phase information of the mixing signal is obtained based on the in-phase component (I) and the quadrature component (Q) of the mixing signal, which can ensure the accuracy of the phase calculation. Further, the phase difference between two adjacent scattering enhancement points is calculated, and the phase change between adjacent scattering enhancement points can be detected, which is used to analyze dynamic changes such as vibration and strain.

[0077] In one embodiment, after calculating the phase difference information between each two adjacent scattering enhancement points based on the phase information, it also includes performing phase unwrapping based on the phase difference information to obtain continuous phase information;

[0078] When the phase difference is greater than π, it is determined that a phase jump occurs between two adjacent scattering enhancement points, and the wrapped phase value is adjusted based on the first phase expansion formula; wherein the expression of the first phase expansion formula is:

[0079] φ unwrap (n) = φ wrap (n) -2π×k;

[0080] In the formula, φ unwrap is the unfolded phase value of the nth scattering enhancement point; k is the number of jumps;

[0081] When the phase difference is less than -π, it is determined that a phase jump occurs between two adjacent scattering enhancement points, and the wrapped phase value is adjusted based on the second phase unwrapping formula; wherein the expression of the second phase unwrapping formula is:

[0082] φ unwrap (n) = φ wrap (n)-2π×k.

[0083] The wrapped phase value is usually in the range of [-π,π], and there may be periodic phase jumps (i.e., phase wrapping phenomenon). In an embodiment of the present invention, the phase difference Δφ(n) between adjacent scattering enhancement points is calculated to determine whether a phase jump has occurred. When it is detected that the phase difference Δφ(n) is greater than π or less than -π, it is determined that a phase jump has occurred and phase unwrapping is required. The purpose of phase unwrapping is to restore the continuity of the phase and obtain true global phase information. Continuous phase information can more accurately reflect the dynamic changes between scattering enhancement points (such as vibration, strain, etc.), providing a reliable data basis for subsequent analysis.

[0084] Step 104: Perform Fourier transform on the phase difference information to obtain frequency information between the scattering enhancement points. When there is a frequency component in the frequency information, it is determined that there is optical cable vibration between the two adjacent scattering enhancement points.

[0085] In an embodiment of the present invention, a fast Fourier transform (FFT) algorithm is used to perform frequency domain conversion on the phase difference information Δφ(n). Fourier transform converts discrete signals in the time domain into frequency components in the frequency domain. Furthermore, before applying the fast Fourier transform (FFT) algorithm, a window function (such as a Hanning window or a Hamming window) can be used to perform windowing on the phase difference data to reduce spectrum leakage and improve spectrum resolution. The spectrum obtained by the Fourier transform is analyzed to find out whether there is a significant frequency peak. The peak in the spectrum indicates that the intensity of the frequency component is high and may correspond to a certain vibration phenomenon. According to the distribution of the frequency components, the location where the vibration occurs can be inferred by combining the length of the optical cable and the location information of the scattering enhancement point. Components with lower frequencies usually correspond to areas farther away from the optical cable, while components with higher frequencies may correspond to areas closer. Preferably, if a frequency component is detected, its frequency value can be further analyzed to identify the specific frequency of the vibration. Different frequencies may correspond to different vibration sources or fault types.

[0086] In an embodiment of the present invention, an optical cable vibration detection device is also provided, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the above-mentioned optical cable vibration detection method is implemented.

[0087] In an embodiment of the present invention, a computer-readable storage medium is further provided. The computer-readable storage medium includes a stored computer program. When the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the above-mentioned optical cable vibration detection method.

[0088] Exemplarily, the computer program can be divided into one or more modules, one or more modules are stored in a memory and executed by a processor to complete the present invention. One or more modules can be a series of computer program instruction segments that can complete specific functions, and the instruction segments are used to describe the execution process of the computer program in the optical cable vibration detection device.

[0089] The optical cable vibration detection device can be a computing device such as a desktop computer, a notebook, a PDA, and a cloud server. The optical cable vibration detection device can include, but is not limited to, a processor, a memory, and a display. Those skilled in the art can understand that the above components are merely examples of optical cable vibration detection devices and do not constitute a limitation on optical cable vibration detection devices. It can include more or fewer components than the components, or combine certain components, or different components. For example, the optical cable vibration detection device can also include input and output devices, network access devices, buses, etc.

[0090] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the optical cable vibration detection device, and uses various interfaces and lines to connect various parts of the entire optical cable vibration detection device.

[0091] The memory can be used to store computer programs and / or modules. The processor realizes various functions of the optical cable vibration detection device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, a text conversion function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, text message data, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (FlashCard), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0092] Wherein, if the module based on the vibration detection of the optical cable is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Wherein, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0093] The embodiment of the present invention provides a method for detecting vibration of an optical cable, in which scattering enhancement points are arranged in the optical cable to be tested. The arrangement of the scattering enhancement points makes the source position of the scattered signal more fixed, reduces the interference effect between pulses, ensures the time consistency of the demodulated signal, and can also enhance the intensity of the Rayleigh scattered signal, thereby improving the detection accuracy. The design of the scattering enhancement points reduces the coherent fading of the signal, thereby reducing the detection blind area and improving the overall coverage and reliability of vibration detection. The continuous optical signal is modulated to generate pulsed light, which is convenient for propagation in the optical fiber and obtaining the scattered signal. The scattered signal is then mixed with the continuous optical signal, and the obtained mixed signal can convert the frequency of the scattered signal to a lower intermediate frequency range, which is convenient for subsequent processing and analysis. In addition, the mixing process retains the phase information of the scattered signal and will not affect subsequent detection.

[0094] Example 2

[0095] See also Figure 2 , Figure 2 The structure diagram of an optical cable vibration detection system provided in an embodiment of the present invention. The embodiment of the present invention provides an optical cable vibration detection system, which is suitable for executing the optical cable vibration detection method described in the above embodiment, including: a laser 1, an optical fiber coupler 2, an acousto-optic modulator 3, an electro-optic modulator 4, a first erbium-doped optical fiber amplifier 5, a circulator 6, a second erbium-doped optical fiber amplifier 8, a dense wavelength division multiplexer 9, a four-port optical fiber coupler 10, a balanced detector 11, a data acquisition card 12, a radio frequency signal source 13 and a direct current source 14;

[0096] The optical signal output end of the laser 1 is connected to the optical signal input end of the optical fiber coupler 2; wherein the laser 1 is used to output a continuous optical signal;

[0097] The first optical signal output end of the optical fiber coupler 2 is connected to the optical signal input end of the acousto-optic modulator 3; wherein the acousto-optic modulator 3 is used to modulate the continuous optical signal into an optical pulse signal;

[0098] The optical signal output end of the acousto-optic modulator 3 is connected to the optical signal input end of the electro-optic modulator 4; wherein the electro-optic modulator 4 is used to modulate the optical pulse signal into a chirped pulse light;

[0099] The optical signal output end of the electro-optic modulator 4 is connected to the input end of the first erbium-doped fiber amplifier 5; wherein the first erbium-doped fiber amplifier 5 is used to amplify the optical power of the chirped pulse light;

[0100] The output end of the first erbium-doped fiber amplifier 5 is connected to the first port of the circulator 6, and is connected to the optical cable to be tested through the second port of the circulator 6;

[0101] The third port of the circulator 6 is connected to the input end of the second erbium-doped fiber amplifier 8; wherein the third port of the circulator 6 is used to capture the scattered signal fed back by the optical cable 7 to be tested and send the scattered signal to the second erbium-doped fiber amplifier 8; the second erbium-doped fiber amplifier 8 is used to perform echo amplification on the scattered signal;

[0102] The output end of the second erbium-doped fiber amplifier 8 is connected to the input end of a dense wavelength division multiplexer 9; the dense wavelength division multiplexer 9 is used to filter out broadband noise;

[0103] The output end of the dense wavelength division multiplexer 9 is connected to the first input end of the four-port optical fiber coupler 10;

[0104] The second optical signal output end of the optical fiber coupler 2 is connected to the second input end of the four-port optical fiber coupler 10; wherein the four-port optical fiber coupler 10 is used to mix the continuous optical signal and the scattered signal;

[0105] The third port and the fourth port of the four-port optical fiber coupler 10 are connected to the first input end and the second input end of the balanced detector 11;

[0106] The output end of the balance detector 11 is connected to the electrical signal input end of the data acquisition card 12;

[0107] The radio frequency signal source 13 is used to drive the acousto-optic modulator 3;

[0108] The RF signal source 13 and the DC source 14 jointly drive the electro-optic modulator 4 .

[0109] In the embodiment of the present invention, the laser 1 is used to output a stable high-frequency continuous optical signal, which is the optical signal source of the entire system. The optical fiber coupler 2 distributes the optical signal output by the laser to different modules to ensure the reasonable distribution and transmission of the optical signal. The acousto-optic modulator 3 modulates the continuous optical signal into an optical pulse signal, and drives the optical signal through a radio frequency signal source so that the optical signal has a pulse characteristic, which is convenient for the subsequent generation of chirped pulse light. The electro-optic modulator 4 is used to modulate the optical pulse signal into a chirped pulse light, and generates a chirped pulse light with frequency modulation characteristics through the joint drive of the radio frequency signal source and the direct current source, providing rich frequency information for the scattered signal in the optical fiber. The first erbium-doped fiber amplifier 5 is used to amplify the power of the chirped pulse light to ensure that the optical signal has sufficient intensity, can be injected into the optical cable to be tested and produce a significant scattering effect. The circulator 6 is used to realize the unidirectional transmission of the optical signal and the capture of the scattered signal, inject the amplified chirped pulse light into the optical cable to be tested, and capture the scattered signal fed back by the optical cable through the third port. The second erbium-doped fiber amplifier 8 is used to amplify the captured scattered signal, increase the intensity of the scattered signal, and facilitate subsequent signal processing and detection. The dense wavelength division multiplexer 9 is used to filter out broadband noise in the scattered signal, improve the signal-to-noise ratio, and ensure the purity of the scattered signal. The four-port fiber coupler 10 is used to mix the scattered signal with the continuous optical signal, and extract useful information from the scattered signal through the mixing operation, which is convenient for subsequent phase demodulation and vibration detection. The balanced detector 11 is used to detect the signal output electrical signal after mixing, and convert the optical signal into an electrical signal, which is convenient for data collection and processing. The data acquisition card 12 is used to collect the electrical signal output by the balanced detector for digital processing. It should be noted that the optical cable vibration detection system provided in the embodiment of the present invention only describes the hardware equipment involved. For the data collected by the data acquisition card, it is also necessary to perform matched filtering, phase demodulation, phase difference calculation and other data processing steps through the host computer or intelligent device. The specific implementation process can refer to the phase vibration detection method described in Example 1.

[0110] In one embodiment, the output power range of the laser is 20mW-30mW, and the wavelength range is 1549-1551nm.

[0111] In one embodiment, the dense wavelength division multiplexer is a narrowband filter; and the detection bandwidth range of the balanced detector is 0 MHz-1 GHz.

[0112] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0113] The embodiment of the present invention provides a phase vibration detection system, which realizes accurate detection from continuous optical signal to vibration signal through modular design. The system includes a laser, a modulator, an amplifier, a circulator, a filter, a mixer, a detector and a data acquisition module. Through a precise signal processing process, it ensures accurate extraction of optical cable vibration information and high-sensitivity detection. The overall effect is to achieve high-precision detection and analysis of optical cable vibration through the combination of optical and electronic technologies.

[0114] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for detecting optical cable vibration, characterized in that: include: Modulating a continuous optical signal to obtain pulsed light, and sending the pulsed light to an optical cable to be tested; wherein the optical cable to be tested includes an optical fiber with a scattering enhancement point arranged at a preset position; Acquire a scattering signal of each scattering enhancement point based on the pulse light feedback, and mix the scattering signal with the continuous light signal to obtain a mixed signal; Demodulating the mixing signal, obtaining phase information of each mixing signal, and calculating phase difference information between each two adjacent scattering enhancement points based on the phase information; The phase difference information is subjected to Fourier transformation to obtain frequency information between the scattering enhancement points. When a frequency component exists in the frequency information, it is determined that there is an optical cable vibration phenomenon between the two adjacent scattering enhancement points.

2. A method for detecting optical cable vibration as claimed in claim 1, characterized in that: The step of modulating the continuous optical signal to obtain pulsed light and sending the pulsed light to the optical cable to be tested specifically includes: Acquire a continuous light signal output by a laser, and input the continuous light signal into an acousto-optic modulator to obtain an optical pulse signal; The optical pulse signal is input into an electro-optical modulator for linear frequency sweep modulation to obtain a chirped pulse light, and the chirped pulse light is sent to the optical cable to be tested.

3. A method for detecting optical cable vibration as claimed in claim 1, characterized in that: The obtaining of the scattered signal of each of the scattered enhancement points based on the pulse light feedback and mixing the scattered signal with the continuous light signal to obtain a mixed signal specifically includes: An initial scattering signal fed back by each of the scattering enhancement points; Performing echo amplification and noise filtering on the initial scattered signal to obtain the scattered signal; The scattered signal and the continuous optical signal are input into a coupler for mixing to obtain the mixed signal.

4. The optical cable vibration detection method according to claim 1, characterized in that: The demodulating the mixed signals to obtain phase information of each mixed signal specifically includes: Inputting the mixing signal into the first mixer and the second mixer in sequence to obtain a first mixing signal; wherein the phase difference between the first mixer and the second mixer is 90 degrees; The first mixing signal is input into a filter for filtering, an in-phase component and a quadrature component of the first mixing signal are extracted, and the phase information is obtained based on the in-phase component and the quadrature component; wherein the expression of the phase information is: Where φ is the wrapping phase value, Q is the quadrature component, and I is the in-phase component. The phase difference information between each two adjacent scattering enhancement points is calculated based on the adjacent point difference method, wherein the expression of the phase difference information is: Δφ(n)=φ wrap (n)-φ wrap (n-1); Where Δφ(n) is the phase difference; φ wrap (n) is the wrapping phase value of the nth scattering enhancement point; φ wrap (n-1) is the wrapping phase value of the (n-1)th scattering enhancement point.

5. A method for detecting optical cable vibration as claimed in claim 4, characterized in that: After calculating the phase difference information between each two adjacent scattering enhancement points based on the phase information, the method further includes performing phase unwrapping based on the phase difference information to obtain continuous phase information; When the phase difference is greater than π, it is determined that a phase jump occurs between two adjacent scattering enhancement points, and the wrapped phase value is adjusted based on the first phase expansion formula; wherein the expression of the first phase expansion formula is: f unwrap (n)=φ wrap (n)-2π×k; In the formula, φ unwrap is the unfolded phase value of the nth scattering enhancement point; k is the number of jumps; When the phase difference is less than -π, it is determined that a phase jump occurs between two adjacent scattering enhancement points, and the wrapped phase value is adjusted based on the second phase unwrapping formula; wherein the expression of the second phase unwrapping formula is: f unwrap (n)=φ wrap (n)-2π×k.

6. An optical cable vibration detection system, characterized in that: Used to perform the optical cable vibration detection method as described in any one of claims 1 to 5, comprising: a laser, an optical fiber coupler, an acousto-optic modulator, an electro-optic modulator, a first erbium-doped optical fiber amplifier, a circulator, a second erbium-doped optical fiber amplifier, a dense wavelength division multiplexer, a four-port optical fiber coupler, a balanced detector, a data acquisition card, a radio frequency signal source and a direct current source; The optical signal output end of the laser is connected to the optical signal input end of the optical fiber coupler; wherein the laser is used to output a continuous optical signal; The first optical signal output end of the optical fiber coupler is connected to the optical signal input end of the acousto-optic modulator; wherein the acousto-optic modulator is used to modulate the continuous optical signal into an optical pulse signal; The optical signal output end of the acousto-optic modulator is connected to the optical signal input end of the electro-optic modulator; wherein the electro-optic modulator is used to modulate the optical pulse signal into a chirped pulse light; The optical signal output end of the electro-optic modulator is connected to the input end of the first erbium-doped fiber amplifier; wherein the first erbium-doped fiber amplifier is used to amplify the optical power of the chirped pulse light; The output end of the first erbium-doped fiber amplifier is connected to the first port of the circulator, and is connected to the optical cable to be tested through the second port of the circulator; The third port of the circulator is connected to the input end of the second erbium-doped fiber amplifier; wherein the third port of the circulator is used to capture the scattered signal fed back by the optical cable to be tested and send the scattered signal to the second erbium-doped fiber amplifier; the second erbium-doped fiber amplifier is used to perform echo amplification on the scattered signal; The output end of the second erbium-doped fiber amplifier is connected to the input end of a dense wavelength division multiplexer; the dense wavelength division multiplexer is used to filter out broadband noise; The output end of the dense wavelength division multiplexer is connected to the first input end of the four-port optical fiber coupler; The second optical signal output end of the optical fiber coupler is connected to the second input end of the four-port optical fiber coupler; wherein the four-port optical fiber coupler is used to mix the continuous optical signal and the scattered signal; The third port and the fourth port of the four-port optical fiber coupler are connected to the first input end and the second input end of the balanced detector; The output end of the balanced detector is connected to the electrical signal input end of the data acquisition card; The radio frequency signal source is used to drive the acousto-optic modulator; The radio frequency signal source and the direct current source jointly drive the electro-optic modulator.

7. An optical cable vibration detection system as claimed in claim 6, characterized in that: The output power range of the laser is 20mW-30mW, and the wavelength range is 1549-1551nm.

8. An optical cable vibration detection system as claimed in claim 6, characterized in that: The dense wavelength division multiplexer is a narrowband filter; the detection bandwidth range of the balanced detector is 0MHz-1GHz.

9. A terminal device, characterized in that: The invention comprises a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, and the optical cable vibration detection method according to any one of claims 1 to 5 is implemented when the processor executes the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the optical cable vibration detection method according to any one of claims 1 to 5.

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