CN116576920A - Cable vibration and strain monitoring device and method - Google Patents

Abstract

The invention relates to the technical field of distributed optical fiber sensing, and discloses a cable vibration and strain monitoring device and method. Module, circulator, second optical splitter, first photodetector, reference signal processing module, coupler, second photodetector and data acquisition module. The invention utilizes the dual-mechanism distributed sensing of a single narrow-linewidth laser and a single sensing fiber, and separates the Brillouin scattering from the laser signal generated by the narrow-linewidth pulse laser according to the frequency difference of the scattering signal by using a spectrum filter. Signal and Rayleigh scattering signal, use Brillouin optical time domain reflectometer and phase sensitive optical time domain reflectometer to detect Brillouin scattering signal and Rayleigh scattering signal respectively, and then analyze and obtain the vibration and strain information of the cable to be tested to realize In order to simultaneously measure the vibration and strain of the cable to be tested, the device has a simple structure and low cost.

Description

A cable vibration and strain monitoring device and method

technical field

The invention relates to the technical field of distributed optical fiber sensing, in particular to a cable vibration and strain monitoring device and method.

Background technique

The optical time domain reflectometer based on Brillouin scattering and Rayleigh scattering, because the sensing principle is based on the change of the frequency of Brillouin scattered light transmitted in the optical fiber and the phase of Rayleigh scattered light, so its measurement accuracy and sensitivity are extremely high , ideal for detection of strain and vibration events.

With the development and application of optical fiber sensing technology, multi-parameter monitoring has become an inevitable development trend of optical fiber monitoring system, and it also provides a more comprehensive judgment basis and a more effective way for the comprehensive identification of fault events. The optical time domain reflectometer based on Brillouin scattering or Rayleigh scattering can only measure a single physical quantity, such as the Brillouin optical time domain reflectometer (B-OTDR) can only detect the strain along the optical fiber, and the phase sensitive optical time domain The optical domain reflectometer (Φ-OTDR) can only detect the vibration and distribution along the optical fiber; the phase-sensitive optical time domain reflectometer detects Rayleigh scattered light, and the Brillouin optical time domain reflectometer detects Brillouin scattered light. Therefore, a single device cannot meet the monitoring application requirements of multi-parameter physical fields; for ordinary single-mode optical fibers, there is a Brillouin frequency shift difference of about 11 GHz between the two scattered lights, and the existing detection equipment cannot use single-mode optical fibers to achieve detection. Simultaneous measurement of two scattered lights; usually two laser generators and two sensing fibers are required for multi-parameter monitoring, and the device is complex and costly.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the inability to use a single device to achieve joint measurement of Brillouin scattered light and Rayleigh scattered light in the prior art, resulting in the inability to use a single device to obtain strain and vibration information at the same time.

In order to solve the above technical problems, the present invention provides a cable vibration and strain monitoring device, including:

The sensing optical fiber is attached to the cable to be tested, so that its own vibration state and strain state are consistent with the cable to be tested;

Narrow-linewidth lasers for emitting narrow-linewidth pulsed light sources;

The first optical splitter, the input end of which is connected to the narrow linewidth laser, is used to divide the narrow linewidth pulse light source into two paths, which are the initial detection signal and the initial reference signal;

A detection signal processing module, connected to the output end of the first optical splitter, for modulating the initial detection signal into a pulse signal with a preset modulation signal, amplifying the power of the pulse signal, and outputting a modulated detection signal;

a circulator, the first port of which is connected to the output end of the detection signal processing module, and is used to pass the modulated detection signal into the sensing fiber from its second port, and backscatter the sensing fiber The sensor detects light, returns to its second port, and outputs from the third port;

The second optical splitter, the input end of which is connected to the third port of the circulator, is used to divide the backscattered sensing detection light output by the third port of the circulator into two paths, which are respectively the first output signal and the second output signal ;

The first photodetector is connected to the output end of the second beam splitter, and is used to detect the first output signal and obtain the electrical signal of the backscattered sensing detection light;

A reference signal processing module, connected to the output end of the first optical splitter, for modulating the phase, frequency and polarization of the initial reference signal, and outputting the modulated reference signal;

A coupler whose input end is connected to the output end of the reference signal processing module and the second optical splitter, obtains the modulated reference signal and the second output signal and performs coherent detection to obtain a difference frequency containing the position information of the cable to be tested Signal;

The second photodetector is connected to the output end of the coupler, detects the difference frequency signal, and obtains an electrical signal of the difference frequency signal;

The data acquisition module is connected to the output terminals of the first photodetector and the second photodetector, acquires the electrical signal of the backscattering sensing detection light and the electrical signal of the difference frequency signal, and separates the Brillouin scattering The signal and the Rayleigh scattering signal are analyzed separately to obtain the strain distribution, vibration and amplitude distribution along the optical fiber.

In one embodiment of the present invention, the detection signal processing module includes:

an acousto-optic modulator, connected to the output end of the first optical splitter, based on the acousto-optic effect, using a preset modulation signal to modulate the initial detection signal;

a pulse generator connected to the acousto-optic modulator to provide a preset electronic driving signal for the acousto-optic modulator;

The optical pulse amplifier, whose input end is connected to the output end of the acousto-optic modulator, is used to amplify the pulse power of the modulated initial detection signal, reduce the nonlinear effect of the optical fiber, and output the detection signal.

In one embodiment of the present invention, the reference signal processing module includes:

An electro-optic modulator, the input end of which is connected to the output end of the first optical splitter, and uses the electro-optic effect to modulate the phase, frequency and polarization of the initial reference signal;

a microwave driver, connected to the electro-optic modulator, for driving the electro-optic modulator to generate a preset bandwidth;

A polarization scrambler, the input end of which is connected to the output end of the electro-optic modulator, to eliminate the polarization damage of the output signal of the electro-optic modulator;

A single-sideband filter, the input end of which is connected to the output end of the polarization scrambler, filters the output signal of the polarization scrambler, and outputs a reference signal.

In one embodiment of the invention, the data collection module includes:

A spectrum filter, whose input end is connected to the output end of the first photodetector and the second photodetector, obtains the electrical signal of the backscattered sensing detection light and the electrical signal of the difference frequency signal, and separates therefrom The Brillouin scattering signal and the Rayleigh scattering signal are filtered and amplified respectively;

A Brillouin optical time domain reflectometer is connected to the output end of the spectrum filter to obtain the separated Brillouin scattering signal, and analyze the strain distribution along the optical fiber;

A phase-sensitive optical time-domain reflectometer is connected to the output end of the spectrum filter to obtain the separated Rayleigh scattering signal, and analyze the vibration and amplitude distribution along the optical fiber.

In one embodiment of the present invention, the sensing optical fiber is fixedly arranged inside the cable to be tested.

In one embodiment of the present invention, the sensing optical fiber is fixedly arranged on the outer surface of the cable to be tested.

The embodiment of the present invention also provides a cable vibration and strain monitoring method, which is applied to the cable vibration and strain monitoring device as described above, including:

Attach the sensing fiber to the cable to be tested;

The light source emitted by the narrow-linewidth pulsed light source is divided into an initial reference signal and an initial detection signal;

Based on the acousto-optic effect, the initial detection signal is modulated to obtain a modulated detection signal; the modulated detection signal passes through the sensing optical fiber to generate backscattered sensing detection light;

Based on the electro-optical effect, the initial reference signal is modulated to generate a modulated reference signal; and the modulated reference signal is coherently detected with the backscattered sensing detection light to obtain a difference containing position information of the cable to be tested. frequency signal;

Obtain the electrical signal of the backscattering sensing detection light and the difference frequency signal, and separate the Brillouin scattering signal and the Rayleigh scattering signal therefrom according to the frequency difference of the optical signal;

According to the Brillouin scattering signal, obtain the strain distribution along the optical fiber of the cable to be tested;

According to the Rayleigh scattering signal, the vibration and amplitude distribution along the optical fiber of the cable to be tested are obtained.

In one embodiment of the present invention, the acquisition of the electric signal of the backscattering sensing detection light and the difference frequency signal, and separating the Brillouin scattering signal and the Rayleigh scattering signal according to the frequency difference of the optical signal ,include:

Using a photodetector to detect light and difference frequency signals based on backscattering sensing, and obtain their corresponding electrical signals;

The spectrum filter is used to separate the Brillouin scattering signal and the Rayleigh scattering signal from the electrical signal according to the frequency difference between the Brillouin scattering signal and the Rayleigh scattering signal.

In one embodiment of the present invention, the acquisition of the strain distribution along the optical fiber of the cable to be tested according to the Brillouin scattering signal includes:

Using a coherent detection method to detect the Brillouin scattering signal, and using Lorentz fitting to obtain the center frequency of the Brillouin scattering signal;

Based on the center frequency, the strain distribution along the optical fiber of the cable to be tested is obtained.

In one embodiment of the present invention, the acquisition of the vibration and amplitude distribution along the optical fiber of the cable to be tested according to the Rayleigh scattering signal includes:

The Rayleigh scattering signal is detected by a direct detection method, and the vibration and amplitude distribution along the optical fiber of the cable to be tested are obtained by Fourier transform analysis.

The above technical solution of the present invention has the following advantages compared with the prior art:

The cable vibration and strain monitoring device of the present invention utilizes the dual-mechanism distributed sensing of a single narrow-linewidth laser and a single sensing fiber, and from the laser signal generated by the narrow-linewidth pulse laser, according to the frequency difference of the scattered signal, The Brillouin scattering signal and the Rayleigh scattering signal are separated by a spectrum filter, and the Brillouin scattering signal and the Rayleigh scattering signal are detected by a Brillouin optical time domain reflectometer and a phase-sensitive optical time domain reflectometer, and then analyzed and obtained Vibration and strain information of the cable under test. The invention uses a single excitation light generated by a single narrow-linewidth laser to pass through a single sensing optical fiber to simultaneously measure the Rayleigh scattering signal and the Brillouin scattering signal in the sensing optical fiber, thereby realizing the simultaneous measurement of the vibration and strain of the cable to be measured , avoiding the synchronous sensing problem of general dual systems, the device has a simple structure and low cost.

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

Fig. 1 is the structural representation of cable vibration and strain monitoring device provided by the present invention;

Fig. 2 is the structural representation of the data acquisition module in the cable vibration and strain monitoring device provided by the present invention;

Fig. 3 is a schematic diagram of the frequency spectrum of the sensing detection signal provided by the present invention;

Fig. 4 is a flow chart of the steps of the cable vibration and strain monitoring method provided by the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

With reference to shown in Fig. 1, the structural representation of cable vibration and strain device of the present invention, device specifically comprises:

The sensing optical fiber is attached to the cable to be tested, so that its own vibration state and strain state are consistent with the cable to be tested;

Narrow-linewidth lasers for emitting narrow-linewidth pulsed light sources;

The first optical splitter, the input end of which is connected to the narrow linewidth laser, is used to divide the narrow linewidth pulse light source into two paths, which are the initial detection signal and the initial reference signal;

A detection signal processing module, connected to the output end of the first optical splitter, for modulating the initial detection signal into a pulse signal with a preset modulation signal, amplifying the power of the pulse signal, and outputting a modulated detection signal;

a circulator, the first port of which is connected to the output end of the detection signal processing module, and is used to pass the modulated detection signal into the sensing fiber from its second port, and backscatter the sensing fiber The sensor detects light, returns to its second port, and outputs from the third port;

The second optical splitter, the input end of which is connected to the third port of the circulator, is used to divide the backscattered sensing detection light output by the third port of the circulator into two paths, which are respectively the first output signal and the second output signal ;

The first photodetector is connected to the output end of the second beam splitter, and is used to detect the first output signal and obtain the electrical signal of the backscattered sensing detection light;

A reference signal processing module, connected to the output end of the first optical splitter, for modulating the phase, frequency and polarization of the initial reference signal, and outputting the modulated reference signal;

A coupler whose input end is connected to the output end of the reference signal processing module and the second optical splitter, obtains the modulated reference signal and the second output signal and performs coherent detection to obtain a difference frequency containing the position information of the cable to be tested Signal;

The second photodetector is connected to the output end of the coupler, detects the difference frequency signal, and obtains an electrical signal of the difference frequency signal;

The data acquisition module is connected to the output terminals of the first photodetector and the second photodetector, acquires the electrical signal of the backscattering sensing detection light and the electrical signal of the difference frequency signal, and separates the Brillouin scattering The signal and the Rayleigh scattering signal are analyzed separately to obtain the strain distribution, vibration and amplitude distribution along the optical fiber.

Specifically, in one embodiment of the present invention, the sensing fiber is fixed inside the cable to be tested; the internal arrangement makes the sensing fiber and the cable to be tested tightly connected, so that the sensing fiber can more accurately characterize the cable to be tested vibration and strain state.

In another embodiment of the present invention, the sensing optical fiber is fixedly arranged on the outer surface of the cable to be tested; it is convenient to connect and disassemble the sensing optical fiber and the cable to be tested, and is convenient to use.

In this embodiment, the narrow linewidth laser is the only sensing optical signal source, used to generate the sensing optical signal, using high-precision automatic power and automatic control technology, so that the wavelength and power output by the light source have a very high At the same time, the line width of the light source is narrow enough, which greatly reduces the impact of the signal-to-noise ratio drop caused by the dispersion of the light source.

Specifically, the first optical splitter divides the sensing light signal generated by the narrow linewidth laser into two paths; one path of detection signal is modulated by the detection signal processing module to generate pulsed sensing excitation light, which is amplified and filtered to generate phase-sensitive light time-domain reflection Commonly required by the Brillouin optical time domain reflectometer and the Brillouin optical time domain reflectometer, as the modulated detection signal of the sensing excitation light, it is input to the sensing fiber through the circulator; the other detection signal is processed by the reference signal processing module for phase, frequency and Polarization modulation generates the reference signal required for coherent detection, which is input to the signal detection and acquisition module, and the backscattered sensing detection light generated by the modulated detection signal in the sensing fiber is used for coherent detection and spectral separation of the sensing detection signal; According to the signal spectrum difference, the Rayleigh scattered light detection signal of the phase sensitive optical time domain reflectometer and the Brillouin scattered light detection signal of the Brillouin optical time domain reflectometer are separated.

Specifically, the detection signal preprocessing module is used to sequentially modulate the input optical signal into a pulse through an acousto-optic modulator and then enter the optical fiber through an optical pulse amplifier and a circulator as a detection signal, specifically including:

An acousto-optic modulator connected to the output end of the first optical splitter, using the acousto-optic effect, using a preset modulation signal to generate an ultrasonic field in the modulator to change the refractive index of the device, change the phase of light passing through the device, and realize optical modulation ;

a pulse generator connected to the acousto-optic modulator to provide a preset electronic driving signal for the acousto-optic modulator;

The optical pulse amplifier, whose input end is connected to the output end of the acousto-optic modulator, outputs the amplified laser pulse power, reduces the nonlinear effect of the optical fiber, and outputs the detection signal.

Specifically, the circulator transmits the incident wave entering any port to the next port sequentially according to the direction determined by the static bias magnetic field; that is, the signal input from the first port is output from the second port, and the signal input from the second port The signal of will be output from the third port, and the signal input from the third port will be output from the first port.

Specifically, the reference signal processing module, after the initial reference signal is frequency-modulated by the electro-optic modulator, eliminates the polarization-related damage in optical information transmission through the action of the polarization scrambler, and then enters the coupler after being filtered by the single-sideband filter, Specifically include:

An electro-optic modulator, the input end of which is connected to the output end of the first optical splitter, and uses the electro-optic effect to modulate the phase, frequency and polarization of the initial reference signal;

A microwave driver, connected to the electro-optic modulator, is used to drive the electro-optic modulator to generate a preset bandwidth, and has performances such as high gain, low jitter, and ultra-fast pulse response;

A polarization scrambler, the input end of which is connected to the output end of the electro-optic modulator, to eliminate the polarization damage of the output signal of the electro-optic modulator;

A single-sideband filter, the input end of which is connected to the output end of the polarization scrambler, filters the output signal of the polarization scrambler, and outputs a reference signal.

Specifically, the second optical splitter divides the input detection signal in the optical fiber into Rayleigh scattering signals and Brillouin scattering signals in relation to its effects; one output signal is input to the coupler and mixed with the reference signal, A difference frequency signal containing position information is obtained, and the difference frequency signal is analyzed to obtain strain information along the optical fiber; the other output signal is directly received and collected by the first photodetector to analyze vibration information along the optical fiber.

The first photodetector and the second photodetector filter and amplify the separated phase-sensitive optical time-domain reflectometer detection signal and Brillouin optical time-domain reflectometer detection signal respectively, and convert it into an electrical signal through the photovoltaic effect before inputting to the data acquisition module.

Specifically, as shown in FIG. 2, the data acquisition module uses a dual-channel data collector to sample, integrates B-OTDR and Φ-OTDR technology, and performs Lorentzian fitting to the Brillouin scattering signal data. As a result, the central frequency of the Brillouin scattering signal was obtained, and the strain distribution along the optical fiber was obtained through analysis; the Rayleigh scattering signal was analyzed by Fourier transform to obtain the vibration and amplitude distribution along the optical fiber, and the dual-parameter measurement of vibration and strain was realized. include:

A spectrum filter, whose input end is connected to the output end of the first photodetector and the second photodetector, obtains the electrical signal of the backscattered sensing detection light and the electrical signal of the difference frequency signal, and separates therefrom The Brillouin scattering signal and the Rayleigh scattering signal are filtered and amplified respectively;

A Brillouin optical time domain reflectometer is connected to the output end of the spectrum filter to obtain the separated Brillouin scattering signal, and analyze the strain distribution along the optical fiber;

A phase-sensitive optical time-domain reflectometer is connected to the output end of the spectrum filter to obtain the separated Rayleigh scattering signal, and analyze the vibration and amplitude distribution along the optical fiber.

Referring to Figure 3, there is a frequency difference of about 11 GHz between the Brillouin scattered light and the Rayleigh scattered light. When the two scattered lights are coherently detected together, the frequency difference of the generated sensing detection signal is also about 11GHz, therefore, the Brillouin scattering signal can be easily separated from the Rayleigh scattering signal through the spectrum difference. In this embodiment, using the 11GHz frequency difference between the Brillouin scattering signal and the Rayleigh scattering signal, the phase-sensitive OTDR sensing detection signal and the Brillouin OTDR The sensing detection signal is separated, filtered and amplified.

The cable vibration and strain monitoring device of the present invention utilizes the dual-mechanism distributed sensing of a single narrow-linewidth laser and a single sensing fiber, and from the laser signal generated by the narrow-linewidth pulse laser, according to the frequency difference of the scattered signal, The Brillouin scattering signal and the Rayleigh scattering signal are separated by a spectrum filter, and the Brillouin scattering signal and the Rayleigh scattering signal are detected by a Brillouin optical time domain reflectometer and a phase-sensitive optical time domain reflectometer, and then analyzed and obtained Vibration and strain information of the cable under test. The invention uses a single excitation light generated by a single narrow-linewidth laser to pass through a single sensing optical fiber to simultaneously measure the Rayleigh scattering signal and the Brillouin scattering signal in the sensing optical fiber, thereby realizing the simultaneous measurement of the vibration and strain of the cable to be measured , avoiding the synchronous sensing problem of general dual systems, the device has a simple structure and low cost.

Based on the above-mentioned cable vibration and strain monitoring device, an embodiment of the present invention provides a cable vibration and strain monitoring method, as shown in FIG. 4 , the specific steps include:

S1: Attach the sensing fiber to the cable to be tested;

S2: Divide the light source emitted by the narrow-linewidth pulsed light source into an initial reference signal and an initial detection signal;

S3: Based on the acousto-optic effect, modulate the initial detection signal to obtain a modulated detection signal; the modulated detection signal passes through the sensing optical fiber to generate backscattered sensing detection light;

S4: Based on the electro-optic effect, modulate the initial reference signal to generate a modulated reference signal; and perform coherent detection on the modulated reference signal and the backscatter sensing detection light to obtain position information including the cable to be tested The difference frequency signal;

S5: Obtain the electrical signal of the backscatter sensing detection light and the difference frequency signal, and separate the Brillouin scattering signal and the Rayleigh scattering signal therefrom according to the frequency difference of the optical signal;

Using a photodetector to detect light and a difference frequency signal based on backscattering sensing, and obtain the corresponding electrical signal; using a spectrum filter, according to the frequency difference between the Brillouin scattering signal and the Rayleigh scattering signal, from the electrical signal Separate the Brillouin scattering signal and the Rayleigh scattering signal in the middle;

S6: Using a coherent detection method to detect the Brillouin scattering signal, and using Lorentz fitting to obtain the center frequency of the Brillouin scattering signal; based on the center frequency, obtain the strain distribution along the optical fiber of the cable to be tested;

S7: Using a direct detection method to detect the Rayleigh scattering signal, and using Fourier transform analysis to obtain the vibration and amplitude distribution along the optical fiber of the cable to be tested.

Since the intensity of the Brillouin scattering signal in the optical fiber is about 3 orders of magnitude weaker than that of the Rayleigh scattering signal, the influence of the Brillouin scattering signal intensity on the Rayleigh scattering signal can be ignored, and the intensity of the Rayleigh scattering signal can be detected by direct detection Variety.

The cable vibration and strain monitoring method provided by the present invention is based on the above-mentioned cable vibration and strain monitoring method device, based on the same sensing excitation light and the same sensing optical fiber, and coherently detects the detection signal and reference signal returned by the sensing optical fiber , to generate spectrum-separated phase-sensitive optical time-domain reflectometer sensing signals and Brillouin optical time-domain reflectometer sensing signals, thereby realizing dual-mechanism simultaneous distributed sensing, realizing strain and vibration multi-state perception detection, and overcoming the Simultaneous detection problem for multi-system sensing.

Apparently, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation. For those of ordinary skill in the art, on the basis of the above description, other changes or changes in various forms can also be made. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (10)

1. A cable vibration and strain monitoring device, comprising:

the sensing optical fiber is attached to the cable to be tested, so that the vibration state and the strain state of the sensing optical fiber are consistent with those of the cable to be tested;

the narrow linewidth laser is used for emitting a narrow linewidth pulse light source;

the input end of the first light splitter is connected with the narrow linewidth laser and is used for dividing the narrow linewidth pulse light source into two paths, namely an initial detection signal and an initial reference signal;

the detection signal processing module is connected with the output end of the first beam splitter and is used for modulating the initial detection signal into a pulse signal by using a preset modulation signal, amplifying the power of the pulse signal and outputting the modulated detection signal;

the first port of the circulator is connected with the output end of the detection signal processing module, and is used for transmitting the modulated detection signal into the sensing optical fiber from the second port of the circulator, and the backscattering sensing detection light generated by the sensing optical fiber is returned to the second port of the circulator and is output from the third port;

the input end of the second light splitter is connected with the third port of the circulator and is used for dividing the backward scattering sensing detection light output by the third port of the circulator into two paths which are a first output signal and a second output signal respectively;

the first photoelectric detector is connected with the output end of the second beam splitter and is used for detecting the first output signal to acquire the electric signal of the backward scattering sensing detection light;

the reference signal processing module is connected with the output end of the first optical splitter and used for modulating the phase, the frequency and the polarization of the initial reference signal and outputting the modulated reference signal;

the input end of the coupler is connected with the reference signal processing module and the output end of the second optical splitter, and the modulated reference signal and the second output signal are obtained and are subjected to coherent detection to obtain a difference frequency signal containing the position information of the cable to be detected;

the second photoelectric detector is connected with the output end of the coupler and used for detecting the difference frequency signal to obtain an electric signal of the difference frequency signal;

the data acquisition module is connected with the output ends of the first photoelectric detector and the second photoelectric detector, acquires the electric signals of the backward scattering sensing detection light and the electric signals of the difference frequency signal, separates out the Brillouin scattering signal and the Rayleigh scattering signal, and respectively analyzes the Brillouin scattering signal and the Rayleigh scattering signal to obtain the strain distribution, the vibration and the amplitude distribution of the optical fiber along the line.

2. The cable vibration and strain monitoring device of claim 1, wherein the probe signal processing module comprises:

the acousto-optic modulator is connected with the output end of the first beam splitter and modulates the initial detection signal by a preset modulation signal based on an acousto-optic effect;

the pulse generator is connected with the acousto-optic modulator and provides a preset electronic driving signal for the acousto-optic modulator;

and the input end of the optical pulse amplifier is connected with the output end of the acousto-optic modulator and is used for amplifying the pulse power of the modulated initial detection signal, reducing the nonlinear effect of the optical fiber and outputting the detection signal.

3. The cable vibration and strain monitoring device of claim 1, wherein the reference signal processing module comprises:

the input end of the electro-optical modulator is connected with the output end of the first optical splitter, and the phase, the frequency and the polarization of the initial reference signal are modulated by utilizing an electro-optical effect;

the microwave driver is connected with the electro-optical modulator and used for driving the electro-optical modulator to generate a preset bandwidth;

the input end of the scrambler is connected with the output end of the electro-optic modulator, so that the polarization damage of the output signal of the electro-optic modulator is eliminated;

and the input end of the single sideband filter is connected with the output end of the scrambler, filters the output signal of the scrambler and outputs a reference signal.

4. The cable vibration and strain monitoring device of claim 1, wherein the data acquisition module comprises:

the input end of the spectrum filter is connected with the output ends of the first photoelectric detector and the second photoelectric detector, acquires the electric signals of the backward scattering sensing detection light and the electric signals of the difference frequency signal, separates out the Brillouin scattering signal and the Rayleigh scattering signal, and respectively carries out filtering and amplifying treatment;

the Brillouin optical time domain reflectometer is connected with the output end of the frequency spectrum filter, and the separated Brillouin scattering signals are obtained and analyzed to obtain strain distribution along the optical fiber;

and the phase sensitive optical time domain reflectometer is connected with the output end of the frequency spectrum filter, acquires the separated Rayleigh scattering signals, and analyzes and obtains vibration and amplitude distribution along the optical fiber.

5. The cable vibration and strain monitoring device of claim 1, wherein the sensing optical fiber is fixedly arranged inside the cable to be tested.

6. The cable vibration and strain monitoring device of claim 1, wherein the sensing optical fiber is fixedly arranged on the outer surface of the cable to be tested.

7. A cable vibration and strain monitoring method, applied to the cable vibration and strain monitoring device according to any one of claims 1 to 6, comprising:

attaching the sensing optical fiber to the cable to be tested;

dividing a light source emitted by a narrow linewidth pulse light source into an initial reference signal and an initial detection signal;

modulating the initial detection signal based on an acousto-optic effect to obtain a modulated detection signal; the modulated detection signal passes through the sensing optical fiber to generate backward scattering sensing detection light;

modulating the initial reference signal based on an electro-optical effect to generate a modulated reference signal; performing coherent detection on the modulated reference signal and the backward scattering sensing detection light to obtain a difference frequency signal containing the position information of the cable to be detected;

acquiring electric signals of the backward scattering sensing detection light and the difference frequency signal, and separating a Brillouin scattering signal and a Rayleigh scattering signal from the electric signals according to the frequency difference of the optical signals;

according to the Brillouin scattering signal, strain distribution along the optical fiber of the cable to be tested is obtained;

and according to the Rayleigh scattering signal, obtaining vibration and amplitude distribution of the cable optical fiber to be tested along the line.

8. The method for monitoring vibration and strain of a cable according to claim 7, wherein obtaining the electric signals of the back-scattering sensing detection light and the difference frequency signal, and separating the brillouin scattering signal and the rayleigh scattering signal from the electric signals according to the optical signal frequency difference, comprises:

detecting light and a difference frequency signal based on backward scattering sensing by using a photoelectric detector to obtain a corresponding electric signal;

and utilizing a frequency spectrum filter to separate the Brillouin scattering signal and the Rayleigh scattering signal from the electric signal according to the frequency difference between the Brillouin scattering signal and the Rayleigh scattering signal.

9. The method for monitoring vibration and strain of a cable according to claim 7, wherein obtaining strain distribution along a cable optical fiber to be tested according to brillouin scattering signals comprises:

detecting the Brillouin scattering signal by using a coherent detection mode, and obtaining the center frequency of the Brillouin scattering signal by using Lorentz fitting;

and based on the center frequency, acquiring strain distribution of the cable optical fiber to be tested along the line.

10. The method for monitoring vibration and strain of cable according to claim 7, wherein the step of obtaining vibration and amplitude distribution along the cable fiber to be tested according to the rayleigh scattering signal comprises:

and detecting the Rayleigh scattering signal by using a direct detection mode, and obtaining vibration and amplitude distribution of the cable optical fiber to be detected along the line by using Fourier transform analysis.