A distributed high-frequency vibration monitoring method and device with ultra-large measurement range

Abstract

The present invention provides a distributed high-frequency vibration monitoring method and device with an ultra-large measurement range. The method comprises the following steps: a laser is used to send a swept-frequency optical signal of a central wavelength within a preset wavelength range to an optical fiber to be tested; a relationship calibration is performed in advance on the preset wavelength range based on a reflected Rayleigh scattering signal; a laser is used to emit a single-frequency optical signal within a preset wavelength range, and frequency comb modulation is performed on each single pulse of the single-frequency optical signal. The modulated optical signal is sent to the optical fiber to be tested, and the Rayleigh scattering signal reflected from the optical fiber to be tested is obtained. The surrounding environment of the optical fiber to be tested is detected based on the Rayleigh scattering signal within the preset wavelength range and the corresponding relationship calibration. The frequency comb modulation is used to load multiple frequency components onto a single pulse, thereby reducing the time consumption of a single group of detection signals. At the same time, the relationship calibration is performed in advance on the preset wavelength range, thereby realizing the monitoring of dynamic signals within the preset wavelength range.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to a distributed high-frequency vibration monitoring method and device with an ultra-large measurement range. Background Art

[0002] In traditional sweep frequency detection systems, each set of detection signals includes multiple different detection frequencies, and each different detection frequency is performed independently. As a result, it often takes several minutes to complete a set of detection signals, which is time-consuming and has a slow response speed. Therefore, real-time monitoring of dynamic signals cannot be achieved, and dynamic monitoring is difficult to achieve.

[0003] On the other hand, the signal measurement range of the traditional swept-frequency detection system is determined by the total swept-frequency bandwidth. To achieve an ultra-large measurement range, the signal modulation bandwidth of a single group of detection signals needs to be large enough, that is, a single group of detection signals with a single output can complete the detection of an ultra-large measurement range at one time. In order for a single group of detection signals to have a large enough signal modulation bandwidth, more pulse signals need to be provided while ensuring the frequency resolution. Too many pulse signals in a single group of detection signals, on the one hand, cause the single group of detection signals to take longer time and cannot detect dynamic signals. On the other hand, it also requires high hardware costs.

[0004] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to realize dynamic signal monitoring within a relatively larger wavelength range in frequency sweep detection.

[0006] The present invention adopts the following technical solutions:

[0007] In a first aspect, a distributed high-frequency vibration monitoring method with an ultra-large measurement range is provided, comprising:

[0008] A swept frequency optical signal of a preset wavelength range is sent to the optical fiber under test through a laser. The relationship between position, light intensity and pulse frequency in the preset wavelength range is calibrated based on the first Rayleigh scattering signal reflected from the optical fiber under test to obtain a reference spectrum corresponding to the preset wavelength range.

[0009] emitting a single-frequency optical signal of a central wavelength within a preset wavelength range through a laser, performing frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse, using a first preset number of frequency comb modulated pulses as a group of detection signals, and sending all detection signals within the preset wavelength range to the optical fiber to be tested;

[0010] A second Rayleigh scattering signal reflected by the optical fiber to be tested within the preset wavelength range is obtained, and the surrounding environment of the optical fiber to be tested is detected based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum.

[0011] Preferably, the step of emitting a single-frequency optical signal in a preset wavelength range through a laser, performing frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse, and using a first preset number of frequency comb modulated pulses as a group of detection signals specifically includes:

[0012] Adding a second preset number of equally spaced frequency components to the single-frequency optical signal through electro-optical modulation and acousto-optical modulation to obtain a frequency comb modulated pulse; the first preset number is 1;

[0013] The method comprises the following steps: an interval between two adjacent frequency components on each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse; a total bandwidth of all frequency components on a single single pulse is less than or equal to twice the bandwidth of the acousto-optic modulation; and a frequency difference between the lowest frequency of the modulated original frequency comb signal and the frequency shift of the acousto-optic modulation is greater than or equal to twice the bandwidth of the acousto-optic modulation.

[0014] Preferably, the step of emitting a single-frequency optical signal in a preset wavelength range through a laser, performing frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse, and using a first preset number of frequency comb modulated pulses as a group of detection signals specifically includes:

[0015] Adding a second preset number of equally spaced frequency components to the single-frequency optical signal through electro-optical modulation and acousto-optical modulation to obtain a frequency comb modulated pulse; wherein a third preset number of sub-frequency combs are added to each frequency component;

[0016] The first preset number is greater than or equal to 2, the interval between two adjacent frequency components on each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse; the total bandwidth of all frequency components on a single single pulse is less than or equal to twice the bandwidth of the acousto-optic modulation; and the frequency difference between the lowest frequency of the modulated original frequency comb signal and the frequency shift of the acousto-optic modulation is greater than or equal to twice the bandwidth of the acousto-optic modulation.

[0017] Preferably, the calibration of the relationship among position, light intensity and pulse frequency in a preset wavelength range based on the first Rayleigh scattering signal reflected from the optical fiber to be tested to obtain a reference spectrum corresponding to the preset wavelength range specifically includes:

[0018] receiving in sequence each first pulse signal in the reflected first Rayleigh scattering signal, and acquiring corresponding light intensity information, position information, and pulse frequency information according to each first pulse signal;

[0019] The calibration function relationship corresponding to the first pulse signal is obtained according to the light intensity information, position information and pulse frequency information corresponding to the first pulse signal, and the calibration function relationships corresponding to all first pulse signals in the preset wavelength range are integrated into the reference spectrum.

[0020] Preferably, obtaining the second Rayleigh scattering signal reflected by the optical fiber to be tested within the preset wavelength range, and detecting the surrounding environment of the optical fiber to be tested based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum, specifically includes:

[0021] Sequentially receiving each second pulse signal in the second Rayleigh scattering signal within a preset wavelength range, and acquiring corresponding actual light intensity information, position information, and pulse frequency information according to each second pulse signal;

[0022] Obtaining a calibration function relationship corresponding to each second pulse signal segment, and substituting the position information and pulse frequency information corresponding to each second pulse signal segment into the corresponding calibration function relationship to obtain the calibrated light intensity information of each second pulse signal segment;

[0023] The calibrated light intensity information is compared with the actual light intensity information to obtain detection information of the optical fiber to be tested at the corresponding position.

[0024] In a second aspect, a distributed high-frequency vibration monitoring device with an ultra-large measurement range is provided, which is used to apply the distributed high-frequency vibration monitoring method with an ultra-large measurement range, including: a tunable laser 1, a first coupler 2, a modulator module 3, a first circulator 4, a detection optical fiber 5, a second coupler 6 and a detection module 7, wherein:

[0025] The output end of the tunable laser 1 is connected to the input end of the first coupler 2, one of the output ends of the first coupler 2 is connected to the input end of the modulator module 3, the output end of the modulator module 3 is connected to the first port 41 of the first circulator 4, the second port 42 of the first circulator 4 is connected to the detection optical fiber 5, the third port 43 of the first circulator 4 is connected to one of the input ends of the second coupler 6, the other input end of the second coupler 6 is connected to the other output end of the first coupler 2, and the output end of the second coupler 6 is connected to the input end of the detection module 7;

[0026] The tunable laser 1 is used to send a swept frequency optical signal in a preset wavelength range to the detection optical fiber 5. The detection optical fiber 5 is used to reflect back the first Rayleigh scattered signal and transmit it to the detection module 7 through the first circulator 4. The detection module 7 is used to calibrate the relationship between the position, light intensity and pulse frequency of the first Rayleigh scattered signal in the preset wavelength range to obtain a reference spectrum;

[0027] The tunable laser 1 is further configured to send a single-frequency optical signal within a preset wavelength range to the modulator module 3. The modulator module 3 is configured to perform frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse. A first preset number of frequency comb modulated pulses is used as a group of detection signals. All detection signals within the preset wavelength range are sent to the detection optical fiber 5. The detection optical fiber 5 is further configured to reflect back a second Rayleigh scattering signal within the preset wavelength range. The detection module 7 is further configured to detect the surrounding environment of the detection optical fiber 5 based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum.

[0028] Preferably, the modulator module 3 includes: an electro-optic modulator 31 and an acousto-optic modulator 32, wherein:

[0029] The input end of the electro-optic modulator 31 is connected to one of the output ends of the first coupler 2, the output end of the electro-optic modulator 31 is connected to the input end of the acousto-optic modulator 32, and the output end of the acousto-optic modulator 32 is connected to the first port 41 of the first circulator 4;

[0030] The electro-optic modulator 31 is used to add a second preset number of equally spaced frequency components to the single-frequency optical signal, and the acousto-optic modulator 32 is used to modulate the single-frequency optical signal into a pulse signal.

[0031] Preferably, the detection module 7 includes: a photoelectric detector 71, a first acquisition unit 72 and a data processing module 73, wherein:

[0032] The input end of the photodetector 71 is connected to the output end of the second coupler 6 , the output end of the photodetector 71 is connected to the input end of the first acquisition unit 72 , and the output end of the first acquisition unit 72 is connected to the input end of the data processing module 73 ;

[0033] The photoelectric detector 71 is used to convert the optical signal from the second coupler 6 into an electrical signal and send it to the first acquisition unit 72. The first acquisition unit 72 is used to collect the received electrical signal; the data processing module 73 is used to perform relationship calibration or detect the surrounding environment of the optical fiber 5 based on the collected electrical signal.

[0034] Preferably, the distributed high-frequency vibration monitoring device with an ultra-large measurement range further includes: an erbium-doped fiber amplifier 8, a second circulator 9 and a Bragg grating 10, wherein:

[0035] The input end of the erbium-doped fiber amplifier 8 is connected to the output end of the modulator module 3, the output end of the erbium-doped fiber amplifier 8 is connected to the fourth port 91 of the second circulator 9, the fifth port 92 of the second circulator 9 is connected to the first port 41 of the first circulator 4, and the sixth port 93 of the second circulator 9 is connected to the Bragg grating 10;

[0036] The erbium-doped fiber amplifier 8 is used to amplify the optical signal from the modulator module 3 , and the Bragg grating 10 is used to filter out spontaneous emission noise in the optical signal.

[0037] Preferably, the distributed high-frequency vibration monitoring device with an ultra-large measurement range further includes: a third coupler 11 and a reference interference module 12, wherein:

[0038] The input end of the third coupler 11 is connected to the output end of the tunable laser 1, one of the output ends of the third coupler 11 is connected to the input end of the first coupler 2, and the other output end of the third coupler 11 is connected to the input end of the reference interferometer module 12;

[0039] The reference interference module 12 is used to calibrate and calibrate the linear frequency sweep characteristics of the optical signal output by the tunable laser 1 .

[0040] The present invention provides a distributed high-frequency vibration monitoring method and device with an ultra-large measurement range. The method comprises the following steps: a laser is used to send a swept-frequency optical signal of a central wavelength in a preset wavelength range to an optical fiber to be tested; a relationship calibration is performed in advance on the preset wavelength range based on the reflected Rayleigh scattering signal; a laser is used to emit a single-frequency optical signal in the preset wavelength range, and frequency comb modulation is performed on each single pulse of the single-frequency optical signal. The modulated optical signal is sent to the optical fiber to be tested, and the Rayleigh scattering signal reflected from the optical fiber to be tested is obtained. The surrounding environment of the optical fiber to be tested is detected based on the Rayleigh scattering signal in the preset wavelength range and the corresponding relationship calibration. The frequency comb modulation is used to load multiple frequency components on a single pulse, thereby reducing the time consumption of a single group of detection signals. At the same time, the relationship calibration is performed in advance on the preset wavelength range, thereby realizing the monitoring of dynamic signals in the preset wavelength range. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0042] Figure 1This is a method flow chart of a distributed high-frequency vibration monitoring method with an ultra-large measurement range provided by an embodiment of the present invention;

[0043] Figure 2 This is a frequency-light intensity coordinate diagram of frequency comb modulation of a distributed high-frequency vibration monitoring method with an ultra-large measurement range provided by an embodiment of the present invention;

[0044] Figure 3 This is a frequency-light intensity coordinate diagram of frequency comb modulation of another distributed high-frequency vibration monitoring method with an ultra-large measurement range provided by an embodiment of the present invention;

[0045] Figure 4 This is a method flow chart of a calibration mode of a distributed high-frequency vibration monitoring method with an ultra-large measurement range provided by an embodiment of the present invention;

[0046] Figure 5 Schematic diagram of a calibration function relationship in a calibration mode of a distributed high-frequency vibration monitoring method with an ultra-large measurement range provided by an embodiment of the present invention;

[0047] Figure 6 This is a method flow chart of a detection mode of a distributed high-frequency vibration monitoring method with an ultra-large measurement range provided by an embodiment of the present invention;

[0048] Figure 7 1 is a schematic diagram of a distributed high-frequency vibration monitoring device with an ultra-large measurement range provided by an embodiment of the present invention;

[0049] Figure 8 Schematic diagram of waveforms of various modulators in different modes of a distributed high-frequency vibration monitoring device with an ultra-large measurement range provided by an embodiment of the present invention;

[0050] Figure 9 1 is a schematic diagram of another distributed high-frequency vibration monitoring device with an ultra-large measurement range provided by an embodiment of the present invention;

[0051] Figure 10 Schematic diagram of a filtering and reorganization matrix and cross-correlation calculation of sampling results of a distributed high-frequency vibration monitoring device with an ultra-large measurement range provided by an embodiment of the present invention;

[0052] Figure 11 Schematic diagram of the cross-correlation spectrum and peak fitting results of a distributed high-frequency vibration monitoring device with an ultra-large measurement range provided by an embodiment of the present invention;

[0053] The diagram numbers are as follows:

[0054] Tunable laser 1; first coupler 2; modulator module 3; electro-optic modulator 31; acousto-optic modulator 32; first circulator 4; first port 41; second port 42; third port 43; detection fiber 5; second coupler 6; detection module 7; photodetector 71; first acquisition unit 72; data processing module 73; erbium-doped fiber amplifier 8; second circulator 9; fourth port 91; fifth port 92; sixth port 93; Bragg grating 10; third coupler 11; reference interferometer module 12; balanced photodetector 121; second acquisition unit 122; waveform generator 13; stable signal source 14; delay fiber 125; fourth coupler 123; fifth coupler 124. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0056] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0057] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "multiple" means two or more. In addition, for example, the description may also use the method of adding "A" and "B" at the end to describe the same type of nouns as two independent individuals. In this case, the corresponding features defined as "A" and "B" are only used to distinguish the description purposes of the same type of individuals, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0058] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity, i.e., the limitations of the measurement system.

[0059] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as meaning open inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" and the like are intended to indicate that the specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner, that is, although they may be carried in the embodiments or examples of the above terms due to reasons such as the order and position of appearance, it is not limited to that they can be carried in combination by one embodiment or example.

[0060] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0061] Embodiment 1:

[0062] In the prior art, when sending a detection light signal to the optical fiber to be tested, it is carried out in the form of sending a group of detection signals to the optical fiber to be tested each time, wherein each group of detection signals includes multiple pulse signals; in order to realize the detection of the set wavelength range, it is necessary to ensure that the total wavelength range of a single group of detection signals is consistent with the set wavelength range, and to ensure that the single group of detection signals output by a single detection can complete the detection of the set wavelength range at one time; but the problem is that: when the set wavelength range is larger, the number of pulse signals in each group of detection signals needs to be more, which, on the one hand, causes the single group of detection signals to take longer time and cannot realize the detection of dynamic signals, and on the other hand, it also requires high hardware costs.

[0063] In order to solve the above problems, this embodiment provides a distributed high-frequency vibration monitoring method with a large measurement range, such as Figure 1 As shown, the method flow includes:

[0064] In step 101, a swept frequency optical signal of a preset wavelength range is sent to the optical fiber to be tested by a laser, and the relationship between position, light intensity and pulse frequency in the preset wavelength range is calibrated based on the first Rayleigh scattering signal reflected by the optical fiber to be tested, so as to obtain a reference spectrum corresponding to the preset wavelength range.

[0065] In this embodiment, the frequency-swept optical signal refers to an optical signal whose optical wavelength changes linearly and continuously over time within a certain range.

[0066] In this embodiment, the laser is used to emit a corresponding optical signal to the optical fiber to be tested. The optical fiber to be tested is used to be placed in a scene to be tested. Changes in the environment at different positions in the scene to be tested will affect the optical signal in the optical fiber to be tested at that position. The environment of the scene to be tested is monitored based on the parameter changes of the optical signal in the optical fiber to be tested at different positions.

[0067] In this embodiment, the preset wavelength range is set by those skilled in the art. The setting of the preset wavelength range should meet the transmission requirements of the sensing optical fiber used. In this embodiment, the preset wavelength range can be the C band, which can be 1530nm-1565nm.

[0068] In order to achieve rapid detection of dynamic signals in a preset wavelength range on the basis of setting fewer pulse signals in each group of detection signals, a swept-frequency optical signal in a preset wavelength range is pre-emitted to the optical fiber to be tested. The optical fiber to be tested will correspondingly reflect a first Rayleigh scattering signal. The first Rayleigh scattering signal can be used to represent the detection of the environment around the optical fiber to be tested by the swept-frequency optical signal in the preset wavelength range. Therefore, the light intensity at different positions on the optical fiber to be tested at different pulse frequencies is obtained based on the reflected first Rayleigh scattering signal. The position and pulse frequency are used as independent variables, and the light intensity is used as the dependent variable to obtain a functional relationship between the position, light intensity and pulse frequency. All functional relationships within the preset wavelength range are integrated into the reference spectrum to complete the relationship calibration within the preset wavelength range under the current environment.

[0069] After obtaining the reference spectrum, since the frequency relationship curves are all random and the frequency relationship curves at different positions are quite different, the frequency relationship of any detection signal can find a matching correspondence in the reference spectrum. Even if the wavelength range of a single group of detection signals is much smaller than the preset wavelength range, the detection of the entire preset wavelength range can be completed by matching each group of detection signals with the corresponding frequency relationship curve in the reference spectrum. Therefore, when performing subsequent detection, even if the wavelength range of a single detection signal is relatively small, it can also be matched with the reference spectrum to complete the acquisition of detection information. There is no need to limit the number of pulse signals in a single group of detection signals. The number of pulses in each group of detection signals can be only one or a few. The above calibration process can be regarded as a calibration mode, which is a preparation stage before formal detection.

[0070] Existing technologies rely on external frequency modulation of the single-frequency laser output by an EOM to achieve laser frequency sweep detection. There are two main methods for this modulation: using a wide-bandwidth microwave source as the external modulation signal source, or using an arbitrary waveform generator (AWG) as the modulation signal source. The wide-bandwidth microwave source approach suffers from long frequency switching times, which means that a wide frequency sweep range of 10 GHz requires several minutes or even tens of minutes to achieve. Furthermore, the Rayleigh scattering signal reference spectrum calibrated over such a long time is difficult to eliminate environmental influences, especially variations in the reference spectrum caused by temperature changes, and therefore cannot be used as a reference spectrum for vibration signals. The AWG approach has comparable detection speed to the internal laser modulation scheme used in the present invention, but is limited by the bandwidth and memory depth hardware parameters of the AWG, making it difficult to achieve a wide frequency sweep range of 10 GHz (and even if it can be achieved, it would be extremely costly), making it impractical. In contrast, the laser intra-modulation scheme used in the present invention can achieve low-cost ultra-wide-range fast linear frequency sweeping, and can complete a large frequency sweep range of the order of 10 GHz within 1 second; since the actual measurement time of calibration is very short, the reference spectrum changes caused by environmental changes can be ignored, so a highly reliable ultra-wide-range Rayleigh scattering reference spectrum can be obtained, which can be used for correlation matching of subsequent frequency comb detection results.

[0071] In step 102, a single-frequency optical signal having a central wavelength within a preset wavelength range is emitted by a laser, and frequency comb modulation is performed on each single pulse in the single-frequency optical signal to obtain frequency comb modulated pulses. A first preset number of frequency comb modulated pulses are used as a group of detection signals, and all detection signals within the preset wavelength range are sent to the optical fiber to be tested.

[0072] The central wavelength of the preset wavelength range is the wavelength at the middle position of the preset wavelength range. In this embodiment, the single-frequency optical signal refers to an optical signal with a constant optical wavelength. After the calibration mode is completed and the reference spectrum corresponding to the preset wavelength range is obtained, it is possible to switch to the detection mode, and use a laser to emit a single-frequency optical signal in the preset wavelength range to the optical fiber to be tested for formal detection; in the prior art, in order to achieve high-sensitivity detection, each group of detection signals usually includes a plurality of pulses of different frequencies, and a group of pulses of different frequencies is used to obtain the Rayleigh scattering signal to reconstruct the Rayleigh frequency shift spectrum along the optical fiber, and then quantitatively analyze the size of the external disturbance signal, thereby achieving quantitative detection with ultra-high sensitivity. However, the problem is that setting multiple pulses of different frequencies in a group of detection signals will cause the transmission and reception of a single group of detection signals to take too long and the response speed to be too slow. Although the sensitivity is sufficient, it cannot be applied to the detection of dynamic signals.

[0073] In order to solve the above problems, in this embodiment, frequency comb modulation is performed on each single pulse in the single-frequency optical signal. Through frequency comb modulation, multiple frequency components of different frequencies are loaded on each single pulse. Only one pulse signal meets the conditions of multiple frequencies, and the requirements of high-sensitivity measurement are achieved. At the same time, since a single pulse signal meets the conditions of multiple frequencies, there is no need to set too many pulses in each group of detection signals (the number of pulses required in each group of detection signals in the existing technology is determined by the number of frequencies required). At the same time, it also greatly reduces the transmission and reception time of a single group of detection signals, improves the response speed, and can be applied to the detection of dynamic signals.

[0074] In this embodiment, the first preset number is set according to actual conditions. In this embodiment, the first preset number may be 1 or greater than or equal to 2 according to different conditions.

[0075] In step 103, a second Rayleigh scattering signal reflected from the optical fiber to be tested within the preset wavelength range is obtained, and the surrounding environment of the optical fiber to be tested is detected based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum.

[0076] Each set of detection signals in the second Rayleigh scattering signal is substituted into the corresponding functional relationship in the reference spectrum to calculate the light intensity during calibration. By comparing the light intensity during calibration with the actual light intensity, the environmental conditions at the corresponding position can be detected.

[0077] Furthermore, in this embodiment, when frequency comb modulation is performed on the single-frequency optical signal emitted by the laser, the following designs are involved:

[0078] A second preset number of equally spaced frequency components is added to the single-frequency optical signal through electro-optical modulation and acousto-optical modulation to obtain a frequency comb modulated pulse; the first preset number is 1.

[0079] The invention relates to a method for obtaining a 3D image of a single pulse having a spacing between two adjacent frequency components and a frequency shift between the two components. The method comprises the following steps: (1) a spacing between two adjacent frequency components on each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse, thereby satisfying the constraints of the Fourier time-frequency commutation relation; (2) a total bandwidth of all frequency components on a single single pulse is less than or equal to twice the bandwidth of the acousto-optic modulation; and (3) a frequency difference between the lowest frequency of the modulated original frequency comb signal and the frequency shift of the acousto-optic modulation is greater than or equal to twice the bandwidth of the acousto-optic modulation.

[0080] like Figure 2 As shown, is the total bandwidth of all frequency components on a single pulse, is the interval between two adjacent frequency components, is the bandwidth of the acousto-optic modulation, is the frequency difference between the acousto-optic modulation and the starting frequency position of the single pulse.

[0081] This design enables the addition of a second preset number of frequency components to each single pulse in the single-frequency optical signal, ensuring the inclusion of multiple frequencies within a single detection signal. This eliminates the need for excessive pulses within a single detection signal, significantly reducing measurement time while ensuring high-sensitivity detection. The electro-optical modulation is used for frequency comb modulation, while the acousto-optic modulation is used to modulate the original DC signal into a pulsed signal. In this case, a single pulse is sufficient within a single detection signal.

[0082] The above design is applicable to scenarios with low frequency resolution and spatial resolution. When the detection scenario requires higher frequency resolution and higher spatial resolution, this embodiment also involves the following design:

[0083] A second preset number of equally spaced frequency components are added to the single-frequency optical signal through electro-optical modulation and acousto-optical modulation to obtain a frequency comb modulated pulse; wherein a third preset number of sub-frequency combs are added to each frequency component.

[0084] The first preset number is greater than or equal to 2, the interval between two adjacent frequency components on each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse; the total bandwidth of all frequency components on a single single pulse is less than or equal to twice the bandwidth of the acousto-optic modulation; and the frequency difference between the lowest frequency of the modulated original frequency comb signal and the frequency shift of the acousto-optic modulation is greater than or equal to twice the bandwidth of the acousto-optic modulation.

[0085] like Figure 3 As shown, Figure 3 For example, To obtain the total bandwidth of all frequency components on a single pulse, first, equally spaced frequency components are loaded on each single pulse through electro-optical modulation and acousto-optic modulation, and then 5 sub-frequency combs are loaded on each frequency component. The frequency interval between each interval of four sub-frequency combs is , is the bandwidth of the acousto-optic modulation, is the frequency difference between the acousto-optic modulation and the starting frequency of a single pulse. This configuration scheme further applies a sub-comb to each frequency component, ensuring that a single pulse meets the corresponding frequency resolution and spatial resolution requirements. The electro-optical modulation is used for frequency comb modulation, while the acousto-optic modulation is used to modulate the original DC signal into a pulse signal. In this case, five pulses can be set in a single detection signal.

[0086] In this embodiment, since the interval between two adjacent frequency components on each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse, and the interval between two adjacent frequency components on the single pulse is related to the frequency resolution, and the pulse width of the single pulse is related to the spatial resolution, when the pulse width of the single pulse remains unchanged and five sub-frequency combs are added to the original frequency component, the frequency interval in the overall frequency comb after all sub-frequency combs are combined is reduced to one-fifth of the original frequency interval, so the frequency resolution is correspondingly increased by five times, making it suitable for occasions with higher frequency resolution. It is worth mentioning that in order to facilitate the display of relevant information, Figure 3 It is a three-dimensional coordinate system, in which the positive direction of the horizontal axis is frequency, the positive direction of the vertical axis is light intensity, and the negative direction of the vertical axis is time, that is, the five sub-frequency combs on each frequency component are loaded at different times.

[0087] The reasoning behind the aforementioned frequency resolution improvement assumes that the pulse width of a single pulse remains constant. Based on this improved frequency resolution, if the pulse width of a single pulse is reduced to 1 / n of its original value, the minimum resolvable spatial interval also becomes 1 / n of its original value (i.e., an increase of n times). Accordingly, according to the aforementioned time-frequency reciprocity relationship, the frequency interval on each sub-comb (and the complete frequency comb formed by combining all sub-combs) is expanded by a factor of n, and the corresponding frequency resolution is reduced to 1 / n of its original value. That is, for a given number of sub-combs, the product of spatial resolution and frequency resolution is fixed and can be freely traded off based on requirements. Compared to a single frequency comb approach, using n sub-combs achieves both m-fold spatial resolution and n / m-fold frequency resolution.

[0088] In this embodiment, in the calibration mode, after receiving the first Rayleigh scattered signal reflected from the optical fiber to be tested, the relationship calibration is performed based on the relevant information of the position, light intensity and pulse frequency in the first Rayleigh scattered signal, such as Figure 4 As shown, the relevant designs are as follows:

[0089] In step 201, each first pulse signal in the reflected first Rayleigh scattering signal is received in sequence, and corresponding light intensity information, position information and pulse frequency information are obtained according to each first pulse signal.

[0090] In this embodiment, since the laser transmits the corresponding detection signals to the optical fiber to be tested in sequence, the optical fiber to be tested will reflect back the first Rayleigh scattered signals corresponding to each group of detection signals in the corresponding order, and each group of detection signals includes one or more pulse signals. Therefore, receiving the reflected first Rayleigh scattered signals can also be regarded as receiving the reflected first pulse signals in sequence. At the same time, since the time of the first pulse signals reflected back from different positions in the optical fiber to be tested is also different, it is possible to determine which position in the optical fiber to be tested the first pulse signal represents by the time of the received first pulse signal, and then obtain the corresponding light intensity and pulse frequency based on the received first pulse signal.

[0091] like Figure 5 As shown, the image of light intensity information, position information and pulse frequency information on the time domain graph.

[0092] In step 202, a calibration function relationship corresponding to the first pulse signal is obtained based on the light intensity information, position information and pulse frequency information corresponding to the first pulse signal, and the calibration function relationships corresponding to all first pulse signals in the preset wavelength range are integrated into the reference spectrum.

[0093] The position information and pulse frequency information serve as independent variables in the calibration function relationship, and the light intensity information serves as the dependent variable in the calibration function relationship. By calibrating all reflected first pulse signals within a preset wavelength range, a corresponding calibration function relationship is obtained, and all calibration function relationships within the preset wavelength range are integrated into the reference spectrum. During subsequent formal detection, the calibration function relationship is used as a calculation basis to obtain changes in the environment around the optical fiber to be tested. It is worth mentioning that in this embodiment, when performing the calibration mode, continuous linear frequency sweeping within a certain wavelength range can be achieved by controlling the current and temperature of the laser.

[0094] After completing the calibration of the preset wavelength range, it can be switched to the detection mode, and a single-frequency optical signal of the preset wavelength range is sent through the laser, and the single-frequency optical signal is frequency comb modulated to obtain a frequency comb modulated pulse. The first preset number of frequency comb modulated pulses is used as a group of detection signals, and all detection signals within the preset wavelength range are sent to the optical fiber to be tested. The optical fiber to be tested reflects back the second Rayleigh scattering signal, and the information corresponding to each second pulse signal in the second Rayleigh scattering signal is obtained by collecting and photoelectrically converting each second pulse signal in the second Rayleigh scattering signal, and the change information of the surrounding environment of the optical fiber to be tested is obtained by calculating the reference spectrum, such as Figure 6 As shown, the corresponding method is designed as follows:

[0095] In step 301, each second pulse signal in a second Rayleigh scattering signal within a preset wavelength range is received in sequence, and corresponding actual light intensity information, position information, and pulse frequency information are acquired according to each second pulse signal.

[0096] In step 302, the calibration function relationship corresponding to each second pulse signal is obtained, and the position information and pulse frequency information corresponding to each second pulse signal are brought into the corresponding calibration function relationship to obtain the calibrated light intensity information of each second pulse signal.

[0097] In step 303, the calibrated light intensity information is compared with the actual light intensity information to obtain detection information of the optical fiber to be tested at the corresponding position.

[0098] The measured spectrum of the Rayleigh scattering signal obtained by the frequency comb is correlated with a pre-calibrated large-scale reference spectrum to calculate the temporal relationship between the frequency values ​​corresponding to the correlation peak positions of the measured spectrum and the reference spectrum at any spatial position. The calculated correlation peak frequency at a spatial position without external disturbance does not change with time. However, when an external disturbance is applied, the correlation peak frequency at the disturbance changes with time, and its functional relationship with time corresponds to the applied external disturbance in a certain proportion (for vibration signals, a frequency change of 150MHz linearly corresponds to a stress of 1 microstrain).

[0099] Example 2:

[0100] Based on Example 1, this embodiment provides a distributed high-frequency vibration monitoring device with a large measurement range, which is used to apply the distributed high-frequency vibration monitoring method with a large measurement range described in Example 1, such as Figure 7 As shown, it includes: a tunable laser 1, a first coupler 2, a modulator module 3, a first circulator 4, a detection fiber 5, a second coupler 6 and a detection module 7, wherein:

[0101] The laser in Example 1 is the tunable laser 1 in this embodiment, and the optical fiber to be tested in Example 1 is the detection optical fiber 5 in this embodiment.

[0102] The output end of the tunable laser 1 is connected to the input end of the first coupler 2, one of the output ends of the first coupler 2 is connected to the input end of the modulator module 3, the output end of the modulator module 3 is connected to the first port 41 of the first circulator 4, the second port 42 of the first circulator 4 is connected to the detection optical fiber 5, the third port 43 of the first circulator 4 is connected to one of the input ends of the second coupler 6, the other input end of the second coupler 6 is connected to the other output end of the first coupler 2, and the output end of the second coupler 6 is connected to the input end of the detection module 7.

[0103] When the device is in calibration mode, the tunable laser 1 is used to send a swept frequency optical signal in a preset wavelength range to the detection optical fiber 5. The detection optical fiber 5 is used to reflect back the first Rayleigh scattered signal and transmit it to the detection module 7 through the first circulator 4. The detection module 7 is used to calibrate the relationship between the position, light intensity and pulse frequency of the first Rayleigh scattered signal in the preset wavelength range to obtain a reference spectrum.

[0104] When the device is in detection mode, the tunable laser 1 is further used to send a single-frequency optical signal within a preset wavelength range to the modulator module 3. The modulator module 3 is used to perform frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse. A first preset number of frequency comb modulated pulses is used as a group of detection signals. All detection signals within the preset wavelength range are sent to the detection optical fiber 5. The detection optical fiber 5 is further used to reflect back a second Rayleigh scattering signal within the preset wavelength range. The detection module 7 is further used to detect the surrounding environment of the detection optical fiber 5 based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum.

[0105] In this embodiment, the first port 41 of the first circulator 4 is used to receive the optical signal from the modulator module 3 and output it to the detection optical fiber 5 through the second port 42 of the first circulator 4. The detection optical fiber 5 reflects the first Rayleigh scattered signal back to the second port 42. The first circulator 4 sends the received first Rayleigh scattered signal to the detection module 7 through the third port 43, thereby realizing the corresponding transmission path.

[0106] When the device is in calibration mode, the first coupler 2 is used to split the swept-frequency optical signal emitted by the tunable laser 1 into two beams, one of which is sent to the detection optical fiber 5 to detect the detection optical fiber 5, and the other is sent to the second coupler 6. The second coupler 6 also receives the first Rayleigh scattering signal reflected back by the detection optical fiber 5, and coheres the first Rayleigh scattering signal with the other swept-frequency optical signal to enhance the signal strength of the first Rayleigh scattering signal.

[0107] When the device is in detection mode, the first coupler 2 is used to split the single-frequency optical signal emitted by the tunable laser 1 into two beams, one of which is sent to the modulator module 3. The modulator module 3 modulates the received single-frequency optical signal to obtain a frequency comb modulated pulse. The detection signal composed of the frequency comb modulated pulse is further transmitted to the detection optical fiber 5 for detection in the detection optical fiber 5. The other single-frequency optical signal is sent to the second coupler 6. The second coupler 6 also receives the second Rayleigh scattered signal reflected back by the detection optical fiber 5, and coheres the second Rayleigh scattered signal with the other single-frequency optical signal to enhance the signal strength of the second Rayleigh scattered signal.

[0108] The modulator module 3 includes an electro-optic modulator 31 and an acousto-optic modulator 32. The input of the electro-optic modulator 31 is connected to one of the outputs of the first coupler 2, the output of the electro-optic modulator 31 is connected to the input of the acousto-optic modulator 32, and the output of the acousto-optic modulator 32 is connected to the first port 41 of the first circulator 4. The electro-optic modulator 31 is configured to add a second preset number of equally spaced frequency components to the single-frequency optical signal, and the acousto-optic modulator 32 is configured to modulate the single-frequency optical signal into a pulse signal.

[0109] In this embodiment, the second preset number is set by those skilled in the art, and the second preset number may be consistent with the number of frequencies that need to be set in each pulse.

[0110] In this embodiment, the electro-optic modulator 31 is also connected to the waveform generator 13, and the electro-optic modulator 31 is controlled by the waveform generator 13. The acousto-optic modulator 32 is also connected to the stable signal source 14, and the acousto-optic modulator 32 is controlled by the stable signal source 14. The stable signal source 14 is also connected to the tunable laser 1, and the stable signal source 14 is also used to define and control the tunable laser 1.

[0111] It should be noted that if Figure 8 As shown in (a) in the figure, when the device is in calibration mode, the bias voltage of the electro-optic modulator 31 can be adjusted by the waveform generator 13 so that it works in a state with minimum loss. The control signal of the electro-optic modulator 31 is set to a DC signal by the stable signal source 14, the control signal of the acousto-optic modulator 32 is set to an equally spaced pulse signal, and the control signal of the tunable laser 1 is set to a sawtooth wave signal.

[0112] like Figure 8As shown in (b), when the device is in the detection mode, the bias voltage of the electro-optic modulator 31 can be adjusted by the waveform generator 13 to make it work in the carrier suppression state. The control signal of the electro-optic modulator 31 is a pre-designed frequency comb signal, the control signal of the acousto-optic modulator 32 is an equally spaced pulse signal, and the control signal of the tunable laser 1 is a DC signal.

[0113] The detection module 7 includes: a photodetector 71, a first acquisition unit 72 and a data processing module 73, wherein: the input end of the photodetector 71 is connected to the output end of the second coupler 6, the output end of the photodetector 71 is connected to the input end of the first acquisition unit 72, and the output end of the first acquisition unit 72 is connected to the input end of the data processing module 73.

[0114] The photoelectric detector 71 is used to convert the optical signal from the second coupler 6 into an electrical signal and send it to the first acquisition unit 72. The first acquisition unit 72 is used to collect the received electrical signal; the data processing module 73 is used to perform relationship calibration or detect the surrounding environment of the optical fiber 5 based on the collected electrical signal.

[0115] In this embodiment, when the device is in calibration mode and the laser is operating in a swept frequency characteristic, the signal collected by the first acquisition unit 72 is a relatively low-frequency, approximately single-frequency signal (typically between 1kHz and 10kHz, depending on specific hardware and parameter selection). In this mode, the acquired target signal is subjected to a short-time Fourier transform (SFT), a discrete Fourier transform (DFT), or any other operation capable of demodulating the instantaneous frequency characteristics of the signal to obtain the frequency-time characteristic of the reference interferometer. The time integration of this frequency-time characteristic yields the true swept frequency characteristic of the tunable laser 1, which is typically approximately linear. In particular, to mitigate the effects of measurement noise, a polynomial fit can be performed on the time integration result to completely eliminate errors that may be caused by measurement noise. The obtained true swept frequency characteristic of the laser typically requires removing approximately the first 10% of the time length. This is because the first portion of each laser sweep cycle is severely distorted and is used to resample the frequency coordinates of the Rayleigh scattering reference spectrum to achieve linear correction of the Rayleigh scattering reference spectrum.

[0116] When the device is in Rayleigh scattering calibration mode, the collected heterodyne Rayleigh scattering signal is a rapidly varying single-frequency signal whose center frequency is equal to the frequency shift of the electro-optical modulator 31. The collected signal is periodically clipped according to the detection pulse interval and arranged into a two-dimensional frequency-position matrix. Coherent demodulation is then performed to obtain its intensity information. Subsequently, frequency domain resampling is performed based on the previously obtained true frequency sweep characteristics of the laser to achieve spectral linearity correction. The result is the required ultra-wide-range Rayleigh scattering reference spectrum, which is used for subsequent demodulation of the vibration signal.

[0117] When the system works in the target signal detection mode, the collected heterodyne Rayleigh scattering signal contains three main frequency components, namely the reference carrier frequency, the upper sideband of the modulation frequency comb and the lower sideband of the modulation frequency comb. Under the guidance of the aforementioned frequency comb design principles, the upper sideband and the lower sideband of the modulation frequency comb should be two continuous frequencies or frequencies with a certain frequency interval, while the reference carrier frequency will exist alone at the lower part of the frequency band, and there will be an easily distinguishable frequency interval between it and the two frequency combs. The collected data is first periodically trimmed according to the detection pulse interval on the computer, and then time-series separation and frequency domain filtering are performed according to the frequency comb settings to arrange each group of detection results as follows: Figure 10 The Rayleigh scattering trajectory matrix distributed according to frequency is shown in the figure. These Rayleigh scattering trajectory matrices are the measurement spectra. Subsequently, the cross-correlation between the reference spectrum and the measurement spectrum at each moment is calculated through the cross-correlation algorithm or other vector similarity estimation algorithm to obtain the cross-correlation spectrum, that is, Figure 11 As shown in (a); Figure 11 Panel (b) shows the peak fitting results of several 500Hz sinusoidal signals of varying amplitudes at the dynamic signal location on the cross-correlation spectrum, validating the dynamic quantitative monitoring capability of this method. From this result, the magnitude of the correlation peak frequency shift at any spatial location on the fiber can be retrieved, thereby obtaining the location of the external disturbance and dynamically monitoring its magnitude. For common communication fibers, this correspondence is typically approximately 150MHz / με.

[0118] like Figure 9 As shown, the distributed high-frequency vibration monitoring device with an ultra-large measurement range further includes: an erbium-doped fiber amplifier 8, a second circulator 9 and a Bragg grating 10, wherein:

[0119] The input end of the erbium-doped fiber amplifier 8 is connected to the output end of the modulator module 3, the output end of the erbium-doped fiber amplifier 8 is connected to the fourth port 91 of the second circulator 9, the fifth port 92 of the second circulator 9 is connected to the first port 41 of the first circulator 4, and the sixth port 93 of the second circulator 9 is connected to the Bragg grating 10; the erbium-doped fiber amplifier 8 is used to amplify the optical signal from the modulator module 3, and the Bragg grating 10 is used to filter out spontaneous radiation noise in the optical signal.

[0120] like Figure 9 As shown, the distributed high-frequency vibration monitoring device with an ultra-large measurement range further includes: a third coupler 11 and a reference interference module 12, wherein:

[0121] The input end of the third coupler 11 is connected to the output end of the tunable laser 1, one of the output ends of the third coupler 11 is connected to the input end of the first coupler 2, and the other output end of the third coupler 11 is connected to the input end of the reference interference module 12; the reference interference module 12 is used to calibrate and calibrate the linear frequency sweep characteristics of the optical signal output by the tunable laser 1.

[0122] like Figure 9 As shown, in this embodiment, the reference interferometer module 12 includes a fourth coupler 123, a fifth coupler 124, a delay fiber 125, a balanced photodetector 121 and a second acquisition unit 122. The input end of the fourth coupler 123 is connected to the other output end of the third coupler 11, and is used to receive the optical signal from the third coupler 11. One of the output ends of the fourth coupler 123 is connected to one of the input ends of the fifth coupler 124. The other output end of the fourth coupler 123 is connected to the delay fiber 125. The input end of the delay optical fiber 125 is connected to the other input end of the fifth coupler 124, the output end of the fifth coupler 124 is connected to the input end of the balanced photodetector 121, and the output end of the balanced photodetector 121 is connected to the input end of the second acquisition unit 122. The optical signal is sampled and converted into an electrical signal by the balanced photodetector 121, and then the electrical signal is acquired by the second acquisition unit 122 to complete the calibration and correction of the linear frequency sweep effect of the tunable laser 1.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A distributed high-frequency vibration monitoring method with an ultra-large measurement range, characterized in that: include: A swept frequency optical signal of a preset wavelength range is sent to the optical fiber under test through a laser. The relationship between position, light intensity and pulse frequency in the preset wavelength range is calibrated based on the first Rayleigh scattering signal reflected from the optical fiber under test to obtain a reference spectrum corresponding to the preset wavelength range. emitting a single-frequency optical signal of a central wavelength within a preset wavelength range through a laser, performing frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse, using a first preset number of frequency comb modulated pulses as a group of detection signals, and sending all detection signals within the preset wavelength range to the optical fiber to be tested; Wherein, the interval between two adjacent frequency components of each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse; Acquire a second Rayleigh scattering signal reflected by the optical fiber to be tested within the preset wavelength range, and detect the surrounding environment of the optical fiber to be tested based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum; Each second pulse signal in the second Rayleigh scattering signal within a preset wavelength range is received in sequence, and corresponding actual light intensity information, position information, and pulse frequency information are obtained according to each second pulse signal; a calibration function relationship corresponding to each second pulse signal is obtained, and the position information and pulse frequency information corresponding to each second pulse signal are substituted into the corresponding calibration function relationship to obtain calibrated light intensity information of each second pulse signal; the calibrated light intensity information is compared with the actual light intensity information to obtain detection information of the optical fiber to be tested at the corresponding position.

2. The distributed high-frequency vibration monitoring method with an ultra-large measurement range according to claim 1, characterized in that: The method comprises: emitting a single-frequency optical signal in a preset wavelength range through a laser, performing frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse, and using a first preset number of frequency comb modulated pulses as a group of detection signals. Adding a second preset number of equally spaced frequency components to the single-frequency optical signal through electro-optical modulation and acousto-optical modulation to obtain a frequency comb modulated pulse; the first preset number is 1; The total bandwidth of all frequency components on a single pulse is less than or equal to twice the bandwidth of the acousto-optic modulation; and the frequency difference between the lowest frequency of the modulated original frequency comb signal and the frequency shift of the acousto-optic modulation is greater than or equal to twice the bandwidth of the acousto-optic modulation.

3. The distributed high-frequency vibration monitoring method with an ultra-large measurement range according to claim 1, characterized in that: The method comprises: emitting a single-frequency optical signal in a preset wavelength range through a laser, performing frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse, and using a first preset number of frequency comb modulated pulses as a group of detection signals. Adding a second preset number of equally spaced frequency components to the single-frequency optical signal through electro-optical modulation and acousto-optical modulation to obtain a frequency comb modulated pulse; wherein a third preset number of sub-frequency combs are added to each frequency component; The first preset number is greater than or equal to 2, the interval between two adjacent frequency components on each single pulse is greater than or equal to twice the inverse of the pulse width of the single pulse; the total bandwidth of all frequency components on a single single pulse is less than or equal to twice the bandwidth of the acousto-optic modulation; and the frequency difference between the lowest frequency of the modulated original frequency comb signal and the frequency shift of the acousto-optic modulation is greater than or equal to twice the bandwidth of the acousto-optic modulation.

4. The distributed high-frequency vibration monitoring method with an ultra-large measurement range according to claim 1, characterized in that: The calibration of the relationship between position, light intensity, and pulse frequency in a preset wavelength range based on the first Rayleigh scattering signal reflected from the optical fiber to be tested to obtain a reference spectrum corresponding to the preset wavelength range specifically includes: receiving in sequence each first pulse signal in the reflected first Rayleigh scattering signal, and acquiring corresponding light intensity information, position information, and pulse frequency information according to each first pulse signal; The calibration function relationship corresponding to the first pulse signal is obtained according to the light intensity information, position information and pulse frequency information corresponding to the first pulse signal, and the calibration function relationships corresponding to all first pulse signals in the preset wavelength range are integrated into the reference spectrum.

5. A distributed high-frequency vibration monitoring device with an ultra-large measurement range, used for applying the distributed high-frequency vibration monitoring method with an ultra-large measurement range as described in any one of claims 1 to 4, characterized in that: include: A tunable laser (1), a first coupler (2), a modulator module (3), a first circulator (4), a detection optical fiber (5), a second coupler (6) and a detection module (7), wherein: The output end of the tunable laser (1) is connected to the input end of the first coupler (2), one of the output ends of the first coupler (2) is connected to the input end of the modulator module (3), the output end of the modulator module (3) is connected to the first port (41) of the first circulator (4), the second port (42) of the first circulator (4) is connected to the detection optical fiber (5), the third port (43) of the first circulator (4) is connected to one of the input ends of the second coupler (6), the other input end of the second coupler (6) is connected to the other output end of the first coupler (2), and the output end of the second coupler (6) is connected to the input end of the detection module (7); The tunable laser (1) is used to send a frequency-sweeping optical signal in a preset wavelength range to a detection optical fiber (5); the detection optical fiber (5) is used to reflect back a first Rayleigh scattered signal and transmit it to the detection module (7) through the first circulator (4); the detection module (7) is used to calibrate the relationship between the position, light intensity and pulse frequency of the first Rayleigh scattered signal in the preset wavelength range to obtain a reference spectrum; The tunable laser (1) is further used to send a single-frequency optical signal within a preset wavelength range to the modulator module (3); the modulator module (3) is used to perform frequency comb modulation on each single pulse in the single-frequency optical signal to obtain a frequency comb modulated pulse; a first preset number of frequency comb modulated pulses are used as a group of detection signals; all detection signals within the preset wavelength range are sent to a detection optical fiber (5); the detection optical fiber (5) is further used to reflect back a second Rayleigh scattering signal within the preset wavelength range; the detection module (7) is further used to detect the surrounding environment of the detection optical fiber (5) based on the second Rayleigh scattering signal within the preset wavelength range and the reference spectrum.

6. The distributed high-frequency vibration monitoring device with an ultra-large measurement range according to claim 5, characterized in that: The modulator module (3) includes an electro-optic modulator (31) and an acousto-optic modulator (32), wherein: The input end of the electro-optic modulator (31) is connected to one of the output ends of the first coupler (2), the output end of the electro-optic modulator (31) is connected to the input end of the acousto-optic modulator (32), and the output end of the acousto-optic modulator (32) is connected to the first port (41) of the first circulator (4); The electro-optic modulator (31) is used to load a second preset number of equally spaced frequency components onto the single-frequency optical signal, and the acousto-optic modulator (32) is used to modulate the single-frequency optical signal into a pulse signal.

7. The distributed high-frequency vibration monitoring device with an ultra-large measurement range according to claim 5, characterized in that: The detection module (7) comprises: a photoelectric detector (71), a first acquisition unit (72) and a data processing module (73), wherein: The input end of the photodetector (71) is connected to the output end of the second coupler (6), the output end of the photodetector (71) is connected to the input end of the first acquisition unit (72), and the output end of the first acquisition unit (72) is connected to the input end of the data processing module (73); The photoelectric detector (71) is used to convert the optical signal from the second coupler (6) into an electrical signal and send it to the first acquisition unit (72), and the first acquisition unit (72) is used to collect the received electrical signal; the data processing module (73) is used to perform relationship calibration or detect the surrounding environment of the optical fiber (5) based on the collected electrical signal.

8. The distributed high-frequency vibration monitoring device with an ultra-large measurement range according to claim 5, characterized in that: The distributed high-frequency vibration monitoring device with an ultra-large measurement range further includes: an erbium-doped fiber amplifier (8), a second circulator (9) and a Bragg grating (10), wherein: The input end of the erbium-doped fiber amplifier (8) is connected to the output end of the modulator module (3), the output end of the erbium-doped fiber amplifier (8) is connected to the fourth port (91) of the second circulator (9), the fifth port (92) of the second circulator (9) is connected to the first port (41) of the first circulator (4), and the sixth port (93) of the second circulator (9) is connected to the Bragg grating (10); The erbium-doped fiber amplifier (8) is used to amplify the optical signal from the modulator module (3), and the Bragg grating (10) is used to filter out spontaneous radiation noise in the optical signal.

9. The distributed high-frequency vibration monitoring device with an ultra-large measurement range according to claim 5, characterized in that: The distributed high-frequency vibration monitoring device with an ultra-large measurement range further includes: a third coupler (11) and a reference interference module (12), wherein: The input end of the third coupler (11) is connected to the output end of the tunable laser (1), one of the output ends of the third coupler (11) is connected to the input end of the first coupler (2), and the other output end of the third coupler (11) is connected to the input end of the reference interference module (12); The reference interference module (12) is used to calibrate and calibrate the linear frequency sweep characteristics of the optical signal output by the tunable laser (1).

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