Method and apparatus for eliminating coherent fading noise of das, and device

Abstract

A method for eliminating coherent fading noise of a DAS. The method comprises: acquiring original IQ data, which is output by a distributed fiber-optic sensing collection instrument (S101); performing a phase decoupling operation on the original IQ data, so as to obtain a shifted phase of a signal to be subjected to measurement (S102); on the basis of the shifted phase obtained after decoupling, and the amplitude of the original IQ data, determining updated IQ data (S103); performing local spatial-window summation for the updated IQ data, so as to determine summed IQ data (S104); on the basis of the summed IQ data, determining a demodulated phase from which coherent fading noise is eliminated (S105); and performing phase unwrapping on the demodulated phase from which coherent fading noise is eliminated, so as to obtain fiber-optic-sensing demodulated phase data from which coherent fading noise is eliminated (S106). Phase demodulation can be efficiently performed, and the impact of coherent fading noise can be eliminated, such that the accuracy of collected fiber-optic sensing data is improved, thereby meeting actual requirements of technicians. Further disclosed are an apparatus for eliminating coherent fading noise of a DAS, and an electronic device and a computer-readable storage medium.

Description

Method, device and equipment for eliminating DAS coherent fading noise Technical Field

[0001] The present invention relates to the technical field of optical fiber sensing signal processing, and in particular to a method for eliminating DAS coherent fading noise, a device for eliminating DAS coherent fading noise, an electronic device and a computer-readable storage medium. Background Art

[0002] Fiber-optic distributed acoustic sensing technology has developed rapidly in recent years. This technology typically uses a phase-sensitive optical time-domain reflectometer (φ-OTDR) instrument, which utilizes Rayleigh backscattering from an optical fiber through phase demodulation to acquire vibration information around the fiber. Fiber serves as both a sensing and transmission medium, continuously sensing acoustic vibration information around the fiber and recording it through high-density temporal and spatial sampling. This technology has been widely used in applications such as wellbore seismic data acquisition, dam safety monitoring, perimeter security, and pipeline monitoring.

[0003] Distributed fiber optic sensing technology primarily utilizes Rayleigh backscattering generated by laser light propagating through optical fibers. When the medium surrounding the fiber vibrates, the Rayleigh backscattering also changes accordingly. Through coherent detection and phase demodulation of this optical signal, the vibration wave field or strain information of the medium can be obtained. Because the instrument architecture generally employs narrow-linewidth laser source coherent detection, the scattering points in the fiber are randomly distributed. The local coherent superposition of Rayleigh backscatter within the pulse width exhibits the characteristics of vector superposition. When opposite phases cancel each other out, coherent fading occurs, and the demodulated phase becomes highly unstable, affecting the signal-to-noise ratio of the sensing signal.

[0004] Research indicates that current methods for suppressing coherent fading noise in distributed fiber optic sensing phase demodulation typically employ local averaging or interpolation, which have numerous shortcomings in practical applications and are prone to phase distortion. Therefore, there is an urgent need to accurately and efficiently perform phase demodulation and eliminate the effects of coherent fading noise.

[0005] Summary of the Invention

[0006] The purpose of the embodiments of the present invention is to provide a method for eliminating DAS coherent fading noise, at least to solve the technical problem that the coherent fading noise suppression method in the prior art is prone to phase distortion.

[0007] To achieve the above-mentioned objectives, in a first aspect, a method for eliminating DAS coherent fading noise is provided, which comprises the following steps: obtaining raw IQ data output by a distributed optical fiber sensing acquisition instrument, wherein the raw IQ (In-phase and Quadrature component) data includes IQ signals at different optical fiber sensing signal sensing positions at different sampling times, and the IQ signals include in-phase signals and quadrature signals; performing a phase decoupling operation on the raw IQ data to obtain a displacement phase of a signal to be measured; determining updated IQ data based on the decoupled displacement phase and the amplitude of the raw IQ data; performing a local spatial window summation on the updated IQ data to determine the summed IQ data; determining a demodulation phase after eliminating coherent fading noise based on the summed IQ data; and performing phase unwarping on the demodulation phase after eliminating coherent fading noise to obtain optical fiber sensing demodulation phase data after eliminating coherent fading noise.

[0008] In a second aspect, a device for eliminating DAS coherent fading noise is provided, the device comprising: an original IQ data acquisition unit, a phase decoupling operation unit, an IQ data updating unit, an IQ data local summation unit, a demodulation phase determination unit, and a phase unwinding unit; the original IQ data acquisition unit is used to acquire the original IQ data output by the distributed optical fiber sensing acquisition instrument, the original IQ data including IQ signals at different optical fiber sensing signal sensing positions at different sampling times, and the IQ signals including in-phase signals and orthogonal signals; the phase decoupling operation unit is used to phase the original IQ data A decoupling operation is performed to obtain the displacement phase of the signal to be measured; an IQ data updating unit is used to determine the updated IQ data based on the decoupled displacement phase and the amplitude of the original IQ data; an IQ data local summing unit is used to perform local spatial window summing on the updated IQ data to determine the summed IQ data; a demodulation phase determination unit is used to determine the demodulation phase after eliminating coherent fading noise based on the summed IQ data; a phase unwinding unit is used to perform phase unwinding on the demodulation phase after eliminating coherent fading noise to obtain the optical fiber sensing demodulation phase data after eliminating coherent fading noise.

[0009] In a third aspect, an electronic device is provided, comprising a processor and a memory, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by one or more of the processors so that the processor performs the above-mentioned method for eliminating DAS coherent fading noise.

[0010] In a fourth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores at least one program code, and the program code is loaded and executed by a processor to enable the computer to perform the above-mentioned method for eliminating DAS coherent fading noise.

[0011] One of the above technical solutions has the following beneficial effects:

[0012] (1) The method for eliminating coherent fading noise provided by the above technical solution can efficiently perform phase demodulation and eliminate the influence of coherent fading noise, thereby improving the accuracy of the collected optical fiber sensing data, thereby meeting the actual needs of technicians;

[0013] (2) The method for eliminating coherent fading noise provided by the above technical solution can not only restore the phase response information of the wave field to be measured without losing the low-wavenumber wave field information, but also reduce the noise level to an ideal level by suppressing the coherent fading noise, thereby improving the practical application effect of optical fiber sensing.

[0014] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0016] FIG1 is a flow chart of a method for eliminating DAS coherent fading noise provided by an embodiment of the present invention;

[0017] FIG2 is a diagram of the amplitude strength of an optical fiber IQ signal provided by an embodiment of the present invention;

[0018] FIG3 is a diagram showing a demodulated optical fiber IQ signal according to an embodiment of the present invention;

[0019] FIG4 is a recording diagram of the elimination of coherent fading noise after phase demodulation of an optical fiber IQ signal according to an embodiment of the present invention;

[0020] FIG5 is a structural block diagram of an apparatus for eliminating DAS coherent fading noise provided by an embodiment of the present invention;

[0021] FIG6 is a structural block diagram of an electronic device provided by an embodiment of the present invention.

[0022] Explanation of Reference Signs 101 - original IQ data acquisition unit, 102 - phase decoupling operation unit, 103 - IQ data updating unit, 104 - IQ data local summing unit, 105 - demodulation phase determination unit, 106 - phase unwrapping unit, 201 - processor, 202 - memory DETAILED DESCRIPTION

[0023] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0024] In the present invention, unless otherwise indicated, directional terms such as "upper, lower, top, and bottom" are generally used to describe the relative positions of components relative to the directions shown in the drawings, or relative to the vertical, perpendicular, or gravitational directions. "First," "second," etc. are merely for convenience of description and distinction and should not be construed as indicating or implying relative importance.

[0025] It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "installation" and "connection" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integrated connection; direct connection, indirect connection, wired connection, or wireless connection. Those skilled in the art will understand the specific meanings of the above terms in the present invention depending on the specific circumstances.

[0026] To address the technical issues of coherent DAS fading noise suppression, which are prone to phase distortion and inability to completely eliminate coherent fading noise, in existing distributed fiber optic sensing phase demodulation methods, the present invention provides a method for eliminating coherent fading noise. This method utilizes the initial phase of the laser pulse, the initial phase of the receiving point at each sensing position, the optical path integral phase, and the displacement phase, contained in the receiving phase, to gradually decouple the measured signal. This method then eliminates coherent fading noise by performing a local spatial window summation on the recalculated IQ signal of the measured signal. In practical production applications, this method is of great significance for improving the quality of fiber optic sensing data acquisition and protecting low-wavenumber wavefield information.

[0027] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0028] Referring to FIG1 , an embodiment of the present invention provides a method for eliminating DAS coherent fading noise, the method comprising the following steps:

[0029] Step S101: obtaining original IQ data output by a distributed optical fiber sensing acquisition instrument.

[0030] Here, it should be noted that the optical fiber can be laid out in the environment to be tested and a certain means can be used to fully couple the optical fiber with the environment. instrument, The instrument emits narrow-linewidth laser pulses and obtains the IQ quadrature data (i.e., raw IQ data) of the Rayleigh backscatter of the light pulses through coherent detection. The raw IQ data includes the IQ signals of different fiber optic sensing signal sensing positions at different sampling times. The IQ signals are the in-phase (In-phase) signal I(i, j) and the quadrature (Quadrature) signal Q(i, j), where i represents the sampling time sequence number and j represents the fiber optic sensing signal sensing position sequence number. It should be noted here that multiple optical fibers are deployed in the measured environment, and each optical fiber has a corresponding deployment position, which is the fiber optic sensing signal sensing position.

[0031] In addition, before performing IQ phase demodulation on the original IQ data, amplitude and phase imbalance correction should be performed on the IQ signal to ensure the orthogonality of the IQ signal.

[0032] Step S102: Perform phase decoupling operation on the original IQ data to obtain the shift phase of the signal to be measured

[0033] Step S103: Based on the decoupled displacement phase and the amplitude A(i, j) of the original IQ data to determine the updated IQ data.

[0034] Step S104: performing local spatial window summation on the updated IQ data to determine the summed IQ data.

[0035] Step S105: Determine the demodulation phase after eliminating the coherent fading noise based on the summed IQ data

[0036] Step S106: performing phase unwrapping on the demodulated phase after the coherent fading noise is eliminated, to obtain optical fiber sensing demodulated phase data after the coherent fading noise is eliminated.

[0037] Furthermore, in a possible implementation, in step S102, the original IQ data is subjected to a phase decoupling operation to obtain the shift phase of the signal to be measured. The process may include but is not limited to the following sub-steps S1021 to S1022.

[0038] Sub-step S1021: Determine the IQ demodulation initial phase ω0(i,j) based on the original IQ data.

[0039] Specifically, the IQ demodulation initial phase ω0(i,j) is calculated for the original IQ data using the following formula:

[0040] In formula (1), ω0(i, j) is the IQ demodulation initial phase of the distributed optical fiber sensing instrument at the jth optical fiber sensing signal sensing position at the i-th sampling time; I(i, j) is the original in-phase signal output by the distributed optical fiber sensing acquisition instrument at the j-th optical fiber sensing signal sensing position at the i-th sampling time; Q(i, j) is the original orthogonal signal output by the distributed optical fiber sensing acquisition instrument at the j-th optical fiber sensing signal sensing position at the i-th sampling time.

[0041] Sub-step S1022: perform phase decoupling operation step by step for the IQ demodulation initial phase ω0(i,j), and eliminate the initial phase of the receiving point of the optical fiber sensing signal sensing position in the IQ demodulation initial phase ω0(i,j) in turn. Laser pulse initial phase and optical path integrated phase Get the displacement phase of the signal to be measured

[0042] Since the distributed optical fiber sensing acquisition instrument is based on As the core instrument, the IQ demodulation initial phase ω0 consists of four parts, namely the initial phase of the receiving point of each optical fiber sensor position Laser pulse initial phase Optical path integrated phase and the phase shift of the signal to be measured Right now:

[0043] In formula (2), ω0(i,j) is the initial phase of IQ demodulation of the jth optical fiber sensing signal sensing position of the distributed optical fiber sensing instrument at the i-th sampling time; is the initial phase of the laser pulse of the distributed optical fiber sensing instrument at the i-th sampling moment; is the initial phase of the receiving point of the distributed optical fiber sensing instrument at the jth optical fiber sensing signal sensing position; is the optical path integral phase of the jth optical fiber sensing signal sensing position of the distributed optical fiber sensing instrument at the i-th sampling moment; is the displacement phase of the signal to be measured at the jth optical fiber sensing signal sensing position of the distributed optical fiber sensing instrument at the i-th sampling moment.

[0044] That is to say, by determining the initial phase of the receiving point of each optical fiber sensor position Laser pulse initial phase and optical path integrated phase After that, the phase of the above three parts is gradually eliminated from the initial phase ω0 of IQ demodulation to obtain the displacement phase of the signal to be measured.

[0045] Furthermore, in a possible implementation, in sub-step S1022, a phase decoupling operation is gradually performed on the IQ demodulation initial phase ω0(i, j), and the initial phase of the receiving point of the optical fiber sensing signal sensing position in the IQ demodulation initial phase ω0(i, j) is eliminated in sequence. Laser pulse initial phase and optical path integrated phase Get the displacement phase of the signal to be measured The process may include but is not limited to the following sub-steps S10221 to S10228.

[0046] Sub-step S10221: Based on the IQ demodulation initial phase ω0(i,j), determine the initial phase of the receiving point of the optical fiber sensing signal sensing position

[0047] For example, the initial phase of the receiving point at the optical fiber sensing signal sensing position j can be obtained by performing point-by-point statistical analysis on each optical fiber sensing position without external acoustic wave signals. The specific calculation formula is:

[0048] In formula (3), is the initial phase of the receiving point of the j-th optical fiber sensing signal sensing position; m is the number of time samples at each sensing position before the arrival of the signal to be measured; ω0(i,j) is the initial phase of IQ demodulation of the j-th optical fiber sensing signal sensing position at the i-th sampling moment.

[0049] Sub-step S10222: Set the initial phase of the receiving point Subtract it from the IQ demodulation initial phase ω0(i,j) to obtain the first decoupling phase ω1(i,j) that eliminates the influence of the initial phase of the sensing position receiving point.

[0050] That is to say, the first decoupling phase ω1(i,j) that eliminates the influence of the initial phase of the sensor position is:

[0051] In formula (4), ω1(i, j) is the first decoupling phase of the j-th optical fiber sensing signal sensing position at the i-th sampling moment; ω0(i, j) is the IQ demodulation initial phase of the j-th optical fiber sensing signal sensing position at the i-th sampling moment; is the initial phase of the receiving point of the j-th optical fiber sensing signal sensing position.

[0052] The first decoupling phase corresponding to each optical fiber sensing signal sensing position at different sampling moments can be calculated using the above formula (4).

[0053] Sub-step S10223: Determine a linear fitting relationship between the first decoupling phase ω1(i,j) and the optical fiber sensing signal sensing position j by performing linear fitting on the first decoupling phases corresponding to different optical fiber sensing signal sensing positions.

[0054] Combining equations (2) and (4), we can see that the first decoupled phase ω1(i, j) after eliminating the influence of the initial phase of the sensor position receiving point is equal to the initial phase of the laser pulse Optical path integrated phase and the displacement phase of the signal to be measured The following relationship should be satisfied:

[0055] The optical path integral phase The calculation formula is:

[0056] At this time, if we assume The mean of is zero, that is, there is no external disturbance in the optical fiber or the mean of the disturbance signal is 0. Then, combining equations (5) and (6), we can know that the first decoupling phase ω1(i, j) is related to the initial phase of the laser pulse and the displacement phase of the signal to be measured It should satisfy a linear function relationship, that is:

[0057] That is to say, by determining the first decoupling phase corresponding to different optical fiber sensing signal sensing positions at the i-th sampling moment, multiple data points such as (1, ω1(i,1)), (2, ω1(i,2))...(j, ω1(i,j)) are obtained, and then these data points are plotted as a curve of ω1 at the i-th sampling moment versus the optical fiber sensing signal sensing position j. Then, several data points are selected from the ω1-j variation curve for linear fitting, and the linear fitting relationship between the first decoupling phase ω1(i,j) and the optical fiber sensing signal sensing position j can be obtained.

[0058] In addition, it should be noted that due to The mean value in the fitting section must be zero to have no effect on the fitting parameters. Therefore, in order to eliminate To minimize the impact on fitting accuracy, the fitting segment should be located at the far end of the fiber, where the measured signal is weaker and arrives later. Furthermore, to ensure fitting accuracy, the fitting segment should not be too short; it should generally be at least one-quarter of the fiber length. The effects of phase wrapping should be considered during fitting, and unwrapping should be performed.

[0059] Sub-step S10224: Determine the intercept of the linear fitting relationship of ω1-j as the initial phase of the laser pulse The slope of the linear fitting relationship of ω1-j is determined as the phase linear change factor k(i).

[0060] Sub-step S10225: Determine the optical path integral phase based on the phase linear variation factor k(i)

[0061] Sub-step S10226: Initial phase of laser pulse and optical path integrated phase Subtracting from the first decoupled phase ω1(i,j) yields the second decoupled phase ω2(i,j).

[0062] Sub-step S10227: Repeat the above sub-steps S10221 to S10226 to obtain a second decoupling phase after multiple iterations.

[0063] In each iteration, the value of the current IQ demodulation initial phase ω0(i, j) needs to be updated to the value of the second decoupling phase ω2(i, j) obtained in the previous iteration.

[0064] Sub-step S10228: Determine the second decoupling phase after multiple iterations as the displacement phase of the signal to be measured

[0065] Furthermore, in a possible implementation, in step S103, the updated IQ data is:

[0066] In formulas (8) to (10), I d (i, j) is the updated in-phase signal of the j-th optical fiber sensor signal sensing position at the i-th sampling moment; Q d (i, j) is the updated orthogonal signal of the jth optical fiber sensing signal sensing position at the i-th sampling moment; is the displacement phase of the signal to be measured at the jth optical fiber sensing signal sensing position at the i-th sampling moment; A(i,j) is the amplitude of the original IQ data at the j-th optical fiber sensing signal sensing position at the i-th sampling moment; I(i,j) is the original in-phase signal output by the distributed optical fiber sensing acquisition instrument at the j-th optical fiber sensing signal sensing position at the i-th sampling moment; Q(i,j) is the original orthogonal signal output by the distributed optical fiber sensing acquisition instrument at the j-th optical fiber sensing signal sensing position at the i-th sampling moment.

[0067] Furthermore, in a possible implementation, in step S104, the calculation formula for performing local spatial window summation on the updated IQ data is:

[0068] In formula (11) to formula (12), Isum (i, j) is the in-phase signal of the j-th optical fiber sensing signal sensing position at the i-th sampling moment after summation; Q sum (i, j) is the summed orthogonal signal of the jth optical fiber sensing signal sensing position at the i-th sampling moment; n is the spatial window size; I d (i, j+k) is the in-phase signal of the j+kth optical fiber sensor signal sensing position at the i-th sampling moment after update; Q d (i, j+k) is the updated orthogonal signal of the j+kth optical fiber sensing signal sensing position at the i-th sampling moment.

[0069] Furthermore, in a possible implementation manner, in step S105, the demodulated phase after eliminating the coherent fading noise is:

[0070] In formula (13), To eliminate the demodulation phase after the coherent fading noise; I sum (i, j) is the in-phase signal of the j-th optical fiber sensing signal sensing position at the i-th sampling moment after summation; Q sum (i, j) is the summed orthogonal signal of the j-th optical fiber sensing signal sensing position at the i-th sampling moment.

[0071] In order to verify the effectiveness and practicability of the method for eliminating DAS coherent fading noise in the present invention, an actual optical fiber in an oil well was used to Taking the collected IQ data as an example, the above-mentioned method for eliminating coherent fading noise is used to perform speed sensing phase demodulation on the IQ data. Specifically, the processing flow may include the following:

[0072] (1) Using distributed fiber optic sensing The instrument is connected to the optical fiber coupled to the environment to be measured, and emits narrow linewidth and highly coherent optical pulses at a certain frequency. The original IQ data of different observation points at different times are obtained through the IQ demodulation device.

[0073] (2) The original IQ data is calculated using formula (1) to determine the initial phase ω0(i,j) of IQ demodulation.

[0074] (3) Perform point-by-point statistical analysis on each sensing position of the optical fiber sensor without external acoustic wave signals to obtain the initial phase of the receiving point of the optical fiber sensor signal sensing position j

[0075] (4) The initial phase of IQ demodulation ω0(i,j) minus the initial phase of the receiving point corresponding to each sensor position The first decoupling phase ω1(i, j) is obtained after eliminating the influence of the initial phase of each sensor position receiving point.

[0076] (5) Using the first decoupled phase ω1(i, j) after eliminating the initial phase influence of each sensor position receiving point, it is assumed that the signal to be measured is The mean value of the laser pulse is 0, and the phase of the laser pulse at each time sampling moment is obtained by linear fitting. and the phase linear variation factor k(i).

[0077] (6) Solving equation (14) can obtain the displacement sensing phase to be measured

[0078] (7) To ensure the demodulation accuracy, use Instead of ω0(i,j), multiple iterative calculations are performed, that is, steps (3) to (6) are repeated.

[0079] (8) Using the amplitude of the IQ signal and the phase of the displacement to be measured Recalculate the IQ signal.

[0080] (9) Perform local spatial window summation on the IQ signal recalculated from the measured signal, and then calculate the demodulation phase after eliminating the coherent fading noise according to formula (13):

[0081] (10) Demodulation phase Then, phase unwrapping is performed to complete the phase demodulation process of eliminating coherent fading noise.

[0082] (11) Repeat steps S201 to S210 for all I / Q signals to be demodulated and recorded, and transpose them to obtain conventional channel sequence wave field recording data. After completing the above steps, the coherent fading noise suppression obtained by phase demodulation of the optical fiber acquisition data is completed.

[0083] (12) In order to further eliminate the residual phase low wavenumber noise, the subsequent data is subjected to zero wavenumber filtering to obtain the final fiber optic sensing demodulation phase data.

[0084] (13) Resample the data according to actual needs to complete the subsequent practical application of fiber optic sensing data.

[0085] Figure 2 shows the amplitude strength of the optical fiber IQ signal; Figure 3 shows the record of the optical fiber IQ signal after phase demodulation; Figure 4 shows the record of the optical fiber IQ signal after phase demodulation with coherent fading noise eliminated. Combining Figures 2 to 4, it can be seen that the optical fiber sensing demodulation phase data processed by this method can achieve phase demodulation that eliminates coherent fading noise and obtain the optical cable The recorded phase sensing information achieves the purpose of maintaining full-band information and highlighting effective seismic waves.

[0086] In addition, the implementation environment of this embodiment includes at least one terminal and a server, and the method is executed on the terminal or the server respectively. The terminal and the server can be connected in communication to realize the interactive transmission of information.

[0087] Among them, the terminal can be any electronic product that can interact with the user through one or more methods such as keyboard, touchpad, touch screen, voice interaction, etc., such as PC (Personal Computer), PPC (Pocket Personal Computer), tablet computer, etc.

[0088] A server can be a single server or a server cluster consisting of multiple servers. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN (Content Delivery Network), as well as big data and artificial intelligence platforms.

[0089] In the second aspect, an embodiment of the present invention provides a device for eliminating DAS coherent fading noise. Referring to Figure 5, the device includes: an original IQ data acquisition unit 101, a phase decoupling operation unit 102, an IQ data update unit 103, an IQ data local summation unit 104, a demodulation phase determination unit 105 and a phase unwrapping unit 106.

[0090] The original IQ data acquisition unit 101 is used to acquire the original IQ data output by the IQ demodulation device. The original IQ data includes IQ signals of different optical fiber sensing signal sensing positions at different sampling times. The IQ signals include in-phase signals I(i, j) and quadrature signals Q(i, j).

[0091] Phase decoupling operation unit 102 is used to perform phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured.

[0092] The IQ data updating unit 103 is used to update the IQ data based on the decoupled displacement phase. and the amplitude A(i, j) of the original IQ data to determine the updated IQ data.

[0093] The IQ data local summing unit 104 is configured to perform local spatial window summation on the updated IQ data to determine summed IQ data.

[0094] The demodulation phase determination unit 105 is used to determine the demodulation phase after eliminating the coherent fading noise based on the summed IQ data.

[0095] The phase unwinding unit 106 is configured to perform phase unwinding on the demodulated phase after the coherent fading noise is eliminated, so as to obtain the optical fiber sensing demodulated phase data after the coherent fading noise is eliminated.

[0096] Furthermore, in a possible embodiment, the phase decoupling operation unit 102 may include: an IQ demodulation initial phase determination module, a receiving point initial phase determination module, a first decoupling phase determination module, a linear fitting module, a laser pulse initial phase determination module, a linear change factor determination module, an optical path integral phase determination module, a second decoupling phase determination module, an iteration module and a displacement phase determination module.

[0097] The IQ demodulation initial phase determination module is used to determine the IQ demodulation initial phase ω0(i, j) based on the original IQ data.

[0098] The receiving point initial phase determination module is used to determine the receiving point initial phase of the optical fiber sensing signal sensing position based on the IQ demodulation initial phase ω0(i,j)

[0099] The first decoupling phase determination module is used to determine the initial phase of the receiving point Subtract it from the IQ demodulation initial phase ω0(i,j) to obtain the first decoupling phase ω1(i,j) after eliminating the influence of the initial phase of the sensing position receiving point.

[0100] The linear fitting module is used to determine the linear fitting relationship between the first decoupling phase ω1(i,j) and the optical fiber sensing signal sensing position j by performing linear fitting on the first decoupling phases corresponding to different optical fiber sensing signal sensing positions.

[0101] The laser pulse initial phase determination module is used to determine the intercept of the linear fitting relationship as the laser pulse initial phase

[0102] The linear variation factor determination module is configured to determine the slope of the linear fitting relationship as the phase linear variation factor k(i).

[0103] The optical path integral phase determination module is used to determine the optical path integral phase based on the phase linear change factor k(i).

[0104] The second decoupling phase determination module is used to determine the initial phase of the laser pulse and optical path integrated phase Subtracting from the first decoupled phase ω1(i,j) yields the second decoupled phase ω2(i,j).

[0105] The iteration module is used to repeatedly perform the phase decoupling operation to obtain a second decoupling phase after multiple iterations; wherein, during each iteration, the current IQ demodulation initial phase is updated to the second decoupling phase obtained in the previous iteration.

[0106] The displacement phase determination module is used to determine the second decoupling phase after multiple iterations as the displacement phase of the signal to be measured

[0107] It should be noted that the above-mentioned device only uses the division of the above-mentioned functional modules as an example to illustrate its functions. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device provided in the above embodiment and the method provided in the above embodiment are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0108] In a third aspect, an embodiment of the present invention further provides an electronic device, see Figure 6, which includes a processor 201 and a memory 202, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by one or more of the above-mentioned processors to enable the processor to implement the method for eliminating DAS coherent fading noise in the above-mentioned embodiment.

[0109] Of course, the electronic device may also have components such as a wired or wireless network interface, a keyboard, and an input / output interface for input and output. The electronic device may also include other components for realizing various functions of the device, which will not be described in detail here.

[0110] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, which stores at least one program code, and the program code is loaded and executed by a processor to enable the computer to implement the method for eliminating DAS coherent fading noise in the above embodiment.

[0111] Optionally, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc (CD-ROM), a magnetic tape, a floppy disk, or an optical disc data storage device. Those skilled in the art will appreciate that all or part of the steps in the above-mentioned embodiment method can be accomplished by instructing the relevant hardware through a program, and the program is stored in a storage medium, including several instructions for causing a single-chip microcomputer, a chip, or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc.

[0112] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0113] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0114] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for eliminating DAS coherent fading noise, characterized in that: The method comprises: Acquire original IQ data output by a distributed optical fiber sensing acquisition instrument, wherein the original IQ data includes IQ signals of different optical fiber sensing signal sensing positions at different sampling times, and the IQ signals include in-phase signals and orthogonal signals; Perform phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured; Determine updated IQ data based on the decoupled shift phase and the amplitude of the original IQ data; Performing local spatial window summation on the updated IQ data to determine the summed IQ data; Determine a demodulation phase after eliminating coherent fading noise based on the summed IQ data; The demodulated phase after the coherent fading noise is eliminated is phase unwrapped, and finally the optical fiber sensing demodulated phase data after the coherent fading noise is eliminated is obtained.

2. The method for eliminating DAS coherent fading noise according to claim 1, characterized in that: The performing phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured includes: Determine the IQ demodulation initial phase ω0(i,j) based on the original IQ data; Phase decoupling operation is performed step by step for the initial phase ω0(i, j) of IQ demodulation, and the initial phase of the receiving point of the optical fiber sensing signal sensing position in the initial phase ω0(i, j) of IQ demodulation is eliminated in turn. Laser pulse initial phase and the optical path integrated phase Get the displacement phase of the signal to be measured 3. The method for eliminating DAS coherent fading noise according to claim 2, characterized in that: The phase decoupling operation is performed step by step on the initial phase ω0(i, j) of the IQ demodulation, and the initial phase of the receiving point of the optical fiber sensing signal sensing position in the initial phase ω0(i, j) of the IQ demodulation is eliminated in sequence. Laser pulse initial phase and the optical path integrated phase Get the displacement phase of the signal to be measured include: Based on IQ demodulation initial phase Determine the initial phase of the receiving point of the optical fiber sensing signal sensing position The initial phase of the receiving point Subtract it from the initial phase ω0(i,j) of IQ demodulation to obtain the first decoupled phase ω1(i,j) that eliminates the influence of the initial phase of the receiving point; By performing linear fitting on the first decoupling phases corresponding to different optical fiber sensing signal sensing positions, a linear fitting relationship between the first decoupling phase ω1(i,j) and the optical fiber sensing signal sensing position j is determined; The intercept of the linear fitting relationship is determined as the initial phase of the laser pulse. The slope of the linear fitting relationship is determined as the phase linear variation factor k(i); Based on the phase linear change factor k(i), determine the optical path integral phase The laser pulse initial phase and the optical path integrated phase From the first decoupled phase ω1(i,j) Subtract from , and obtain the second decoupled phase ω2(i,j); Repeat the above steps to obtain a second decoupling phase after multiple iterations; wherein, in each iteration, the current IQ demodulation initial phase is updated to the second decoupling phase obtained in the previous iteration; The second decoupled phase after multiple iterations is determined as the displacement phase of the signal to be measured 4. The method for eliminating DAS coherent fading noise according to claim 3, characterized in that: The calculation formula of the initial phase of the receiving point is: in, is the initial phase of the receiving point of the j-th optical fiber sensor signal sensing position; m is the number of time samples used for statistics at each sensing position before the signal to be measured arrives, that is, when the optical fiber is in a static state without external disturbance; ω0(i,j) is the initial phase of IQ demodulation of the j-th optical fiber sensor signal sensing position at the ith sampling moment, i is the sampling time serial number, and j is the optical fiber sensor signal sensing position serial number.

5. The method for eliminating DAS coherent fading noise according to claim 1, characterized in that: The updated IQ data is: Among them, I d (i, j) is the in-phase signal of the jth optical fiber sensor signal sensing position at the i-th sampling moment after update; Q d (i, j) is the updated orthogonal signal of the sensing position of the jth optical fiber sensing signal at the i-th sampling moment; is the displacement phase of the measured signal at the jth optical fiber sensing signal sensing position at the ith sampling moment; A(i,j) is the amplitude of the original IQ data at the jth optical fiber sensing signal sensing position at the ith sampling moment; I(i,j) is the original in-phase signal of the distributed optical fiber sensing acquisition instrument at the jth optical fiber sensing signal sensing position at the ith sampling moment; Q(i,j) is the original orthogonal signal of the distributed optical fiber sensing acquisition instrument at the jth optical fiber sensing signal sensing position at the ith sampling moment.

6. The method for eliminating DAS coherent fading noise according to claim 1, characterized in that: The calculation formula for the local spatial window summation of the updated IQ data is: Among them, I sum (i, j) is the in-phase signal of the jth optical fiber sensor signal sensing position at the i-th sampling moment after summation; Q sum (i, j) is the summed orthogonal signal of the jth optical fiber sensor signal sensing position at the i-th sampling moment; n is the spatial window size; I d (i, j+k) is the in-phase signal of the j+kth optical fiber sensor signal sensing position at the i-th sampling moment after update; Q d (i, j+k) is the updated orthogonal signal of the sensing position of the j+kth optical fiber sensing signal at the i-th sampling moment.

7. The method for eliminating DAS coherent fading noise according to claim 1, characterized in that: The demodulation phase after eliminating the coherent fading noise is: in, To eliminate the demodulation phase after the coherent fading noise; I sum (i, j) is the in-phase signal of the j-th optical fiber sensor signal sensing position at the i-th sampling moment after summation; Q sum (i, j) is the orthogonal signal of the jth optical fiber sensor signal sensing position at the i-th sampling moment after summation.

8. A device for eliminating DAS coherent fading noise, characterized in that: The device comprises: an original IQ data acquisition unit, a phase decoupling operation unit, an IQ data update unit, an IQ data local summation unit, a demodulation phase determination unit and a phase unwrapping unit; An original IQ data acquisition unit is used to acquire the original IQ data output by the distributed optical fiber sensing acquisition instrument, wherein the original IQ data includes IQ signals of different optical fiber sensing signal sensing positions at different sampling times, and the IQ signals include in-phase signals and orthogonal signals; A phase decoupling operation unit is used to perform phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured; An IQ data updating unit, configured to determine updated IQ data based on the decoupled displacement phase and the amplitude of the original IQ data; An IQ data local summing unit, used for performing local spatial window summing on the updated IQ data to determine the summed IQ data; A demodulation phase determination unit, used to determine the demodulation phase after eliminating the coherent fading noise based on the summed IQ data; The phase unwinding unit is used to perform phase unwinding on the demodulated phase after the coherent fading noise is eliminated, so as to obtain the optical fiber sensing demodulated phase data after the coherent fading noise is eliminated.

9. An electronic device, characterized in that: The electronic device includes a processor and a memory, wherein the memory stores at least one computer program, and the at least one computer program is loaded and executed by one or more of the above processors, so that the processor executes the method for eliminating DAS coherent fading noise according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one program code, and the program code is loaded and executed by a processor to enable a computer to execute the method for eliminating DAS coherent fading noise according to any one of claims 1 to 7.

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