Method, system and device for improving performance of phase-sensitive optical time domain reflection system and storage medium

Abstract

The invention discloses a method, system and device for improving the performance of a phase-sensitive optical time domain reflection system and a storage medium, and the method comprises the steps: obtaining a high-coherence laser pulse, injecting the high-coherence laser pulse into an optical fiber, and obtaining a laser pulse of the optical fiber; enabling the laser pulse of the optical fiber to interact with an external disturbance signal, extracting a backward Rayleigh scattering signal from the optical fiber, and staggering the backward Rayleigh scattering signal to obtain a first beat frequency signal and a second beat frequency signal; performing first operation on the first beat frequency signal and the second beat frequency signal to obtain a signal after the first operation; demodulating the signals after the first operation to obtain demodulated phase signals, and performing second operation to obtain signals after second operation; and optimizing the signal after the second operation, and performing signal processing on the optimized signal after the second operation to obtain an anti-interference signal, thereby improving the performance of the phase-sensitive optical time domain reflection system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of phase-sensitive optical time domain reflectometry, and particularly relates to a method, system, device and storage medium for improving the performance of a phase-sensitive optical time domain reflectometry system. BACKGROUND

[0002] Phase-sensitive optical time domain reflectometry (Φ-OTDR) is a kind of vibration monitoring technology that uses optical fiber itself as a distributed sensing medium, and is widely used in perimeter intrusion detection and structural health monitoring in fields such as border security, oil and gas pipelines, power transmission lines, railways, and bridges. The Φ-OTDR system injects pulsed laser into the optical fiber and uses the phase information contained in the backscattered Rayleigh signal to realize the spatial positioning and identification of the disturbance along the line. Compared with the traditional OTDR technology, Φ-OTDR has the advantages of high spatial resolution, no need to lay external sensors, and long-distance coverage. However, in practical applications, the measurement performance of the Φ-OTDR system is limited by environmental noise (such as temperature and mechanical stress changes) and signal-to-noise ratio, and false alarms, false alarms or inaccurate disturbance signal identification problems are prone to occur. Especially in weak disturbance conditions, the system sensitivity is insufficient, leading to blurred signal boundaries and decreased positioning accuracy, which further affects its practicality.

[0003] In the prior art, most Φ-OTDR systems use a single optical fiber single-channel measurement to detect disturbances through the phase information contained in the backscattered Rayleigh light signal. However, due to the dependence on only one optical signal, it is difficult to effectively distinguish between weak disturbances and common-mode noise (such as temperature drift), resulting in weak system anti-interference ability. Some research has proposed methods based on multi-frequency excitation or spectral analysis to improve signal-to-noise ratio and detection accuracy, but these methods often involve complex light source modulation or high-performance demodulation algorithms, increasing system complexity. In the study of multi-parameter (such as strain, temperature, gas concentration, displacement, etc.) measurement conditions and coupling problems, some propose to use multiple optical fibers or multi-core optical fibers to realize space division multiplexing to solve the problem of cross-sensitivity in multi-parameter measurement. At the same time, limited by the pulse width, the spatial resolution of the system measurement is low, and generally only meter-level positioning can be achieved. SUMMARY

[0004] In view of the above existing problems, the present application is proposed.

[0005] The present application provides a method, system, device and storage medium for improving the performance of a phase-sensitive optical time domain reflectometry system to solve the problem that the existing single optical fiber system cannot effectively distinguish between real disturbances and background noise or temperature drift, has low spatial resolution, and the sensitivity and robustness are difficult to balance.

[0006] To solve the above technical problems, the present application provides the following technical solutions:

[0007] In a first aspect, the present application provides a method for improving the performance of a phase-sensitive optical time domain reflectometry system, comprising:

[0008] Obtaining a high-coherence laser pulse, injecting the high-coherence laser pulse into an optical fiber to obtain a laser pulse of the optical fiber;

[0009] Interacting the laser pulse of the optical fiber with an external disturbance signal, extracting a backscattered Rayleigh signal from the optical fiber, and staggering the backscattered Rayleigh signal to obtain a first beat frequency signal and a second beat frequency signal;

[0010] Performing a first operation on the first beat frequency signal and the second beat frequency signal to obtain a first operation signal;

[0011] Respectively demodulating the first operation signal to obtain a demodulated phase signal, and performing a second operation to obtain a second operation signal;

[0012] Optimizing the second operation signal, and performing signal processing on the optimized second operation signal to obtain an anti-interference signal, thereby improving the performance of the phase-sensitive optical time domain reflectometry system.

[0013] As a preferred scheme of the method for improving the performance of the phase-sensitive optical time domain reflectometry system, the first operation on the first beat frequency signal and the second beat frequency signal comprises:

[0014] Using a first signal processing method to operate on the first beat frequency signal and the second beat frequency signal to obtain a time delay of the first beat frequency signal and the second beat frequency signal;

[0015] Adjusting the time delay by controlling the refractive index of the optical fiber, thereby improving the positioning accuracy from the meter level to the millimeter level.

[0016] The preferred technical scheme has the beneficial effect of using cross-correlation operation to process the beat frequency signal, accurately measuring the time delay, and combining the refractive index regulation of the optical fiber to achieve millimeter-level high-precision positioning.

[0017] As a preferred scheme of the method for improving the performance of the phase-sensitive optical time domain reflectometry system, the second operation signal comprises:

[0018] Respectively demodulating the first operation signal using a first demodulation method;

[0019] Performing a delay difference calculation on the demodulated phase signal to obtain a difference signal, i.e., the second operation signal.

[0020] As a preferred scheme of the method for improving the performance of a phase-sensitive optical time domain reflection system, wherein: the optimization of the second calculated signal comprises:

[0021] The differential signal is optimized by using a first optimization algorithm.

[0022] The optimized differential signal is extracted to obtain an anti-interference signal by using a first time domain signal processing method.

[0023] As a preferred scheme of the method for improving the performance of a phase-sensitive optical time domain reflection system, wherein: the injection of the high-coherence laser pulse into the optical fiber comprises:

[0024] The same short pulse in the high-coherence laser pulse is injected into the asymmetric optical fiber at the same time.

[0025] The round-trip time of each optical fiber is twice the length of the optical fiber multiplied by the refractive index of the corresponding optical fiber divided by the speed of light in vacuum.

[0026] The beneficial effects of the preferred technical scheme are that the high-coherence laser pulse is injected, and the positioning accuracy and anti-interference ability of the system are significantly improved by using the asymmetric optical fiber characteristics.

[0027] As a preferred scheme of the method for improving the performance of a phase-sensitive optical time domain reflection system, wherein: the extraction of the backscattered Rayleigh signal from the optical fiber comprises:

[0028] The backscattered Rayleigh signal is obtained by using the same circulator, passing through a band-pass filter and a coherent receiver, and obtaining a channel transmission beat signal.

[0029] The channel transmission beat signal is offset in the time domain due to the delay difference, and a first beat signal and a second beat signal are obtained.

[0030] The beneficial effects of the preferred technical scheme are that the backscattered Rayleigh signal is extracted from the optical fiber, the beat signal is separated in the time domain by coherent reception and filtering, and the positioning accuracy and system stability are improved.

[0031] As a preferred scheme of the method for improving the performance of a phase-sensitive optical time domain reflection system, wherein: the operation of the first beat signal and the second beat signal by using a first signal processing method comprises:

[0032] The first beat signal and the second beat signal are cross-correlated.

[0033] At each time point, the product of the signal and the delayed signal is calculated, and the product is integrated over all times to obtain a function of the time delay.

[0034] In a second aspect, the present application provides a system for improving the performance of a phase-sensitive optical time domain reflectometry system, comprising:

[0035] A pulse emission module is configured to obtain high-coherence laser pulses, inject the high-coherence laser pulses into an optical fiber, and obtain laser pulses of the optical fiber.

[0036] A back Rayleigh scattering signal acquisition module is configured to interact the laser pulses of the optical fiber with external disturbance signals, extract back Rayleigh scattering signals from the optical fiber, and stagger the back Rayleigh scattering signals to obtain first beat frequency signals and second beat frequency signals.

[0037] A first operation module is configured to perform a first operation on the first beat frequency signals and the second beat frequency signals to obtain first operation signals.

[0038] A differential demodulation module is configured to demodulate the first operation signals respectively to obtain demodulated phase signals, perform a second operation on the demodulated phase signals, and obtain second operation signals.

[0039] A signal processing module is configured to optimize the second operation signals, perform signal processing on the optimized second operation signals, and obtain anti-interference signals, thereby improving the performance of the phase-sensitive optical time domain reflectometry system.

[0040] In a third aspect, the present application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor performs the steps of the method for improving the performance of the phase-sensitive optical time domain reflectometry system when executing the computer program.

[0041] In a fourth aspect, the present application provides a computer readable storage medium storing a computer program, wherein the computer program performs the steps of the method for improving the performance of the phase-sensitive optical time domain reflectometry system when executed by a processor.

[0042] Compared with the prior art, the present application has the following advantages: the traditional Φ-OTDR system is limited by pulse width, and the spatial resolution is generally in the order of meters; the present application introduces an asymmetric double-fiber channel, utilizes the pulse delay difference of the two fibers during propagation, and makes the time domain signals of the two fibers present a double-peak feature at the reflection point; after cross-correlation operation, the spatial resolution of the measurement can be improved from meters to millimeters, thereby significantly improving the positioning accuracy; temperature drift and slow strain background have consistent effects on the two fibers, and can be cancelled in differential processing, thereby enhancing the significance of the disturbance signal; through differential enhancement means, the phase change or intensity change caused by small disturbances is effectively amplified; the cooperative channel comparison mechanism reduces the false alarm probability caused by environmental noise; and the present scheme does not depend on complex light source modulation and demodulation algorithms, and is convenient for engineering implementation and multi-point deployment. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the overall process logic of a method for improving the performance of a phase-sensitive optical time-domain reflectometry system according to an embodiment of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0046] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for improving the performance of a phase-sensitive optical temporal reflectance system is provided, comprising:

[0047] S100: Obtain a highly coherent laser pulse, inject the highly coherent laser pulse into the optical fiber, and obtain the laser pulse of the optical fiber;

[0048] S200: The laser pulse in the optical fiber interacts with the external disturbance signal to extract the backscattered Rayleigh signal from the optical fiber, and the backscattered Rayleigh signal is staggered to obtain the first beat frequency signal and the second beat frequency signal.

[0049] S300: Perform a first operation on the first beat frequency signal and the second beat frequency signal to obtain the signal after the first operation;

[0050] S400: Demodulate the signals after the first operation to obtain the demodulated phase signals, and perform the second operation to obtain the signals after the second operation;

[0051] S500: Optimizes the signal after the second operation, processes the optimized signal after the second operation to obtain an anti-interference signal, and improves the performance of the phase-sensitive optical time-domain reflectometry system.

[0052] It should be explained that by introducing the asymmetric dual-fiber channel, combined with the cross-correlation and differential measurement strategy, the common-mode noise interference in the Phi-OTDR system is effectively suppressed, and the spatial resolution and signal-to-noise ratio of the system are significantly improved. The present application enables the system to accurately identify weak disturbances in complex environments, avoid false alarms, and enhance the robustness of the system. At the same time, by precisely controlling the refractive index of the optical fiber and further optimizing the time delay, the positioning accuracy is improved from the traditional meter level to the millimeter level. The cross-correlation and differential measurement strategy effectively suppresses the common-mode noise interference, improves the spatial resolution and signal-to-noise ratio of the system, and thus improves the accuracy and robustness of disturbance identification.

[0053] In the embodiment of the present application, the above step S100 includes the following sub-steps A1-A2.

[0054] In A1: simultaneously inject the same short pulse in the high-coherence laser pulse into the asymmetric optical fibers;

[0055] In A2: the round-trip time of each optical fiber is twice the length of the optical fiber multiplied by the refractive index of the corresponding optical fiber divided by the speed of light in vacuum.

[0056] Specifically, the high-coherence laser pulse has high time stability and narrow linewidth, which is used to improve the phase detection accuracy.

[0057] In the embodiment of the present application, the above step S100 includes the following sub-steps A1-A2.

[0058] The same short pulse, for example, 0ns pulse width, corresponds to the traditional resolution of 1m, and is simultaneously injected into the asymmetric optical fibers. Due to the asymmetry, the propagation time of the pulse in the two optical fibers is different:

[0059] The round-trip time of optical fiber 1 is:

[0060]

[0061] The round-trip time of optical fiber 2 is:

[0062]

[0063] Where n1 and n2 are the refractive indices of optical fibers 1 and 2, respectively, L is the length of the optical fiber, and C is the speed of light in vacuum.

[0064] It should be noted that the high time stability and narrow linewidth characteristics of the high coherence laser pulse are utilized to significantly improve the phase detection accuracy.

[0065] In the embodiment of the present application, the step S200 includes the following sub-steps B1-B2.

[0066] In B1, the back Rayleigh scattering signal is processed by the same circulator, a band-pass filter and a coherent receiver to obtain beat signals transmitted by the channels.

[0067] In B2, the beat signals transmitted by the channels are offset in the time domain due to the delay difference to obtain first and second beat signals.

[0068] Specifically, the back scattering signal light transmitted by the two channels is processed by two same circulators, a 100G band-pass filter and a coherent receiver to obtain two-channel beat signals, and the two signals are offset in the time domain due to the delay difference to form a "double peak" feature, i.e., to obtain first and second beat signals.

[0069] It should be noted that the back Rayleigh scattering signal is processed by the circulator, the band-pass filter and the coherent receiver to obtain two beat signals offset in the time domain due to the refractive index difference of the optical fiber, form a "double peak" feature, and effectively improve the positioning accuracy and anti-interference ability.

[0070] In the embodiment of the present application, the step S300 includes the following sub-steps C1-C4.

[0071] In C1, the first and second beat signals are operated by a first signal processing method to obtain the time delay of the first and second beat signals.

[0072] In C2, the refractive index of the optical fiber is adjusted to control the time delay, and the positioning accuracy is improved from meter level to millimeter level.

[0073] In C3, the first and second beat signals are cross-correlated.

[0074] In C4, at each time point, the product of the signal and the delayed signal is calculated, and the product is integrated over all times to obtain a function about the time delay.

[0075] In an alternative embodiment, the first signal processing method can be a generalized quadratic joint correlation algorithm based on Hilbert transform, the extracted two-way beat frequency signals are respectively subjected to wavelet soft threshold noise reduction processing, the Hilbert transform algorithm is used to sharpen and highlight the peak values of the signals after noise reduction, the signals are converted from time domain to frequency domain through Fourier transform, the self-power spectrum and the mutual power spectrum of the signals are calculated, the self-power spectrum is cumulated and then multiplied by the conjugate of the mutual power spectrum to obtain the final mutual power spectrum, the cross-correlation function is obtained through inverse Fourier transform, and the time delay estimation value is solved through peak value detection.

[0076] In another alternative embodiment, the first signal processing method can also be a lock-in amplification method, the two-way beat frequency signals are respectively subjected to pre-amplification and pre-filtering to generate a reference signal with the same frequency as the target signal, a phase-sensitive detector (PSD) is used to realize spectrum shift, a direct current component is extracted through a low-pass filter to suppress high-frequency noise, and finally accurate time delay information is extracted through the lock-in amplification method.

[0077] In the embodiment of the application, the first signal processing method comprises cross-correlation.

[0078] Specifically, the cross-correlation operation of the extracted two-way beat frequency signals is represented as:

[0079]

[0080] Wherein, S1(t) is the backward Rayleigh scattering signal extracted from the optical fiber 1, S2(t+τ) is the backward Rayleigh scattering signal extracted from the optical fiber 2, and the signal is delayed in time, τ is the time delay, d t is the integral variable.

[0081] The peak position of the cross-correlation function corresponds to the time delay between the two signals, and by accurately controlling the refractive index of the two optical fibers, the size of the time delay can be adjusted, and a larger time delay can improve the accuracy of the cross-correlation operation, thereby improving the positioning accuracy from the meter level to the millimeter level.

[0082] It should be noted that the two-way beat frequency signals are processed by cross-correlation operation, the time delay is accurately measured, and the refractive index of the optical fiber is controlled to significantly improve the positioning accuracy from the meter level to the millimeter level, and enhance the system anti-interference ability and detection accuracy.

[0083] In the embodiment of the application, the above step S400 comprises the following sub-steps D1-D4.

[0084] In D1, the first demodulation method is used to demodulate the first operated signal respectively.

[0085] In D2, the demodulated phase signal is subjected to delay difference calculation to obtain a difference signal, i.e., the second operated signal.

[0086] In an alternative embodiment, the first demodulation method can be a phase-locked loop demodulation method, the two beat signals are input into a phase-locked loop respectively, a phase detector in the phase-locked loop calculates the phase difference between the input signal and the local oscillator signal, the phase difference is filtered through a loop filter, and the frequency of a voltage-controlled oscillator (VCO) is adjusted so that the output signal of the VCO is aligned with the frequency and phase of the input signal, and the phase or frequency change of the external vibration signal is extracted through the output signal of the phase-locked loop;

[0087] In another alternative embodiment, the first demodulation method can also be a DCM (digital clock manager) demodulation method, the two beat signals are input into a DCM module respectively, the DCM adjusts the frequency and phase of the input signal through a digital algorithm so that it is aligned with a reference clock signal, and the phase or frequency change of the external vibration signal is extracted through the output signal of the DCM;

[0088] In the embodiment of the present application, the first demodulation method includes a passive homodyne demodulation algorithm;

[0089] Specifically, the output signal is multiplied by a carrier signal, and then a high-frequency part is filtered out through a suitable low-pass filter to obtain a sideband signal containing the measured signal, and the sideband signal is subjected to a differential cross-multiplication method and then integrated to demodulate the external vibration signal;

[0090] The interference signal I (t) is mixed with a signal with an angular frequency of ω c and an amplitude of G and an angular frequency of 2ω c and an amplitude of H, respectively, and then passes through low-pass filters LPF 1 and LPF 2, and the signal passing through LPF 1 is multiplied by the signal passing through LPF 2 and subjected to a differential operation, and at the same time, the signal passing through LPF 2 is multiplied by the signal passing through LPF 1 and subjected to a differential operation, that is, the differential cross-multiplication of the two signals is realized, and then the difference and integration operations are performed on the output two signals, and the signal output after high-pass filtering can finally be expressed as:

[0091]

[0092] wherein S PGC-DCM (t) is the output signal obtained after PGC-DCM demodulation algorithm processing, B is the intensity of the interference light, G is the signal amplitude related to the angular frequency ω c , and H is the signal amplitude related to the angular frequency 2ω c , J1(C) is the first function of the first-order Bessel function, J2(C) is the first function of the second-order Bessel function, is the measured signal of the disturbance information.

[0093] The disturbance phase signals obtained by two optical fiber demodulations are respectively and Differential calculation is performed on the two demodulated phase signals at the same sampling point n, and it is expressed as:

[0094]

[0095] in, Let n be the demodulated phase signal of fiber 1 at time t and sampling point n. Let be the phase signal demodulated by fiber 2 at time t+τ and sampling point n.

[0096] It should be noted that the passive zero-difference demodulation algorithm, combined with the differential cross-multiplication (DCM) method, effectively extracts external vibration signals. By differentially calculating the phase signals after demodulation of the two optical fibers, common-mode noise is significantly suppressed, improving the system's anti-interference capability and the detection accuracy of disturbance signals.

[0097] In this embodiment of the invention, step S500 includes the following sub-steps E1-E4;

[0098] In E1: The differential signal is optimized using the first optimization algorithm;

[0099] In E2: The optimized differential signal is extracted using the first time-domain signal processing method to obtain the anti-interference signal.

[0100] In one optional embodiment, the first optimization algorithm can be a wavelet denoising algorithm, which performs wavelet decomposition on the differential signal, selects an appropriate wavelet basis and decomposition level, performs thresholding on the decomposed wavelet coefficients to remove small coefficients and retain large coefficients, and performs wavelet reconstruction on the processed coefficients to obtain the denoised differential signal;

[0101] In another optional embodiment, the first optimization algorithm can also be an adaptive filtering algorithm, which initializes the weights and parameters of the filter, such as the learning rate and the filter order, processes the differential signal point by point, calculates the output and error of the filter, updates the weights of the filter according to the error, gradually optimizes the filtering effect, and finally obtains the optimized differential signal.

[0102] In this embodiment of the invention, the first optimization algorithm includes a sliding window filtering algorithm and a normalization calibration algorithm;

[0103] Specifically, by selecting an appropriate window, a sliding window averaging filter is applied to the differential signal to obtain a smoothed signal, represented as follows:

[0104]

[0105] in, For the differential signal at the sampling point k, L is the length of the sliding window, n is the number of the current sampling point, and k is the number of the sampling point in the window;

[0106] The maximum and minimum values of the signal in the sliding window are calculated, the smoothed signal is normalized, and a normalized signal is obtained.

[0107] It should be noted that the sliding window filtering and normalization calibration algorithm can effectively smooth the signal, suppress noise and signal amplitude fluctuation, thereby improving the stability and detection accuracy of the system.

[0108] In an alternative embodiment, the first time-domain signal processing method can be a principal component analysis method, the differential signal is divided into a plurality of data windows, each window containing a certain number of sampling points, a covariance matrix is calculated for each data window, the covariance matrix reflects the correlation between the dimensions of the signal, and the eigenvalues and eigenvectors of the covariance matrix are calculated. The eigenvalues represent the variance of the principal components, and the eigenvectors represent the directions of the principal components. The eigenvectors corresponding to the first few largest eigenvalues are selected as the principal components. These principal components contain most of the information of the signal. The original signal is projected onto the principal component direction to reconstruct a new anti-interference signal.

[0109] In another alternative embodiment, the first time-domain signal processing method can also be Kalman filtering. A linear system model is established according to the dynamic characteristics of the signal, including a state equation and an observation equation. The initial state estimation and the initial error covariance matrix are set, the prediction error variance is calculated, the Kalman gain is calculated, the state estimation is updated, the error estimation is updated, and an anti-interference signal is obtained.

[0110] In the embodiment of the application, the first time-domain signal processing method includes envelope detection and FFT algorithm processing.

[0111] Specifically, the differential signal is preprocessed, such as removing DC bias and filtering. The signal is full-wave rectified, i.e. all negative values are changed to positive values, to obtain a signal containing only positive values. The rectified signal is filtered through a low-pass filter to remove high-frequency noise components. The cutoff frequency of the low-pass filter should be selected near the envelope frequency of the signal. After low-pass filtering, the obtained signal is the envelope signal of the original signal.

[0112] The differential signal is sampled, the sampling frequency is ensured to meet the Nyquist sampling theorem, the FFT transformation is performed on the sampled signal, the frequency spectrum of the signal is obtained, the frequency spectrum is analyzed, and the main frequency component and the noise frequency component of the signal are identified. Generally, the noise component is concentrated in certain specific frequency range, and the noise component in the frequency spectrum is removed by designing a filter. For example, if the noise is concentrated in the high frequency band, a low pass filter can be used to remove the high frequency noise. The inverse FFT transformation is performed on the filtered frequency spectrum, the signal is converted from the frequency domain to the time domain, and the anti-interference signal is obtained, that is, the waveform of the amplitude and the number of sampling points and the waveform of the phase and the number of sampling points.

[0113] It should be noted that the effective removal of high frequency noise significantly improves the signal anti-interference ability, enhances the signal feature extraction accuracy, and optimizes the performance of the monitoring system.

[0114] The above is a schematic scheme of the method for improving the performance of the phase-sensitive optical time domain reflection system. It should be noted that the technical scheme of the system for improving the performance of the phase-sensitive optical time domain reflection system belongs to the same concept as the above-mentioned technical scheme of the method for improving the performance of the phase-sensitive optical time domain reflection system. The technical scheme of the system for improving the performance of the phase-sensitive optical time domain reflection system in this embodiment is not described in detail, and can be referred to the description of the above-mentioned technical scheme of the method for improving the performance of the phase-sensitive optical time domain reflection system.

[0115] The system for improving the performance of the phase-sensitive optical time domain reflection system in this embodiment comprises:

[0116] The pulse emission module is configured to obtain a high-coherence laser pulse, inject the high-coherence laser pulse into an optical fiber, and obtain a laser pulse of the optical fiber.

[0117] The back Rayleigh scattering signal acquisition module is configured to interact the laser pulse of the optical fiber with an external disturbance signal, extract a back Rayleigh scattering signal from the optical fiber, and stagger the back Rayleigh scattering signal to obtain a first beat frequency signal and a second beat frequency signal.

[0118] The first operation module is configured to perform a first operation on the first beat frequency signal and the second beat frequency signal to obtain a first operation signal.

[0119] The differential demodulation module is configured to demodulate the first operation signal respectively to obtain a demodulated phase signal, and perform a second operation to obtain a second operation signal.

[0120] The signal processing module is configured to optimize the second operation signal, perform signal processing on the optimized second operation signal, and obtain an anti-interference signal, thereby improving the performance of the phase-sensitive optical time domain reflection system.

[0121] The embodiment also provides a computer device suitable for improving the performance of a phase-sensitive optical time domain reflection system, and the computer device comprises the following components:

[0122] The memory is used for storing computer executable instructions, and the processor is used for executing the computer executable instructions to realize the method for improving the performance of the phase-sensitive optical time domain reflection system.

[0123] The embodiment also provides a storage medium, which stores a computer program, and the computer program is executed by a processor to realize the method for improving the performance of the phase-sensitive optical time domain reflection system.

[0124] The storage medium provided by the embodiment belongs to the same inventive concept as the method for improving the performance of the phase-sensitive optical time domain reflection system, and the technical details not described in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0125] Through the above description of the embodiments, those skilled in the art can clearly understand that the present application can be realized by means of software and necessary universal hardware, and of course can also be realized by hardware. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, and the computer software product can be stored in a computer readable storage medium, such as a floppy disk, a read-only memory (ROM), a random access memory (RAM), a FLASH memory, a hard disk, or an optical disc, and includes a number of instructions for causing a computing device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of various embodiments of the present application.

[0126] Embodiment 2, which is different from the first embodiment, provides a verification test of the method for improving the performance of the phase-sensitive optical time domain reflection system, to verify the technical effects adopted in the method.

[0127] By comparing the performance of the traditional Φ-OTDR system and the asymmetric double-fiber Φ-OTDR system, it can be seen that;

[0128] For the spatial resolution, the spatial resolution of the traditional Φ-OTDR system is 1 meter, while the spatial resolution of the asymmetric double-fiber Φ-OTDR system is improved to 0.2 meters through the cross-correlation technology, achieving a 5-fold improvement.

[0129] For the vibration sensitivity, the vibration sensitivity of the traditional Φ-OTDR system is 1.0 (relative unit), while the vibration sensitivity of the asymmetric double optical fiber Φ-OTDR system is increased to 1.7 due to the use of high refractive index optical fiber, and the sensitivity is significantly enhanced.

[0130] For the anti-common mode noise capability, the anti-common mode noise capability of the traditional Φ-OTDR system is weak, while the asymmetric double optical fiber Φ-OTDR system greatly enhances the anti-common mode noise capability through differential and normalization calibration processing.

[0131] For the noise signal-to-noise ratio, the noise signal-to-noise ratio of the traditional Φ-OTDR system is 18 dB, while the noise signal-to-noise ratio of the asymmetric double optical fiber Φ-OTDR system is increased to 25 dB after optimization through differential processing, and the signal quality is significantly improved.

[0132] For the processing algorithm complexity, the processing algorithm complexity of the traditional Φ-OTDR system is at a medium level, while the processing algorithm complexity of the asymmetric double optical fiber Φ-OTDR system is also at a medium level due to the addition of the cross-correlation and differential modules, but is slightly higher than that of the traditional system.

[0133] For the system implementation cost, the implementation cost of the traditional Φ-OTDR system is at a normal level, while the system implementation cost of the asymmetric double optical fiber Φ-OTDR system is slightly higher due to the addition of optical fibers and channels.

[0134] In summary, after adopting high-coherence laser pulses and introducing asymmetric double optical fiber channels, the spatial resolution can be improved from 1 meter of the traditional system to 0.2 meters through the delay difference and cross-correlation algorithm of the two scattered signals, and the positioning accuracy is significantly improved. At the same time, due to the stronger acoustic sensitivity response of the high-refractive microstructured optical fiber, the signal response amplitude is increased by about 70% compared to the conventional single-mode optical fiber, and the differential algorithm is used for processing the double optical fiber sensing, which effectively suppresses the noise caused by the common mode environmental disturbance and improves the signal-to-noise ratio (SNR). In terms of comprehensive performance, the system is significantly better than the traditional scheme in terms of resolution, sensitivity and noise resistance, and provides reliable technical support for high-precision and long-distance distributed vibration monitoring.

[0135] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A method for improving the performance of a phase-sensitive optical time-domain reflectometry system, characterized in that, include: A highly coherent laser pulse is obtained, and the highly coherent laser pulse is injected into an optical fiber to obtain a laser pulse in the optical fiber; The laser pulse in the optical fiber interacts with an external disturbance signal to extract a backscattered Rayleigh signal from the optical fiber. The backscattered Rayleigh signal is then staggered to obtain a first beat frequency signal and a second beat frequency signal. Perform a first operation on the first beat frequency signal and the second beat frequency signal to obtain the signal after the first operation; The signals after the first operation are demodulated to obtain demodulated phase signals, and then the second operation is performed to obtain the signals after the second operation. The signal after the second operation is optimized, and the optimized signal after the second operation is processed to obtain an anti-interference signal, thereby improving the performance of the phase-sensitive optical time-domain reflectometry system.

2. The method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in claim 1, characterized in that, The first operation performed on the first beat frequency signal and the second beat frequency signal includes: The first beat frequency signal and the second beat frequency signal are processed using the first signal processing method to obtain the time delay between the first beat frequency signal and the second beat frequency signal. By adjusting the time delay by controlling the refractive index of the optical fiber, the positioning accuracy can be improved from the meter level to the millimeter level.

3. The method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in claim 2, characterized in that, The signal after the second operation includes: The first demodulation method is used to demodulate the signals after the first operation. The demodulated phase signal is delayed and differentially calculated to obtain the differential signal, which is the signal after the second operation.

4. The method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in claim 3, characterized in that, Optimizing the signal after the second operation includes: The differential signal is optimized using the first optimization algorithm; The optimized differential signal is used to extract the anti-interference signal using the first time-domain signal processing method.

5. The method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in claim 1, characterized in that, Injecting the highly coherent laser pulse into the optical fiber includes: For the simultaneous injection of the same short pulse in a highly coherent laser pulse into an asymmetric fiber; The round-trip time for each optical fiber is twice the length of the fiber multiplied by the refractive index of the corresponding fiber divided by the speed of light in a vacuum.

6. The method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in claim 5, characterized in that, Extracting the backscattered Rayleigh signal from an optical fiber includes: The backscattered Rayleigh signal is processed by the same circulator, bandpass filter and coherent receiver to obtain the beat frequency signal of the channel transmission; The beat frequency signals transmitted through the channel are staggered in the time domain due to the delay difference, resulting in the first beat frequency signal and the second beat frequency signal.

7. A method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in claim 2 or 6, characterized in that, The first beat frequency signal and the second beat frequency signal are processed using the first signal processing method, including: Perform cross-correlation operation on the first beat frequency signal and the second beat frequency signal; At each time point, the product of the signal and the delayed signal is calculated, and the product is integrated over all time points to obtain a function of the time delay.

8. A system for improving the performance of a phase-sensitive optical time-domain reflectometry system, comprising the method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in any one of claims 1-7, characterized in that, include: A pulse emission module is used to acquire highly coherent laser pulses and inject the highly coherent laser pulses into an optical fiber to obtain laser pulses in the optical fiber. The backscattering Rayleigh signal acquisition module is used to interact the laser pulse of the optical fiber with the external disturbance signal, extract the backscattering Rayleigh signal from the optical fiber, and stagger the backscattering Rayleigh signal to obtain the first beat frequency signal and the second beat frequency signal. The first arithmetic module is used to perform a first arithmetic operation on the first beat frequency signal and the second beat frequency signal to obtain the signal after the first arithmetic operation. The differential demodulation module is used to demodulate the first processed signal to obtain the demodulated phase signal, and perform a second operation to obtain the second processed signal. The signal processing module is used to optimize the signal after the second operation. The optimized signal after the second operation is processed to obtain an anti-interference signal, thereby improving the performance of the phase-sensitive optical time-domain reflectometry system.

9. A computer device, characterized in that, include: A memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of a method for improving the performance of a phase-sensitive optical time-domain reflectometry system according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the steps of a method for improving the performance of a phase-sensitive optical time-domain reflectometry system as described in any one of claims 1 to 7.

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