Distributed optical fiber sonic sensor with coherent fading suppression and sensing method

Abstract

The invention relates to the technical field of signal processing, in particular to a distributed optical fiber sound wave sensing method and sensor for coherent fading suppression. The method comprises the following steps: the coupler divides continuous light waves into detection light and local oscillation light; the detection light is modulated into difference frequency delay double pulses through a double-pulse generator; the difference frequency delay double pulses are subjected to power amplification through an erbium-doped optical fiber amplifier; after spontaneous radiation noise of the amplified power is filtered out through an optical band-pass filter, the amplified power is injected into an optical fiber to be measured through a circulator; two pulses in the pulse string generate an RBS signal in the optical fiber to be measured, and the RBS signal passes through the circulator and is divided into two beams with equal power through the coupler; one beam and local oscillation light are subjected to frequency mixing through a coupler, and the mixed light beam is received by a balanced photoelectric detector and then is collected by a data collection system; the other beam is directly received by a common photoelectric detector; according to the invention, through combined processing of output signals of the two photoelectric detectors, coherent fading suppression of the distributed optical fiber sonic sensor is realized.

Description

Technical Field

[0001] The invention relates to the technical field of signal processing, and in particular to a distributed optical fiber acoustic wave sensing method and a sensor for suppressing coherent fading. Background Art

[0002] Distributed Optical Fiber Sensing (DOFS) technology is a new sensing method that uses the intrinsic scattering phenomena in optical fibers, including Rayleigh scattering, Raman scattering, and Brillouin scattering, to achieve online distributed monitoring of multiple physical quantities (such as temperature, strain, and acoustic waves) [He Z, Liu Q. Optical Fiber Distributed Acoustic Sensors: A Review [J]. Journal of Lightwave Technology, 2021, 39 (12): 3671-3686.]. Among them, distributed acoustic sensors (DAS) that use Rayleigh scattering in optical fibers to achieve the perception of acoustic and vibration signals have made great progress and have been widely used in recent years. Thanks to the continuous development of technologies such as narrow linewidth lasers, high-speed low-noise data acquisition cards, and large-scale digital signal processing, DAS technology has made great progress in various indicators [He Z, Liu Q. Optical Fiber Distributed Acoustic Sensors: A Review [J]. Journal of Lightwave Technology, 2021, 39 (12): 3671-3686.]. For example, its spatial resolution can currently reach the order of 1 to 10 m, while the sensing distance can be extended to more than 100 km, and the detection frequency ranges from mHz to kHz, which can meet a variety of needs in production, life, and scientific research. DAS's specific advantages such as distributed sensing capability, anti-electromagnetic interference, and resistance to harsh environments make it suitable for extreme environments such as underground, deep earth, and deep sea. In these scenarios, traditional electronic sensors cannot work or have a high probability of failure, which is also a major advantage of DAS technology. At present, DAS technology has been successfully applied in many fields such as seismic exploration, smart city construction, oil and gas industry, and defense industry, and has achieved good results, showing great application potential, and has become the forefront of the development of optoelectronics at this stage.

[0003] At present, there are two main technical solutions for suppressing coherent fading in DAS systems. One is to obtain RBS signals with different characteristics through frequency, mode, transmission fiber, etc., and then combine and divide the amplitude minimum point in the RBS signal to suppress the impact of coherent fading. This type of method usually places high requirements on system complexity. The other is to use various signal processing methods on RBS to suppress the demodulation noise caused by coherent fading. However, this method needs to assume some characteristics of the RBS signal, has a limited range of action, and is not universally adaptable. Summary of the invention

[0004] In order to solve the technical problems that the existing solutions need to assume some characteristics of the RBS signal, have a limited scope of action, and are not universally adaptable, the embodiments of the present invention provide a distributed optical fiber acoustic wave sensor and a sensing method with coherent fading suppression. The technical solution is as follows:

[0005] On the one hand, a distributed optical fiber acoustic wave sensing method with coherent fading suppression is provided, the method comprising:

[0006] A distributed optical fiber acoustic wave sensing method for coherent fading suppression, characterized in that the method comprises:

[0007] S1, a continuous light wave is emitted through a narrow linewidth laser, and the continuous light wave passes through a coupler 1 and is divided into two beams, namely a detection light and a local oscillator light;

[0008] S2, the detection light passes through the dual pulse generator, and the detection light is modulated into a difference frequency delayed dual pulse;

[0009] S3, the difference frequency delayed double pulses pass through the erbium-doped fiber amplifier and are amplified to a suitable power;

[0010] S4, after filtering out the spontaneous radiation noise through an optical bandpass filter, the power-amplified difference frequency delayed double pulse is propagated to port 2 through port 1 of circulator 1 and injected into the optical fiber to be tested; wherein circulator 1 includes three ports, namely: port 1, port 2 and port 3;

[0011] S5. The two pulses in the pulse train will generate RBS signals in the optical fiber to be tested. After the RBS signal is transmitted from port 2 to port 3 of circulator 1, it is divided into two beams with equal power through coupler 4. One of the beams is mixed with the local oscillator light separated by coupler 1 through coupler 5. The mixed beam is received by a balanced photodetector, and the other beam is directly received by a photodetector.

[0012] S6, the electrical signals output by the balanced photodetector and the photodetector are collected by the data acquisition system.

[0013] Optionally, the coupler 1 is a coupler with a splitting ratio of 1:99, and the two light beams after splitting respectively include: 99% of the detection light and 1% of the local oscillator light.

[0014] Optionally, the implementation forms of the double pulse include: an integrated modulation mode and a discrete modulation mode.

[0015] Optionally, the integrated modulation method includes:

[0016] The pulse electrical signal required to be modulated is generated by any signal generator and input into the driver. The driver modulates the electrical signal and outputs the electrical signal to the dual pulse generator to generate the corresponding optical pulse waveform.

[0017] Optionally, discrete modulation formats include:

[0018] The detection light is split into two beams of equal power through a coupler 2 with a splitting ratio of 50:50, and the two beams enter the upper arm and lower arm of the Mach-Zehnder interferometer respectively;

[0019] Insert an optical modulator 1 into the upper arm to modulate a continuous probe light beam into a pulse light;

[0020] Insert the optical modulator 2 in the lower arm to modulate the other continuous detection light into pulse light; and insert the delay optical fiber in the lower arm at the same time, and determine the time interval between the two pulses in the generated difference frequency delay double pulse by the length of the delay optical fiber;

[0021] The pulses generated by the upper arm and the lower arm are combined through a 50:50 coupler 3 to obtain a difference frequency delayed double pulse.

[0022] Optionally, the dual pulse generator further comprises:

[0023] The change in the frequency of the light wave caused by optical modulation is controlled by the AWG and driver in the system and adjusted according to actual needs.

[0024] Optionally, the AWG and the driver in the integrated modulation mode are in single-channel form;

[0025] The AWG and driver in the discrete modulation mode are dual-channel.

[0026] On the other hand, a distributed optical fiber acoustic wave sensor with coherent fading suppression is provided, characterized in that the sensor is applied to any of the above-mentioned distributed optical fiber acoustic wave sensing methods with coherent fading suppression, and the sensor comprises:

[0027] Narrow linewidth laser, dual pulse generator, erbium-doped fiber amplifier, optical bandpass filter, circulator 1, coupler 1, balanced photodetector, photodetector and data acquisition system;

[0028] A continuous light wave is emitted by a narrow linewidth laser, and the continuous light wave passes through a coupler 1, and the continuous light wave is divided into two beams, namely, a detection light and a local oscillator light;

[0029] The detection light passes through a dual pulse generator, which modulates the detection light into a frequency-difference delayed dual pulse;

[0030] The difference frequency delayed double pulses are amplified to the appropriate power through the erbium-doped fiber amplifier;

[0031] The power-amplified difference frequency delayed double pulse is passed through an optical bandpass filter to filter out the spontaneous radiation noise, and then propagates from port 1 to port 2 of circulator 1 and is injected into the optical fiber to be tested; wherein circulator 1 includes three ports, namely: port 1, port 2, and port 3;

[0032] The two pulses in the pulse train will generate RBS signals in the optical fiber to be tested. The RBS signals are propagated from port 2 of circulator 1 to port 3, and are divided into two beams with equal power through coupler 4. One of the beams is mixed with the local oscillator light separated by coupler 1 through coupler 5. The mixed beam is received by a balanced photodetector, and the other beam is directly received by a photodetector.

[0033] The electrical signals output by the balanced photodetector and the photodetector are collected by the data acquisition system.

[0034] On the other hand, a distributed optical fiber acoustic wave sensing device with coherent fading suppression is provided, the distributed optical fiber acoustic wave sensing device with coherent fading suppression comprising: a processor; a memory, the memory storing computer-readable instructions, and when the computer-readable instructions are executed by the processor, any one of the above-mentioned distributed optical fiber acoustic wave sensing methods with coherent fading suppression is implemented.

[0035] On the other hand, a computer-readable storage medium is provided, wherein at least one instruction is stored in the storage medium, and the at least one instruction is loaded and executed by a processor to implement any one of the above-mentioned distributed optical fiber acoustic wave sensing methods for coherent fading suppression.

[0036] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0037] In an embodiment of the present invention, a new distributed acoustic wave sensor solution capable of achieving coherent fading suppression is proposed. The solution can introduce three RBS signals with different carrier frequencies into the RBS interference signal in a simple way through difference frequency delayed double pulses and composite detection means, and suppress the coherent fading problem caused by a single carrier RBS signal through subsequent signal combination. Compared with the traditional solution, the proposed solution only adds a number of optical couplers and a detector to the hardware structure, and the increase in hardware cost is limited; at the same time, the required difference frequency delayed double pulses have flexible and diverse implementation forms. In terms of back-end signal processing, the solution does not have any preset assumptions for the RBS signal, which makes the proposed solution have a large scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 This is a flow chart of a distributed optical fiber acoustic wave sensing method for coherent fading suppression provided by an embodiment of the present invention;

[0040] Figure 2 1 is a schematic diagram of the structure of a distributed optical fiber acoustic wave sensor with coherent fading suppression provided by an embodiment of the present invention;

[0041] Figure 3 is a structural diagram of a double pulse generator provided by an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0044] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0045] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they intend to express are the same. "of", "corresponding, relevant" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they intend to express are the same.

[0046] In the embodiments of the present invention, sometimes the subscripts such as W 1 It may be written in non-subscript form such as W1. When the difference is not emphasized, the meaning is the same.

[0047] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0048] The embodiment of the present invention provides a distributed optical fiber acoustic wave sensing method with coherent fading suppression, which can be implemented by a distributed optical fiber acoustic wave sensing device with coherent fading suppression, and the distributed optical fiber acoustic wave sensing device with coherent fading suppression can be a terminal or a server. Figure 1 The process flow chart of the distributed optical fiber acoustic wave sensing method for coherent fading suppression shown in the figure may include the following steps:

[0049] S1, a continuous light wave is emitted through a narrow linewidth laser, and the continuous light wave passes through a coupler 1 and is divided into two beams, namely a detection light and a local oscillator light;

[0050] In a feasible implementation, Figure 2 This is a schematic diagram of the innovative structure of the present invention. The light source is a narrow linewidth laser, which provides low-noise, high-stability continuous light waves for the subsequent DAS system, and its output light frequency is recorded as f0. Subsequently, the continuous light wave is divided into two beams by a coupler 1 with a splitting ratio of 1:99. The 99% beam is called "probe light" and the 1% beam is called "local oscillator light".

[0051] S2. The detection light passes through a dual pulse generator, which modulates the detection light into a frequency-difference delayed dual pulse.

[0052] In a feasible implementation, the probe light then passes through a double pulse generator and is modulated into two pulses one after the other. The time delay between the two pulses is τ, the width of each pulse is w, and the corresponding light wave frequencies are f 1 and f 2 The above pulse train is a "difference frequency delayed double pulse", which is repeated in the time domain with a repetition frequency of frep (the inverse of the pulse train repetition period Trep).

[0053] In a feasible implementation mode, according to different working principles, the double pulse has two different implementation forms, such as Figure 3 As shown. The implementation forms of double pulse include: integrated modulation method (such as Figure 3 a) and discrete modulation forms (such as Figure 3 b).

[0054] In a feasible implementation manner, the integrated modulation method includes:

[0055] The required modulated pulse electrical signal is generated by an arbitrary waveform generator (AWG) and input into the driver. The driver amplifies and performs impedance matching on the electrical signal and outputs the electrical signal to the optical modulator, so that the optical modulator can generate the corresponding optical pulse waveform ( Figure 3 Note that the optical modulator here can be either an electro-optic modulator (EOM) or an acousto-optic modulator (AOM). The parameters of the generated difference frequency delayed double pulse include the modulated frequency f 1 (f 2 ), the time interval τ between the two pulses, the pulse width w and the double pulse repetition frequency f rep etc. are all controlled by AWG. Therefore, this solution can flexibly generate dual pulse trains as needed, and only one optical modulator is needed to complete the corresponding function, but it has high requirements for AWG and driver.

[0056] In a feasible implementation manner, the discrete modulation form includes:

[0057] Its basic structure is a Mach-Zehnder interferometer. The detection light is split into two beams by a coupler 2 with a splitting ratio of 50:50 and enters the upper arm and lower arm of the Mach-Zehnder interferometer. In the upper arm, an optical modulator 1 is inserted, which modulates the continuous detection light into pulsed light and changes the optical frequency from f 0 Move to f 1 Similarly, the optical modulator 2 in the lower arm modulates the continuous light passing through into pulsed light, and at the same time changes the optical frequency from f 0 Move to f 2 At the same time, a length of The length of the delay fiber determines the time interval between the two pulses in the generated difference frequency delayed double pulse, that is, , where n is the refractive index of the optical fiber and c is the propagation speed of light waves in a vacuum. The pulses generated in the upper and lower arms will continue to pass through another 50:50 coupler 3 to be combined together, thus forming a time interval of τ, and the optical frequencies before and after are f 1 and f 2 In this scheme, the pulse width w and the pulse train repetition frequency f rep The parameters are controlled by the AWG, and the optical modulator is driven by the driver to make the generated optical pulse train meet the design requirements.

[0058] In a feasible implementation, for the dual pulse generator, it should be noted that: (1) the optical modulator here can be an acousto-optic modulator or an electro-optic modulator, and there is no requirement for its specific form; (2) the change in the frequency of the light wave caused by optical modulation, i.e., f 1 -f 0 and f 2 -f 0 The value is controlled by the AWG and driver in the system and can be adjusted according to actual needs; (3) Figure 3 The integrated modulation method in a requires the AWG and driver to be single-channel; Figure 3 The discrete modulation method in b requires the AWG and driver to be dual-channel to meet the needs when there are optical modulators in both the upper and lower arms.

[0059] S3, the difference frequency delayed double pulses are amplified to the appropriate power through an erbium-doped fiber amplifier (EDFA).

[0060] S4, after the power amplification, the difference frequency delayed double pulse is filtered out by the optical bandpass filter to remove the spontaneous radiation noise, and then propagated from port 1 to port 2 of circulator 1 and injected into the fiber under test (Fiber Under Test, FUT); wherein, circulator 1 includes three ports, namely: port 1, port 2 and port 3

[0061] S5. The two pulses in the pulse train will generate RBS signals in the optical fiber to be tested. After the RBS signal is transmitted from port 2 to port 3 of circulator 1, it is divided into two beams with equal power through coupler 4. One of the beams is mixed with the local oscillator light separated by coupler 1 through coupler 5. The mixed beam is received by a balanced photo detector (BPD), that is, "coherent detection mode", and the other beam is directly received by the photodetector.

[0062] S6, the electrical signals output by the balanced photodetector and the photodetector are collected by the data acquisition system.

[0063] In a feasible implementation, the photocurrent signal can be written as:

[0064] (1)

[0065] The summation symbol represents the superposition of all Rayleigh scattering point signals in the optical fiber. Here we assume that there are N Rayleigh scattering points in the optical fiber. 1i (r 2i )and Respectively represent the optical frequency f 1 (f 2 ) under the action of the Rayleigh scattering intensity and the additional phase introduced at each Rayleigh scattering point in the optical fiber. i is the delay caused by each Rayleigh scattering point. W is the window type of the light pulse, which is the default rectangular window. Here f 1 and f 2 The difference should be greater than the bandwidth of the optical pulse, that is:

[0066] (2)

[0067] Under the premise of satisfying formula (2), the Rayleigh scattering coefficients of two optical signals with different frequencies and the introduced additional phase are not the same, that is, , , the spatial distribution of the coherent fading produced is also different. At the same time, the phase change introduced by the external disturbance , which is the same for two optical signals of different frequencies. The following method can be used in a computer to obtain the phase information contained in RBS in formula (1): using the center frequencies f 1 and f 2 , two bandpass filters with bandwidth greater than 1 / w can separate the RBS signals at two different carriers contained in formula (1), and use Hilbert transform to obtain its complex expression. At the same time, align the delay in the pulse signal, so the following two signals can be obtained:

[0068] (3)

[0069] By extracting the phase of the signals in the two expressions in formula (3) and making a difference with a time interval of τ, the phase change can be obtained as follows:

[0070] (4)

[0071] Additional phase introduced by Rayleigh scattering or Can be done through or It can be removed by subtracting the DC quantity.

[0072] For the RBS signal output from the right branch of coupler 4, a photodetector (PD) is directly used to convert the optical signal into an electrical signal (i.e., "direct detection mode"), which is then collected by the data acquisition system. At this time, its expression is:

[0073] (5)

[0074] The carrier frequency of the RBS signal detected by the PD is f 1 and f 2 The difference between , and is the Rayleigh scattering coefficient generated at this frequency and the additional phase introduced, which should be different from the frequency f 1 or 2 The Rayleigh scattering coefficient of the optical fiber should make the following relationship hold:

[0075] (6)

[0076] For example, you can set f 1 180 MHz, f 2 The frequency is 220 MHz and the pulse width is w = 100 ns. At this time, the conditions of formula (2) and formula (6) can be met.

[0077] On the basis of satisfying the above conditions, a similar algorithm can be used in the computer to obtain the phase information: First, the center frequency is , a bandpass filter with a bandwidth of 1 / w performs bandpass filtering on the signal of expression (5); further, the Hilbert transform is also adopted to obtain the complex form signal:

[0078] (7)

[0079] Then, by solving the angle, the phase change at this time can be obtained as:

[0080] (8)

[0081] The additional phase introduced This can be filtered out by subtracting the mean.

[0082] It can be seen from formula (3) and formula (7) that different RBS signals obtained in this scheme correspond to different Rayleigh scattering coefficients and additional phases, so the locations and distributions of coherent fading are also different. Then, the coherent fading can be suppressed by weighted average (WA). The specific method is:

[0083] (9)

[0084] That is, the RBS phase signal obtained by coherent fading suppression after adopting this scheme, which is proportional to the external sound wave or vibration signal received by the optical fiber under test. The key of this scheme is to generate three groups of RBS signals with different scattering coefficient distributions, so the selection of optical frequency in the pulse is crucial. Formulas (2) and (6) are the prerequisites for the success of this scheme. For most optical modulators and their matching AWGs and drivers, these conditions are very easy to achieve.

[0085] Note that the AWG and data acquisition system in this solution need to be synchronized (including clock synchronization and trigger synchronization) to ensure that the collected data is not chaotic in the time domain.

[0086] In the embodiment of the present invention, a new distributed acoustic wave sensor solution capable of achieving coherent fading suppression is proposed. The solution can introduce three RBS signals with different carrier frequencies into the RBS interference signal in a simple way through difference frequency delayed double pulses and composite detection means, and suppress the coherent fading problem caused by a single carrier RBS signal through subsequent signal combination. Compared with the traditional solution, the proposed solution only adds a number of optical couplers and a detector to the hardware structure, and the increase in hardware cost is limited; at the same time, the required difference frequency delayed double pulses have flexible and diverse implementation forms. In terms of back-end signal processing, the solution does not have any preset assumptions for the RBS signal, which makes the proposed solution have a large scope of application.

[0087] Figure 2 The block diagram of a distributed optical fiber acoustic wave sensing sensor with coherent fading suppression is shown according to an exemplary embodiment. The sensor is used in a distributed optical fiber acoustic wave sensing method with coherent fading suppression. Figure 2 , the sensor includes a narrow linewidth laser, a dual pulse generator, an erbium-doped fiber amplifier, an optical bandpass filter, a circulator 1, a coupler 1, a balanced photodetector, a photodetector and a data acquisition system;

[0088] A continuous light wave is emitted by a narrow linewidth laser, and the continuous light wave passes through a coupler 1, and the continuous light wave is divided into two beams, namely, a detection light and a local oscillator light;

[0089] The detection light passes through a dual pulse generator, which modulates the detection light into a frequency-difference delayed dual pulse;

[0090] The difference frequency delayed double pulses are amplified to the appropriate power through the erbium-doped fiber amplifier;

[0091] The power-amplified difference frequency delayed double pulse is passed through an optical bandpass filter to filter out the spontaneous radiation noise, and then propagates from port 1 to port 2 of circulator 1 and is injected into the optical fiber to be tested; wherein circulator 1 includes three ports, namely: port 1, port 2, and port 3;

[0092] The two pulses in the pulse train will generate RBS signals in the optical fiber to be tested. The RBS signals are propagated from port 2 of circulator 1 to port 3, and are divided into two beams with equal power through coupler 4. One of the beams is mixed with the local oscillator light separated by coupler 1 through coupler 5. The mixed beam is received by a balanced photodetector, and the other beam is directly received by a photodetector.

[0093] The electrical signals output by the balanced photodetector and the photodetector are collected by the data acquisition system

[0094] In the embodiment of the present invention, a new distributed acoustic wave sensor solution capable of achieving coherent fading suppression is proposed. The solution can introduce three RBS signals with different carrier frequencies into the RBS interference signal in a simple way through difference frequency delayed double pulses and composite detection means, and suppress the coherent fading problem caused by a single carrier RBS signal through subsequent signal combination. Compared with the traditional solution, the proposed solution only adds a number of optical couplers and a detector to the hardware structure, and the increase in hardware cost is limited; at the same time, the required difference frequency delayed double pulses have flexible and diverse implementation forms. In terms of back-end signal processing, the solution does not have any preset assumptions for the RBS signal, which makes the proposed solution have a large scope of application.

[0095] Figure 4 is a schematic diagram of the structure of a distributed optical fiber acoustic wave sensing device with coherent fading suppression provided by an embodiment of the present invention, such as Figure 4 As shown, the distributed optical fiber acoustic wave sensing device with coherent fading suppression may include the above Figure 2 The distributed optical fiber acoustic wave sensing sensor with coherent fading suppression is shown. Optionally, the distributed optical fiber acoustic wave sensing device 410 with coherent fading suppression may include a first processor 2001 .

[0096] Optionally, the distributed optical fiber acoustic wave sensing device 410 with coherent fading suppression may further include a memory 2002 and a transceiver 2003 .

[0097] The first processor 2001, the memory 2002 and the transceiver 2003 may be connected via a communication bus.

[0098] Combine the following Figure 4 The components of the distributed optical fiber acoustic wave sensing device 410 for coherent fading suppression are specifically introduced as follows:

[0099] The first processor 2001 is the control center of the distributed optical fiber acoustic wave sensing device 410 with coherent fading suppression, and can be a processor or a general term for multiple processing elements. For example, the first processor 2001 is one or more central processing units (CPUs), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention, such as one or more microprocessors (digital signal processors, DSPs), or one or more field programmable gate arrays (field programmable gate arrays, FPGAs).

[0100] Optionally, the first processor 2001 can perform various functions of the distributed optical fiber acoustic wave sensing device 410 with coherent fading suppression by running or executing a software program stored in the memory 2002 and calling data stored in the memory 2002 .

[0101] In a specific implementation, as an embodiment, the first processor 2001 may include one or more CPUs, such as Figure 4 CPU0 and CPU1 are shown in FIG.

[0102] In a specific implementation, as an embodiment, the distributed optical fiber acoustic wave sensing device 410 with coherent fading suppression may also include multiple processors, such as Figure 4 The first processor 2001 and the second processor 2004 are shown in FIG. Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). The processor here may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0103] The memory 2002 is used to store the software program for executing the solution of the present invention, and is controlled to be executed by the first processor 2001. The specific implementation method can refer to the above method embodiment, which will not be repeated here.

[0104] Optionally, the memory 2002 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 2002 may be integrated with the first processor 2001, or may exist independently, and may be connected to the first processor 2001 through the interface circuit ( Figure 4 (not shown) is coupled to the first processor 2001, which is not specifically limited in this embodiment of the present invention.

[0105] The transceiver 2003 is used to communicate with a network device or a terminal device.

[0106] Optionally, the transceiver 2003 may include a receiver and a transmitter ( Figure 4 The receiver is used to implement a receiving function, and the transmitter is used to implement a sending function.

[0107] Optionally, the transceiver 2003 may be integrated with the first processor 2001, or may exist independently, and communicate with the first processor 2001 through the interface circuit ( Figure 4 (not shown) is coupled to the first processor 2001, which is not specifically limited in this embodiment of the present invention.

[0108] It should be noted that Figure 4 The structure of the distributed fiber optic acoustic wave sensing device 410 with coherent fading suppression shown in the figure does not constitute a limitation on the router. The actual knowledge structure recognition device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0109] In addition, the technical effects of the distributed optical fiber acoustic wave sensing device 410 with coherent fading suppression can refer to the technical effects of the distributed optical fiber acoustic wave sensing method with coherent fading suppression described in the above method embodiment, which will not be repeated here.

[0110] It should be understood that the first processor 2001 in the embodiment of the present invention may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0111] It should also be understood that the memory in the embodiments of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0112] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable sensors. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0113] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0114] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0115] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0116] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0117] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0118] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention.

[0119] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A distributed optical fiber acoustic wave sensing method with coherent fading suppression, characterized in that: The method comprises: S1, emitting a continuous light wave through a narrow linewidth laser, the continuous light wave passes through a coupler 1, and the continuous light wave is divided into two beams, the two beams being a detection light and a local oscillator light; S2, the detection light passes through a double pulse generator, and the detection light is modulated into a difference frequency delayed double pulse; S3, the difference frequency delayed double pulse is amplified to a suitable power through an erbium-doped fiber amplifier; S4, after filtering out the spontaneous radiation noise through an optical bandpass filter, the power-amplified difference frequency delayed double pulse is propagated to port 2 through port 1 of circulator 1 and injected into the optical fiber to be tested; wherein, the circulator 1 includes three ports, namely: port 1, port 2 and port 3; S5. The two pulses in the pulse train will generate RBS signals in the optical fiber to be tested. After the RBS signal is transmitted from port 2 to port 3 of circulator 1, it is divided into two beams with equal power through coupler 4. One of the beams is mixed with the local oscillator light separated by coupler 1 through coupler 5. The mixed beam is received by a balanced photodetector, and the other beam is directly received by a photodetector. S6. The electrical signals output by the balanced photodetector and the photodetector are collected by a data collection system.

2. The distributed optical fiber acoustic wave sensing method with coherent fading suppression according to claim 1, characterized in that: The coupler 1 is a coupler with a splitting ratio of 1:99, and the two beams of light after splitting respectively include: 99% of the detection light and 1% of the local oscillator light.

3. The distributed optical fiber acoustic wave sensing method with coherent fading suppression according to claim 1, characterized in that: The implementation forms of the double pulse include: an integrated modulation mode and a discrete modulation mode.

4. The distributed optical fiber acoustic wave sensing method with coherent fading suppression according to claim 3, characterized in that: The integrated modulation method includes: The pulse electrical signal required to be modulated is generated by any signal generator and input into the driver. The driver modulates the electrical signal and outputs the electrical signal to the dual pulse generator to generate the corresponding optical pulse waveform.

5. The distributed optical fiber acoustic wave sensing method with coherent fading suppression according to claim 3, characterized in that: The discrete modulation forms include: The detection light is split into two beams of equal power through a coupler 2 with a splitting ratio of 50:50, and the two beams of light enter the upper arm and the lower arm of the Mach-Zehnder interferometer respectively; Insert an optical modulator 1 into the upper arm to modulate a continuous probe light beam into a pulse light; Insert an optical modulator 2 into the lower arm to modulate another continuous probe light into a pulse light; and insert a delay optical fiber into the lower arm at the same time, and determine the time interval between the two pulses in the generated difference frequency delay double pulse by the length of the delay optical fiber; The pulses generated by the upper arm and the lower arm are combined through a 50:50 coupler 3 to obtain a difference frequency delayed double pulse.

6. The distributed optical fiber acoustic wave sensing method with coherent fading suppression according to claims 4 and 5, characterized in that: The double pulse generator also includes: The change in the frequency of the light wave caused by optical modulation is controlled by the AWG and driver in the system and adjusted according to actual needs.

7. The distributed optical fiber acoustic wave sensing method with coherent fading suppression according to claim 1, characterized in that: The AWG and driver in the integrated modulation method are in single-channel form; The AWG and the driver in the discrete modulation format are in a dual-channel format.

8. A distributed optical fiber acoustic wave sensor with coherent fading suppression, characterized in that: The sensor is applied to the distributed optical fiber acoustic wave sensing method for coherent fading suppression according to any one of claims 1 to 7, and the sensor comprises: Narrow linewidth laser, dual pulse generator, erbium-doped fiber amplifier, optical bandpass filter, circulator 1, coupler 1, balanced photodetector, photodetector and data acquisition system; The narrow linewidth laser emits a continuous light wave, the continuous light wave passes through the coupler 1, and the continuous light wave is divided into two beams, namely, a detection light and a local oscillator light; The detection light passes through a double pulse generator, and the detection light is modulated into a difference frequency delayed double pulse; The difference frequency delayed double pulses are amplified to a suitable power by passing through an erbium-doped fiber amplifier; The power-amplified difference frequency delayed double pulse is passed through an optical bandpass filter to filter out the spontaneous radiation noise, and then propagated from port 1 to port 2 of the circulator 1 and injected into the optical fiber to be tested; wherein the circulator 1 includes three ports, namely: port 1, port 2 and port 3; The two pulses in the pulse train will generate RBS signals in the optical fiber to be tested. The RBS signals are propagated from port 2 of circulator 1 to port 3, and are divided into two beams with equal power through coupler 4. One of the beams is mixed with the local oscillator light separated by coupler 1 through coupler 5. The mixed beam is received by a balanced photodetector, and the other beam is directly received by a photodetector. The balanced photodetector and the electrical signals output by the photodetector are collected by the data collection system.

9. A distributed optical fiber acoustic wave sensing device with coherent fading suppression, characterized in that: The distributed optical fiber acoustic wave sensing device with coherent fading suppression comprises: processor; A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program codes, and the program codes can be called by a processor to execute the method for coherent fading suppression as described in any one of claims 1 to 7.

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