CABLE TEST SYSTEM, ANALYSIS DEVICE, CABLE TEST METHOD, AND PROGRAM

Abstract

The purpose of the present invention is to provide a cable test system, an analysis device, a cable test method, and a program for identifying a slack section of an aerial cable without dispatching a worker to the site.　The cable test system according to the present invention comprises: an optical fiber vibration distribution measurement device 11 that acquires a vibration distribution waveform, represented by the domains of time and longitudinal distance, for an aerial optical fiber cable 50 to be tested; and an analysis device 12 that calculates the propagation velocity of vibrations propagating through the aerial optical fiber cable 50 from the vibration distribution waveform and detects, as a cable slack section, a section of the aerial optical fiber cable 50 in which the propagation velocity is less than or equal to a threshold value.

Description

[Technical field]

[0001] The present disclosure relates to a cable testing system, an analysis device, a cable testing method, and a program that detects slack in an optical fiber cable using a distributed acoustic sensor (DAS) that acquires a vibration distribution of an optical fiber from incident test light. [Background technology]

[0002] Because there is a risk of communication interruption due to a vehicle coming into contact with a loose overhead cable, overhead cables are visually inspected for slack as part of communication equipment maintenance (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Masaaki Inoue, Jin Arakaki, Tomoya Shimizu, Hiroyuki Oshida, "Study on 3D modeling of linear structures using MMS measurement point clouds", Institute of Electronics, Information and Communication Engineers, 2020 General Conference, B-13-24, 2020. Summary of the Invention [Problem to be solved by the invention]

[0004] The visual inspection requires manual operation because workers must be dispatched to the site, and this poses problems in terms of labor and costs. In order to solve the above problems, the present invention aims to provide a cable testing system, an analysis device, a cable testing method, and a program that can identify slack sections of an overhead cable without dispatching workers to the site. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, the cable testing system of the present invention calculates the propagation velocity of vibration propagating in the longitudinal direction of the cable from the vibration distribution of an aerial optical fiber cable measured using an optical fiber vibration distribution measuring device, and identifies sections where the calculated vibration propagation velocity is lower than a predetermined value as cable slack sections.

[0006] Specifically, the cable testing system according to the present invention comprises: an optical fiber vibration distribution measuring device for acquiring a vibration distribution waveform represented in the domains of time and longitudinal distance for an aerial optical fiber cable under test; an analysis device that calculates a propagation velocity of vibration propagating through the overhead optical fiber cable from the vibration distribution waveform, and detects a section of the overhead optical fiber cable where the propagation velocity is equal to or less than a threshold value as a cable slack section; Equipped with.

[0007] In addition, the analysis device of the present invention is characterized in that a vibration distribution waveform expressed in terms of time and longitudinal distance obtained from the aerial optical fiber cable being tested is input, the propagation velocity of vibration propagating through the aerial optical fiber cable is calculated from the vibration distribution waveform, and a section of the aerial optical fiber cable where the propagation velocity is below a threshold value is detected as a cable slack section.

[0008] Furthermore, the cable testing method according to the present invention includes: Obtaining a vibration distribution waveform expressed in the domains of time and longitudinal distance for the aerial optical fiber cable under test; Calculating the propagation velocity of vibration propagating through the aerial optical fiber cable from the vibration distribution waveform; and detecting a section of the aerial optical fiber cable in which the propagation velocity is equal to or less than a threshold as a cable slack section; It is characterized by:

[0009] This cable testing system can identify slack sections in an aerial optical fiber cable through optical testing using an optical fiber vibration distribution measurement device installed in a communication building. Therefore, the present invention can provide a cable testing system, an analysis device, and a cable testing method that can identify slack sections in an aerial cable without dispatching workers to the site.

[0010] Here, the analysis device detects peaks or valleys of vibration values ​​appearing in the vibration distribution waveform in an arbitrary section, and the slope of an approximation straight line tracing the peaks or valleys from one end of the arbitrary section to the other end can be regarded as the propagation speed of the vibration in the arbitrary section.

[0011] In addition, the analysis device may perform a two-dimensional Fourier transform of the vibration distribution waveform in an arbitrary section to obtain a plurality of vibration modes expressed in the wave number and frequency domains, and the slope of an approximation line obtained from each of the vibration modes may be regarded as the propagation speed of the vibration in the arbitrary section.

[0012] Furthermore, the present invention relates to a program for causing a computer to function as the analysis device. The analysis device of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0013] The above-mentioned inventions can be combined as much as possible. Effect of the Invention

[0014] The present invention can provide a cable testing system, an analysis device, a cable testing method, and a program that can identify slack sections of an overhead cable without dispatching workers to the site. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a cable testing system according to the present invention. [Diagram 2]1 is a diagram for explaining a method for analyzing the propagation velocity of vibration in an analysis device according to the present invention. FIG. [Diagram 3] 1 is a diagram for explaining a method for analyzing the propagation velocity of vibration in an analysis device according to the present invention. FIG. [Figure 4] 1A to 1C are diagrams illustrating a cable testing method according to the present invention. [Diagram 5] FIG. 1 is a diagram illustrating a cable testing system according to the present invention. [Figure 6] FIG. 1 is a diagram illustrating a cable testing system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0017] (Embodiment 1) FIG. 1 is a diagram illustrating a cable testing system according to the present embodiment. an optical fiber vibration distribution measuring device 11 for acquiring a vibration distribution waveform represented in the domains of time and longitudinal distance for an aerial optical fiber cable 50 to be tested; an analysis device (12) that calculates a propagation velocity of vibration propagating through the aerial optical fiber cable (50) from the vibration distribution waveform, and detects a section of the aerial optical fiber cable (50) where the propagation velocity is equal to or less than a threshold value as a cable slack section; Equipped with.

[0018] The optical fiber vibration distribution measuring device 11 is a distributed acoustic sensor (DAS) using C-OTDR (Coherent-OTDR) technology. The DAS may be any method of detecting phase fluctuation of Rayleigh scattered light caused by vibration of the optical fiber under test. Note that vibration may be applied to the aerial optical fiber cable 50 during testing, but since the aerial optical fiber cable 50 is constantly vibrating due to wind, it may also be possible to measure this vibration.

[0019] The analysis device 12 inputs a vibration distribution waveform obtained from the aerial optical fiber cable 50 and expressed in terms of areas of time and longitudinal distance, calculates the propagation velocity of vibration propagating through the aerial optical fiber cable 50 from the vibration distribution waveform, and detects sections of the aerial optical fiber cable 50 where the propagation velocity is below a threshold value as cable slack sections. There are two methods that the analysis device uses to calculate the vibration propagation velocity:

[0020] (Method 1) Fig. 2 is a diagram of a vibration distribution waveform explaining this technique. The vibration distribution waveform is a distribution in which the vibration of an arbitrary section of the aerial optical fiber cable 50 acquired by optical fiber vibration distribution measurement (DAS) is expressed as a two-dimensional waveform of distance and time. In the case of Fig. 2, the arbitrary section is a section from 110 m (one end) to 130 m (the other end) from the vibration distribution measuring device 11 in the longitudinal direction of the aerial optical fiber cable 50.

[0021] Method 1 is a method in which a peak or a valley of vibration values ​​appearing in the vibration distribution waveform in an arbitrary section is detected, and the slope of an approximation line tracing the peak or the valley from one end of the arbitrary section to the other end of the arbitrary section is regarded as the propagation speed of the vibration in the arbitrary section.

[0022] The analysis device 12 calculates the propagation speed of the vibration propagating in the longitudinal direction of the optical fiber cable by analyzing the vibration distribution of the aerial optical fiber cable 50 acquired by optical fiber vibration distribution measurement (DAS). Specifically, the analysis device 12 draws a straight line so as to trace the part of high vibration (peak part) or the part of low vibration (valley part) in the two-dimensional waveform of distance-time in FIG. 2. Note that the "peak part" and the "valley part" in the vibration distribution in FIG. 2 are shown in dark colors. Moreover, "drawing a straight line so as to trace" the peak part or the valley part means finding a part of multiple peaks (valleys) arranged in an approximately straight line, and drawing a straight line from one end to the other end so as to touch the part. For example, the center point of the peak (valley) part may be detected, and the straight line may be detected by the least squares method.

[0023] After drawing a straight line on the vibration distribution in Figure 2, the analysis device 12 detects the slope of the line and regards the slope as the vibration propagation speed in the section. In the case of Figure 2, line A is a straight line drawn to trace the mountain part, and the vibration propagation speed is calculated from the slope. Distance 20m ÷ Time 1.06s = Propagation speed 18.9m / s It becomes.

[0024] (Method 2) Fig. 3 is a diagram of a two-dimensional spectrum explaining this method. The analysis device 12 performs a two-dimensional Fourier transform on the vibration distribution waveform as shown in Fig. 2, and obtains a two-dimensional spectral distribution in the wave number (k) and frequency (ω) domain as shown in Fig. 3. The dark parts of this two-dimensional spectrum represent the vibration mode.

[0025] Method 2 is a method in which the vibration distribution waveform of an arbitrary section is subjected to a two-dimensional Fourier transform to obtain multiple vibration modes expressed in the wave number and frequency domains, and the slope of an approximation line obtained from each of the vibration modes is taken as the propagation speed of the vibration in the arbitrary section.

[0026] The analysis device 12 calculates the propagation speed of the vibration propagating in the longitudinal direction of the optical fiber cable by analyzing the vibration modes represented by the two-dimensional spectrum in Fig. 3. Specifically, the analysis device 12 obtains two approximation lines (lines B and C) from the multiple vibration modes appearing in the two-dimensional wavenumber-frequency spectrum in Fig. 3. For example, the analysis device 12 may detect the center points of the vibration modes (dark parts) and detect the approximation lines by the least squares method. Line B is a backward wave (k<0) in the longitudinal direction of the optical fiber cable, and line C is a progressive wave (k>0) in the longitudinal direction of the optical fiber cable.

[0027] Since the propagation speed of vibration is given by ν=ω / k, the slope of the approximation line (B, C) represents the propagation speed. In the case of Figure 3, the propagation speed of vibration is given by the slope of the approximation line (B, C), Frequency 3.625s -1 / wave number 0.191m -1 = Propagation speed 18.9m / s It becomes.

[0028] This cable testing system calculates the vibration propagation velocity for each section of the aerial optical fiber cable 50 and detects sections where slack has occurred in the cable. The vibration propagation velocity is proportional to the square root of the cable tension as follows:

number

[0029] Since the cable tension T is low in the cable slack section, the analysis device 12 can identify the section where the vibration propagation velocity v is low as expressed by the formula (1) as the cable slack section.

[0030] FIG. 4 is a flowchart illustrating a cable testing method performed by the present cable testing system. This test method is A vibration distribution waveform (see, for example, FIG. 2 ) expressed in the domain of time and longitudinal distance is acquired for the aerial optical fiber cable 50 to be tested (step S01); Calculating the propagation velocity of the vibration propagating through the aerial optical fiber cable 50 from the vibration distribution waveform (see, for example, the above-mentioned methods 1 and 2) (step S02); and Detecting a section of the aerial optical fiber cable 50 in which the propagation velocity is equal to or lower than a threshold as a cable slack section (step S03); It is characterized by:

[0031] (Example) 5 is a diagram for explaining an embodiment in which the cable testing system tests an aerial optical fiber cable 50. For ease of explanation, the aerial optical fiber cable 50 has two sections. Section #1 is between utility pole 55-1 and utility pole 55-2, and section #2 is between utility pole 55-2 and utility pole 55-3.

[0032] Vibration distribution waveforms in sections #1 and #2 are obtained by optical testing using a vibration distribution measuring device 11 of a cable testing system installed in a communications building 15. The analysis device 12 calculates the vibration propagation velocity of each section of the aerial optical fiber cable 50 from the vibration distribution waveform by method 1. Alternatively, the analysis device 12 calculates the vibration propagation velocity of each section of the aerial optical fiber cable 50 from a two-dimensional spectrum obtained by performing a two-dimensional Fourier transform on the vibration distribution waveform by method 2. The analysis device 12 compares the vibration propagation speed in each section with a threshold value (e.g., 30 m / s) and determines that section #2 where the propagation speed is faster than the threshold value is a "normal section," and that section #2 where the propagation speed is slower than the threshold value is "cable slack."

[0033] This cable testing system can identify slack sections of the cable through optical testing from the communications building 15, reducing the amount of manual work required.

[0034] (Embodiment 2) The analysis device 12 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network. 6 shows a block diagram of a system 100. The system 100 includes a computer 105 connected to a network 135.

[0035] Network 135 is a data communications network. Network 135 may be a private or public network and may include any or all of the following: (a) a personal area network, e.g., covering a room; (b) a local area network, e.g., covering a building; (c) a campus area network, e.g., covering a campus; (d) a metropolitan area network, e.g., covering a city; (e) a wide area network, e.g., covering an area that crosses city, regional, or national boundaries; or (f) the Internet. Communications are conducted by electronic and optical signals over network 135.

[0036] Computer 105 includes a processor 110 and a memory 115 connected to processor 110. Although computer 105 is depicted herein as a stand-alone device, it is not limited to such, but rather may be connected to other devices not shown in a distributed processing system.

[0037] Processor 110 is an electronic device made up of logic circuits that responds to and executes instructions.

[0038] The memory 115 is a tangible computer-readable storage medium in which a computer program is encoded. In this regard, the memory 115 stores data and instructions, i.e., program code, that can be read and executed by the processor 110 to control the operation of the processor 110. The memory 115 can be implemented as a random access memory (RAM), a hard drive, a read-only memory (ROM), or a combination thereof. One component of the memory 115 is a program module 120.

[0039] The program modules 120 include instructions for controlling the processor 110 to perform the processes described herein. Although operations are described herein as being performed by the computer 105 or a method or process or sub-process thereof, those operations are actually performed by the processor 110.

[0040] The term "module" is used herein to refer to a functional operation that may be embodied either as a stand-alone component or as an integrated configuration of multiple subcomponents. Thus, program module 120 may be implemented as a single module or as multiple modules operating in coordination with one another. Furthermore, although program module 120 is described herein as being installed in memory 115 and thus implemented in software, it may be implemented in any of hardware (e.g., electronic circuitry), firmware, software, or a combination thereof.

[0041] Although the program module 120 is shown as already loaded into the memory 115, it may be configured to be located on the storage device 140 for later loading into the memory 115. The storage device 140 is a tangible computer-readable storage medium that stores the program module 120. Examples of the storage device 140 include compact disks, magnetic tapes, read-only memories, optical storage media, memory units consisting of a hard drive or multiple parallel hard drives, and Universal Serial Bus (USB) flash drives. Alternatively, the storage device 140 may be a random access memory or other type of electronic storage device located in a remote storage system not shown and connected to the computer 105 via the network 135.

[0042] System 100 further includes data source 150A and data source 150B, collectively referred to herein as data sources 150, that are communicatively connected to network 135. In practice, data sources 150 may include any number of data sources, i.e., one or more data sources. Data sources 150 may include unstructured data and may include social media.

[0043] The system 100 further includes a user device 130 operated by the user 101 and connected to the computer 105 via a network 135. The user device 130 includes an input device, such as a keyboard or a voice recognition subsystem, to enable the user 101 to communicate information and command selections to the processor 110. The user device 130 further includes an output device, such as a display device or a printer or a voice synthesizer. A cursor control, such as a mouse, trackball, or touch-sensitive screen, enables the user 101 to manipulate a cursor on a display device to communicate further information and command selections to the processor 110.

[0044] The processor 110 outputs the results 122 of the execution of the program modules 120 to a user device 130. Alternatively, the processor 110 can provide the output to a storage device 125, such as a database or memory, or via a network 135 to a remote device, not shown.

[0045] 4 may be the program module 120. The system 100 may operate as the analysis device 12.

[0046] The term "comprising" or "comprising" is to be interpreted as specifying the presence of the stated features, integers, steps or components, but not excluding the presence of one or more other features, integers, steps or components or groups thereof. The terms "a" and "an" are indefinite articles and therefore do not exclude embodiments having a plurality thereof.

[0047] (Other embodiments) In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. In short, the present invention is not limited to the above-described embodiment, and the components can be modified and embodied without departing from the spirit of the present invention at the implementation stage.

[0048] In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components across different embodiments may be appropriately combined. [Explanation of symbols]

[0049] 11: Vibration distribution measuring device 12: Analysis device 15: Communications Building 50: Aerial optical fiber cable 55: Electric pole 100: System 101:User 105: Computer 110: Processor 115: Memory 120: Program module 122:Result 125: Storage device 130: User device 135: Network 140: Storage device 150: Data source

Claims

1. an optical fiber vibration distribution measuring device for acquiring a vibration distribution waveform represented by a region of vibration measurement time and a longitudinal distance for an aerial optical fiber cable to be tested; an analysis device that calculates a propagation velocity of vibration propagating through the overhead optical fiber cable from the vibration distribution waveform, and detects a section of the overhead optical fiber cable where the propagation velocity is equal to or less than a threshold value as a cable slack section; A cable testing system comprising:

2. The analysis device includes:

2. The cable testing system according to claim 1, wherein a peak or a valley of a vibration value appearing in the vibration distribution waveform of an arbitrary section is detected, and a slope of an approximation straight line tracing the peak or the valley from one end of the arbitrary section to the other end of the arbitrary section is determined as a propagation speed of the vibration in the arbitrary section.

3. The analysis device includes:

2. The cable testing system according to claim 1, wherein the vibration distribution waveform of an arbitrary section is subjected to a two-dimensional Fourier transform to obtain a plurality of vibration modes expressed in the wave number and frequency domains, and the slope of an approximation line obtained from each of the vibration modes is set as the propagation velocity of the vibration in the arbitrary section.

4. An analysis device characterized in that a vibration distribution waveform obtained from a test object aerial optical fiber cable and expressed in regions of vibration measurement time and longitudinal distance is input, the device calculates the propagation velocity of vibration propagating through the aerial optical fiber cable from the vibration distribution waveform, and detects sections of the aerial optical fiber cable where the propagation velocity is below a threshold value as cable slack sections.

5. Obtaining a vibration distribution waveform represented by a region of vibration measurement time and longitudinal distance for the aerial optical fiber cable under test; Calculating the propagation velocity of vibration propagating through the aerial optical fiber cable from the vibration distribution waveform; and detecting a section of the aerial optical fiber cable in which the propagation velocity is equal to or less than a threshold as a cable slack section; A cable testing method comprising:

6. A program for causing a computer to function as the analysis device according to claim 4.

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