Optical cable unit monitoring device and optical cable unit monitoring method

Abstract

An optical cable unit monitoring device and an optical cable unit monitoring method are provided that suitably detect abnormal locations in an optical cable unit due to breakage of a support wire. [Solution] A monitoring device 600 for an optical cable unit in which an optical cable is supported by a support wire, comprising: a distortion waveform acquisition unit 620 that acquires a distortion waveform in the monitored section of the optical cable unit; a disturbance factor acquisition unit 630 that acquires disturbance factors in the monitored section of the optical cable unit; a disturbance waveform acquisition unit 640 that acquires a disturbance waveform in the monitored section of the optical cable unit based on the disturbance factors; and an abnormality point acquisition unit 650 that acquires abnormal points in the optical cable unit due to a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform from the distortion waveform.

Description

[Technical Field]

[0001] The present invention relates to an optical cable unit monitoring device and an optical cable unit monitoring method. [Background technology]

[0002] Patent Document 1 describes an optical fiber cable monitoring method for monitoring multiple specific points arranged along the length of an optical fiber cable. This optical fiber cable monitoring method includes a distance information acquisition procedure, a linking procedure, an abnormality detection procedure, and a position acquisition procedure. The distance information acquisition procedure involves optical measurement, which propagates measurement light to acquire information on the distance of the optical fiber cable, to acquire distance information for specific points on the optical fiber cable. The linking procedure involves using the previously acquired order and geographical location information of the specific points to link the geographical location information and distance information for each specific point based on the order of the specific points. The abnormality detection procedure involves optical monitoring, which is less sensitive than optical measurement and propagates monitoring light to acquire information on the distance of the optical fiber cable, to detect distance information for abnormal points on the optical fiber cable that occur on the optical fiber cable. The position acquisition procedure involves using the geographical location information and distance information of the specific points linked in the linking procedure to acquire geographical location information for the specific points corresponding to the abnormal points from the distance information of the abnormal points detected in the abnormality detection procedure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-152630 A Summary of the Invention [Problem to be solved by the invention]

[0004] Known optical cable units include those in which an optical cable is supported by a support wire (self-supporting cables in which the optical cable and support wire are integrated, and optical cable units in which a longitudinally extending support wire and an optical cable are connected at the neck).

[0005] In such optical cable units, abnormalities in the optical cable unit due to breakage of the support wire (for example, even if the optical cable is intact, if the support wire breaks, the optical cable loses its supporting force and is pulled, eventually causing the optical cable to break as well) are a serious problem.

[0006] In this regard, conventional technologies including the above-mentioned Patent Document 1 are unable to effectively detect abnormal portions of an optical cable unit caused by breakage of a support wire. For example, it is unable to detect breakage of a support wire early and with high accuracy before it has a detrimental effect (chain breakage) on the optical cable.

[0007] The present invention has been made in consideration of the above-mentioned concerns, and aims to provide an optical cable unit monitoring device and an optical cable unit monitoring method that can effectively detect abnormal areas in an optical cable unit caused by a break in a support wire. [Means for solving the problem]

[0008] The optical cable unit monitoring device of this embodiment is a monitoring device for an optical cable unit in which an optical cable is supported by a support wire, and is characterized by having a distortion waveform acquisition unit that acquires a distortion waveform in the monitored section of the optical cable unit, a disturbance factor acquisition unit that acquires disturbance factors in the monitored section of the optical cable unit, a disturbance waveform acquisition unit that acquires a disturbance waveform in the monitored section of the optical cable unit based on the disturbance factors, and an abnormality point acquisition unit that acquires an abnormal point in the optical cable unit due to a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform from the distorted waveform.

[0009] The optical cable unit monitoring method of this embodiment is a method for monitoring an optical cable unit in which an optical cable is supported by a support wire, and is characterized by comprising the steps of: acquiring a distorted waveform in a monitored section of the optical cable unit; acquiring a disturbance factor in the monitored section of the optical cable unit; acquiring a disturbance waveform in the monitored section of the optical cable unit based on the disturbance factor; and acquiring an abnormality in the optical cable unit in the monitored section of the optical cable unit due to a break in the support wire based on a removed waveform obtained by removing the disturbance waveform from the distorted waveform. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an optical cable unit monitoring device and an optical cable unit monitoring method that can suitably detect an abnormal portion of an optical cable unit due to a break in a support wire. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of a schematic configuration of an FTTH system. [Figure 2] FIG. 1 is a diagram illustrating an example of a state in which an abnormality occurs in an FTTH system. [Figure 3] 10A and 10B are diagrams illustrating an example of a mechanism by which distortion occurs due to breakage of a support wire of an optical cable unit. [Figure 4] FIG. 1 is a diagram illustrating an example of a cross-sectional structure of an optical cable. [Figure 5] FIG. 1 is a diagram illustrating an example of a schematic configuration of a monitoring device for an optical cable unit. [Figure 6] 10 is a diagram illustrating an example of a disturbance factor of a monitoring target section of an optical cable unit, which is acquired by a disturbance factor acquisition unit; FIG. [Figure 7] 10A and 10B are diagrams showing an example of the amount of change in strain before and after the breakage of a support line in the presence and absence of a disturbance factor. [Figure 8] 1A to 1C are diagrams illustrating steps of a method for monitoring an optical cable unit. DETAILED DESCRIPTION OF THE INVENTION

[0012] The optical cable unit monitoring device and the optical cable unit monitoring method of this embodiment will be described below. The optical cable unit monitoring device and the optical cable unit monitoring method of this embodiment are applied to, for example, optical line maintenance work and are used to identify abnormalities (fault locations, fault locations) in the optical line.

[0013] Furthermore, the optical cable unit monitoring device and optical cable unit monitoring method of the present embodiment focus on the fact that, for example, when a support wire of an overhead optical cable breaks, the optical cable loses its supporting force and is pulled toward the utility pole, and by measuring and analyzing the strain that occurs in the optical fiber, it is possible to identify the fault location non-destructively. In particular, by using machine learning to separate strain changes caused by the influence of outside temperature, wind, etc., it is possible to extract only the strain change caused by the support wire break and identify the fault location.

[0014] <Conventional technical issues> Overhead optical cables laid between utility poles can be damaged by strong winds or contact with trees. For example, in cables where the optical cable and support wire are integrated, such as self-supporting cables, the support wire may break. If this condition is left unattended, the optical cable may not be able to withstand the tension and may eventually break, which could have a serious impact on communication services.

[0015] Conventionally, optical cable damage has been identified by visual inspection or by measuring the light intensity using an optical time domain reflectometer (OTDR). However, visual inspection requires manual intervention, making it difficult to comprehensively identify damage and time-consuming. An OTDR is installed in a terminal facility or a central office, sends out optical pulses, and measures the intensity change of backscattered light generated within the optical fiber to measure the distance to the fault and identify the fault. While it can identify extreme bends and breaks that cause optical loss, it is difficult to detect precursors to a break. Therefore, there is no technology that effectively identifies damage to overhead optical cables, particularly breaks in support wires. Therefore, the OTDR is limited to identifying the location of a break in the optical cable after a break in the support wire has occurred.

[0016] As such, technology that can remotely and comprehensively identify breaks in support wires that could cause optical cable breaks is important for rapid recovery after disasters such as typhoons, and there is a strong demand for such technology, but there is no conventional technology that can meet this demand.

[0017] <Basic technical concept of this embodiment> The inventors recognized the above-mentioned problems as important technical challenges and came up with the idea of ​​an optical cable unit monitoring device and an optical cable unit monitoring method that can effectively detect abnormal areas in an optical cable unit caused by a break in a support wire in an optical cable unit (e.g., an aerial optical cable) in which an optical cable is supported by a support wire.

[0018] More specifically, optical fiber strain distribution sensing is a technology that measures the distribution of strain that occurs in optical fibers.By focusing on the fact that when a support wire breaks, the optical cable loses its supporting force and is pulled toward the utility pole, and measuring the strain that occurs there, it is possible to effectively detect abnormal areas in the optical cable unit caused by a support wire break.

[0019] This embodiment discloses a monitoring device and a monitoring method for an optical cable unit in which an optical cable is supported by a support wire. A distortion waveform acquisition unit acquires a distortion waveform of a monitored section of the optical cable unit in a distortion waveform acquisition step. A disturbance factor acquisition unit acquires a disturbance factor of the monitored section of the optical cable unit in a disturbance factor acquisition step. A disturbance waveform acquisition unit acquires a disturbance waveform of the monitored section of the optical cable unit based on the disturbance factor in the disturbance waveform acquisition step. An abnormality location acquisition unit acquires an abnormality location of the optical cable unit caused by a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform from the distortion waveform in the abnormality location acquisition step.

[0020] This makes it possible to suitably detect an abnormality in the optical cable unit due to a break in the support wire. That is, by detecting the precursor to a break in the support wire leading to a break in the optical cable, it is possible to suitably detect an abnormality in the optical cable unit at a stage before a chain reaction of breaks occurs in the optical cable (at a stage when the optical cable is functioning normally), and to carry out appropriate repairs or treatment.

[0021] <Specific embodiment> 1 is a diagram illustrating an example of a schematic configuration of an FTTH (Fiber To The Home) system 100. The FTTH system 100 includes a terminal (sometimes referred to as terminal equipment) 200, an accommodation station 300, and an optical cable unit 400 that connects the terminal equipment 200 and the accommodation station 300.

[0022] The terminal facility 200 is a general term for wiring facilities and terminal devices installed at installation locations such as detached houses, apartment buildings, and offices. The accommodation station 300 is a communication station for an optical line on the provider side that supplies communication light to the terminal 200 via an optical cable unit 400. In FIG. 1, each terminal 200 and the accommodation station 300 are shown connected via an optical cable unit 400, but in reality, multiple (many) terminals 200 are connected to one accommodation station 300 via the optical cable unit 400. Furthermore, in FIG. 1, three relay units (e.g., utility poles) 500A, 500B, and 500C are shown as examples at intermediate positions between the terminal 200 and the accommodation station 300 to which the optical cable unit 400 is connected.

[0023] 1, the section between the terminal 200 and the repeater unit 500A, the section between the repeater unit 500A and the repeater unit 500B, the section between the repeater unit 500B and the repeater unit 500C, and the section between the repeater unit 500C and the station 300 can each be the "section to be monitored by the optical cable unit 400." Of course, the entire section between the terminal 200 and the station 300 may also be the "section to be monitored by the optical cable unit 400."

[0024] FIG. 2 is a diagram illustrating an example of a state in which an abnormality (failure, fault) occurs in the FTTH system 100. The optical cable unit 400 is an optical cable 400Y supported by a support wire 400X (a self-supporting cable in which the optical cable 400Y and the support wire 400X are integrated). More specifically, the support wire 400X and the optical cable 400Y extend side by side in the longitudinal direction, and the support wire 400X and the optical cable 400Y are connected in the transverse direction by neck portions 400Z provided intermittently in the longitudinal direction. The optical cable unit 400 may also be referred to as an aerial optical cable or an aerial optical cable unit. A monitoring device 600 is connected to the optical cable unit 400 to identify (detect) the occurrence of an abnormality (failure, fault) in the optical cable unit 400. In the example of FIG. 2, the monitoring device 600 for the optical cable unit 400 is depicted as a simplified block diagram to facilitate understanding of the invention.

[0025] 2, the optical cable unit 400 comes into contact with a tree between the repeater section 500A and the repeater section 500B (the section monitored by the optical cable unit 400), causing a portion of the support wire 400X to break. As a result, the optical cable 400Y, which is separated from the support wire 400X, loses its supporting force and is pulled to both sides between the repeater section 500A and the repeater section 500B.

[0026] 3A and 3B are diagrams showing an example of a strain generation mechanism due to breakage of the support wire 400X of the optical cable unit 400. FIG. 3A shows a normal state in which the support wire 400X is not broken, and FIG. 3B shows an abnormal state in which the support wire 400X is broken. In the normal state of FIG. 3A, tension is always applied to the support wire 400X, and the optical cable 400Y supported by the support wire 400X is in a free state (a state with moderate slack), and no stretch (strain) occurs in the optical cable 400Y. In contrast, when a portion of the support wire 400X breaks, the abnormal state of FIG. 3B occurs, in which the optical cable 400Y loses its supporting force and is pulled by the broken support wire 400X, causing stretch (strain) in the optical cable 400Y.

[0027] FIG. 4 is a diagram showing an example of the cross-sectional structure of an optical cable 400Y. The optical cable 400Y has multiple optical fibers built in. As shown in FIG. 4, the optical cable 400Y may be a spacer-type optical cable. In the example of FIG. 4, the optical cable 400Y has a spacer 410 with multiple spiral slots 420 formed on its outer periphery, and multiple stacked optical fiber bundles (tape-shaped optical fibers) 430, each of which has multiple (e.g., four) optical fibers 430a arranged in parallel, are housed in each slot 420. A tension member 440 is provided at the central axis position of the spacer 410, and a water stop tape 450 and an outer jacket (sheath) 460 are sequentially provided around the spacer 410. Note that the optical cable 400Y is not limited to the spacer-type.

[0028] 5 is a diagram showing an example of the schematic configuration of an optical cable unit monitoring device (hereinafter sometimes simply referred to as "monitoring device") 600. The monitoring device 600 has a monitoring section identification unit 610, a distorted waveform acquisition unit 620, a disturbance factor acquisition unit 630, a disturbance waveform acquisition unit 640, and an abnormality location acquisition unit 650.

[0029] The optical cable unit monitoring method of this embodiment is realized, for example, by each component (including a computer) of the monitoring device 600 executing (causing each component to execute) various processing steps. The monitoring device 600 may be read as a distortion measuring device and a distortion analyzing device, and can be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0030] The monitoring section specifying unit 610 specifies (acquires, measures, detects) a monitoring section (an estimated abnormality section, an estimated failure section) of the optical cable unit 400 between the terminal equipment 200 and the accommodating station 300. There is a degree of freedom in how the monitoring section specifying unit 610 specifies the monitoring section of the optical cable unit 400, and various design modifications are possible. For example, the monitoring section specifying unit 610 can specify the entire section between the terminal equipment 200 and the accommodating station 300 as the monitoring section of the optical cable unit 400. Alternatively, the monitoring section specifying unit 610 may specify the monitoring section of the optical cable unit 400 using an arbitrary range specified by the user. In the following description, it is assumed that the entire section between the terminal equipment 200 and the accommodating station 300 is the monitoring section of the optical cable unit 400.

[0031] The distortion waveform acquiring unit 620 acquires a distortion waveform of the monitored section (the entire section between the terminal 200 and the exchange 300) of the optical cable unit 400. The distortion waveform acquiring unit 620 may be configured, for example, by an optical fiber strain distribution measuring device (an optical fiber distributed sensing device using time domain measurement technology).

[0032] The distortion waveform acquisition unit 620 may acquire a distortion waveform of the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the exchange 300) using a BOTDR (Brillouin Optical Time Domain Reflectometer), which measures frequency changes in Brillouin scattered light. The BOTDR acquires distortion caused by temperature changes or stress applied to the optical fiber used as a sensor as continuous data over a predetermined distance (e.g., several tens of kilometers) in the longitudinal direction of the sensor optical fiber. The BOTDR can acquire data two-dimensionally (on a surface) or three-dimensionally (stereoscopically) depending on the installation method of the sensor optical fiber. Light incident on an optical fiber generates various types of scattered light as it travels through the optical fiber. The BOTDR can measure the frequency shift of Brillouin scattered light, which depends on distortion and temperature changes, from one end of the scattered light.

[0033] By checking the characteristics of the optical fiber to be used for measurement in advance and using the strain and temperature coefficients of the optical fiber in the frequency shift of the measured Brillouin scattered light, it is possible to measure changes in strain and temperature. Because the speed of light propagating through an optical fiber is constant, it is possible to identify the position in the optical fiber where the Brillouin scattered light was generated by measuring the elapsed time from when a pulse of light is input until the Brillouin scattered light returns. Based on the frequency shift distribution of the Brillouin scattered light processed in the time and wavelength domains, strain and temperature data along the optical fiber can be obtained.

[0034] In addition to the above-mentioned BOTDR, the distortion waveform acquisition unit 620 may also combine a COTDR (Coherent Optical Time Domain Reflectometer) that measures phase changes in Rayleigh scattered light, a TW-COTDR (Tunable Wavelength Coherent Optical Time Domain Reflectometer) that measures frequency changes in Rayleigh scattering, and a ROTDR (Raman Optical Time Domain Reflectometer) that measures intensity changes in Raman scattered light. These measurement methods are based on the OTDR as their fundamental principle, but differ in the scattered light, wavelength, and detection method they measure.

[0035] The distortion waveform of the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the receiving station 300) acquired by the distortion waveform acquisition unit 620 has the longitudinal position of the optical cable unit 400 (the distance from the reference position of the optical cable unit 400) plotted on the horizontal axis and the amount of distortion change of the optical cable unit 400 plotted on the vertical axis.

[0036] Furthermore, as will be described later, the distortion waveform of the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the receiving station 300) acquired by the distortion waveform acquisition unit 620 may include, as distortion change amounts on the vertical axis, distortion change amounts caused by abnormalities in the optical cable unit 400 (e.g., breakage of the support wire 400X) and distortion change amounts based on disturbance factors (e.g., environmental information such as temperature information, sunshine information, humidity information, wind information, rain information, etc.) in the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the receiving station 300).

[0037] The disturbance factor acquisition unit 630 acquires disturbance factors for the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300). The disturbance factor acquisition unit 630 acquires environmental information for the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) as the disturbance factors. The disturbance factor acquisition unit 630 acquires temperature information, sunshine information, humidity information, wind information, and rain information for the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) as the disturbance factors. The disturbance factor acquisition unit 630 has a temperature sensor that acquires temperature information, a sunshine sensor that acquires sunshine information, a humidity sensor that acquires humidity information, a wind sensor that acquires wind information, and a rain sensor that acquires rain information for the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300).

[0038] The temperature sensor may be, for example, a resistance temperature detector, a thermocouple, a radiation thermometer, an alcohol thermometer, a bimetal thermometer, a pressure thermometer, or a thermistor thermometer. The sunshine sensor may be, for example, a pyranometer or a direct pyranometer. The humidity sensor may be, for example, an electric (electronic) humidity sensor, a wet / dry bulb humidity sensor (wet / dry bulb hygrometer), an electrolyte humidity sensor, a ceramic humidity sensor, or a thermal conduction humidity sensor. The wind sensor may be, for example, a rotary type (cup type or windmill type), a wind pressure type (pitot tube type), an ultrasonic type, or a thermal type (hot wire type). The rain sensor may be, for example, a type that collects rain in a bucket and measures it, or an optical type or a capacitance type.

[0039] In addition, the disturbance factor acquisition unit 630 may acquire information other than the above-mentioned temperature information, sunlight information, humidity information, wind information, and rain information as disturbance factors (additional sensors other than the temperature sensor, sunlight sensor, humidity sensor, wind sensor, and rain sensor may be provided).

[0040] The disturbance factor acquisition unit 630 may have multiple temperature sensors, sunlight sensors, humidity sensors, wind sensors, and rain sensors installed throughout (along) the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300).

[0041] Fig. 6 is a diagram showing an example of disturbance factors in the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) acquired by the disturbance factor acquisition unit 630. In Fig. 6, the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) is divided into divided monitored sections 400-1, 400-2, ..., 400-N (N is a natural number equal to or greater than 2). Then, for each of the divided monitored sections 400-1 to 400-N, temperature information from a temperature sensor, sunshine information from a sunshine sensor, humidity information from a humidity sensor, wind information from a wind sensor, and rain information from a rain sensor are acquired (measured).

[0042] The disturbance waveform acquisition unit 640 acquires a disturbance waveform of the monitoring target section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) based on the disturbance factor acquired by the disturbance factor acquisition unit 630. The disturbance waveform acquisition unit 640 acquires a disturbance waveform of the monitoring target section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) based on the environmental information (temperature information, sunshine information, humidity information, wind information, and rain information) acquired as the disturbance factor by the disturbance factor acquisition unit 630. The disturbance waveform acquired by the disturbance waveform acquisition unit 640 is plotted on the horizontal axis with the longitudinal position of the optical cable unit 400 (the distance from the reference position of the optical cable unit 400) and on the vertical axis with the amount of distortion change due to the disturbance factor of the monitoring target section of the optical cable unit 400.

[0043] As a calibration process, the disturbance waveform acquisition unit 640 stores a reference waveform in a reference state in which there are no distortion factors or disturbance factors in the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300). This reference waveform may be, for example, a linear waveform in which the horizontal axis represents the longitudinal position of the optical cable unit 400 (the distance from the reference position of the optical cable unit 400) and the vertical axis represents the amount of change in distortion of the optical cable unit 400, and the vertical axis always remains zero or a constant value.

[0044] The disturbance waveform acquisition unit 640 performs calculations with reference to the above-mentioned reference waveform, using disturbance factors (environmental information including temperature information, sunshine information, humidity information, wind information, and rain information) of the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) as input parameters, and the disturbance waveform of the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) as output parameters.

[0045] The processing will be explained as follows based on the divided monitoring target sections 400-1 to 400-N illustrated in Fig. 6. The disturbance factors (environmental information including temperature information, sunshine information, humidity information, wind information, and rain information) acquired for the divided monitoring target sections 400-1 to 400-N change from moment to moment and may differ for each divided monitoring target section.

[0046] For example, when a set of temperature information, sunshine information, humidity information, wind information, and rainfall information is input for divided monitoring section 400-1, a distortion change amount 1 for divided monitoring section 400-1 is calculated as an output parameter based on that input set. Similarly, when a different set of temperature information, sunshine information, humidity information, wind information, and rainfall information is input for divided monitoring section 400-2, a distortion change amount 2 for divided monitoring section 400-2 is calculated as an output parameter based on that input set. Calculations like this are continued, and when yet another set of temperature information, sunshine information, humidity information, wind information, and rainfall information is input for divided monitoring section 400-N, a distortion change amount N for divided monitoring section 400-N is calculated as an output parameter based on that input set. Then, an approximate straight line connecting the distortion change amounts 1 to N calculated for the divided monitoring target sections 400-1 to 400-N is calculated as the disturbance waveform for the monitoring target section (all sections between the terminal 200 and the accommodation station 300) of the optical cable unit 400. The calculation of the approximate straight line can be performed using, for example, the least squares method.

[0047] The algorithm by which the disturbance waveform acquisition unit 640 calculates output parameters from input parameters has a degree of freedom, and various design modifications are possible, but for example, estimation of a disturbance waveform from a disturbance factor by machine learning can be used. The disturbance waveform acquisition unit 640 may cooperate with a large-scale language model (not shown) (which may be read as a generative AI (Artificial Intelligence)) to perform input / output conversion from a disturbance factor to a disturbance waveform that will be acquired, calculated, and estimated by machine learning in the future, based on an input / output conversion model from a disturbance factor to a disturbance waveform that has been acquired, calculated, estimated, and accumulated in the past by machine learning (regression analysis by AI may also be used).

[0048] Alternatively, the disturbance waveform acquisition unit 640 may determine the distortion change amount 1 to the distortion change amount N for each of the divided monitored sections 400-1 to 400-N by substituting the relevant information into an arithmetic expression or calculation table with temperature information, sunshine information, humidity information, wind information, and rain information as input parameters for each of the divided monitored sections 400-1 to 400-N, and acquire an approximate straight line connecting the distortion change amount 1 to the distortion change amount N as the disturbance waveform for the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300).

[0049] The abnormality location acquisition unit 650 acquires abnormal locations in the optical cable unit 400 caused by breakage of the support wire 400X in the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300) based on the removed waveform obtained by removing the disturbance waveform acquired by the disturbance waveform acquisition unit 640 from the distorted waveform acquired by the distorted waveform acquisition unit 620.

[0050] More specifically, the abnormality point acquisition unit 650 acquires, within the monitored section of the optical cable unit 400 (the entire section between the terminal 200 and the accommodating station 300), a section where the amplitude of the removed waveform obtained by removing the disturbance waveform acquired by the disturbance waveform acquisition unit 640 from the distorted waveform acquired by the distorted waveform acquisition unit 620 is equal to or greater than a threshold, as an abnormality point of the optical cable unit 400 caused by a break in the support wire 400X.

[0051] 7A and 7B are diagrams showing an example of the amount of change in strain before and after the breakage of the support wire 400X in the cases where there is and is not an external disturbance factor.

[0052] FIG. 7A shows an ideal strain change amount in the absence of any disturbance factors. That is, in a steady state where the support wire 400X is not broken, the strain waveform is a linear waveform in which the vertical axis, which represents the strain change amount of the optical cable unit 400, always maintains a constant value, relative to the horizontal axis, which represents the longitudinal position of the optical cable unit 400 (the distance from the reference position of the optical cable unit 400). In contrast, when the support wire 400X breaks, the strain change amount of the optical cable unit 400 has a local peak only at a portion of the horizontal axis, which represents the longitudinal position of the optical cable unit 400 (the distance from the reference position of the optical cable unit 400), corresponding to the break in the support wire 400X. When the local peak of the strain change amount of the optical cable unit 400 exceeds a fixed threshold, an abnormality in the optical cable unit 400 due to a break in the support wire 400X can be detected. However, an ideal strain change amount without any disturbance factors, such as that shown in FIG. 7A, is practically impossible (cannot be expected).

[0053] 7B shows the actual amount of strain change when there is a disturbance factor. When there is a disturbance factor, even in a steady state where the support wire 400X is not broken, a strain change occurs in the strain waveform according to environmental information such as temperature information, sunshine information, humidity information, wind information, and rain information. Furthermore, when the support wire 400X breaks, the amount of strain change at the portion corresponding to the break in the support wire 400X is added (superimposed) on the strain waveform. As a result, there are multiple locations (three locations in the illustrated example) where the amount of strain change in the optical cable unit 400 exceeds the fixed threshold, making it difficult to identify the abnormal portion of the optical cable unit 400 due to the break in the support wire 400X and also leading to false detection.

[0054] Therefore, this embodiment discloses a monitoring technique for the optical cable unit 400 that removes fluctuations in the distorted waveform due to disturbances, performs highly accurate analysis of the distorted waveform, and suitably detects an abnormality in the optical cable unit 400 due to a break in the support wire 400X. More specifically, disturbance factors (environmental information including temperature information, sunshine information, humidity information, wind information, and rain information) that change from moment to moment and may vary depending on the longitudinal position of the optical cable unit 400 (distance from the reference position of the optical cable unit 400) are acquired in a timely manner (in real time), and changes in distortion due to the disturbance factors are predicted by machine learning using regression analysis to obtain a disturbance waveform. Then, based on a removed waveform obtained by removing the disturbance waveform from the distorted waveform, an abnormality in the optical cable unit 400 due to a break in the support wire 400X is detected (identified, acquired, and understood).

[0055] 8A, 8B, and 8C are diagrams showing the steps of a method for monitoring the optical cable unit 400. FIG.

[0056] As shown in FIG. 8A, in the calibration process, the disturbance factors in the steady state (environmental information including temperature information, sunshine information, humidity information, wind information, and rain information) and the associated distortion change amount of the distorted waveform are learned (the relationship between the explanatory variables and distortion change in the steady state is learned).

[0057] As shown in FIG. 8B, in the actual monitoring process, the disturbance factors (the distribution of environmental information including temperature information, sunshine information, humidity information, wind information, and rain information in the longitudinal direction) of the monitored section of the optical cable unit 400 are acquired. Then, the disturbance factors (the distribution of environmental information including temperature information, sunshine information, humidity information, wind information, and rain information in the longitudinal direction) of the monitored section of the optical cable unit 400 are matched with the learning data obtained in FIG. 8A to acquire the disturbance waveform of the monitored section of the optical cable unit 400 (changes due to disturbances are predicted from the learning data). In FIG. 8B, the disturbance waveform is depicted with a dashed line. Also, FIG. 8B depicts a distortion waveform in which the amount of strain change due to the breakage of the support wire 400X and the amount of strain change due to the disturbance factors occurring during the actual monitoring process are combined (superimposed). The amount of strain change due to the disturbance factors is mainly depicted with a thin solid line, and the portion where the amount of strain change due to the breakage of the support wire 400X is combined (superimposed) is depicted with a bold solid line.

[0058] As shown in Fig. 8C, an abnormality location in the optical cable unit 400 caused by a break in the support wire 400X is detected based on a removed waveform obtained by removing the disturbance waveform from the distorted waveform (a waveform obtained by subtracting a predicted value from the distorted waveform to remove the disturbance). More specifically, within the monitored section of the optical cable unit 400, a location where the amplitude of the removed waveform (the peak of the amount of change in strain and its vicinity) is equal to or greater than a threshold is detected as an abnormality location in the optical cable unit 400 caused by a break in the support wire 400X. As shown in Fig. 8C, because a removed waveform obtained by removing the disturbance waveform from the distorted waveform is used, there is only one location where the amplitude of the removed waveform (the peak of the amount of change in strain and its vicinity) is equal to or greater than the threshold, and the abnormality location in the optical cable unit 400 caused by a break in the support wire 400X can be detected with high accuracy and pinpoint accuracy.

[0059] Here, the estimation of the disturbance waveform from the disturbance factor by machine learning will be described in more detail. As described above, the disturbance waveform acquisition unit 640 may cooperate with an AI (Artificial Intelligence) including a large-scale language model (not shown), a generative AI, or the like, to perform input / output conversion from the disturbance factor by machine learning to be acquired, calculated, and estimated in the future to a disturbance waveform, based on an input / output conversion model from the disturbance factor by machine learning to a disturbance waveform that has been acquired, calculated, estimated, and accumulated in the past.

[0060] The machine learning model used in this embodiment may use linear regression with distortion as the objective variable and each sensor data as the explanatory variable. As an example, in the following formula, Y represents distortion, which is the objective variable, and X1, X2, . . . , Xp (p is a natural number of 2 or more) represent each sensor data (e.g., temperature information, sunshine information, humidity information, wind information, rain information, . . .) which is the explanatory variable. By performing regression analysis for each divided monitoring target section 400-1 to 400-N to obtain each of the constants β0, β1, β2, . . . , βp (p is a natural number of 2 or more), and by obtaining an additional constant ε for the machine learning model, it is possible to predict distortion with high accuracy. Y=β0+β1·X1+β2·X2+···+βp·Xp+ε

[0061] As described above, the optical cable unit monitoring device of this embodiment is a monitoring device for an optical cable unit in which an optical cable is supported by a support wire, and includes: a distortion waveform acquisition unit that acquires a distortion waveform of a monitored section of the optical cable unit; a disturbance factor acquisition unit that acquires a disturbance factor of the monitored section of the optical cable unit; a disturbance waveform acquisition unit that acquires a disturbance waveform of the monitored section of the optical cable unit based on the disturbance factor; and an abnormality location acquisition unit that acquires an abnormality location of the optical cable unit caused by a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform from the distortion waveform. This makes it possible to preferably detect an abnormality location of the optical cable unit caused by a break in the support wire. In other words, by capturing the precursor to a break in the support wire leading to a break in the optical cable, it is possible to preferably detect an abnormality location of the optical cable unit at a stage before a chain reaction of breaks in the optical cable occurs (a stage when the optical cable is functioning normally), and to perform appropriate repairs or treatment.

[0062] Furthermore, according to the optical cable unit monitoring device of this embodiment, optical fiber strain distribution sensing can be used to identify the location where a support wire breakage has occurred in the optical cable unit from the amount of change in the strain distribution characteristics, thereby enabling rapid inspection.

[0063] Furthermore, according to the optical cable unit monitoring device of this embodiment, the disturbance factor acquisition unit and the disturbance waveform acquisition unit cooperate to acquire a disturbance waveform (disturbance waveform generated by machine learning), and the abnormality location acquisition unit acquires an abnormal location in the optical cable unit due to a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform (disturbance waveform generated by machine learning) from the distorted waveform acquired by the distorted waveform acquisition unit. For example, if measurement data from a temperature sensor, a sunlight sensor, a humidity sensor, a rain sensor, a wind sensor, etc. are collected as disturbance factors, a disturbance waveform in line with the measurement data is automatically estimated by machine learning, and the disturbance waveform is removed from the distorted waveform, thereby enabling the abnormal location to be identified with high accuracy (disturbance removal by machine learning becomes possible). In addition, the structure of the device can be simplified, made smaller, and reduced in cost.

[0064] Furthermore, the optical cable unit monitoring device of this embodiment includes a strain measuring instrument that measures strain occurring at each position along the longitudinal direction of the optical fiber and a strain analysis device that acquires and analyzes the strain measurement data, and the strain analysis device executes the strain analysis method of this embodiment. The strain analysis method of this embodiment analyzes changes in strain occurring at each position along the longitudinal direction of the optical fiber to identify the location of a support wire break, separating strain changes caused by the influence of outside temperature and wind, extracting the strain change due to the support wire break, and identifying the location of the change. Because the strain that changes due to a support wire break has a local peak, it is expected that an abnormality due to a support wire break can be identified by setting an appropriate threshold and detecting the position that deviates from the threshold. However, because the strain of the optical fiber changes overall due to the influence of outside temperature, wind, etc. (external disturbance factors), it is usually difficult to identify only the strain due to the support wire break. Therefore, in this embodiment, by predicting changes in strain due to external disturbances using machine learning based on regression analysis and removing them, the location of the support wire break can be reliably identified.

[0065] The optical cable unit monitoring method (distortion analysis method) of this embodiment is realized by, for example, executing the following processing. (1) In a section of the optical cable where it is known that no damage has occurred, reference strain distribution data is obtained in a state without any disturbance. (2) The amount of change in strain relative to the reference strain data is measured for an arbitrary period in a section of the optical cable where it is known that no damage has occurred, under the presence of a disturbance. (3) The relationship between the amount of change in distortion data over a given period and the disturbance data (e.g., environmental information such as outside temperature and wind) that is the cause is obtained by regression analysis. For example, observation data from the Japan Meteorological Agency may be used as the disturbance data. (4) The strain distribution data in the section where the support line breakage is to be identified is compared with the reference data to calculate the amount of change. (5) The amount of change in distortion due to the disturbance is calculated from the disturbance data at the measurement time and subtracted from the reference amount of change in distortion. (6) Any deviation from a given threshold is detected as an abnormality caused by a support line break.

[0066] The optical cable unit monitoring technology of this embodiment enables advanced signal processing that removes the effects of disturbances. This embodiment employs a method for separating and removing the effects of distortion caused by disturbances (such as outside temperature and wind) using regression analysis. Normally, it is difficult to completely remove the effects of environmental changes when measuring distortion using optical fiber sensing, and simple threshold-based judgments have a high risk of false detection. Therefore, this embodiment establishes a technology that combines regression analysis to extract only steep peaks such as support lines. This technology is distinct from conventional technology because it requires not just a combination of mathematical formulas but also the spatial frequency characteristics of distortion and parameter design (selection of a regression model) that works effectively with a company's communications infrastructure equipment. (This technology is not easily invented even by those skilled in the art.)

[0067] The optical cable unit monitoring technology of this embodiment enables linking to physical phenomena. While technologies such as BOTDR are widely used in the field of optical fiber strain analysis, this embodiment adds signal processing technology to achieve more accurate anomaly detection. However, the characteristics of strain data acquired by BOTDR when a support wire breaks cannot be determined simply by acquiring sensor data. For example, it is impossible to predict what physical phenomenon and characteristics will be obtained when a support wire breaks without understanding the type and structure of the communication cable. Therefore, this embodiment does not simply use a strain sensor; it requires a deep understanding of the mechanical properties of the communication cable, making it a technology that stands out from conventional technology (and is not easily invented even by those skilled in the art).

[0068] The optical cable unit monitoring technology of this embodiment makes it possible to establish an analysis flow for highly accurate anomaly detection. This embodiment systematizes a series of processes from measurement data acquisition to anomaly detection (calibration processing for grasping the correspondence between disturbance factors and disturbance waveforms, acquisition of the disturbance waveform from the disturbance factors in the actual monitoring process, acquisition of a cleared waveform in which the disturbance waveform is removed from the distorted waveform, and threshold determination using the cleared waveform). While a typical business operator might be limited to simple anomaly detection based on threshold setting alone, this embodiment achieves improved accuracy by combining data analysis techniques. Putting this technology to a practical level requires the accumulation of experimental data and simulations in an environment with a wide-area optical fiber network, making it a technology that stands out from conventional technology (and one that even a person skilled in the art would not easily invent).

[0069] Although the invention according to the present disclosure has been described in detail above, it is clear to those skilled in the art that the invention according to the present disclosure is not limited to the embodiments described in the present disclosure. The invention according to the present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the invention as defined by the description of the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not impose any limiting meaning on the invention according to the present disclosure. [Explanation of symbols]

[0070] 100 FTTH systems 200 terminals (terminal equipment) 300 Receiving Station 400 Optical cable unit (self-supporting cable, aerial optical cable, aerial optical cable unit) 400X support line 400Y optical cable 400Z neck 400-1~400-N Split monitoring section 410 Spacer 420 Slots 430 Optical fiber bundle (tape-shaped optical fiber) 430a optical fiber 440 Tension member 450 Waterproof Tape 460 Outer skin (sheath) 500A 500B 500C Relay section (electric pole) 600 Optical cable unit monitoring device 610 Monitoring target section identification unit 620 Distortion waveform acquisition unit 630 Disturbance factor acquisition unit 640 Disturbance waveform acquisition unit 650 Abnormality location acquisition unit

Claims

1. A monitoring device for an optical cable unit in which an optical cable is supported on a support wire, a distortion waveform acquiring unit for acquiring a distortion waveform of a section to be monitored of the optical cable unit; a disturbance factor acquisition unit that acquires a disturbance factor of the monitoring target section of the optical cable unit; a disturbance waveform acquisition unit that acquires a disturbance waveform of the monitoring target section of the optical cable unit based on the disturbance factor; an abnormality location acquisition unit that acquires an abnormality location of the optical cable unit due to a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform from the distorted waveform; 1. A monitoring device for an optical cable unit, comprising:

2. the disturbance factor acquisition unit acquires, as the disturbance factor, environmental information in the monitored section of the optical cable unit; the disturbance waveform acquisition unit acquires the disturbance waveform based on the environmental information.

2. The optical cable unit monitoring device according to claim 1.

3. the disturbance factor acquisition unit acquires, as the disturbance factors, temperature information, sunshine information, humidity information, wind information, and rain information in the monitored section of the optical cable unit; 2. The optical cable unit monitoring device according to claim 1.

4. the disturbance waveform acquisition unit executes a calculation using the disturbance factors in the monitored section of the optical cable unit as input parameters and the disturbance waveform in the monitored section of the optical cable unit as output parameters, while referring to a reference waveform in a reference state in which there are no distortion factors and no disturbance factors in the monitored section of the optical cable unit.

2. The optical cable unit monitoring device according to claim 1.

5. the abnormality location acquisition unit acquires a location in the monitored section of the optical cable unit where the amplitude of the removed waveform is equal to or greater than a threshold as an abnormality location of the optical cable unit caused by a break in the support wire.

2. The optical cable unit monitoring device according to claim 1.

6. A monitoring method for an optical cable unit in which an optical cable is supported on a support wire, comprising: acquiring a distortion waveform of a monitored section of the optical cable unit; acquiring a disturbance factor of the monitored section of the optical cable unit; acquiring a disturbance waveform of the monitored section of the optical cable unit based on the disturbance factor; acquiring an abnormality location of the optical cable unit due to a break in the support wire in the monitored section of the optical cable unit based on a removed waveform obtained by removing the disturbance waveform from the distorted waveform; 1. A method for monitoring an optical cable unit, comprising:

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