A method and apparatus for measuring strain in a cable based on fiber optic elongation

Abstract

A method and device for measuring cable strain based on fiber stretching, which belongs to the field of online monitoring of optical fiber cables, and the method comprises the following steps: modulating a correlation sequence onto a probe wavelength to form a probe optical signal, and sending the probe optical signal to an optical fiber line of a cable to be measured; receiving a reflected signal or a loopback signal in the optical fiber line, and performing correlation operation on the reflected signal or the loopback signal and the correlation sequence to determine a time delay of a correlation peak of the reflected signal or the loopback signal; determining an optical fiber length passed by the optical signal from a transmitting end to each reflection point according to the time delay of the reflected signal, or determining an optical fiber length of the optical fiber line from one end to the other end according to the time delay of the loopback signal; comparing the optical fiber length with a corresponding reference record to obtain a strain of the optical fiber; and obtaining a strain of the cable to be measured according to a corresponding relationship between the strain of the optical fiber and the strain of the cable to be measured. The application can avoid interference with the measurement results under temperature and dynamic conditions, and solve the technical problem that cable strain cannot be accurately measured in the prior art.

Description

Technical Field

[0001] This application relates to the field of online monitoring with fiber optic cables, and specifically to a method and apparatus for measuring cable strain based on fiber optic tensile testing. Background Technology

[0002] High-voltage power grids are subject to complex factors such as weather, terrain, and topography, making the management of overhead transmission lines extremely difficult and posing severe challenges to grid stability, power supply capacity, and disaster resistance. Real-time monitoring of long-distance high-voltage transmission lines has always been a key challenge for power companies. Previously, transmission line inspections relied primarily on manual labor, which was not only costly in terms of manpower, resources, and finances but also failed to obtain accurate real-time data. Currently, high-voltage transmission lines utilize fiber optic cables for transmission. Through fiber optic distributed sensing technology, leveraging the integrated sensing and transmission capabilities of fiber optics, personnel can monitor the fiber optic status using sensors, gaining real-time insight into the strain on the high-voltage transmission lines along the same route.

[0003] The fundamental parameters of power transmission lines are temperature and stress. Only by simultaneously measuring the temperature and stress values ​​of the transmission line cables can the cable strain be analyzed. However, due to the inherent cross-sensitivity of fiber optic sensors to temperature and stress, wavelength demodulation-based measurements cannot distinguish between wavelength changes caused by temperature and stress in practical applications. Furthermore, overhead cables require special monitoring of complex dynamic conditions such as galloping and light wind vibrations. These conditions can cause severe damage to the cables, but unlike static tension, the dynamically changing stress cannot be simply measured under these swaying conditions. These complexities reduce the accuracy of fiber optic sensing in measuring cable strain, posing new challenges to practical applications. Summary of the Invention

[0004] This application provides a method and apparatus for measuring cable strain based on optical fiber tensile testing, which can solve the technical problem that the strain of cables cannot be accurately measured in the prior art.

[0005] In a first aspect, embodiments of this application provide a method for measuring cable strain based on optical fiber tensile testing, the method comprising:

[0006] The relevant sequence is modulated onto the detection wavelength to form a detection optical signal, which is then sent to the optical fiber line of the cable under test.

[0007] Receive reflected or loopback signals from the optical fiber line, and perform correlation operations with the correlation sequence to determine the time delay of the correlation peak of the reflected or loopback signals;

[0008] Based on the time delay of the reflected signal, determine the length of the optical fiber that the optical signal travels from the transmitting end to each reflection point; or based on the time delay of the loopback signal, determine the length of the optical fiber line from one end to the other.

[0009] The strain of the optical fiber is obtained by comparing its length with the corresponding reference record.

[0010] The strain of the cable is obtained by calculating the relationship between the strain of the optical fiber and the strain of the cable.

[0011] In conjunction with the first aspect, in one implementation, determining the optical fiber length traversed by the optical signal from the transmitting end to each reflection point based on the time delay of the reflected signal includes:

[0012] Based on the time delay of the reflected signal and the speed of light transmission in the optical fiber, the optical path distance traversed by the optical signal from transmission to reception is calculated. Half of this optical path distance is the length of the optical fiber traversed from the transmitting end to each reflection point.

[0013] In conjunction with the first aspect, in one implementation, determining the fiber length of the fiber optic line from one end to the other based on the time delay of the loopback signal includes:

[0014] Based on the time delay of the loopback signal and the speed of light transmission in the optical fiber, the optical path distance traversed by the optical signal from transmission to reception is calculated. Half of this optical path distance is the length of the optical fiber line from one end to the other.

[0015] In conjunction with the first aspect, in one embodiment, the reference record is: after the cable is first installed, without the action of external force, the fiber length is determined based on the reflected signal or loopback signal according to the method of measuring cable strain by fiber tension.

[0016] In conjunction with the first aspect, in one implementation, the strain of the cable is obtained based on the relationship between the fiber strain and the strain of the cable, including:

[0017] In the tensile load and strain curve of optical fiber, find the tensile load of optical fiber corresponding to the strain of optical fiber.

[0018] On the tensile load and strain curve of the cable, find the state point that is the same as the tensile load of the optical fiber, and then determine the strain of the cable based on the state point.

[0019] In conjunction with the first aspect, in one embodiment, the refresh rate of the cable strain measurement is increased by increasing the frequency at which the probe optical signal is sent to the optical fiber line.

[0020] Secondly, embodiments of this application provide an optical fiber strain measuring device for measuring the strain of an optical fiber in any of the methods described above for measuring cable strain based on optical fiber tensile testing. The device includes:

[0021] The transmitting end is used to modulate the relevant sequence onto the detection wavelength to form a detection optical signal, which is then sent to the optical fiber line of the cable under test.

[0022] The receiving end is used to receive the reflected signal or loopback signal of the optical fiber line, and perform correlation operations with the correlation sequence to determine the time delay of the correlation peak of the reflected signal or loopback signal; based on the time delay of the reflected signal, the optical fiber length from the transmitting end to each reflection point is determined; or based on the time delay of the loopback signal, the optical fiber length from one end to the other end of the optical fiber line is determined; and the optical fiber length is compared with the corresponding reference record to obtain the strain of the optical fiber.

[0023] A coupler is used to couple the probe optical signal emitted by the transmitter into the optical fiber line, and also to separate the reflected or looped optical signal in the optical fiber line.

[0024] In conjunction with the second aspect, in one embodiment, the transmitting end includes:

[0025] The sequence generation module is used to generate correlated sequences with autocorrelation.

[0026] The digital-to-analog conversion module is used to convert related sequences from digital signals into corresponding analog electrical signals;

[0027] An electro-optic modulator, used to modulate the analog electrical signal onto an optical carrier to form a probe optical signal;

[0028] A first optical amplifier is used to amplify the probe optical signal and send it to the coupler.

[0029] In conjunction with the second aspect, in one embodiment, the receiving end includes:

[0030] The second optical amplifier is used to amplify reflected or loopback signals in the optical fiber line;

[0031] A filter, for reflected signals, is used to filter out optical signals outside the reflected wavelength; for loopback signals, it is used to filter out optical signals outside the loopback signal.

[0032] A photodetector is used to detect optical signals filtered by a filter and convert them into electrical signals;

[0033] The signal processing module is used to sample the electrical signal and perform correlation operations with the correlation sequence to determine the time delay of the correlation peak of the reflected signal or loopback signal detected by the photodetector; determine the optical fiber length from the transmitting end to each reflection point based on the time delay of the reflected signal; or determine the optical fiber length from one end to the other based on the time delay of the loopback signal; and also to compare the optical fiber length with the corresponding reference record to obtain the strain of the optical fiber.

[0034] In conjunction with the second aspect, in one embodiment, the transmitting end and the receiving end are hardware-mounted together, and the coupler is a power splitter or an optical circulator.

[0035] The beneficial effects of the technical solutions provided in this application include:

[0036] By performing correlation calculations on reflected or loopback signals in the optical fiber line, the corresponding time delay can be obtained. Based on the time delay of the reflected signal, the length of the optical fiber traversed from the transmitting end to each reflection point can be determined; or, based on the time delay of the loopback signal, the length of the optical fiber line from one end to the other can be determined, and then the fiber strain can be obtained by comparing the fiber length with the corresponding reference record. Based on the correlation between the fiber strain and the strain of the cable, the strain of the cable can be obtained. Using this method, the strain of the optical fiber in the cable can be dynamically and accurately obtained, and then the strain of the cable can be calculated based on the correlation, avoiding interference from temperature and dynamic conditions on the measurement results, and solving the technical problem of inaccurate cable strain measurement in existing technologies.

[0037] Furthermore, since the accuracy of measuring the length of optical fiber can reach the centimeter level, by sending the correlation sequence at high speed and modulating it onto the detection wavelength to form a detection optical signal, the duration of each bit of the correlation sequence can be reduced, thereby obtaining high resolution. At the same time, high resolution also ensures that the correlation sequence of a limited length can be sent quickly, enabling multiple measurements to be performed quickly and obtaining a high dynamic refresh rate. The measurement frequency can reach hundreds of times per second, thus allowing for dynamic and accurate monitoring of changes in the cable. Attached Figure Description

[0038] Figure 1 This is a schematic flowchart of an embodiment of the method for measuring cable strain based on optical fiber tensile testing according to this application;

[0039] Figure 2 This is a schematic diagram of optical signal reflection in an optical fiber line according to an embodiment of this application;

[0040] Figure 3 This is a schematic diagram of optical signal loopback in an optical fiber line according to an embodiment of this application;

[0041] Figure 4 This is a schematic diagram showing the relationship between the strain of the optical fiber and the strain of the cable in this application;

[0042] Figure 5 This is a schematic diagram of an embodiment of the fiber optic strain measurement device of this application.

[0043] In the picture:

[0044] 1. Transmitter; 11. Sequence generation module; 12. Digital-to-analog converter module; 13. Electro-optic modulator; 14. First optical amplifier.

[0045] 2. Receiver end; 21. Second optical amplifier; 22. Filter; 23. Photodetector; 24. Signal processing module.

[0046] 3. Coupler. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0048] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0050] In a first aspect, embodiments of this application provide a method for measuring cable strain based on optical fiber tensile testing.

[0051] In one embodiment, reference is made to Figure 1 , Figure 1 This is a schematic flowchart illustrating an embodiment of the method for measuring cable strain based on fiber optic tensile testing according to this application. Figure 1 As shown, the method for measuring cable strain based on fiber optic tensile testing includes the following steps:

[0052] S1. Modulate the relevant sequence onto the detection wavelength to form a detection optical signal, and send it to the optical fiber line of the cable under test.

[0053] S2. Receive the reflected signal or loopback signal in the optical fiber line, and perform correlation operation with the aforementioned correlation sequence to determine the time delay of the correlation peak corresponding to the reflected signal or loopback signal.

[0054] S3. Determine the length of the optical fiber from the transmitter to each reflection point based on the time delay of the reflected signal; or determine the length of the optical fiber from one end to the other based on the time delay of the loopback signal.

[0055] S4. Compare the fiber length determined in S3 with the corresponding reference record to obtain the fiber strain;

[0056] S5. Based on the relationship between the fiber strain and the strain of the cable, obtain the strain of the cable.

[0057] The above benchmark record is as follows: after the cable is first installed, without any external force, the fiber length is initially determined based on the reflected signal or loopback signal according to the above method for measuring cable strain by fiber tension. The purpose is to provide a basis for comparison later.

[0058] The above method can dynamically and accurately obtain the strain of the optical fiber in the cable, and then calculate the strain of the cable according to the corresponding relationship, avoiding the interference of temperature and dynamic conditions on the measurement results, and solving the technical problem that the cable strain cannot be accurately measured in the existing technology.

[0059] The above-mentioned method for measuring cable strain based on fiber optic tensile testing has two implementation methods. For example... Figure 2 As shown, in one embodiment, the optical fiber line is a single-fiber bidirectional line. The probe optical signal is transmitted along the optical fiber of the cable under test and passes through each reflection point in the optical fiber line (such as reflection point 1 and reflection point 2) in sequence, forming reflected signals respectively.

[0060] In this embodiment, step S2 receives the reflected signal in the optical fiber line, performs correlation operation on the reflected signal and the correlation sequence modulated onto the detection wavelength in step S1, and obtains the time delay and peak value of the correlation peak corresponding to the reflected signal.

[0061] Based on the time delay of the reflected signal obtained in step S2, the optical path distance ΔD traversed by each optical signal from the transmitting end to the reflection point and back to the receiving end is calculated according to the formula ΔD=ct, where c is the propagation speed of light in the optical fiber, and t is the time delay of the optical signal carrying the relevant sequence from transmission to reception; in this embodiment, it is the time delay of the reflected signal. When the optical fiber length is fixed, in step S3 above, half of the optical path distance ΔD can be determined by the time delay of the reflected signal, which is the length of the optical fiber traversed by the optical signal from the transmitting end to each reflection point, i.e. When multiple reflection points exist, by monitoring the different reflection signals of each reflection point, the distance of each reflection point from the monitoring device (the receiving end in this embodiment) can be determined.

[0062] like Figure 3 As shown, in another embodiment, the optical fiber line is a loopback line, and the probe optical signal returns through two optical fibers in the same cable, and can pass through an optical amplifier in the middle of the optical fiber line.

[0063] In this embodiment, step S2 receives the loopback signal in the optical fiber line, performs correlation operation on the loopback signal and the correlation sequence modulated onto the detection wavelength in step S1, and obtains the time delay and peak value of the correlation peak corresponding to the loopback signal.

[0064] Based on the time delay of the loopback signal obtained in step S2, using the same calculation method as in the previous embodiment, the optical path distance ΔD traversed by the optical signal from transmission to loopback can be calculated according to the formula ΔD=ct, where c is the propagation speed of light in the optical fiber, and t is the time delay of the optical signal carrying the relevant sequence from transmission to reception; in this embodiment, it is the time delay of the loopback signal. When the optical fiber length is fixed, in step S3 above, the time delay of the loopback signal determines that the optical fiber length from one end to the other is half of the optical path distance ΔD, i.e. .

[0065] In step S4 above, for each reflected signal, the fiber strain (in this embodiment, the fiber tension length) can be obtained by comparing the fiber length determined in S3 with the corresponding reference record. For the loopback signal, the fiber strain (in this embodiment, the fiber tension length) can be obtained by directly comparing it with the reference record.

[0066] Furthermore, in one embodiment, step S5 above, obtaining the strain of the cable based on the relationship between the fiber strain and the strain of the cable, specifically includes the following:

[0067] like Figure 4 The diagram shows the relationship between fiber strain and the strain of the cable. Figure 4 The horizontal axis represents tensile load (i.e., stress), and the vertical axis represents strain. Figure 4 This includes the tensile load and strain curves of optical fibers and cables. The relationship between tensile load and strain can be determined by the cable manufacturing process and the overhead laying conditions, and can be measured in the actual environment. When the cable is subjected to "long-term tension under design meteorological conditions," the reserve capacity of the optical fiber is completely released, and the optical fiber is stretched. Since there is a linear correlation between the tensile length of the optical fiber and the strain of the optical fiber, the strain of the cable, and the tensile load of the cable, the actual deformation and stress (i.e., tensile load) of the cable can be determined based on the tensile length of the optical fiber.

[0068] Specifically, in the tensile load and strain curve of the optical fiber, find the tensile load corresponding to the fiber strain; on the tensile load and strain curve of the cable, find the state point that corresponds to the tensile load of the optical fiber, and then determine the strain of the cable based on this state point. For example, if the strain of the optical fiber is obtained as i in S4, find point E with the vertical coordinate i in the tensile load and strain curve of the optical fiber, and then obtain the horizontal coordinate j of point E, where j is the tensile load. Then, on the tensile load and strain curve of the cable, find point F (state point) with the tensile load j, and obtain the vertical coordinate k based on point F, where k is the strain of the cable.

[0069] The spatial resolution achievable using the above method can be determined according to the formula Δd = cΔt, where c is the speed of light in the optical fiber and Δt is the duration of each bit in the correlation sequence. High-speed transmission of the correlation sequence allows for extremely short Δt values, resulting in a very small Δd and thus high resolution. Simultaneously, the extremely short Δt ensures the rapid transmission of the finite-length correlation sequence, enabling rapid multiple measurements, increasing the frequency, and achieving a high dynamic refresh rate. Therefore, it allows for dynamic and precise monitoring of cable changes.

[0070] Secondly, embodiments of this application also provide an optical fiber strain measuring device for measuring optical fiber strain in any of the above-described embodiments of the method for measuring cable strain based on optical fiber tensile testing.

[0071] In one embodiment, reference is made to Figure 5 , Figure 5 This is a functional module diagram of an embodiment of the fiber optic strain measurement device of this application. Figure 5 As shown, the measuring device includes a transmitter 1, a receiver 2, and a coupler 3.

[0072] Transmitter 1 is used to modulate the relevant sequence onto the detection wavelength to form a detection optical signal, which is then sent to the optical fiber line of the cable under test.

[0073] Receiver 2 is used to receive the reflected signal or loopback signal of the optical fiber line, and perform correlation operations with the aforementioned correlation sequence to determine the time delay of the correlation peak of the reflected signal or loopback signal; based on the time delay of the reflected signal, determine the optical fiber length from the transmitter to each reflection point; or based on the time delay of the loopback signal, determine the optical fiber length from one end to the other end of the optical fiber line; and compare the determined optical fiber length with the corresponding reference record to obtain the strain of the optical fiber.

[0074] Coupler 3 is used to couple the probe optical signal emitted by transmitter 1 into the optical fiber line, and also to separate the reflected or looped optical signal in the optical fiber line.

[0075] Furthermore, in one embodiment, the transmitting end 1 includes: a sequence generation module 11, a digital-to-analog conversion module 12, an electro-optic modulator 13, and a first optical amplifier 14.

[0076] The sequence generation module 11 is used to generate correlated sequences with good autocorrelation.

[0077] The digital-to-analog conversion module 12 is used to convert the relevant sequence from digital signals into corresponding analog electrical signals.

[0078] Electro-optic modulator 13 is used to modulate an analog electrical signal onto an optical carrier to form a probe optical signal.

[0079] The first optical amplifier 14 is used to amplify the detection optical signal and send it to the coupler 3 for long-distance optical fiber transmission and detection.

[0080] In another embodiment, the receiver 2 includes a second optical amplifier 21, a filter 22, a photodetector 23, and a signal processing module 24.

[0081] The second optical amplifier 21 is used to amplify the reflected or loopback signals in the optical fiber line.

[0082] Filter 22 is used to filter optical signals outside the reflected wavelength for both reflected and loopback signals.

[0083] The photodetector 23 is used to detect the optical signal after it has been filtered by the filter and convert it into an electrical signal.

[0084] The signal processing module 24 is used to sample, average, and reduce the noise of the electrical signal, and then perform correlation operations. Specifically, it performs correlation operations between the denoised signal and the correlation sequence to determine the time delay of the correlation peak of the reflected signal or loopback signal detected by the photodetector; based on the time delay of the reflected signal, it determines the fiber length from the transmitting end to each reflection point; or based on the time delay of the loopback signal, it determines the fiber length from one end to the other; it is also used to compare the fiber length with the corresponding reference record to obtain the fiber strain.

[0085] For ease of use, the aforementioned fiber optic strain measurement device integrates the hardware of transmitter 1 and receiver 2, allowing it to be placed in a central equipment room or similar location. Downlink optical signals are coupled into the fiber optic line via coupler 3, while uplink optical signals are separated from the fiber optic line via coupler 3. Coupler 3 can be a power splitter or an optical circulator.

[0086] Through the various embodiments of the above measuring device, the strain of the optical fiber in the cable can be obtained dynamically and accurately.

[0087] It should be noted that the sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0088] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0089] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0090] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0091] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0092] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0093] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for measuring cable strain based on optical fiber tensile testing, characterized in that, The method includes: The relevant sequence is modulated onto the detection wavelength to form a detection optical signal, which is then sent to the optical fiber line of the cable under test. Receive reflected or loopback signals from the optical fiber line, and perform correlation operations with the correlation sequence to determine the time delay of the correlation peak of the reflected or loopback signals; Based on the time delay of the reflected signal, determine the length of the optical fiber that the optical signal travels from the transmitting end to each reflection point; or based on the time delay of the loopback signal, determine the length of the optical fiber line from one end to the other. The strain of the optical fiber is obtained by comparing its length with the corresponding reference record. The strain of the cable is obtained by determining the relationship between the strain of the optical fiber and the strain of the cable. This includes: finding the optical fiber tensile load corresponding to the strain in the tensile load and strain curve of the optical fiber; finding the state point that is the same as the tensile load of the optical fiber in the tensile load and strain curve of the cable; and then determining the strain of the cable based on the state point.

2. The method for measuring cable strain based on fiber optic tensile testing as described in claim 1, characterized in that, Based on the time delay of the reflected signal, determine the length of the optical fiber traversed by the optical signal from the transmitting end to each reflection point, including: Based on the time delay of the reflected signal and the speed of light transmission in the optical fiber, the optical path distance traversed by the optical signal from transmission to reception is calculated. Half of this optical path distance is the length of the optical fiber traversed from the transmitting end to each reflection point.

3. The method for measuring cable strain based on fiber optic tensile testing as described in claim 1, characterized in that, Based on the time delay of the loopback signal, the fiber optic line length from one end to the other is determined, including: Based on the time delay of the loopback signal and the speed of light transmission in the optical fiber, the optical path distance traversed by the optical signal from transmission to reception is calculated. Half of this optical path distance is the length of the optical fiber line from one end to the other.

4. The method for measuring cable strain based on fiber optic tensile testing as described in claim 1, characterized in that, The reference record is: after the cable is first installed, without any external force, the fiber length is determined based on the reflected signal or loopback signal according to the method of measuring cable strain by fiber tension.

5. The method for measuring cable strain based on fiber optic tensile testing as described in claim 1, characterized in that: By increasing the frequency at which the probe light signal is sent to the optical fiber line, the refresh rate of the cable strain measurement is improved.

6. A device for measuring fiber strain, comprising measuring the strain of an optical fiber using the method for measuring cable strain based on fiber optic tensile testing as described in any one of claims 1-5, characterized in that, The device includes: The transmitting end is used to modulate the relevant sequence onto the detection wavelength to form a detection optical signal, which is then sent to the optical fiber line of the cable under test. The receiving end is used to receive the reflected signal or loopback signal of the optical fiber line, and perform correlation operations with the correlation sequence to determine the time delay of the correlation peak of the reflected signal or loopback signal; based on the time delay of the reflected signal, the optical fiber length from the transmitting end to each reflection point is determined; or based on the time delay of the loopback signal, the optical fiber length from one end to the other end of the optical fiber line is determined; and the optical fiber length is compared with the corresponding reference record to obtain the strain of the optical fiber. A coupler is used to couple the probe optical signal emitted by the transmitter into the optical fiber line, and also to separate the reflected or looped optical signal in the optical fiber line.

7. The fiber optic strain measuring device as described in claim 6, characterized in that, The sending end includes: The sequence generation module is used to generate correlated sequences with autocorrelation. The digital-to-analog conversion module is used to convert related sequences from digital signals into corresponding analog electrical signals; An electro-optic modulator, used to modulate the analog electrical signal onto an optical carrier to form a probe optical signal; A first optical amplifier is used to amplify the probe optical signal and send it to the coupler.

8. The fiber optic strain measuring device as described in claim 6, characterized in that, The receiving end includes: The second optical amplifier is used to amplify reflected or loopback signals in the optical fiber line; Filters, for both reflected and loopback signals, are used to filter out optical signals outside the reflected wavelength; A photodetector is used to detect optical signals filtered by a filter and convert them into electrical signals; The signal processing module is used to sample the electrical signal and perform correlation operations with the correlation sequence to determine the time delay of the correlation peak of the reflected signal or loopback signal detected by the photodetector; determine the optical fiber length from the transmitting end to each reflection point based on the time delay of the reflected signal; or determine the optical fiber length from one end to the other based on the time delay of the loopback signal; and also to compare the optical fiber length with the corresponding reference record to obtain the strain of the optical fiber.

9. The fiber optic strain measuring device as described in claim 6, characterized in that: The transmitter and receiver are installed together, and the coupler is a power splitter or an optical circulator.

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