Method and system for correcting imbalance of orthogonal demodulation of optical fiber distributed acoustic wave sensing data

Abstract

The present invention provides a method and system for correcting quadrature demodulation imbalance in optical fiber distributed acoustic wave sensing data. The method comprises: obtaining I / Q signals I0 and Q0 at each observation point on an optical fiber; performing DC offset correction on the I / Q signals I0 and Q0 to obtain DC offset-corrected I / Q signals I1 and Q1; performing amplitude imbalance correction on the DC offset-corrected I / Q signals I1 and Q1 using a Hilbert transform to obtain amplitude imbalance-corrected I / Q signals I2 and Q2; and performing phase imbalance correction on the amplitude imbalance-corrected I / Q signals I2 and Q2 using a Hilbert transform to obtain imbalance-corrected I / Q signals I3 and Q3. The method provided by the present invention can accurately correct I / Q signals, accurately and efficiently suppress optical fiber demodulation noise, and improve the quality of optical fiber distributed acoustic wave sensing data acquisition.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensing and seismic exploration, and in particular to a method for correcting an imbalance in quadrature demodulation of optical fiber distributed acoustic wave sensing data and a system for correcting an imbalance in quadrature demodulation of optical fiber distributed acoustic wave sensing data. Background Art

[0002] Distributed fiber acoustic sensing (DAS) is a revolutionary new technology that uses optical fiber as both a sensing and transmission medium. It can sense acoustic vibrations around the fiber and record them through high-density temporal and spatial sampling. It is widely used in well seismic data acquisition, dam safety monitoring, perimeter security, and pipeline monitoring. Fiber-optic distributed acoustic sensing (DAS) primarily utilizes the Rayleigh backscattering generated by laser light propagating through optical fiber. Vibrations in the surrounding medium cause corresponding changes in Rayleigh backscattering. Continuous observation and demodulation of this optical signal can reveal seismic information about the formation.

[0003] Fiber-optic distributed acoustic sensing (DAS) technology generally uses a phase-sensitive optical time-domain reflectometer (OTDR) to obtain Rayleigh scattering phase information through in-phase / quadrature (I / Q) phase demodulation. However, inherent errors in fiber-optic sensors, such as DC bias, amplitude imbalance, and phase imbalance, can cause the output I / Q values ​​to exhibit elliptical variations in the crossplot. The demodulated phase exhibits a nonlinear relationship with the measured physical quantity, severely impacting phase demodulation accuracy. The resulting phase noise is difficult to remove in subsequent signal processing. Achieving high-precision DAS phase demodulation has become a key and challenging issue restricting the development of this technology, and many experts at home and abroad are dedicated to eliminating this complex interference. Summary of the Invention

[0004] In response to the technical problem in the existing technology that phase noise is difficult to remove in signal processing, the present invention provides a method and system for correcting orthogonal demodulation imbalance in optical fiber distributed acoustic wave sensing data. This method can accurately correct I / Q signals, accurately and efficiently suppress optical fiber demodulation noise, and improve the data acquisition quality of optical fiber distributed acoustic wave sensing.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for correcting imbalance in quadrature demodulation of optical fiber distributed acoustic wave sensing data, comprising the following steps: obtaining I / Q signals I0 and Q0 at each observation point on an optical fiber; performing DC offset correction on the I / Q signals I0 and Q0 to obtain DC offset-corrected I / Q signals I1 and Q1; performing amplitude imbalance correction on the DC offset-corrected I / Q signals I1 and Q1 using a Hilbert transform to obtain amplitude imbalance-corrected I / Q signals I2 and Q2; and performing phase imbalance correction on the amplitude imbalance-corrected I / Q signals I2 and Q2 using a Hilbert transform to obtain imbalance-corrected I / Q signals I3 and Q3.

[0006] Furthermore, the DC offset correction is performed on the I / Q signals I0 and Q0 to obtain the I / Q signals I1 and Q1 after DC offset correction, including: calculating the corresponding DC offset factor D according to the I / Q signals I0 and Q0 i and D q ; Using the DC bias factor D i and D q A DC offset correction is performed on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after the DC offset correction.

[0007] Furthermore, the corresponding DC bias factor D is calculated based on the I / Q signals I0 and Q0. i and D q , including: calculating the corresponding DC bias factor D according to the mean values ​​of I / Q signals I0 and Q0 at different time points i and D q .

[0008] Furthermore, the Hilbert transform is used to perform amplitude imbalance correction on the I / Q signals I1 and Q1 after DC bias correction to obtain the I / Q signals I2 and Q2 after amplitude imbalance correction, including: using the Hilbert transform and the I / Q signals I1 and Q1 after DC bias correction to calculate the corresponding amplitude imbalance factor A i and A q ;According to the amplitude imbalance factor A i and A q Amplitude imbalance correction is performed on the I / Q signals I1 and Q1 after the DC offset correction to obtain I / Q signals I2 and Q2 after the amplitude imbalance correction.

[0009] Furthermore, the Hilbert transform and the DC offset corrected I / Q signals I1 and Q1 are used to calculate the corresponding amplitude imbalance factor A. i and A q, including: calculating the corresponding instantaneous amplitudes of the I / Q signals I1 and Q1 through Hilbert transform; calculating the corresponding amplitude imbalance factor A according to the average value of the corresponding instantaneous amplitudes at different time points i and A q .

[0010] Furthermore, the method of performing phase imbalance correction on the I / Q signals I2 and Q2 after the amplitude imbalance correction using the Hilbert transform to obtain the I / Q signals I3 and Q3 after the imbalance correction includes: calculating the phase ψ corresponding to the I / Q signals I2 and Q2 using the Hilbert transform and the I / Q signals I2 and Q2 after the amplitude imbalance correction i and ψ q ; According to the phase ψ corresponding to the I / Q signals I2 and Q2 i and ψ q Calculate a phase imbalance factor θ; and perform phase imbalance correction on the I / Q signals I2 and Q2 after amplitude imbalance correction according to the phase imbalance factor θ to obtain I / Q signals I3 and Q3 after imbalance correction.

[0011] Furthermore, the phase ψ corresponding to the I / Q signals I2 and Q2 is calculated using the Hilbert transform and the I / Q signals I2 and Q2 after amplitude imbalance correction. i and ψ q , including: obtaining the corresponding phase ψ by the inverse tangent function of the ratio of the I / Q signals I2 and Q2 to the corresponding I / Q signal after Hilbert transform i and ψ q .

[0012] Furthermore, the phase ψ corresponding to the I / Q signal i and ψ q Calculate the phase imbalance factor θ, including: using the phase ψ at different time points q and ψ i The mean of the difference determines the phase imbalance factor θ.

[0013] Furthermore, phase imbalance correction is performed on the I / Q signals I2 and Q2 after amplitude imbalance correction according to the phase imbalance factor θ in the following manner to obtain I / Q signals I3 and Q3 after imbalance correction:

[0014] I3=I2;

[0015]

[0016] A second aspect of the present invention provides an imbalance correction system for orthogonal demodulation of optical fiber distributed acoustic wave sensing data, characterized in that the imbalance correction system includes: an acquisition module for acquiring I / Q signals I0 and Q0 at each observation point on the optical fiber; a DC bias correction module for performing DC bias correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after the DC bias correction; an amplitude imbalance correction module for performing amplitude imbalance correction on the I / Q signals I1 and Q1 after the DC bias correction using a Hilbert transform to obtain I / Q signals I2 and Q2 after the amplitude imbalance correction; and a phase imbalance correction module for performing phase imbalance correction on the I / Q signals I2 and Q2 after the amplitude imbalance correction using a Hilbert transform to obtain I / Q signals I3 and Q3 after the imbalance correction.

[0017] The technical solution provided by the present invention has at least the following technical effects:

[0018] The present invention discloses a method for correcting orthogonal demodulation imbalance of optical fiber distributed acoustic wave sensing data. The method obtains I / Q signals I0 and Q0 at each observation point on an optical fiber, performs DC offset correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after DC offset correction, then uses Hilbert transform to perform amplitude imbalance correction on the I / Q signals I1 and Q1 after DC offset correction to obtain I / Q signals I2 and Q2 after amplitude imbalance correction, and then uses Hilbert transform to perform phase imbalance correction on the I / Q signals I2 and Q2 after amplitude imbalance correction to obtain I / Q signals I3 and Q3 after imbalance correction. The method provided by the present invention can accurately correct I / Q signals, accurately and efficiently suppress optical fiber demodulation noise, and improve the data acquisition quality of optical fiber distributed acoustic wave sensing.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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:

[0021] Figure 1 A flowchart of a method for correcting imbalance in orthogonal demodulation of optical fiber distributed acoustic sensing data provided by an embodiment of the present invention;

[0022] Figure 2 The I / Q signal I0(t i ) and Q0(t i)

[0023] Figure 3 The I / Q signal I1 (t i ) and Q1(t i )

[0024] Figure 4 The I / Q signal I2(t i ) and Q2(t i )

[0025] Figure 5 A schematic diagram of a phase and phase difference θ curve of an I / Q signal obtained by Hilbert transform in a method for orthogonal demodulation imbalance correction of optical fiber distributed acoustic sensor data provided by an embodiment of the present invention;

[0026] Figure 6 The I / Q signal I3 (t i ) and Q3(t i )

[0027] Figure 7 The I / Q signal I2(t i ) and Q2(t i ) is a partially enlarged schematic diagram;

[0028] Figure 8 The I / Q signal I3 (t i ) and Q3(t i ) is a partially enlarged schematic diagram;

[0029] Figure 9 A schematic diagram of a demodulation phase and a demodulation phase difference curve before and after imbalance correction in a method for orthogonal demodulation imbalance correction of optical fiber distributed acoustic wave sensing data provided by an embodiment of the present invention;

[0030] Figure 10 A schematic diagram of amplitude curves before and after imbalance correction in the imbalance correction method for orthogonal demodulation of optical fiber distributed acoustic sensing data provided by an embodiment of the present invention;

[0031] Figure 11A schematic diagram of an I / Q cross-plot before and after imbalance correction in the method for orthogonal demodulation of optical fiber distributed acoustic sensor data provided by an embodiment of the present invention;

[0032] Figure 12 A schematic diagram of I / Q demodulation background noise before and after imbalance correction in the method for orthogonal demodulation imbalance correction of optical fiber distributed acoustic sensing data provided by an embodiment of the present invention;

[0033] Figure 13 A schematic diagram of the I / Q demodulated seismic wave field before and after imbalance correction in the method for orthogonal demodulation of optical fiber distributed acoustic sensing data provided by an embodiment of the present invention;

[0034] Figure 14 A schematic diagram of an imbalance correction device for orthogonal demodulation of optical fiber distributed acoustic sensing data provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] 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.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other.

[0037] In the present invention, unless otherwise specified, directional words such as "up, down, top, bottom" are usually used to describe the relative positions of components in the directions shown in the drawings or in the vertical, perpendicular or gravity directions.

[0038] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0039] Please refer to Figure 1 The first aspect of the present invention provides a method for correcting imbalance of orthogonal demodulation of optical fiber distributed acoustic wave sensing data, comprising the following steps:

[0040] S101: Obtain I / Q signals I0 and Q0 at each observation point on the optical fiber.

[0041] Specifically, in embodiments of the present invention, a fiber-optic distributed acoustic wave sensing instrument is connected to an optical fiber coupled to the object to be measured. It emits optical pulses at a constant frequency. In the absence of external acoustic signals near the fiber, each observation point on the fiber outputs I / Q signals, I0 and Q0. This instrument is based on a phase-sensitive optical time-domain reflectometer (OTDR). The I / Q signals are in-phase and quadrature signals, assuming no external acoustic signals are near each observation point on the fiber.

[0042] S102: Perform DC offset correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after DC offset correction.

[0043] Furthermore, the DC bias correction is performed on the I / Q signals I0 and Q0 to obtain the I / Q signals I1 and Q1 after DC bias correction, including: calculating the corresponding DC bias factor D according to the average value of the I / Q signals I0 and Q0 at different time points i and D q :

[0044]

[0045]

[0046] Among them, I0(t i ) and Q0(t i ) is t i I / Q signals I0 and Q0 at time instant.

[0047] Using the DC bias factor D i and D q Perform DC offset correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after DC offset correction:

[0048] I1(t i )=I0(t i )-D i ;

[0049] Q1(t i )=Q0(t i )-D q ;

[0050] Among them, I1(t i ) and Q1(t i ) is t i I / Q signals I1 and Q1 at time instant.

[0051] S103: Perform amplitude imbalance correction on the I / Q signals I1 and Q1 after DC offset correction using Hilbert transform to obtain I / Q signals I2 and Q2 after amplitude imbalance correction.

[0052] Furthermore, the Hilbert transform is used to perform amplitude imbalance correction on the I / Q signals I1 and Q1 after DC bias correction to obtain the I / Q signals I2 and Q2 after amplitude imbalance correction, including: calculating the corresponding instantaneous amplitudes of the I / Q signals I1 and Q1 through the Hilbert transform; calculating the corresponding amplitude imbalance factor A according to the average of the corresponding instantaneous amplitudes at different time points i and Aq :

[0053]

[0054]

[0055] in, and is the I / Q signal I1 after DC offset correction (t i ) and Q1(t i ) I / Q signal obtained after Hilbert transform;

[0056] According to the amplitude imbalance factor A i and A q Perform amplitude imbalance correction on the I / Q signals I1 and Q1 after DC offset correction to obtain I / Q signals I2 and Q2 after amplitude imbalance correction:

[0057] i2(t i )=I1(t i ) / A i ;

[0058] Q2(t i )=Q1(t i ) / A q ;

[0059] Among them, I2(t i ) and Q2(t i ) is t i I / Q signals I2 and Q2 at moment .

[0060] S104: Perform phase imbalance correction on the amplitude imbalance-corrected I / Q signals I2 and Q2 using Hilbert transform to obtain imbalance-corrected I / Q signals I3 and Q3.

[0061] Furthermore, the phase imbalance correction is performed on the I / Q signals I2 and Q2 after the amplitude imbalance correction using the Hilbert transform to obtain the I / Q signals I3 and Q3 after the imbalance correction, including: obtaining the corresponding phase ψ by the inverse tangent function of the ratio of the I / Q signals I2 and Q2 to the corresponding I / Q signal after the Hilbert transform i and ψ q :

[0062]

[0063]

[0064] in, and is the I / Q signal I2 after amplitude imbalance correction (ti ) and Q2(t i ) I / Q signal obtained after Hilbert transform;

[0065] Using the phase ψ at different time points q and ψ i The mean of the difference determines the phase imbalance factor θ:

[0066]

[0067] The I / Q signal I2 (t i ) and Q2(t i ) to perform phase imbalance correction and obtain the I / Q signal I3(t i ) and Q3(t i ):

[0068] I3(t i )=I2(t i );

[0069]

[0070] Afterwards, the above data can be used for subsequent phase demodulation processing and phase unwrapping to obtain the demodulated phase ω and amplitude Amp, and obtain the acoustic wave field data. The calculation formula for the demodulated phase ω and amplitude is as follows:

[0071]

[0072]

[0073] In the embodiment of the present invention, the DC bias factor D i and D q , Amplitude imbalance factor A i and A q The sum of the phase imbalance factors θ can be obtained by uniformly selecting positions without external acoustic signals after obtaining the I / Q signals I0 and Q0 at each observation point on the optical fiber, and then applied to all collected data at all observation points.

[0074] Example

[0075] The fiber optic distributed acoustic wave sensor acquisition instrument is connected to the optical fiber in the casing of a certain well, and the optical pulse is emitted at a frequency of 10K. When there is no ground artificial source excitation and no external acoustic wave signal around the optical fiber, the optical pulses at each observation point on the optical fiber are collected at t i The I / Q signal I0 (t i ) and Q0(t i ),like Figure 2 shown.

[0076] According to the I / Q signal I0(t i ) and Q0(t i ) Calculate the corresponding DC bias factor D by taking the average of multiple points i and D q :

[0077]

[0078]

[0079] Using the DC bias factor D i and D q For I / Q signal I0(t i ) and Q0(t i ) to perform DC offset correction and obtain the I / Q signal I1(t i ) and Q1(t i ),like Figure 3 As shown:

[0080] I1(t i )=I0(t i )-D i ;

[0081] Q1(t i )=Q0(t i )-D q .

[0082] Then, the corresponding amplitude imbalance factor A is calculated using the Hilbert transform and the DC offset corrected I / Q signals I1(t) and Q1(t). i and A q :

[0083]

[0084]

[0085] in, and is the I / Q signal I1 after DC offset correction (t i ) and Q1(t i ) I / Q signal obtained after Hilbert transform;

[0086] According to the amplitude imbalance factor A i and A q The I / Q signal I1(t i ) and Q1(t i ) to perform amplitude imbalance correction and obtain the I / Q signal I2(t i) and Q2(t i ),like Figure 4 As shown:

[0087] I2(t i )=I1(t i ) / A i ;

[0088] Q2(t i )=Q1(t i ) / A q .

[0089] Then, the I / Q signal I2(t i ) and Q2(t i ) calculates the I / Q signal I2(t i ) and Q2(t i ) corresponds to the phase ψ i (t i ) and ψ q (t i ),like Figure 5 As shown:

[0090]

[0091]

[0092] in, and is the I / Q signal I2 after amplitude imbalance correction (t i ) and Q2(t i ) is the I / Q signal obtained after Hilbert transform.

[0093] Please refer to Figure 5 , according to the phase ψ corresponding to the I / Q signal i (t i ) and ψ1(t i ) Calculate the phase imbalance factor. The I / Q signal itself should be an orthogonal signal. Therefore, the phase imbalance factor (phase difference) θ is:

[0094]

[0095] In this embodiment, the average phase difference is -14 degrees.

[0096] The I / Q signal I2(t i ) and Q2(t i ) to perform phase imbalance correction and obtain the I / Q signal I3(t i ) and Q3(ti ),like Figure 6-8 As shown, Figure 7 and Figure 8 This is a partial enlarged diagram of the I / Q signal before and after phase imbalance correction:

[0097] I3(t i )=I2(t i );

[0098]

[0099] After obtaining the imbalance-corrected I / Q signal, the above data can be used for subsequent phase demodulation and phase unwrapping to obtain the demodulated phase ω and amplitude Amp, and obtain the acoustic wave field data. The calculation formula for the demodulated phase ω and amplitude Amp is as follows:

[0100]

[0101]

[0102] Please refer to Figures 9-12 The demodulation phase and demodulation phase difference curves before and after phase imbalance correction are as follows: Figure 9 As shown in the figure, the amplitude curves before and after phase imbalance correction are as follows: Figure 10 As shown, the I / Q cross-plot before and after imbalance correction is as follows Figure 11 As shown, it can be seen that the shape is elliptical before correction and circular after correction. The I / Q demodulation background noise before and after imbalance correction is as follows: Figure 12 As shown, the noise level is reduced by more than 60% by the method of the present invention. The I / Q demodulated seismic wave field before and after the imbalance correction is shown in FIG. Figure 13 As shown, the signal-to-noise ratio is improved by 3-4 times through the method of the present invention.

[0103] Please refer to Figure 14 According to a second aspect of the present invention, a quadrature demodulation imbalance correction system for optical fiber distributed acoustic wave sensing data is provided. The imbalance correction system includes: an acquisition module for acquiring I / Q signals I0 and Q0 at each observation point on an optical fiber; a DC bias correction module for performing DC bias correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after the DC bias correction; an amplitude imbalance correction module for performing amplitude imbalance correction on the I / Q signals I1 and Q1 after the DC bias correction using a Hilbert transform to obtain I / Q signals I2 and Q2 after the amplitude imbalance correction; and a phase imbalance correction module for performing phase imbalance correction on the I / Q signals I2 and Q2 after the amplitude imbalance correction using a Hilbert transform to obtain I / Q signals I3 and Q3 after the imbalance correction.

[0104] 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.

[0105] 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.

[0106] 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.

Claims

1. A method for correcting imbalance in orthogonal demodulation of optical fiber distributed acoustic wave sensing data, characterized in that: The method comprises: Obtain the I / Q signals I0 and Q0 at each observation point on the optical fiber; Performing DC offset correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after DC offset correction; Performing amplitude imbalance correction on the I / Q signals I1 and Q1 after DC offset correction using Hilbert transform to obtain I / Q signals I2 and Q2 after amplitude imbalance correction; Performing phase imbalance correction on the I / Q signals I2 and Q2 after amplitude imbalance correction using Hilbert transform to obtain I / Q signals I3 and Q3 after imbalance correction; wherein, the method specifically includes: calculating the phase of the I / Q signals I2 and Q2 corresponding to the I / Q signals I2 and Q2 using Hilbert transform and the I / Q signals I2 and Q2 after amplitude imbalance correction; and ; According to the phase corresponding to the I / Q signal I2 and Q2 and Calculate the phase imbalance factor θ; where the phase at different time points is used The phase imbalance factor θ is determined by the mean of the difference; and phase imbalance correction is performed on the I / Q signals I2 and Q2 after amplitude imbalance correction according to the phase imbalance factor θ to obtain I / Q signals I3 and Q3 after imbalance correction.

2. The method according to claim 1, characterized in that The DC offset correction is performed on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after DC offset correction, including: Calculate the corresponding DC bias factor D based on the I / Q signals I0 and Q0 i and D q ; Using the DC bias factor D i and D q A DC offset correction is performed on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after the DC offset correction.

3. The method according to claim 2, characterized in that The corresponding DC bias factor D is calculated based on the I / Q signals I0 and Q0. i and D q ,include: Calculate the corresponding DC bias factor D according to the mean of I / Q signals I0 and Q0 at different time points i and D q .

4. The method according to claim 1, wherein The method of performing amplitude imbalance correction on the I / Q signals I1 and Q1 after DC offset correction by using Hilbert transform to obtain I / Q signals I2 and Q2 after amplitude imbalance correction includes: Calculate the corresponding amplitude imbalance factor A using the Hilbert transform and the DC offset corrected I / Q signals I1 and Q1 i and A q ; According to the amplitude imbalance factor A i and A q Amplitude imbalance correction is performed on the I / Q signals I1 and Q1 after the DC offset correction to obtain I / Q signals I2 and Q2 after the amplitude imbalance correction.

5. The method according to claim 4, characterized in that The Hilbert transform and the DC offset corrected I / Q signals I1 and Q1 are used to calculate the corresponding amplitude imbalance factor A. i and A q ,include: Calculate the corresponding instantaneous amplitudes of the I / Q signals I1 and Q1 through Hilbert transform; Calculate the corresponding amplitude imbalance factor A according to the average value of the corresponding instantaneous amplitude at different time points i and A q .

6. The method according to claim 1, characterized in that The phases corresponding to the I / Q signals I2 and Q2 are calculated by using the Hilbert transform and the I / Q signals I2 and Q2 after the amplitude imbalance correction. and ,include: The corresponding phase is obtained by the inverse tangent function of the ratio of the I / Q signal I2 and Q2 to the corresponding I / Q signal after Hilbert transform and .

7. The method according to claim 1, characterized in that Phase imbalance correction is performed on the I / Q signals I2 and Q2 after amplitude imbalance correction according to the phase imbalance factor θ in the following manner to obtain I / Q signals I3 and Q3 after imbalance correction: ； 。 8. A fiber-optic distributed acoustic sensor data orthogonal demodulation imbalance correction system, characterized in that: The imbalance correction system comprises: An acquisition module is used to obtain the I / Q signals I0 and Q0 of each observation point on the optical fiber; A DC offset correction module is used to perform DC offset correction on the I / Q signals I0 and Q0 to obtain I / Q signals I1 and Q1 after DC offset correction; an amplitude imbalance correction module, configured to perform amplitude imbalance correction on the I / Q signals I1 and Q1 after DC bias correction using a Hilbert transform, to obtain I / Q signals I2 and Q2 after amplitude imbalance correction; The phase imbalance correction module is used to perform phase imbalance correction on the I / Q signals I2 and Q2 after amplitude imbalance correction using Hilbert transform to obtain I / Q signals I3 and Q3 after imbalance correction; wherein, the module specifically includes: calculating the phase of the I / Q signals I2 and Q2 corresponding to the I / Q signals I2 and Q2 using Hilbert transform and the I / Q signals I2 and Q2 after amplitude imbalance correction; and ; According to the phase corresponding to the I / Q signal I2 and Q2 and Calculate the phase imbalance factor θ; where the phase at different time points is used The phase imbalance factor θ is determined by the mean of the difference; and phase imbalance correction is performed on the I / Q signals I2 and Q2 after amplitude imbalance correction according to the phase imbalance factor θ to obtain I / Q signals I3 and Q3 after imbalance correction.

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