Hydrophone system based on optical frequency comb and phase generated carrier (PGC) demodulation method

Abstract

The invention relates to the technical field of acoustic signal sensing, and provides a hydrophone system based on an optical frequency comb and a phase generated carrier (PGC) demodulation method, and the hydrophone system comprises an optical frequency comb light source, a phase modulator, a wavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module and a PGC modulation and demodulation module. According to the invention, the optical frequency comb light source is adopted, the equal-frequency interval multi-wavelength output of the optical frequency comb is utilized, the comb tooth interval can be accurately matched with the standard channel grid, and the characteristic of single-source generation is utilized, so that the synchronization problem of multiple lasers in a traditional wavelength division multiplexing system is avoided. In addition, signal modulation and demodulation can be simplified by using coherence between comb teeth, and optical frequency modulation can be carried out on all input optical signals by using one phase modulation signal during signal modulation; during signal demodulation, algorithm frequency mixing processing can be performed on all channel signals of the optical fiber acoustic array by sharing one group of frequency mixing signals, so that the complexity of signal processing is greatly reduced.

Description

Technical Field

[0001] This application relates to the field of acoustic signal sensing technology, and in particular to a hydrophone system based on an optical frequency comb and a PGC demodulation method. Background Technology

[0002] The ability of fiber optic hydrophones to capture underwater acoustic signals is the cornerstone of fiber optic underwater acoustic detection. Compared to other types of fiber optic hydrophones, interferometric fiber optic hydrophones have higher sensitivity and are widely used. Common interferometric fiber optic hydrophones are mainly based on the Michelson interferometer structure. Because light travels back and forth once in the interferometer arms, its sensitivity to sound pressure response is twice that of the Mach-Zehnder interferometer structure, under the same structural parameters. In addition, the Michelson interferometer is often paired with a 45-degree Faraday rotating mirror as a reflector to achieve a fiber optic interferometer with completely unpolarized characteristics, which can eliminate both polarization fading and polarization-induced phase noise.

[0003] Besides polarization variations affecting the signal-to-noise ratio and phase difference of the interference signal, changes in the initial phase of the interferometer also influence the interference signal. The initial phase of the interferometer is included in the phase of the interference signal. When the initial phase of the interferometer changes randomly with the external environment, the signal-to-noise ratio of the interference signal will also fluctuate randomly, and may even result in complete signal blanking, severely impacting the stability of the fiber optic hydrophone's response to acoustic signals. Signal detection technology is crucial for achieving stable detection of the interferometer's phase.

[0004] Phase carrier modulation and demodulation (PGC) possesses efficient detection capabilities for weak phase signals, strong noise immunity, and good engineering applicability, making it a commonly used method for stable detection of phase changes in interferometers. PGC-based methods can achieve stable demodulation of acoustic signals received by a single hydrophone. However, in underwater detection applications, a single hydrophone has insufficient spatial coverage, making it difficult to capture target location information. Furthermore, even with high sensitivity, a single hydrophone is easily overwhelmed by environmental noise, rapidly deteriorating its ability to pick up weak acoustic signals. Therefore, underwater detection requires assembling fiber optic hydrophones into a sensor array to form a specific beam and obtain the necessary spatial gain and directivity. Signal transmission in a hydrophone array composed of numerous elements is highly complex. To transmit a large number of independent signals within a limited channel, effective signal transmission multiplexing techniques must be employed. Summary of the Invention

[0005] Therefore, it is necessary to provide a hydrophone system based on an optical frequency comb and a PGC demodulation method that can reduce the number of light sources required and lower system costs, in order to address the above-mentioned technical problems.

[0006] A hydrophone system based on an optical frequency comb includes an optical frequency comb light source, a phase modulator, a dewavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module, and a PGC modulation and demodulation module; The fiber optic acoustic array is composed of multiple fiber optic interferometric hydrophones; The optical frequency comb light source outputs N monochromatic lights with equal frequency spacing, coherent phase, and synchronized time to the phase modulator. The N monochromatic lights are uniformly modulated by the phase modulator to generate phase-modulated light, which is then input to the dewavelength division multiplexer. The dewavelength division multiplexer separates the input optical signal into N independent single-wavelength optical signals according to wavelength and inputs them to the fiber optic acoustic array. The phase-modulated light passes through the fiber optic acoustic array to form an interference light signal. The fiber optic acoustic array converts the received underwater target radiated acoustic signal into the phase of the interference light. The interference light signal is input to the signal acquisition module. The signal acquisition module converts the received signal into a digital signal and inputs it to the PGC modulation and demodulation module. The PGC modulation and demodulation module demodulates the input digital signal to obtain the target acoustic signal.

[0007] In one embodiment, the center frequencies of each channel of the dewavelength division multiplexer are accurately aligned with the frequency of the target comb teeth of the optical frequency comb light source, and the channel spacing of the dewavelength division multiplexer is equal to the repetition frequency of the optical frequency comb light source.

[0008] In one embodiment, the modulation signal of the phase modulator is provided by the PGC modulation and demodulation module.

[0009] A PGC demodulation method for the aforementioned hydrophone system based on optical frequency comb, the method comprising the following steps: A hydrophone system based on an optical frequency comb is constructed, including an optical frequency comb light source, a phase modulator, a wavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module, and a PGC modulation and demodulation module. The optical fiber acoustic array is composed of multiple optical fiber interferometric hydrophones. The PGC modulation and demodulation module provides a high-frequency modulation electrical signal to drive a phase modulator to perform phase modulation on the N optical signals of the optical frequency comb light source; The phase-modulated optical signal is separated by the dewavelength division multiplexer to obtain N single-wavelength optical signals of different wavelengths; The separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber acoustic array to generate interference signals with different wavelength division channels. The interference signal contains optical phase changes caused by underwater target radiated acoustic signals. The interference signal with target acoustic signals is output to the signal acquisition module. The signal acquisition module converts the received signal into a digital signal and then inputs it into the PGC modulation and demodulation module. The PGC modulation and demodulation module divides the input single-channel interference signal into two parallel branches for synchronous processing. The first interference signal is mixed with the fundamental harmonic of the modulation signal and then low-pass filtered to generate the channel one filtered signal. The second interference signal is mixed with the second harmonic of the modulation signal and then low-pass filtered to generate the channel two filtered signal. The arctangent operation is applied to the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel. PGC demodulation is performed on the interference signals of N channels to obtain the acoustic disturbance signals of all channels.

[0010] In one embodiment, the PGC modulation and demodulation module provides a high-frequency modulation electrical signal to drive a phase modulator to perform phase modulation on N optical signals of the optical frequency comb light source, including: The PGC modulation and demodulation module generates a sinusoidal wave to drive the phase modulator, so that the phase modulator generates a carrier whose phase magnitude changes sinusoidally with time and is at the same frequency as the modulation signal. When the N optical signals of the optical frequency comb light source pass through the phase modulator, they are subjected to the same phase modulation.

[0011] In one embodiment, the separated single-wavelength optical signal is input into each fiber optic interferometer of the fiber optic acoustic array to generate interference signals in different wavelength division channels, including: The separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber acoustic array to generate interference signals in different wavelength division channels. The interference signals are: ; in, This is an interference signal; The amplitude of the DC component of the output interference light; For the amplitude of the AC component; The phase difference generated by modulating the light source; Phase difference caused by external environmental influences, initial phase difference, and phase difference caused by other factors; The signal of the target to be measured; ; in, Modulation depth; The modulation frequency; For time.

[0012] In one embodiment, the PGC modulation and demodulation module divides the input single-channel interference signal into two parallel branches for synchronous processing. The first interference signal is mixed with the fundamental harmonic of the modulation signal and then low-pass filtered to generate a channel one filtered signal. The second interference signal is mixed with the second harmonic of the modulation signal and then low-pass filtered to generate a channel two filtered signal, including: The PGC modulation and demodulation module splits the single-channel interference signal into two paths. First-channel interference signal mixed with the fundamental harmonic of the modulation signal:

[0013] After mixing and low-pass filtering, the channel 1 filtered signal is generated: ; in, This is the filtered signal for channel one; This is a Bessel function of order 0; For the first The Bessel function of order 1; It includes the target signal and the acoustic disturbance signal affected by external environmental disturbances; This is a first-order Bessel function; Second harmonic mixing of the second interference signal and the modulation signal:

[0014] After mixing and low-pass filtering, a channel two filtered signal is generated: ; in, This is a channel two filtered signal; For the first Rank function.

[0015] In one embodiment, an arctangent operation is performed on the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, including: The arctangent operation is used to demodulate the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel: .

[0016] In one embodiment, the arctangent operation is performed on the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, and the method further includes: Real-time acquisition of frequency components of the interference signal value: ; ; ; in, For frequency The signal components; For frequency The signal components; C Value based on The ratio of the function is derived by inverse calculation.

[0017] In one embodiment, it further includes: The target signal is obtained by high-pass filtering the disturbance signal of the current single channel. .

[0018] The aforementioned hydrophone system and PGC demodulation method based on an optical frequency comb, by employing an optical frequency comb light source, utilizes the equal-frequency interval multi-wavelength output of the optical frequency comb, and the comb tooth spacing can accurately match the standard channel grid. The single-source generation characteristic avoids the synchronization problem of multiple lasers in traditional wavelength division multiplexing systems. Furthermore, the coherence between the comb teeth simplifies signal modulation and demodulation. During signal modulation, a single phase modulation signal can be used to perform optical frequency modulation on all input optical signals; during signal demodulation, a common set of mixing signals can be used to perform algorithmic mixing processing on all channel signals of the fiber optic acoustic array, greatly reducing the complexity of signal processing.

[0019] This invention uses an optical frequency comb as a multi-wavelength laser, replacing the traditional wavelength division multiplexing (WDM) multiple laser scheme, which reduces the number of light sources required, greatly reduces system costs, and improves space utilization. Attached Figure Description

[0020] Figure 1 This is an application scenario diagram of a hydrophone system based on an optical frequency comb and a PGC demodulation method in one embodiment; Figure 2 This is a flowchart illustrating a PGC demodulation method in one embodiment; Figure 3 This is a schematic diagram of the arctangent demodulation process in one embodiment; Figure 4 This is a schematic diagram of a hydrophone system based on an optical frequency comb in one embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] The hydrophone system and PGC demodulation method based on optical frequency comb provided in this application can be applied to, for example... Figure 1 In the application environment shown, the hydrophone system 104 based on optical frequency comb receives acoustic signals from the target 102.

[0023] In one embodiment, such as Figure 4 As shown, a hydrophone system based on an optical frequency comb is provided, including an optical frequency comb light source, a phase modulator, a dewavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module, and a PGC modulation and demodulation module; The fiber optic acoustic array consists of multiple fiber optic interferometric hydrophones; The optical frequency comb source outputs N monochromatic lights with equal frequency spacing, coherent phase, and synchronized time to the phase modulator. After being uniformly modulated by the phase modulator, the N monochromatic lights generate phase-modulated light, which is input to the dewavelength division multiplexer. The dewavelength division multiplexer separates the input optical signal into N independent single-wavelength optical signals according to wavelength and inputs them to the fiber optic acoustic array. The phase-modulated light passes through the fiber optic acoustic array to form an interference light signal. The fiber optic acoustic array converts the received underwater target radiated acoustic signal into the phase of the interference light. The interference light signal is input to the signal acquisition module. The signal acquisition module converts the received signal into a digital signal and inputs it to the PGC modulation and demodulation module. The PGC modulation and demodulation module demodulates the input digital signal to obtain the target acoustic signal.

[0024] In the aforementioned hydrophone system based on an optical frequency comb, the use of an optical frequency comb light source, the equal-frequency interval multi-wavelength output of the comb, and the precise matching of the comb tooth spacing to the standard channel grid, along with the single-source generation characteristic, avoids the synchronization problem of multiple lasers in traditional wavelength division multiplexing systems. Furthermore, the coherence between the comb teeth simplifies signal modulation and demodulation. During signal modulation, a single phase modulation signal can be used to optically modulate all input optical signals; during demodulation, a common set of mixing signals can be used to perform algorithmic mixing processing on all channels of the fiber optic acoustic array, greatly reducing the complexity of signal processing.

[0025] In one embodiment, the center frequencies of each channel of the demultiplexer are precisely aligned with the frequency of the target comb teeth of the optical frequency comb light source, and the channel spacing of the demultiplexer is equal to the repetition frequency of the optical frequency comb light source.

[0026] In this embodiment, when the channel interval is consistent with the repetition frequency, it can be ensured that each comb tooth falls exactly into the corresponding channel to achieve precise separation.

[0027] In one embodiment, the modulation signal of the phase modulator is provided by the PGC modulation and demodulation module.

[0028] In one embodiment, a fiber optic interferometric hydrophone, such as Figure 4 As shown, when an underwater target radiates an acoustic signal, the acoustic signal acts on the signal arm of the hydrophone, causing a phase change in the interference light.

[0029] In one embodiment, reference Figure 2 A PGC demodulation method is provided for use in any of the above embodiments of a hydrophone system based on an optical frequency comb. The method includes the following steps: A hydrophone system based on an optical frequency comb is constructed, including an optical frequency comb light source, a phase modulator, a dewavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module, and a PGC modulation and demodulation module. The optical fiber acoustic array is composed of multiple optical fiber interferometric hydrophones. The PGC modulation and demodulation module provides a high-frequency modulation electrical signal to drive a phase modulator to perform phase modulation on N optical signals from the optical frequency comb light source; The phase-modulated optical signal is separated by a dewavelength division multiplexer to obtain N single-wavelength optical signals of different wavelengths; The separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber acoustic array to generate interference signals in different wavelength division channels. The interference signal contains optical phase changes caused by underwater target radiated acoustic signals. The interference signal with target acoustic signals is output to the signal acquisition module. The signal acquisition module converts the received signal into a digital signal and then inputs it into the PGC modulation and demodulation module; The PGC modulation and demodulation module divides the input single-channel interference signal into two parallel branches for synchronous processing. The first interference signal is mixed with the fundamental harmonic of the modulation signal and then low-pass filtered to generate the channel one filtered signal. The second interference signal is mixed with the second harmonic of the modulation signal and then low-pass filtered to generate the channel two filtered signal. The arctangent operation is applied to the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel. PGC demodulation is performed on the interference signals of N channels to obtain the acoustic disturbance signals of all channels.

[0030] In this embodiment, the adjustment result is not affected by the drift of the interferometer's operating point, and the signal processing of multiple wavelength division channels can be completed in real time. At the same time, the coherence of the optical frequency comb teeth is used to improve the signal-to-noise ratio of the demodulated signal.

[0031] In one embodiment, the PGC modulation and demodulation module provides a high-frequency modulation electrical signal to drive a phase modulator to perform phase modulation on N optical signals from the optical frequency comb light source, including: The PGC modulation and demodulation module generates a sinusoidal wave to drive the phase modulator, which in turn generates a carrier wave whose phase magnitude varies sinusoidally with time and is at the same frequency as the modulated signal. When N optical signals from an optical frequency comb light source pass through a phase modulator, they are subjected to the same phase modulation.

[0032] In this embodiment, by sinusoidally modulating the phase of the optical signal, a large-amplitude phase-modulated carrier wave is generated in the unbalanced interferometer. The weak acoustic signal is loaded onto the large-amplitude, high-frequency carrier wave, thus avoiding being submerged.

[0033] In one embodiment, the separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber optic acoustic array to generate interference signals in different wavelength division channels, including: The separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber optic acoustic array to generate interference signals in different wavelength division channels. The interference signals are: ; in, This is an interference signal; The amplitude of the DC component of the output interference light; For the amplitude of the AC component; The phase difference generated by modulating the light source; Phase difference caused by external environmental influences, initial phase difference, and phase difference caused by other factors; The signal of the target to be measured; ; in, Modulation depth; The modulation frequency; For time.

[0034] Substituting the target signal into the interferometric signal and expanding it using the Bessel function, we can obtain: ; .

[0035] In one embodiment, reference Figure 3 The PGC modulation and demodulation module processes the input single-channel interference signal synchronously in two parallel branches. The first branch mixes the interference signal with the fundamental harmonic of the modulation signal and then performs a low-pass filter to generate the first-channel filtered signal. The second branch mixes the interference signal with the second harmonic of the modulation signal and then performs a low-pass filter to generate the second-channel filtered signal, including: The PGC modulation and demodulation module splits the single-channel interference signal into two paths; First-channel interference signal mixed with the fundamental harmonic of the modulation signal:

[0036] After mixing and low-pass filtering, the channel 1 filtered signal is generated: ; in, This is the filtered signal for channel one; This is a Bessel function of order 0; For the first The Bessel function of order 1; It includes the target signal and the acoustic disturbance signal affected by external environmental disturbances; This is a first-order Bessel function; Second harmonic mixing of the second interference signal and the modulation signal:

[0037] After mixing and low-pass filtering, a channel two filtered signal is generated: ; in, This is a channel two filtered signal; For the first The Bessel function of order 1.

[0038] In this embodiment, the interference signal is split into two paths, which are respectively coupled with the first harmonic reference signal of the carrier. and the second harmonic reference signal Frequency mixing; due to modulation frequency Much larger than the measured signal The frequency is filtered out by a low-pass filter. The filtered signal is obtained by combining the frequency harmonics and their multipliers.

[0039] In one embodiment, an arctangent operation is performed on the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, including: The arctangent operation is used to demodulate the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel: .

[0040] For the arctangent algorithm, when C=2.63, The amplitudes of the two detectors are the same. Although the first derivative is 0 at the peak point, and slight fluctuations in the C value have little impact on the stability of the demodulated signal, the drift of the C value is still significant for weak signals. Therefore, practical systems need to acquire the C value in real time to eliminate the influence of modulation depth.

[0041] In one embodiment, the arctangent operation is performed on the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, and the method further includes: Real-time acquisition of frequency components of the interference signal value: ; ; ; in, For frequency The signal components; For frequency The signal components; C The value is derived by inversely from the ratio of the Bessel function.

[0042] In this embodiment, the ratio of the two values ​​is uniquely determined by the ratio of Bessel functions of different orders to the C value, thus allowing the C value to be obtained in real time. That is, the above formula can be used to deduce... value.

[0043] In one embodiment, the arctangent operation is performed on the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, and the method further includes: The target signal is obtained by high-pass filtering the disturbance signal of the current single channel. .

[0044] because Interferometer initial phase Changes and The process is extremely slow, therefore it is possible to analyze the demodulated phase signal. High-pass filtering is performed to obtain the target signal under test. .

[0045] It should be understood that although Figure 2 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. In addition, Figure 2 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0046] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A hydrophone system based on an optical frequency comb, characterized in that, It includes an optical frequency comb light source, a phase modulator, a wavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module, and a PGC modulation and demodulation module; The fiber optic acoustic array is composed of multiple fiber optic interferometric hydrophones; The optical frequency comb light source outputs N monochromatic lights with equal frequency spacing, coherent phase, and synchronized time to the phase modulator. The N monochromatic lights are uniformly modulated by the phase modulator to generate phase-modulated light, which is then input to the dewavelength division multiplexer. The dewavelength division multiplexer separates the input optical signal into N independent single-wavelength optical signals according to wavelength and inputs them to the fiber optic acoustic array. The phase-modulated light passes through the fiber optic acoustic array to form an interference light signal. The fiber optic acoustic array converts the received underwater target radiated acoustic signal into the phase of the interference light. The interference light signal is input to the signal acquisition module. The signal acquisition module converts the received signal into a digital signal and inputs it to the PGC modulation and demodulation module. The PGC modulation and demodulation module demodulates the input digital signal to obtain the target acoustic signal.

2. The system according to claim 1, characterized in that, The center frequencies of each channel of the dewavelength division multiplexer are accurately aligned with the frequency of the target comb teeth of the optical frequency comb light source, and the channel spacing of the dewavelength division multiplexer is equal to the repetition frequency of the optical frequency comb light source.

3. The system according to claim 1, characterized in that, The modulation signal of the phase modulator is provided by the PGC modulation and demodulation module.

4. A PGC demodulation method, used in the system according to any one of claims 1 to 3, characterized in that, The method includes the following steps: A hydrophone system based on an optical frequency comb is constructed, including an optical frequency comb light source, a phase modulator, a wavelength division multiplexer, an optical fiber acoustic array, a signal acquisition module, and a PGC modulation and demodulation module. The optical fiber acoustic array is composed of multiple optical fiber interferometric hydrophones. The PGC modulation and demodulation module provides a high-frequency modulation electrical signal to drive a phase modulator to perform phase modulation on the N optical signals input from the optical frequency comb light source; The phase-modulated optical signal is separated by the dewavelength division multiplexer to obtain N single-wavelength optical signals of different wavelengths; The separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber acoustic array to generate interference signals with different wavelength division channels. The interference signal contains optical phase changes caused by underwater target radiated acoustic signals. The interference signal with target acoustic signals is output to the signal acquisition module. The signal acquisition module converts the received signal into a digital signal and then inputs it into the PGC modulation and demodulation module. The PGC modulation and demodulation module divides the input single-channel interference signal into two parallel branches for synchronous processing. The first interference signal is mixed with the fundamental harmonic of the modulation signal and then low-pass filtered to generate the channel one filtered signal. The second interference signal is mixed with the second harmonic of the modulation signal and then low-pass filtered to generate the channel two filtered signal. The arctangent operation is applied to the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel. PGC demodulation is performed on the interference signals of N channels to obtain the acoustic disturbance signals of all channels.

5. The method according to claim 4, characterized in that, The PGC modulation and demodulation module provides a high-frequency modulation electrical signal to drive a phase modulator to perform phase modulation on the N optical signals input from the optical frequency comb light source, including: The PGC modulation and demodulation module generates a sinusoidal wave to drive the phase modulator, so that the phase modulator generates a carrier whose phase magnitude changes sinusoidally with time and is at the same frequency as the modulation signal. When the N optical signals of the optical frequency comb light source pass through the phase modulator, they are subjected to the same phase modulation.

6. The method according to claim 4, characterized in that, The separated single-wavelength optical signals are input into each fiber interferometric hydrophone of the fiber acoustic array to generate interference signals in different wavelength division channels, including: The separated single-wavelength optical signal is input into each fiber interferometric hydrophone of the fiber acoustic array to generate interference signals in different wavelength division channels. The interference signals are: in, This is an interference signal; The amplitude of the DC component of the output interference light; For the amplitude of the AC component; The phase difference generated by modulating the light source; Phase difference caused by external environmental influences, initial phase difference, and phase difference caused by other factors; The signal of the target to be measured; in, Modulation depth; The modulation frequency; For time.

7. The method according to claim 6, characterized in that, The PGC modulation and demodulation module processes the input single-channel interference signal synchronously in two parallel branches. The first branch mixes the interference signal with the fundamental harmonic of the modulation signal and then performs a low-pass filter to generate the first-channel filtered signal. The second branch mixes the interference signal with the second harmonic of the modulation signal and then performs a low-pass filter to generate the second-channel filtered signal, including: The PGC modulation and demodulation module splits the single-channel interference signal into two paths. First-channel interference signal mixed with the fundamental harmonic of the modulation signal: After mixing and low-pass filtering, the channel 1 filtered signal is generated: in, This is the filtered signal for channel one; This is a Bessel function of order 0; For the first The Bessel function of order 1; It includes the target signal and the acoustic disturbance signal affected by external environmental disturbances; J 1 represents the first-order Bessel function; Second harmonic mixing of the second interference signal and the modulation signal: After mixing and low-pass filtering, a channel two filtered signal is generated: in, This is a channel two filtered signal; For the first The Bessel function of order 1.

8. The method according to claim 7, characterized in that, Applying arctangent calculation to the two filtered signals yields the acoustic disturbance signal corresponding to the current single channel, including: The arctangent operation is used to demodulate the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel: 。 9. The method according to claim 8, characterized in that, The arctangent operation is applied to the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, which also includes: Real-time acquisition of frequency components of the interference signal value: in, For frequency The signal components; For frequency The signal components; The value is derived by inversely from the ratio of the Bessel function.

10. The method according to claim 8, characterized in that, The arctangent operation is applied to the two filtered signals to obtain the acoustic disturbance signal corresponding to the current single channel, which also includes: The acoustic disturbance signal corresponding to the current single channel is subjected to high-pass filtering to obtain the target signal under test. .

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