Method, device and equipment for eliminating coherent fading noise

Abstract

The invention provides a method, device and equipment for eliminating coherent fading noise, and belongs to the field of optical fiber sensing signal processing, and the method comprises the steps: obtaining original IQ data outputted by a distributed optical fiber sensing collection instrument; performing phase decoupling operation on the original IQ data to obtain a displacement phase of the to-be-measured signal; determining updated IQ data based on the decoupled displacement phase and the amplitude of the original IQ data; carrying out local space window summation on the updated IQ data, and determining the IQ data after summation; determining a demodulation phase after eliminating the coherent fading noise based on the summed IQ data; and performing phase unwrapping on the demodulation phase after the coherent fading noise is eliminated to obtain optical fiber sensing demodulation phase data after the coherent fading noise is eliminated. According to the method provided by the invention, phase demodulation can be efficiently carried out, the influence of coherent fading noise can be eliminated, and the accuracy of the acquired optical fiber sensing data can be improved, so that the actual requirements of technicians can be met.

Description

Technical Field

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

[0002] In recent years, the optical fiber distributed acoustic sensing technology has developed rapidly. This technology generally uses a phase-sensitive optical time domain reflectometer instrument, which mainly uses the Rayleigh backscattering of the optical fiber to obtain the vibration information around the optical fiber through phase demodulation. The optical fiber serves as both a sensing medium and a transmission medium, and can continuously sense the acoustic wave vibration information around the optical fiber and record it through high-density time and space sampling. This technology has been widely applied in aspects such as borehole seismic data acquisition, dam safety monitoring, perimeter security, and pipeline monitoring.

[0003] The distributed optical fiber sensing technology mainly utilizes the Rayleigh backscattering generated when laser propagates in the optical fiber. When the medium around the optical fiber vibrates, the Rayleigh backscattering will also change accordingly. By means of coherent detection and phase demodulation of this optical signal, the vibration wave field information or strain information of the medium can be obtained. Due to the instrument architecture that generally uses a narrow linewidth laser source for coherent detection, the scattering points in the optical fiber have the characteristic of random distribution, and the local coherent superposition of the Rayleigh backscattering within the pulse width has the characteristic of vector superposition. When the phases are opposite and cancel each other out, a coherent fading phenomenon will occur, and the demodulated phase will become very unstable, affecting the signal-to-noise ratio of the sensing signal.

[0004] Research shows that currently, the methods for suppressing coherent fading noise in distributed optical fiber sensing phase demodulation generally use local averaging or interpolation methods, and there are still many deficiencies in practical applications, which are prone to phase distortion. Therefore, the need to accurately and efficiently perform phase demodulation and eliminate the influence of coherent fading noise is extremely urgent. Summary of the Invention

[0005] Aiming at the technical problem that the method for suppressing coherent fading noise in the prior art is prone to phase distortion, the present invention provides a method for eliminating coherent fading noise. By using this method, phase demodulation can be efficiently performed and the influence of coherent fading noise can be eliminated, improving the accuracy of the collected optical fiber sensing data, thereby meeting the actual needs of technicians.

[0006] To achieve the above object, a first aspect of the present invention provides a method for eliminating coherent fading noise, which includes the following steps: obtaining the original IQ data output by a distributed optical fiber sensing acquisition instrument, where the original IQ (In-phase and Quadrature) data includes IQ signals at different sampling times and different optical fiber sensing signal output positions, and the IQ signal includes an in-phase signal and a quadrature signal; performing a phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured; determining the updated IQ data based on the decoupled displacement phase and the amplitude of the original IQ data; performing a local spatial window summation on the updated IQ data to determine the summed IQ data; determining the demodulation phase after eliminating the coherent fading noise based on the summed IQ data; and performing phase unwrapping on the demodulation phase after eliminating the coherent fading noise to obtain the optical fiber sensing demodulation phase data after eliminating the coherent fading noise.

[0007] In an exemplary embodiment of the present invention, the performing a phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured may include: determining the initial IQ demodulation phase ω 0 (i,j); gradually performing a phase decoupling operation on the initial IQ demodulation phase ω 0 (i,j) to sequentially eliminate the initial phase of the receiving point at the optical fiber sensing signal output position in the initial IQ demodulation phase ω 0 (i,j) the initial phase of the laser pulse and the optical path integral phase to obtain the displacement phase of the signal to be measured

[0008] In an exemplary embodiment of the present invention, the gradually performing a phase decoupling operation on the initial IQ demodulation phase ω 0 (i,j) to sequentially eliminate the initial phase of the receiving point at the optical fiber sensing signal output position in the initial IQ demodulation phase ω 0 (i,j) the initial phase of the laser pulse and the optical path integral phase to obtain the displacement phase of the signal to be measured may include: based on the initial IQ demodulation phase ω 0 (i,j), determining the initial phase of the receiving point at the optical fiber sensing signal output position subtracting the initial phase of the receiving point from the initial IQ demodulation phase to obtain the first decoupled phase ω 1 (i,j) after eliminating the influence of the initial phase of the receiving point; determining the first decoupled phase ω 1(i,j) and the linear fitting relationship with the output position j of the fiber optic sensing signal; determine the intercept of the linear fitting relationship as the initial phase of the laser pulse Determine the slope of the linear fitting relationship as the phase linear change factor k(i); based on the phase linear change factor k(i), determine the optical path integral phase The initial phase of the laser pulse And the optical path integral phase Subtract from the first decoupled phase ω 1 (i,j) to obtain the second decoupled phase ω 2 (i,j); repeat the above steps to obtain the second decoupled phase after multiple iterations; where, in each iteration process, update the current IQ demodulation initial phase to the second decoupled phase obtained in the previous iteration; determine the second decoupled phase after multiple iterations as the displacement phase of the signal to be measured

[0009] In an exemplary embodiment of the present invention, the calculation formula for the initial phase of the receiving point may be:

[0010]

[0011] Where Is the initial phase of the receiving point at the j-th fiber optic sensing signal output position; m is the number of time sample points used for statistics before the signal to be measured arrives at each sensing position, that is, when the optical fiber is in a static state without external disturbance; ω 0 (i,j) is the IQ demodulation initial phase according to the j-th fiber optic sensing signal output position at the i-th sampling moment, i is the sampling time sequence number, and j is the fiber optic sensing signal output position sequence number.

[0012] In an exemplary embodiment of the present invention, the updated IQ data is:

[0013]

[0014]

[0015]

[0016] Where I d (i,j) is the in-phase signal of the j-th fiber optic sensing signal output position at the i-th sampling moment after update; Q d (i,j) is the quadrature signal of the j-th fiber optic sensing signal output position at the i-th sampling moment after update; is the displacement phase of the signal to be measured at the j-th optical fiber sensing signal output 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 output 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 output position at the i-th sampling moment; Q(i,j) is the original quadrature signal output by the distributed optical fiber sensing acquisition instrument at the j-th optical fiber sensing signal output position at the i-th sampling moment.

[0017] In an exemplary embodiment of the present invention, the calculation formula for performing local spatial window summation on the updated IQ data can be:

[0018]

[0019]

[0020] where, I sum (i,j) is the in-phase signal at the j-th optical fiber sensing signal output position at the i-th sampling moment after summation; Q sum (i,j) is the quadrature signal at the j-th optical fiber sensing signal output position at the i-th sampling moment after summation; n is the spatial window size; I d (i,j + k) is the in-phase signal at the (j + k)-th optical fiber sensing signal output position at the i-th sampling moment after update; Q d (i,j + k) is the quadrature signal at the (j + k)-th optical fiber sensing signal output position at the i-th sampling moment after update.

[0021] In an exemplary embodiment of the present invention, the demodulation phase after eliminating the coherent fading noise

[0022]

[0023] where, is the demodulation phase after eliminating the coherent fading noise; I sum (i,j) is the in-phase signal at the j-th optical fiber sensing signal output position at the i-th sampling moment after summation; Q sum (i,j) is the quadrature signal at the j-th optical fiber sensing signal output position at the i-th sampling moment after summation.

[0024] The second aspect of the present invention provides an apparatus for eliminating coherent fading noise, which 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; The original IQ data acquisition unit is configured to acquire the original IQ data output by a distributed optical fiber sensing acquisition instrument, where the original IQ data includes IQ signals at different optical fiber sensing signal output positions at different sampling moments, and the IQ signal includes an in-phase signal and a quadrature signal; The phase decoupling operation unit is configured to perform a phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured; The IQ data update unit is configured to determine the updated IQ data based on the decoupled displacement phase and the amplitude of the original IQ data; The IQ data local summation unit is configured to perform local spatial window summation on the updated IQ data to determine the summed IQ data; The demodulation phase determination unit is configured to determine the demodulation phase after eliminating the coherent fading noise based on the summed IQ data; The phase unwrapping unit is configured to perform phase unwrapping on the demodulation phase after eliminating the coherent fading noise to obtain the optical fiber sensing demodulation phase data after eliminating the coherent fading noise.

[0025] The third aspect of the present invention provides an electronic device, which comprises a processor and a memory, and at least one computer program is stored in the memory. The at least one computer program is loaded and executed by one or more of the above-mentioned processors, so that the processor executes the method for eliminating coherent fading noise as described above.

[0026] The fourth aspect of the present invention provides a computer-readable storage medium, which stores at least one program code. The program code is loaded and executed by a processor, so that a computer executes the method for eliminating coherent fading noise as described above.

[0027] Through the technical solution provided by the present invention, the present invention has at least the following technical effects:

[0028] (1) The method for eliminating coherent fading noise provided by the present invention can efficiently perform phase demodulation and eliminate the influence of coherent fading noise, improve the accuracy of the collected optical fiber sensing data, and thus meet the actual needs of technicians;

[0029] (2) The method for eliminating coherent fading noise provided by the present invention 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 actual application effect of optical fiber sensing.

[0030] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. Description of the Drawings

[0031] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and form a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation to the embodiments of the present invention. In the accompanying drawings:

[0032] Figure 1 It is a flowchart of the method for eliminating coherent fading noise provided by the embodiments of the present invention;

[0033] Figure 2 It is an amplitude intensity diagram of the fiber optic IQ signal provided by the embodiments of the present invention;

[0034] Figure 3 It is a recorded diagram of the fiber optic IQ signal after phase demodulation provided by the embodiments of the present invention;

[0035] Figure 4 It is a recorded diagram of the fiber optic IQ signal after eliminating coherent fading noise after phase demodulation provided by the embodiments of the present invention;

[0036] Figure 5 It is a structural diagram of the device for eliminating coherent fading noise provided by the embodiments of the present invention;

[0037] Figure 6 It is a structural diagram of the electronic device provided by the embodiments of the present invention.

[0038] Description of the reference numerals

[0039] 101 - Original IQ data acquisition unit, 102 - Phase decoupling operation unit, 103 - IQ data update unit, 104 - IQ data local summation unit, 105 - Demodulation phase determination unit, 106 - Phase unwrapping unit, 201 - Processor, 202 - Memory. Specific embodiments

[0040] The following details the specific embodiments of the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the embodiments of the present invention and are not used to limit the embodiments of the present invention.

[0041] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0042] In the present invention, "first", "second", etc. are merely for convenience of description and easy distinction, and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, terms such as "installation" and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a direct connection or an indirect connection; it may be a wired connection or a wireless connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In order to solve the technical problems that the coherent fading noise suppression method for distributed fiber optic sensing phase demodulation in the prior art is prone to phase distortion and cannot effectively eliminate coherent fading noise, the present invention provides a method for eliminating coherent fading noise. This method gradually decouples the signal to be measured by using the initial phase of the laser pulse included in the received phase, the initial phase of the receiving point at each sensing position, the optical path integral phase, and the displacement phase, and then performs local spatial window summation on the IQ signal recalculated for the signal to be measured, thus achieving the elimination of coherent fading noise. In actual production applications, this method is of great significance for improving the quality of fiber optic sensing data acquisition and protecting low wavenumber wavefield information.

[0044] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0045] Please refer to Figure 1 , an embodiment of the present invention provides a method for eliminating coherent fading noise, and this method includes the following steps:

[0046] Step S101: Obtain the original IQ data output by the distributed fiber optic sensing acquisition instrument.

[0047] Here, it should be noted that the optical fiber can be laid in the measured environment and the optical fiber can be fully coupled with the environment by certain means. One end of the optical fiber is connected to the instrument, the instrument emits a narrow linewidth laser pulse, and the IQ quadrature information (i.e., the original IQ data) of the Rayleigh backscattering of the optical pulse is obtained through the coherent detection method. The original IQ data includes the IQ signals at different fiber optic sensing signal output positions at different sampling times. The IQ signals are respectively the in-phase (In-phase) signal I(i, j) and the quadrature (Quadrature) signal Q(i, j), where i represents the sampling time serial number and j represents the fiber optic sensing signal output position serial number.

[0048] In addition, before performing IQ phase demodulation on the original IQ data, amplitude and phase imbalance correction should be performed on the IQ signals to ensure the orthogonality of the IQ signals.

[0049] Step S102: Perform phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured

[0050] Step S103: Based on the decoupled displacement phase and the amplitude A(i, j) of the original IQ data, determine the updated IQ data.

[0051] Step S104: Perform local spatial window summation on the updated IQ data to determine the summed IQ data.

[0052] Step S105: Based on the summed IQ data, determine the demodulation phase after eliminating the coherent fading noise

[0053] Step S106: Perform phase unwrapping on the demodulation phase after eliminating the coherent fading noise to obtain the fiber optic sensing demodulation phase data after eliminating the coherent fading noise.

[0054] Further, in a possible implementation manner, in Step S102, the process of performing phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured may include but is not limited to the following sub-steps S1021 to sub-step S1022.

[0055] Sub-step S1021: Determine the initial IQ demodulation phase ω 0 (i, j) based on the original IQ data.

[0056] Specifically, calculate the initial IQ demodulation phase ω 0 (i, j) from the original IQ data through the following formula:

[0057]

[0058] In formula (1), ω 0 (i, j) is the initial IQ demodulation phase at the output position of the j-th fiber optic sensing signal at the i-th sampling moment of the distributed fiber optic sensing instrument; I(i, j) is the original in-phase signal output at the output position of the j-th fiber optic sensing signal at the i-th sampling moment by the distributed fiber optic sensing acquisition instrument; Q(i, j) is the original quadrature signal output at the output position of the j-th fiber optic sensing signal at the i-th sampling moment by the distributed fiber optic sensing acquisition instrument.

[0059] Sub-step S1022: Gradually perform phase decoupling operation on the initial IQ demodulation phase ω 0 (i, j), and sequentially eliminate the initial phase of the receiving point at the output position of the fiber optic sensing signal 0 in the initial IQ demodulation phase ω the initial phase of the laser pulse Optical path integral phase Obtain the displacement phase of the signal to be measured

[0060] Since the distributed optical fiber sensing acquisition instrument is an instrument centered on Therefore, the initial IQ demodulation phase ω 0 Includes four parts, namely the initial phase of the receiving point at each optical fiber sensing output position Initial phase of the laser pulse Optical path integral phase And the displacement phase of the signal to be measured That is:

[0061]

[0062] In Equation (2), ω 0 (i,j) is the initial IQ demodulation phase of the distributed optical fiber sensing instrument at the j-th optical fiber sensing signal output position at the i-th sampling moment; 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 j-th optical fiber sensing signal output position; Is the optical path integral phase of the distributed optical fiber sensing instrument at the j-th optical fiber sensing signal output position at the i-th sampling moment; Is the displacement phase of the signal to be measured of the distributed optical fiber sensing instrument at the j-th optical fiber sensing signal output position at the i-th sampling moment.

[0063] That is to say, by determining the initial phase of the receiving point at each optical fiber sensing output position Initial phase of the laser pulse And the optical path integral phase After that, and gradually eliminating the phases of the above three parts from the initial IQ demodulation phase ω 0 The displacement phase of the signal to be measured can be obtained

[0064] Furthermore, in a possible implementation manner, in sub-step S1022, for the initial IQ demodulation phase ω 0 (i,j), perform phase decoupling operations step by step, and sequentially eliminate the initial phase of the receiving point at the optical fiber sensing signal output position in the initial IQ demodulation phase ω 0 (i,j) Initial phase of the laser pulse And the optical path integral phase Obtain the displacement phase of the signal to be measured The process may include but is not limited to the following sub-steps S10221 to sub-step S10228.

[0065] Sub-step S10221: Based on IQ demodulation initial phase ω 0 (i, j), determine the initial phase of the receiving point where the optical fiber sensor signal is output

[0066] For example, the initial phase of the receiving point at the output position j of the optical fiber sensor signal can be obtained by performing point-by-point statistical analysis on each output position of the optical fiber sensor without external acoustic wave signals. The specific calculation formula is:

[0067]

[0068] In formula (3), is the initial phase of the receiving point at the jth optical fiber sensor signal output position; m is the number of time samples at each sensor position before the signal to be measured arrives; ω 0 (i, j) is the initial phase of IQ demodulation at the jth optical fiber sensor signal output position at the i-th sampling moment.

[0069] Sub-step S10222: Set the initial phase of the receiving point From the IQ demodulation initial phase ω 0 Subtract from (i, j) to obtain the first decoupling phase ω that eliminates the influence of the initial phase of the sensor position receiving point 1 (i,j).

[0070] That is to say, the first decoupling phase ω that eliminates the influence of the initial phase of the sensing position 1 (i,j) is:

[0071]

[0072] In formula (4), ω 1 (i, j) is the first decoupling phase of the jth optical fiber sensor signal output position at the i-th sampling moment; ω 0 (i, j) is the initial phase of IQ demodulation at the jth optical fiber sensor signal output position at the i-th sampling moment; is the initial phase of the receiving point at the jth optical fiber sensor signal output position.

[0073] The first decoupling phase corresponding to the output position of each optical fiber sensor signal at different sampling times can be calculated by the above formula (4).

[0074] Sub-step S10223: Determine the first decoupling phase ω by performing linear fitting on the first decoupling phases corresponding to the output positions of different optical fiber sensor signals. 1 (i, j) is the linear fitting relationship between the output position j of the optical fiber sensor signal.

[0075] Combining equations (2) and (4), it can be seen that the first decoupled phase ω after eliminating the influence of the initial phase at the receiving point of the sensing position 1 (i, j) and the initial phase of the laser pulse The optical path integral phase and the displacement phase of the signal to be measured should satisfy the following relationship:

[0076]

[0077] And the calculation formula of the optical path integral phase is:

[0078]

[0079] At this time, if it is assumed that the mean value is zero, that is, there is no external disturbance on the optical fiber or the mean value of the disturbance signal is 0, then combining equations (5) and (6), it can be seen that the first decoupled phase ω 1 (i, j) and the initial phase of the laser pulse and the displacement phase of the signal to be measured should satisfy a linear function relationship, that is:

[0080]

[0081] That is to say, by determining the first decoupled phase corresponding to different output positions of the optical fiber sensing signals at the i-th sampling moment, multiple data points such as (1, ω 1 (i, 1)), (2, ω 1 (i, 2))... (j, ω 1 (i, j)) etc. are obtained, and then these data points are plotted as the ω 1 variation curve with respect to the output position j of the optical fiber sensing signal at the i-th sampling moment, and then several data points are selected from the ω 1 -j variation curve for linear fitting, and the linear fitting relationship between the first decoupled phase ω 1 (i, j) and the output position j of the optical fiber sensing signal can be obtained.

[0082] In addition, it should be noted that since the mean value in the fitting segment needs to be zero to have no influence on the calculation of the fitting parameters, therefore, in order to eliminate the influence on the fitting accuracy as much as possible, the far end of the optical fiber with a weaker signal to be measured and a later arrival time should be selected as the fitting segment. In addition, to ensure the fitting accuracy, the fitting segment cannot be too short, generally it should reach more than one-fourth of the optical fiber length. The influence of phase wrapping should be considered during fitting and unwrapping processing should be carried out.

[0083] Sub-step S10224: Take ω 1The intercept of the linear fitting relationship of -j is determined as the initial phase of the laser pulse Let ω 1 The slope of the linear fitting relationship of -j is determined as the phase linear change factor k(i).

[0084] Sub-step S10225: Determine the optical path integral phase based on the phase linear change factor k(i)

[0085] Sub-step S10226: Subtract the initial phase of the laser pulse and the optical path integral phase from the first decoupled phase ω 1 (i, j) to obtain the second decoupled phase ω 2 (i, j).

[0086] Sub-step S10227: Repeat the above sub-steps S10221 to S10226 to obtain the second decoupled phase after multiple iterations

[0087] Among them, in each iteration process, the value of the current IQ demodulation initial phase ω 0 (i, j) needs to be updated to the value of the second decoupled phase ω 2 (i, j) obtained in the previous iteration

[0088] Sub-step S10228: Determine the displacement phase of the signal to be measured as the second decoupled phase after multiple iterations

[0089] Furthermore, in a possible implementation manner, in step S103, the updated IQ data is as follows

[0090]

[0091]

[0092]

[0093] In equations (8) to (10), I d (i, j) is the in-phase signal at the output position of the jth fiber optic sensing signal at the ith sampling moment after update; Q d (i, j) is the quadrature signal at the output position of the jth fiber optic sensing signal at the ith sampling moment after update The displacement phase of the signal to be measured at the output position of the j-th fiber optic sensing signal at the i-th sampling moment; A(i,j) is the amplitude of the original IQ data at the output position of the j-th fiber optic sensing signal at the i-th sampling moment; I(i,j) is the original in-phase signal output by the distributed fiber optic sensing acquisition instrument at the output position of the j-th fiber optic sensing signal at the i-th sampling moment; Q(i,j) is the original quadrature signal output by the distributed fiber optic sensing acquisition instrument at the output position of the j-th fiber optic sensing signal at the i-th sampling moment.

[0094] Furthermore, in a possible implementation manner, in step S104, the calculation formula for performing local spatial window summation on the updated IQ data is:

[0095]

[0096]

[0097] In formulas (11) to (12), I sum (i,j) is the in-phase signal at the output position of the j-th fiber optic sensing signal at the i-th sampling moment after summation; Q sum (i,j) is the quadrature signal at the output position of the j-th fiber optic sensing signal at the i-th sampling moment after summation; n is the spatial window size; I d (i,j + k) is the in-phase signal at the output position of the (j + k)-th fiber optic sensing signal at the i-th sampling moment after update; Q d (i,j + k) is the quadrature signal at the output position of the (j + k)-th fiber optic sensing signal at the i-th sampling moment after update.

[0098] Furthermore, in a possible implementation manner, in step S105, the demodulation phase after eliminating the coherent fading noise is:

[0099]

[0100] In formula (13), is the demodulation phase after eliminating the coherent fading noise; I sum (i,j) is the in-phase signal at the output position of the j-th fiber optic sensing signal at the i-th sampling moment after summation; Q sum (i,j) is the quadrature signal at the output position of the j-th fiber optic sensing signal at the i-th sampling moment after summation.

[0101] In order to verify the effectiveness and practicality of the method for eliminating coherent fading noise of the present invention, taking the IQ data actually collected by a certain oil well's optical fiber as an example, the above method for eliminating coherent fading noise is used to perform velocity sensing phase demodulation on the IQ data, and the specific processing flow may include the following:

[0102] (1) Using distributed optical fiber sensing instrument, connect it to the optical fiber coupled to the environment to be measured, emit narrow linewidth and high coherence optical pulses at a certain frequency, and obtain the original IQ data at different observation points at different times through the IQ demodulation device.

[0103] (2) Calculate the original IQ data through formula (1) to determine the initial phase ω 0 (i,j).

[0104] (3) Conduct point-by-point statistical analysis on each output position of the optical fiber sensing without external acoustic signals to obtain the initial phase of the receiving point at the output position j of the optical fiber sensing signal

[0105] (4) Subtract the initial phase of the receiving point at the corresponding output position from the initial phase ω 0 (i,j) to obtain the first decoupled phase ω after eliminating the influence of the initial phase of the receiving point at each sensing position. 1 (i,j).

[0106] (5) Using the first decoupled phase ω 1 (i,j) after eliminating the influence of the initial phase of the receiving point at each sensing position, assuming that the mean value of the signal to be measured is 0, obtain the laser pulse phase and the phase linear change factor k(i) at each time sampling moment through linear fitting.

[0107] (6) Solving equation (14) can obtain the displacement sensing phase to be measured

[0108]

[0109] (7) To ensure the demodulation accuracy, use to replace ω 0 (i,j) for multiple iterative calculations, that is, repeat steps (3) to (6).

[0110] (8) Recalculate the IQ signal using the amplitude of the IQ signal and the displacement sensing phase to be measured .

[0111] (9) Perform local spatial window summation on the recalculated IQ signal of the signal to be measured, and then obtain the demodulated phase after eliminating the coherent fading noise according to formula (13)

[0112] (10) Perform phase unwrapping on the demodulated phase again, and the phase demodulation process of eliminating the coherent fading noise is completed.

[0113] (11) Repeat steps S201 to S210 for all I / Q signals of all records to be demodulated and transpose to obtain a conventional channel sequence record. After completing the above steps, the phase demodulation of the fiber optic acquisition data and the suppression of coherent fading noise are completed.

[0114] (12) To further eliminate the residual phase low wavenumber noise, perform zero wavenumber filtering on the subsequent data to obtain the final fiber optic sensing demodulated phase data.

[0115] (13) Resample the data according to actual needs to complete the actual application of the subsequent fiber optic sensing data.

[0116] Figure 2 shows the amplitude intensity of the fiber optic IQ signal; Figure 3 shows the record after the phase demodulation of the fiber optic IQ signal; Figure 4 shows the record after eliminating the coherent fading noise after the phase demodulation of the fiber optic IQ signal. Combining Figures 2 to 4 It can be seen that through the fiber optic sensing demodulated phase data processed by this method, the phase demodulation of eliminating the coherent fading noise is realized, and the phase sensing information recorded by the optical cable is obtained, achieving the purpose of maintaining the full frequency band information and highlighting the effective seismic waves. reaching the purpose of maintaining full-band information and highlighting effective seismic waves.

[0117] In addition, the implementation environment of this embodiment includes at least one terminal and a server, and this method is executed on the terminal or the server respectively. The terminal and the server can be communicatively connected to realize the interactive transmission of information.

[0118] Among them, the terminal can be any electronic product that can perform human-computer interaction with the user in one or more ways such as keyboard, touchpad, touch screen, voice interaction, etc., such as a PC (Personal Computer, personal computer), PPC (Pocket Personal Computer, palmtop computer), tablet computer, etc.

[0119] The server can be a single server, a server cluster composed of multiple servers, or 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, content delivery network), as well as big data and artificial intelligence platforms.

[0120] The embodiment of the present invention also provides a device for eliminating coherent fading noise. Refer 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.

[0121] The original IQ data acquisition unit 101 is configured to acquire original IQ data output by an IQ demodulation device, where the original IQ data includes IQ signals at different output positions of fiber optic sensing signals at different sampling moments, and the IQ signals include in-phase signals I(i,j) and quadrature signals Q(i,j).

[0122] The phase decoupling operation unit 102 is configured to perform a phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured

[0123] The IQ data update unit 103 is configured to, based on the decoupled displacement phase and the amplitude A(i,j) of the original IQ data, determine the updated IQ data.

[0124] The IQ data local summation unit 104 is configured to perform local spatial window summation on the updated IQ data to determine the summed IQ data.

[0125] The demodulation phase determination unit 105 is configured to determine the demodulation phase after eliminating coherent fading noise based on the summed IQ data

[0126] The phase unwrapping unit 106 is configured to perform phase unwrapping on the demodulation phase after eliminating coherent fading noise to obtain the fiber optic sensing demodulation phase data after eliminating coherent fading noise.

[0127] Further, in a possible implementation manner, the phase decoupling operation unit 102 may include: an IQ demodulation initial phase determination module, a receiving point initial phase determination module, a first decoupled 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 decoupled phase determination module, an iteration module, and a displacement phase determination module.

[0128] The IQ demodulation initial phase determination module is configured to determine the IQ demodulation initial phase ω 0 (i,j) based on the original IQ data.

[0129] The receiving point initial phase determination module is configured to determine the receiving point initial phase at the output position of the fiber optic sensing signal based on the IQ demodulation initial phase ω 0 (i,j)

[0130] The first decoupled phase determination module is configured to use the receiving point initial phase From the initial phase ω of IQ demodulation 0 Subtract from (i,j) to obtain the first decoupled phase ω after eliminating the influence of the initial phase of the receiving point of the sensing position 1 (i,j).

[0131] A linear fitting module for determining the linear fitting relationship between the first decoupled phase ω 1 (i,j) and the output position j of the fiber optic sensing signal

[0132] A laser pulse initial phase determination module for determining the intercept of the linear fitting relationship as the laser pulse initial phase

[0133] A linear change factor determination module for determining the slope of the linear fitting relationship as the phase linear change factor k(i).

[0134] An optical path integral phase determination module for determining the optical path integral phase based on the phase linear change factor k(i)

[0135] A second decoupled phase determination module for subtracting the laser pulse initial phase and the optical path integral phase 1 from the first decoupled phase ω 2 (i,j) to obtain the second decoupled phase ω

[0136] An iteration module for repeatedly performing phase decoupling operations to obtain the second decoupled phase after multiple iterations; wherein, in each iteration process, the current IQ demodulation initial phase is updated to the second decoupled phase obtained in the previous iteration.

[0137] A displacement phase determination module for determining the displacement phase of the signal to be measured as the second decoupled phase after multiple iterations

[0138] It should be noted that when the above-provided device realizes its functions, only the above-mentioned division of each functional module is used for illustration. In actual applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the device is 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 belong to the same concept, and the specific implementation process is detailed in the method embodiment and will not be repeated here.

[0139] An embodiment of the present invention also provides an electronic device. See Figure 6, the electronic device includes a processor 201 and a memory 202. At least one computer program is stored in the memory and is loaded and executed by one or more of the above-mentioned processors, so that the processor implements the method for eliminating coherent fading noise in the above embodiments.

[0140] 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 implementing the various functions of the device, which will not be elaborated here.

[0141] An embodiment of the present invention also provides a computer-readable storage medium. At least one program code is stored in the computer-readable storage medium and is loaded and executed by a processor, so that a computer implements the method for eliminating coherent fading noise in the above embodiments.

[0142] Optionally, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), magnetic tape, a floppy disk, and an optical disc data storage device, etc. Those skilled in the art can understand that all or part of the steps in implementing the method of the above embodiments can be completed by a program instructing relevant hardware. The program is stored in a storage medium and includes 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 foregoing storage medium includes: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc that can store program code.

[0143] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0144] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0145] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for eliminating coherent fading noise, characterized in that, the method includes: obtaining the original IQ data output by a distributed optical fiber sensing acquisition instrument, where the original IQ data includes IQ signals at different optical fiber sensing signal output positions at different sampling times, and the IQ signals include in-phase signals and quadrature signals; performing a phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured; determining the updated IQ data based on the decoupled displacement phase and the amplitude of the original IQ data; performing a local spatial window summation on the updated IQ data to determine the summed IQ data; determining the demodulation phase after eliminating coherent fading noise based on the summed IQ data; performing phase unwrapping on the demodulation phase after eliminating coherent fading noise to obtain the optical fiber sensing demodulation phase data after eliminating coherent fading noise.

2. The method for eliminating coherent fading noise according to claim 1, characterized in that, the performing a phase decoupling operation on the original IQ data to obtain the displacement phase of the signal to be measured includes: Determine the initial phase ω of IQ demodulation based on the original IQ data 0 (i, j); For the initial phase ω of IQ demodulation 0 Perform phase decoupling operations step by step on (i, j) to eliminate the initial phase ω of IQ demodulation 0 The initial phase of the receiving point at the output position of the fiber optic sensing signal in (i, j) The initial phase of the laser pulse And the optical path integral phase Obtain the displacement phase of the signal to be measured 3. The method for eliminating coherent fading noise according to claim 2, characterized in that, The initial phase ω of IQ demodulation 0 (i, j) performs phase decoupling operations step by step to eliminate the initial phase ω of IQ demodulation 0 (i, j) the initial phase of the receiving point at the output position of the fiber optic sensing signal The initial phase of the laser pulse And the optical path integral phase Obtain the displacement phase of the signal to be measured Including: Based on the initial phase ω of IQ demodulation 0 (i, j), determine the initial phase of the receiving point at the output position of the fiber optic sensing signal Subtract the initial phase of the receiving point from the initial phase ω of IQ demodulation 0 (i, j) to obtain the first decoupled phase ω 1 (i, j) that eliminates the influence of the initial phase of the receiving point; Determine the first decoupling phase ω by linearly fitting the first decoupling phases corresponding to different output positions of the fiber optic sensing signals 1 (i, j) and the linear fitting relationship of the output position j of the fiber optic sensing signal; Determine the intercept of the linear fitting relationship as the initial phase of the laser pulse Determine the slope of the linear fitting relationship as the phase linear change factor k(i); Determine the optical path integral phase based on the phase linear change factor k(i) Subtract the initial phase of the laser pulse and the integrated phase of the optical path from the first decoupled phase ω 1 (i,j) to obtain the second decoupled phase ω 2 (i,j); repeatedly executing the above steps to obtain the second decoupled phase after multiple iterations; wherein, in each iteration process, updating the current initial IQ demodulation phase to the second decoupled phase obtained in the previous iteration; Determine the second decoupled phase after multiple iterations as the displacement phase of the signal to be measured 4. The method for eliminating coherent fading noise according to claim 3, characterized in that, the calculation formula for the initial phase of the receiving point is: Among them, is the initial phase of the receiving point at the j-th optical fiber sensing signal output position; m is the number of time sample points 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; ω 0 (i, j) is the initial IQ demodulation phase at the j-th optical fiber sensing signal output position at the i-th sampling moment, where i is the sampling time serial number and j is the serial number of the optical fiber sensing signal output position.

5. The method for eliminating 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 at the output position of the j-th fiber optic sensing signal at the i-th updated sampling moment; Q d (i,j) is the quadrature signal at the output position of the j-th fiber optic sensing signal at the i-th updated sampling moment; is the displacement phase of the signal to be measured at the output position of the j-th fiber optic sensing signal at the i-th sampling moment; A(i,j) is the amplitude of the original IQ data at the output position of the j-th fiber optic sensing signal at the i-th sampling moment; I(i,j) is the original in-phase signal output by the distributed fiber optic sensing acquisition instrument at the output position of the j-th fiber optic sensing signal at the i-th sampling moment; Q(i,j) is the original quadrature signal output by the distributed fiber optic sensing acquisition instrument at the output position of the j-th fiber optic sensing signal at the i-th sampling moment.

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

7. The method for eliminating coherent fading noise according to claim 1, characterized in that, the demodulation phase after eliminating coherent fading noise is: Among them, is the demodulation phase after eliminating the coherent fading noise; I sum (i,j) is the in-phase signal at the output position of the j-th fiber optic sensing signal at the i-th sampling moment after summation; Q sum (i,j) is the quadrature signal at the output position of the j-th fiber optic sensing signal at the i-th sampling moment after summation.

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

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

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