Equivalent self-noise pressure suppression method based on dual-channel distributed sound sensing system

Abstract

The invention discloses an equivalent self-noise pressure suppression method based on a dual-channel distributed acoustic sensing system, and the method comprises the steps: carrying out the light splitting of light emitted by a narrow-linewidth laser through a first coupler C1, enabling one path of light to generate a pulse signal through an acoustic optical modulator (AOM), enabling the other path of light to pass through a second coupler C2, and enabling the other path of light to pass through a second coupler C1; the pulse light is divided into two beams of transmission light, the two beams of transmission light are injected into a connected sensing optical fiber through two groups of erbium-doped optical fiber amplifiers (EDFA), two groups of filters, two groups of circulators and a fan-in coupler Fan-in Coupler, and the pulse light is subjected to backward Rayleigh scattering in the sensing optical fiber; according to the invention, based on a dual-channel DAS system, two fiber cores of the multi-core optical fiber are used as sensing optical fibers, and the space division signals of the two cores are multiplexed, so that the performance that the equivalent self-noise pressure drop is 2.54 dB in the frequency band of 100-1000Hz is realized under the condition that the noise correlation coefficient of the dual-core signals is 0.11, and the detection capability of the system on low-frequency weak signals can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater acoustic detection of distributed acoustic sensor systems, and in particular relates to an equivalent self-noise pressure suppression method based on a dual-channel distributed acoustic sensor system. Background Art

[0002] Fiber-optic distributed acoustic sensing (DAS) technology injects the detection pulse laser emitted by the transmitter into the sensing fiber. Affected by impurities in the sensing fiber, the detection light undergoes coherent back-Rayleigh scattering and returns to the transmitter. Phase demodulation can obtain the strain information of any section of the sensing fiber, and then restore the acoustic wave signal. Therefore, the sensing fiber is a closely arranged acoustic wave sensor. DAS has the characteristics of simple system structure, high spatial resolution, strong anti-electromagnetic interference, and flexible array structure. Therefore, it can provide a new technical means for ocean underwater acoustic sensing and detection. Common DAS systems usually use single-mode optical fiber as the sensing fiber. The back-Rayleigh scattered light is extremely weak during long-distance transmission, and the system equivalent self-noise pressure spectrum level is high. Due to this limitation, the minimum detectable sound pressure performance of the traditional DAS system is poor, and there is a certain difficulty in detecting weak acoustic wave signals.

[0003] In order to improve the equivalent self-noise pressure suppression and sensitivity of the single-mode fiber DAS system, researchers have introduced special optical fibers to improve system performance, such as continuous scattering enhanced fiber, discrete scattering enhanced fiber with ultra-weak fiber Bragg grating (UWFBG) or scattering enhancement points (SEP), and fiber optic sensitivity enhancement. The continuous scattering enhancement scheme mainly includes writing continuous gratings and changing fiber doping. However, while enhancing the amplitude of backward Rayleigh scattering, it will also cause the optical power loss to increase exponentially, greatly reducing the detection distance. The bandwidth of UWFBG is narrow. In special environments such as high pressure and low temperature, the wavelength of the detection light will mismatch with the reflection wavelength of UWFBG, resulting in a sensing blind area. Therefore, it cannot be used in special environments such as underwater. Sensitization optical fiber mainly improves the sensitivity of the signal phase to the change of sound pressure by spiral winding and secondary coating. Spiral winding sensitivity enhancement optical fiber can significantly reduce the equivalent self-noise pressure of the system, but the diameter of the publicly reported spiral sensitivity enhancement structure is not less than 12.5mm, which is difficult to apply to some occasions that require small-sized hydrophones. Secondary coating sensitivity enhancement is to coat a layer of sound pressure sensitive material on the surface of the optical fiber to improve the sound wave detection performance. Its sensitivity is lower than that of the spirally enhanced sensitized optical fiber and it is difficult to meet the needs.

[0004] Researchers have conducted research on the in-phase superposition of multiple detection array output signals, but they mostly analyzed high-frequency land signals and did not consider the correlation of noise. In fact, the noise is added together while accumulating. If the noise of each array element is correlated, the equivalent self-noise pressure cannot be suppressed; and the underwater noise environment is complex, and low-frequency noise such as waves and marine life will interfere with the detection of low-frequency underwater acoustic signals. Therefore, reducing the system's low-frequency equivalent self-noise pressure can improve the detection performance of weak underwater signals. Summary of the invention

[0005] Aiming at the problems of high equivalent self-noise pressure and insufficient detection capability of weak signals in the existing DAS system, the present invention provides a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensor system, designs a dual-channel DAS detection and demodulation system, ensures that the same detection pulse light is emitted by the dual channels at the same time, which is the premise for the subsequent signal superposition; uses multi-core fiber (MCF) as a sensing fiber, connects two channels of the fiber to a DAS module respectively, transmits two sensing cores in parallel, and each core has a consistent response to external disturbances but inconsistent noises, superimposes signals at the same position, reduces the system equivalent self-noise pressure, can improve the system's detection capability for low-frequency weak signals, suppresses the equivalent self-noise pressure spectrum level of the DAS system, reduces the system equivalent self-noise pressure and ensures the small diameter characteristic of the hydrophone unit, which is of great significance for the detection of low-frequency weak signals.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] The embodiment of the present invention provides a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system, which is characterized by comprising the following steps:

[0008] Step 1, the light emitted by the narrow linewidth laser Laser is split by the first coupler C1, one beam of light passes through the acousto-optic modulator AOM to generate a pulse signal, and then is split into two beams of transmission light by the second coupler C2, which are respectively injected into the connected sensing optical fiber through two groups of erbium-doped fiber amplifiers EDFA, two groups of filters Filter, two groups of circulators Circulator, and fan-in coupler Fan-in Coupler. The pulse light is back-scattered by Rayleigh in the sensing optical fiber; wherein the splitting ratio of the first coupler C1 is 98:1:1, and the splitting ratio of the second coupler C2 is 1:1;

[0009] Step 2, when the sensing optical fiber is subjected to the effect of sound pressure, the phase of the backscattered light changes, and interferes with the two 1% local oscillator lights separated by the laser in the third coupler C3 and the fourth coupler C4 respectively. After the photoelectric conversion is completed by the first balanced detector BPD1 and the second balanced detector BPD2, it is acquired by the data acquisition card DAQ, and the phase distribution of the scattered light in the entire sensing optical fiber is obtained by heterodyne phase detection, and then the sound pressure fluctuation information can be obtained from the phase difference of the scattered light between different positions; wherein, the splitting ratios of the third coupler C3 and the fourth coupler C4 are both 1:1;

[0010] Step 3, the sensing optical fiber is set as a multi-core optical fiber, with the two cores of the multi-core optical fiber as the sensing optical fiber, and the two-core space division signals are multiplexed. When the noise correlation coefficient of the dual-core signal is 0.11, the equivalent self-noise pressure reduction performance of 2.54dB in the frequency band of 100-1000Hz is achieved.

[0011] In a preferred embodiment of the present invention, the number of multi-core optical fibers in step 3 is 7, the core Core 7 is located at the center of the seven cores, and the other 6 cores are evenly distributed around the core Core 7;

[0012] The phase difference signals demodulated from core 1 and core 2 are superimposed. When the noises of the two cores are completely uncorrelated, the equivalent self-noise pressure of the system can be reduced by 10lg2=3dB after superposition. However, in fact, part of the noise sources of the two cores come from the same optical device, such as lasers and acousto-optic frequency shifters. The phase noises generated by the two make the noise characteristics of the two cores have a certain correlation. On the other hand, core 1 and core 2 are in a multi-core optical fiber and are adjacent to each other. They have the same response to the surrounding environmental noise and are also correlated. Therefore, the dual-core noise correlation coefficient is calculated first, and on this basis, the actual equivalent self-noise pressure suppression effect after the dual-core signals are superimposed is calculated.

[0013] A preferred embodiment of the present invention further comprises: Step 4, assuming m array element signals s1(t), s2(t), ..., s m (t) linear addition, the average power of the output signal is

[0014]

[0015] In the formula, a is the proportional coefficient. Similarly, the average noise power is:

[0016]

[0017] make The average signal-to-noise ratio of the array can be expressed as:

[0018]

[0019] Among them, (ρ s ) ij ,(ρ n ) ij Respectively represent the mutual correlation coefficient between the signal and noise of the i-th array element and the j-th array element:

[0020]

[0021] The logarithm of the ratio of the accumulated signal-to-noise ratio to the signal-to-noise ratio of a single array element is the array gain:

[0022]

[0023] Therefore, the gain after array accumulation depends on the mutual correlation coefficient of the signal and noise between the array elements; when the signal is completely correlated but the noise is completely uncorrelated,

[0024]

[0025] The array gain after the accumulation of m array elements is AG = 10lgm; when the signal is completely correlated but the noise is partially correlated,

[0026]

[0027] The array gain is:

[0028] Dual-core signal superposition, that is, m = 2, the array gain is

[0029] A preferred embodiment of the present invention further includes: step 5, noise accumulation gain calculation: according to the time domain curve and power spectrum density of the dual-core noise and the accumulated noise, the average power of the noise in the frequency band of 100Hz to 1000Hz is -66.8159dB, -66.5635dB, and -63.2594dB respectively; the result of repeating the experiment five times: calculated by formula (5), the mutual correlation coefficient of the noise is 0.11, that is, the noise has correlation, and the noise improvement is calculated to be 3.46dB.

[0030] A preferred embodiment of the present invention further includes: step 6, equivalent self-noise pressure suppression effect: taking the underwater acoustic sound pressure frequency of 500Hz as an example, the time domain signal and PSD curve of the demodulated phase signal before and after accumulation, the PSDs of the core 1 and the core 2 and the accumulated signal frequency points are -52.24dB, -52.25dB, and -46.25dB, respectively, with an average increase of about 5.995dB; according to the experimental results of multiple frequency points: the PSDs of the signal frequency points after accumulation are actually increased by about 6dB, with an average of about 5.99dB, which is consistent with the theoretical derivation;

[0031] Among them, when the noise correlation coefficient ρ n=0.11, it can be known from formula (9) that the theoretical signal-to-noise ratio gain after the dual-core signal is accumulated is 2.56 dB. The experimental results show that the equivalent self-noise pressure drop of the actual accumulated signal is 2.54 dB, which is close to the theoretical value.

[0032] An embodiment of the present invention provides an electronic device, comprising: at least one memory for storing computer programs; and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system according to the above embodiment.

[0033] An embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system as described in the above embodiment.

[0034] Compared with the prior art, the embodiment of the present invention provides a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system, which has the following beneficial effects: the present invention is based on a dual-channel DAS system, uses the two cores of a multi-core optical fiber as sensing optical fibers, and multiplexes the two-core space-division signals. When the noise correlation coefficient of the dual-core signal is 0.11, the equivalent self-noise pressure is reduced by 2.54 dB in the frequency band of 100 to 1000 Hz, which can improve the system's detection capability for low-frequency weak signals. The suppression of the equivalent self-noise pressure is of great significance for improving the accuracy of the system in restoring vibration signals and enhancing the system's detection capability for underwater low-frequency weak signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic diagram of a corresponding system framework of an equivalent self-noise pressure suppression method based on a dual-channel distributed acoustic sensing system provided in an embodiment of the present application.

[0037] Figure 2 A schematic diagram of a multi-core sensing optical fiber connection based on a fan-in / fan-out coupler provided in an embodiment of the present application.

[0038] Figure 3 A schematic diagram of the multi-core optical fiber distribution of a sensing optical fiber provided in an embodiment of the present application.

[0039] Figure 4 This is a schematic diagram of the time domain curve of the dual-core noise and the accumulated noise provided in the embodiment of the present application.

[0040] Figure 5 A schematic diagram of a power spectral density curve of dual-core noise and accumulated noise provided in an embodiment of the present application.

[0041] Figure 6 The embodiment of the present application provides a schematic diagram of the time domain signal curve before and after the demodulated phase signal is accumulated, taking the underwater acoustic pressure frequency of 500 Hz as an example.

[0042] Figure 7 The embodiment of the present application provides a schematic diagram of the PSD curve before and after the demodulated phase signal is accumulated, taking the underwater acoustic pressure frequency of 500 Hz as an example. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0044] refer to Figure 1 The embodiment of the present invention provides a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system, comprising the following steps:

[0045] Step 1, the light emitted by the narrow linewidth laser Laser is split by the first coupler C1, one path of light passes through the acousto-optic modulator AOM to generate a pulse signal, and then is divided into two beams of transmission light by the second coupler C2, which are respectively injected into the connected sensing optical fiber through two groups of erbium-doped fiber amplifiers EDFA, two groups of filters Filter, two groups of circulators Circulator, and fan-in coupler Fan-inCoupler, and the pulse light undergoes back Rayleigh scattering in the sensing optical fiber; wherein the splitting ratio of the first coupler C1 is 98:1:1, and the splitting ratio of the second coupler C2 is 1:1; the fan-in coupler Fan-inCoupler of this embodiment is optically connected to the multi-core optical fiber MCF.

[0046] Step 2, when the sensing optical fiber is subjected to the effect of sound pressure, the phase of the backscattered light changes, and interferes with the two 1% local oscillator lights separated by the laser in the third coupler C3 and the fourth coupler C4 respectively. After the photoelectric conversion is completed by the first balanced detector BPD1 and the second balanced detector BPD2, it is acquired by the data acquisition card DAQ, and the phase distribution of the scattered light in the entire sensing optical fiber is obtained by heterodyne phase detection, and then the sound pressure fluctuation information can be obtained from the phase difference of the scattered light between different positions; wherein, the splitting ratios of the third coupler C3 and the fourth coupler C4 are both 1:1;

[0047] Step 3, the sensing optical fiber is set as a multi-core optical fiber, with the two cores of the multi-core optical fiber as the sensing optical fiber, and the two-core space division signals are multiplexed. When the noise correlation coefficient of the dual-core signal is 0.11, the equivalent self-noise pressure reduction performance of 2.54dB in the frequency band of 100-1000Hz is achieved.

[0048] refer to Figure 2 and Figure 3 , the number of multi-core optical fibers in step 3 is 7, core 7 is located at the center of the seven cores, and the other 6 cores are evenly distributed around core 7; the sensing fiber is a multi-core fiber. The phase difference signals demodulated from core 1 and core 2 are superimposed. When the noises of the two cores are completely uncorrelated, the equivalent self-noise pressure of the system can be reduced by 10lg2=3dB after superposition. However, in fact, part of the noise source of the dual cores comes from the same optical device, such as lasers and acousto-optic frequency shifters. The phase noise generated by the two makes the dual cores have a certain correlation in noise characteristics; on the other hand, core 1 and core 2 are in a multi-core optical fiber and are adjacent to each other. They have the same response to the surrounding environmental noise and are also correlated. Therefore, the dual-core noise correlation coefficient is first calculated, and on this basis, the actual equivalent self-noise pressure suppression effect after the dual-core signal superposition is calculated.

[0049] A method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensor system also includes: step 4, assuming m array element signals s1(t), s2(t), ..., s with consistent sensitivity m (t) linear addition, the average power of the output signal is:

[0050]

[0051] In the formula, a is the proportional coefficient. Similarly, the average noise power is:

[0052]

[0053] make The average signal-to-noise ratio of the array can be expressed as:

[0054]

[0055] Among them, (ρ s ) ij ,(ρ n ) ij Respectively represent the mutual correlation coefficient between the signal and noise of the i-th array element and the j-th array element:

[0056]

[0057] The logarithm of the ratio of the accumulated signal-to-noise ratio to the signal-to-noise ratio of a single array element is the array gain:

[0058]

[0059] Therefore, the gain after array accumulation depends on the mutual correlation coefficient of the signal and noise between the array elements; when the signal is completely correlated but the noise is completely uncorrelated,

[0060]

[0061] The array gain after the accumulation of m array elements is AG = 10lgm; when the signal is completely correlated but the noise is partially correlated,

[0062]

[0063] The array gain is:

[0064] Dual-core signal superposition, that is, m = 2, the array gain is

[0065] A method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensor system also includes: Step 5, noise accumulation gain calculation: according to the time domain curve of the dual-core noise and the accumulated noise ( Figure 4 ) and power spectral density ( Figure 5 ), the average noise power in the frequency band of 100Hz to 1000Hz is -66.8159dB, -66.5635dB, and -63.2594dB respectively; the results of five repeated experiments (Table 1): calculated by formula (5), the mutual correlation coefficient of the noise is 0.11, that is, the noise has correlation, and the noise improvement is 3.46dB after calculation. From the data in Table 2, it can be seen that the actual average PSD of the accumulated noise is 3.46dB, which is consistent with the calculated value.

[0066] Table 1 Noise PSD (dB / Hz) before and after dual-core signal accumulation

[0067]

[0068] A method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensor system also includes: Step 6, equivalent self-noise pressure suppression effect: Taking the underwater acoustic pressure frequency of 500 Hz as an example, the demodulated phase signal is accumulated before and after the time domain signal ( Figure 6 ) and PSD curves ( Figure 7 ), the PSDs of core 1, core 2 and the accumulated signal frequency points are -52.24dB, -52.25dB and -46.25dB respectively, with an average increase of about 5.995dB; according to the experimental results of multiple frequency points (Table 2): the PSDs of the accumulated signal frequency points actually increase by about 6dB, with an average of about 5.99dB, which is consistent with the theoretical derivation.

[0069] Table 2 PSD data of each frequency point before and after the dual-core signal is accumulated (dB / Hz)

[0070]

[0071] Among them, when the noise correlation coefficient ρ n =0.11, it can be seen from formula (9) that the theoretical signal-to-noise ratio gain after the dual-core signal accumulation is 2.56dB. The experimental results (Table 3) show that the equivalent self-noise pressure of the actual accumulated signal is reduced by 2.54dB, which is close to the theoretical value. The suppression of the system's equivalent self-noise pressure is of great significance for improving the accuracy of the system's restoration of vibration signals and enhancing the system's ability to detect underwater low-frequency weak signals.

[0072] Table 3 Signal-to-noise ratio data of each frequency point before and after the dual-core signal is accumulated (dB)

[0073]

[0074] The present invention is based on a dual-channel DAS system, uses two cores of a multi-core optical fiber as sensing optical fibers, and multiplexes the two-core space division signals. When the noise correlation coefficient of the dual-core signal is 0.11, the equivalent self-noise pressure in the 100-1000Hz frequency band is reduced by 2.54dB, which can improve the system's detection capability for low-frequency weak signals. The suppression of the system's equivalent self-noise pressure is of great significance for improving the accuracy of the system's restoration of vibration signals and enhancing the system's detection capability for underwater low-frequency weak signals.

[0075] An embodiment of the present invention provides an electronic device, comprising: at least one memory for storing computer programs; and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system according to the above embodiment.

[0076] An embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system as described in the above embodiment.

[0077] Although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensor system, characterized in that: The following steps are involved: Step 1, the light emitted by the narrow linewidth laser Laser is split by the first coupler C1, one beam of light passes through the acousto-optic modulator AOM to generate a pulse signal, and then is split into two beams of transmission light by the second coupler C2, which are respectively injected into the connected sensing optical fiber through two groups of erbium-doped fiber amplifiers EDFA, two groups of filters Filter, two groups of circulators Circulator, and fan-in coupler Fan-in Coupler. The pulse light is back-scattered by Rayleigh in the sensing optical fiber; wherein the splitting ratio of the first coupler C1 is 98:1:1, and the splitting ratio of the second coupler C2 is 1:1; Step 2, when the sensing optical fiber is subjected to the effect of sound pressure, the phase of the backscattered light changes, and interferes with the two 1% local oscillator lights separated by the laser in the third coupler C3 and the fourth coupler C4 respectively. After the photoelectric conversion is completed by the first balanced detector BPD1 and the second balanced detector BPD2, it is acquired by the data acquisition card DAQ, and the phase distribution of the scattered light in the entire sensing optical fiber is obtained by heterodyne phase detection, and then the sound pressure fluctuation information can be obtained from the phase difference of the scattered light between different positions; wherein, the splitting ratios of the third coupler C3 and the fourth coupler C4 are both 1:1; Step 3, the sensing optical fiber is set as a multi-core optical fiber, with the two cores of the multi-core optical fiber as the sensing optical fiber, and the two-core space division signals are multiplexed. When the noise correlation coefficient of the dual-core signal is 0.11, the equivalent self-noise pressure reduction performance of 2.54dB in the frequency band of 100-1000Hz is achieved.

2. According to claim 1, a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system is characterized in that: The number of multi-core optical fibers in step 3 is 7, with core Core 7 located at the center of the seven cores, and the other 6 cores evenly distributed around core Core 7; The phase difference signals demodulated from core 1 and core 2 are superimposed. When the noises of the two cores are completely uncorrelated, the equivalent self-noise pressure of the system can be reduced by 10lg2=3dB after superposition. However, in fact, part of the noise sources of the two cores come from the same optical device, such as lasers and acousto-optic frequency shifters. The phase noises generated by the two make the noise characteristics of the two cores have a certain correlation. On the other hand, core 1 and core 2 are in a multi-core optical fiber and are adjacent to each other. They have the same response to the surrounding environmental noise and are also correlated. Therefore, the dual-core noise correlation coefficient is calculated first, and on this basis, the actual equivalent self-noise pressure suppression effect after the dual-core signals are superimposed is calculated.

3. The method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system according to claim 2 is characterized in that: The method further comprises: step 4, assuming m array element signals s1(t), s2(t), ..., s with the same sensitivity. m (t) linear addition, the average power of the output signal is In the formula, a is the proportional coefficient. Similarly, the average noise power is: make The average signal-to-noise ratio of the array can be expressed as: Among them, (ρ s ) ij ,(ρ n ) ij Respectively represent the mutual correlation coefficient between the signal and noise of the i-th array element and the j-th array element: The logarithm of the ratio of the accumulated signal-to-noise ratio to the signal-to-noise ratio of a single array element is the array gain: Therefore, the gain after array accumulation depends on the mutual correlation coefficient of the signal and noise between the array elements; when the signal is completely correlated but the noise is completely uncorrelated, The array gain after the accumulation of m array elements is AG = 10lgm; when the signal is completely correlated but the noise is partially correlated, The array gain is: Dual-core signal superposition, that is, m = 2, the array gain is 4. The method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system according to claim 3 is characterized in that: The method also includes: step 5, noise accumulation gain calculation: according to the time domain curve and power spectrum density of the dual-core noise and the accumulated noise, the average power of the noise in the frequency band of 100Hz to 1000Hz is -66.8159dB, -66.5635dB, and -63.2594dB respectively; the result of repeating the experiment five times: calculated by formula (5), the mutual correlation coefficient of the noise is 0.11, that is, the noise has correlation, and the noise improvement is 3.46dB after calculation.

5. The method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system according to claim 4 is characterized in that: It also includes: Step 6, equivalent self-noise pressure suppression effect: taking the underwater acoustic sound pressure frequency of 500Hz as an example, the time domain signal and PSD curve of the demodulated phase signal before and after accumulation, the PSDs of the core 1 and the core 2 and the accumulated signal frequency points are -52.24dB, -52.25dB, and -46.25dB, respectively, with an average increase of about 5.995dB; according to the experimental results of multiple frequency points: the PSDs of the signal frequency points after accumulation are actually increased by about 6dB, with an average of about 5.99dB, which is consistent with the theoretical derivation; Among them, when the noise cross-correlation coefficient ρ n =0.11, it can be known from formula (9) that the theoretical signal-to-noise ratio gain after the dual-core signal is accumulated is 2.56 dB. The experimental results show that the equivalent self-noise pressure drop of the actual accumulated signal is 2.54 dB, which is close to the theoretical value.

6. An electronic device, characterized in that: include: at least one memory for storing a computer program; At least one processor is used to execute the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the equivalent self-noise pressure suppression method based on a dual-channel distributed acoustic sensing system as described in any one of claims 1 to 5.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program runs on a processor, the processor is enabled to execute a method for suppressing equivalent self-noise pressure based on a dual-channel distributed acoustic sensing system as claimed in any one of claims 1 to 5.

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