Optical communication underground equipment location matching system, optical communication underground equipment location matching method and optical communication underground equipment location matching device

Abstract

The underground equipment location comparison system S disclosed herein is characterized by comprising: a scattered light intensity distribution measuring device 1, which measures the time change of the scattered light intensity distribution along the length direction of the optical fiber F when seismic vibration is applied to the underground optical fiber F; and an underground equipment location comparison device 2, which measures the time change of the strain response distribution along the length direction of the optical fiber F based on the time change of the scattered light intensity distribution along the length direction of the optical fiber F, and estimates the underground equipment status of the optical fiber F based on the time change of the strain response distribution along the length direction of the optical fiber F, so that the underground equipment location of the optical fiber F corresponds to the distance along the length direction of the optical fiber F.

Description

Technical Field

[0001] This disclosure relates to a technique that uses the temporal variation of the scattered light intensity distribution along the length of an optical fiber to make the location of underground equipment corresponding to the distance along the length of the optical fiber. Background Technology

[0002] When laying optical fibers underground, the process involves configuring manholes underground and then connecting the optical fibers to cables within the manholes. Furthermore, if an optical fiber malfunctions at a certain location, the location of the manhole to be addressed must correspond to the longitudinal distance of the optical fiber (see, for example, Non-Patent Literature 1).

[0003] Specific examples of previous optical communication underground equipment location comparison processing techniques Figure 1 As shown. When fiber optic cable F is laid under the ground surface G, it is laid inside the conduit T and connected under the manhole M via a closure C. The optical communication integrated building B is equipped with an underground equipment location tracking system S.

[0004] The underground equipment location reference system S measures the temporal change in the intensity distribution of scattered light along the length direction of optical fiber F when the cover of manhole M is intentionally struck. Then, using methods such as optical time-domain backscattering measurement, the temporal change in the strain response distribution along the length direction of optical fiber F is measured based on this temporal change in the intensity distribution of scattered light along the length direction. Furthermore, based on the temporal change in the strain response distribution along the length direction of optical fiber F, the presence or absence of manhole M is estimated, thus ensuring that the position of manhole M corresponds to the distance along the length direction of optical fiber F.

[0005] Specifically, the time variation in the strain response of fiber F at a distance of approximately 1340m along its length indicates the presence of an intentional impact with a period of 1 second. Conversely, the time variation in the strain response of fiber F at a distance of approximately 1360m along its length does not indicate the presence of an intentional impact with a period of 1 second. Therefore, the underground equipment location reference system S can correspond the location of the manhole M to a distance of approximately 1340m along the length of fiber F.

[0006] Existing technical documents

[0007] Non-patent literature

[0008] Non-patent literature 1: D. Iida, N. Honda, and H. Oshida, “Advances in distributed vibration sensing for optical communication fiber state visualization,” Optical Fiber Technol., 57, 102263, 2020. Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, the underground equipment location matching system S requires dispatching personnel to the site to intentionally strike the cover of the manhole M, which cannot reduce the utilization rate of manpower.

[0011] Therefore, in order to solve the above problems, the purpose of this disclosure is to reduce the human utilization rate when the location of the underground equipment of the optical fiber corresponds to the distance along the length of the optical fiber.

[0012] The means used to solve the problem

[0013] To address the aforementioned issues, the temporal variation of the scattered light intensity distribution along the length of the optical fiber was measured when seismic vibrations were applied to the underground optical fiber.

[0014] Specifically, the optical communication underground equipment location comparison system disclosed herein is characterized by comprising: a scattered light intensity distribution measuring device, which measures the time change of the scattered light intensity distribution along the length direction of the optical fiber when seismic vibration is applied to the underground optical fiber; and an underground equipment location comparison device, which measures the time change of the strain response distribution along the length direction of the optical fiber based on the time change of the scattered light intensity distribution along the length direction of the optical fiber, and estimates the underground equipment status of the optical fiber based on the time change of the strain response distribution along the length direction of the optical fiber, so that the location of the underground equipment of the optical fiber corresponds to the distance along the length direction of the optical fiber.

[0015] Furthermore, the optical communication underground equipment location comparison method disclosed herein is characterized by comprising, in sequence: a scattered light intensity distribution acquisition step, acquiring information on the time change of the scattered light intensity distribution along the length direction of the optical fiber when applying seismic vibration to the underground-laid optical fiber; a strain response distribution measurement step, measuring the time change of the strain response distribution along the length direction of the optical fiber based on the time change of the scattered light intensity distribution along the length direction of the optical fiber; and an underground equipment location comparison step, estimating the underground equipment status of the optical fiber based on the time change of the strain response distribution along the length direction of the optical fiber, so that the location of the underground equipment of the optical fiber corresponds to the distance along the length direction of the optical fiber.

[0016] Furthermore, the optical communication underground equipment location comparison device disclosed herein is characterized by comprising: a scattered light intensity distribution acquisition unit, which acquires information on the time change of the scattered light intensity distribution along the length direction of the optical fiber when seismic vibration is applied to the underground optical fiber; a strain response distribution measurement unit, which measures the time change of the strain response distribution along the length direction of the optical fiber based on the time change of the scattered light intensity distribution along the length direction of the optical fiber; and an underground equipment location comparison unit, which estimates the underground equipment status of the optical fiber based on the time change of the strain response distribution along the length direction of the optical fiber, so that the location of the underground equipment of the optical fiber corresponds to the distance along the length direction of the optical fiber.

[0017] Based on these configurations, instead of intentionally striking the manhole cover, seismic vibrations are applied to the optical fiber, thus reducing the need for manual labor when aligning the location of the underground equipment with the longitudinal distance of the optical fiber.

[0018] Furthermore, the optical communication underground equipment location comparison system disclosed herein is characterized in that the underground equipment location comparison device measures the time change of the vibration frequency distribution along the length direction of the optical fiber based on the time change of the scattered light intensity distribution along the length direction of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the time change of the vibration frequency distribution along the length direction of the optical fiber is continuous or discontinuous along the length direction of the optical fiber, so that the underground equipment location of the optical fiber corresponds to the length direction distance of the optical fiber.

[0019] Based on this configuration, it is possible to determine whether the temporal variation of the vibration frequency distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the positions of manhole sections and pipeline sections correspond to the length of the optical fiber.

[0020] Furthermore, the optical communication underground equipment location comparison system disclosed herein is characterized in that the underground equipment location comparison device measures the time change of the vibration frequency distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the time change of the vibration frequency distribution along the length of the optical fiber is consistent with or inconsistent with the time change of the vibration frequency of the earthquake vibration, so that the location of the underground equipment of the optical fiber corresponds to the distance along the length of the optical fiber.

[0021] Based on this configuration, it is possible to determine whether the temporal variation of the vibration frequency distribution along the length of the optical fiber is consistent with or inconsistent with the temporal variation of the vibration frequency of the seismic vibration, so that the positions of manhole sections and pipeline sections correspond to the distance along the length of the optical fiber.

[0022] Furthermore, the optical communication underground equipment location comparison system disclosed herein is characterized in that the underground equipment location comparison device measures the time change of the strain amplitude distribution along the length direction of the optical fiber based on the time change of the scattered light intensity distribution along the length direction of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the time change of the strain amplitude distribution along the length direction of the optical fiber is continuous or discontinuous along the length direction of the optical fiber, so that the underground equipment location of the optical fiber corresponds to the length direction distance of the optical fiber.

[0023] Based on this configuration, it is possible to determine whether the time variation of the strain amplitude distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the positions of manhole sections and pipeline sections correspond to the length of the optical fiber.

[0024] The effects of the invention

[0025] Thus, this disclosure can reduce the need for manual labor when the location of underground equipment for optical fibers corresponds to the distance along the length of the optical fiber. Attached Figure Description

[0026] Figure 1 This diagram illustrates a specific example of location comparison processing for underground optical communication equipment using previous technologies.

[0027] Figure 2 This is a diagram showing the configuration of the optical communication underground equipment location reference system disclosed herein.

[0028] Figure 3 This is a diagram illustrating the steps of the optical communication underground equipment location comparison process in the first embodiment.

[0029] Figure 4 This is a diagram illustrating a specific example of the optical communication underground equipment location comparison processing in the first embodiment.

[0030] Figure 5 This is a diagram illustrating the steps of the optical communication underground equipment location comparison process in the second embodiment.

[0031] Figure 6 This is a diagram illustrating a specific example of the optical communication underground equipment location comparison processing in the second embodiment. Detailed Implementation

[0032] The embodiments of this disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of this disclosure, and this disclosure is not limited to these embodiments.

[0033] (Configuration of the optical communication underground equipment location reference system disclosed herein)

[0034] The configuration of the optical communication underground equipment location matching system disclosed herein is as follows: Figure 2 As shown. The underground equipment location comparison system S includes: a scattered light intensity distribution measuring device 1 and an underground equipment location comparison device 2. The underground equipment location comparison device 2 includes: a scattered light intensity distribution acquisition unit 21, a strain response distribution measuring unit 22, and an underground equipment location comparison unit 23. The underground equipment location comparison device 2 can... Figure 3 The underground equipment location comparison program shown in Figure 5 (which can be recorded on a storage medium or provided on a network) is installed on a computer to implement this.

[0035] The scattered light intensity distribution measuring device 1 measures the temporal change of the scattered light intensity distribution along the length of the underground optical fiber F when seismic vibration is applied to the fiber F. The scattered light intensity distribution acquisition unit 21 acquires information on the temporal change of the scattered light intensity distribution along the length of the underground optical fiber F when seismic vibration is applied to the fiber F.

[0036] The strain response distribution measurement unit 22 uses optical time-domain backscattering measurement methods, etc., to measure the time change of the strain response distribution along the length of the optical fiber F based on the time change of the scattered light intensity distribution along the length of the optical fiber F. The underground equipment location comparison unit 23 estimates the underground equipment status of the optical fiber F based on the time change of the strain response distribution along the length of the optical fiber F, making the location of the underground equipment correspond to the distance along the length of the optical fiber F, and notifies the optical communication complex building B.

[0037] In this way, instead of intentionally striking the cover of the manhole M, seismic vibrations are applied to the optical fiber F, thus reducing the need for manual labor when aligning the location of the underground equipment on the optical fiber F with the distance along the length of the optical fiber F.

[0038] (Steps for location comparison processing of underground optical communication equipment in the first embodiment)

[0039] The steps of the optical communication underground equipment location comparison processing in the first embodiment are as follows: Figure 3 As shown. The scattered light intensity distribution acquisition unit 21 acquires information on the temporal change of the scattered light intensity distribution along the length direction of the optical fiber F when seismic vibration is applied to the underground-laid optical fiber F (step S1). The strain response distribution measurement unit 22 measures the temporal change of the vibration frequency distribution along the length direction of the optical fiber F based on the temporal change of the scattered light intensity distribution along the length direction of the optical fiber F (step S2).

[0040] Then, the underground equipment location comparison unit 23 estimates the underground equipment status of the optical fiber F based on whether the time change of the vibration frequency distribution along the length direction of the optical fiber F is continuous or discontinuous along the length direction of the optical fiber F (step S3) (steps S4 and S5), so that the underground equipment location of the optical fiber F corresponds to the length direction distance of the optical fiber F (step S6).

[0041] Alternatively, the underground equipment location comparison unit 23 estimates the underground equipment status of the optical fiber F based on whether the time change of the vibration frequency distribution along the length direction of the optical fiber F is consistent with or inconsistent with the time change of the vibration frequency of the earthquake vibration (step S3), so that the underground equipment location of the optical fiber F corresponds to the distance along the length direction of the optical fiber F (step S6).

[0042] Specific examples of the optical communication underground equipment location comparison processing in the first embodiment Figure 4 As shown. When the optical fiber F is laid under the ground G, it is laid inside the pipe T and connected under the manhole M1 through the closure C. Under the manhole M2, it passes through without using the closure C.

[0043] In the vicinity of fiber F at distances of 1320m, 1380m, and 1460m along its length, the temporal variation of the vibration frequency of fiber F exhibits a vibration attenuation of approximately 10 seconds at a high frequency of approximately 10Hz, and a vibration duration of approximately 30 seconds at a low frequency of approximately 1Hz. That is, the temporal variation of the vibration frequency distribution along the length of fiber F is continuous over the length of fiber F (step S3, yes). Alternatively, the temporal variation of the vibration frequency distribution along the length of fiber F is consistent with the temporal variation of the vibration frequency of seismic vibration (step S3, yes). This is because fiber F is in contact with the ground G via conduit T.

[0044] Therefore, the underground equipment location comparison unit 23 can estimate the underground equipment status of the optical fiber F as the interval of the pipeline T in the vicinity of the optical fiber F at distances of 1320m, 1380m and 1460m along the length direction (step S5), so that the position of the pipeline T corresponds to the vicinity of the optical fiber F at distances of 1320m, 1380m and 1460m along the length direction (step S6).

[0045] Near a distance of 1340m along the longitudinal direction of fiber F, the temporal variation of the vibration frequency of fiber F exhibits a vibration duration of approximately 30 seconds at a high frequency of approximately 10Hz, but no vibration is observed at a low frequency of approximately 1Hz. Near a distance of 1420m along the longitudinal direction of fiber F, the temporal variation of the vibration frequency of fiber F exhibits no vibration at a high frequency of approximately 10Hz, but a vibration delay of approximately 30 seconds at a low frequency of approximately 1Hz. That is, the temporal variation of the vibration frequency distribution along the longitudinal direction of fiber F is discontinuous along the longitudinal direction of fiber F (step S3, no). Alternatively, the temporal variation of the vibration frequency distribution along the longitudinal direction of fiber F is inconsistent with the temporal variation of the seismic vibration frequency (step S3, no). This is because fiber F does not contact the ground surface G within manholes M1 and M2.

[0046] Therefore, the underground equipment location comparison unit 23 can estimate the underground equipment state of the optical fiber F as the interval of manhole M1 where the closure member C exists, approximately 1340m along the length direction of the optical fiber F (step S4), so that the position of manhole M1 where the closure member C exists corresponds to the interval of the optical fiber F at approximately 1340m along the length direction of the optical fiber F (step S6). Furthermore, the underground equipment location comparison unit 23 can estimate the underground equipment state of the optical fiber F as the interval of manhole M2 through which the optical fiber F passes, approximately 1420m along the length direction of the optical fiber F (step S4), so that the position of manhole M2 through which the optical fiber F passes corresponds to the interval of the optical fiber F at approximately 1420m along the length direction of the optical fiber F (step S6).

[0047] In this way, it is possible to determine whether the temporal variation of the vibration frequency distribution along the length of the optical fiber F is continuous or discontinuous along the length of the optical fiber F, so that the positions of the intervals of manholes M1 and M2 and the intervals of pipeline T correspond to the length of the optical fiber F.

[0048] On the other hand, it is possible to determine whether the temporal variation of the vibration frequency distribution along the length of the optical fiber F is consistent with or inconsistent with the temporal variation of the vibration frequency of the seismic vibration, so that the positions of the intervals of manholes M1 and M2 and the intervals of pipeline T correspond to the distance along the length of the optical fiber F.

[0049] (Steps for location comparison processing of underground optical communication equipment in the second embodiment)

[0050] The steps for the optical communication underground equipment location comparison processing in the second embodiment are as follows: Figure 5 As shown. The scattered light intensity distribution acquisition unit 21 acquires information on the time change of the scattered light intensity distribution along the length direction of the optical fiber F when seismic vibration is applied to the underground-laid optical fiber F (step S11). The strain response distribution measurement unit 22 measures the time change of the strain amplitude distribution along the length direction of the optical fiber F based on the time change of the scattered light intensity distribution along the length direction of the optical fiber F (step S12).

[0051] Then, the underground equipment location comparison unit 23 estimates the underground equipment status of the fiber F based on whether the time change of the strain amplitude distribution in the length direction of the fiber F is continuous or discontinuous in the length direction of the fiber F (step S13) (steps S14 and S15), so that the underground equipment location of the fiber F corresponds to the length direction distance of the fiber F (step S16).

[0052] Specific examples of the optical communication underground equipment location matching process in the second embodiment Figure 6 As shown. When the optical fiber F is laid under the ground G, it is laid inside the pipe T and connected under the manhole M1 through the closure C. Under the manhole M2, it passes through without using the closure C.

[0053] exist Figure 6 In the middle, using the color ratio of strain amplitude as the full scale, the time variation of the strain amplitude distribution along the length of fiber F is shown in the range of 100nε to -100nε. Figure 6 The lower part of the image uses the color ratio of the strain amplitude as the magnification ratio to show the time variation of the strain amplitude distribution along the length of the fiber F in the range of 5nε to -5nε.

[0054] Around 1320m, 1380m, and 1460m along the length of fiber F, the temporal variation of the strain amplitude distribution along the length of fiber F is continuous over the length of fiber F (step S13, yes). This is because fiber F is in contact with the ground G via pipe T. Around 1440m along the length of fiber F, the temporal variation of the strain amplitude distribution along the length of fiber F is continuous over the length of fiber F (step S13, yes), but with a smaller strain amplitude. This is because fiber F is not in close contact with pipe T, and its contact with the ground G is weaker.

[0055] Therefore, the underground equipment location comparison unit 23 can estimate that the underground equipment state of the optical fiber F is the section of pipeline T in the vicinity of 1320m, 1380m, and 1460m along the length direction of the optical fiber F (step S15), so that the position of pipeline T corresponds to the vicinity of 1320m, 1380m, and 1460m along the length direction of the optical fiber F (step S16). Furthermore, the underground equipment location comparison unit 23 can estimate that the underground equipment state of the optical fiber F is the section of pipeline T that is not in close contact with the optical fiber F in the vicinity of 1440m along the length direction of the optical fiber F (step S15), so that the position of pipeline T that is not in close contact with the optical fiber F corresponds to the vicinity of 1440m along the length direction of the optical fiber F (step S16).

[0056] Near a distance of 1340m along the length of fiber F, the temporal variation of the strain amplitude distribution along the length of fiber F is discontinuous, exhibiting high-frequency strain amplitude (step S13, no). This is because fiber F does not contact the ground G within manhole M1, but is connected via closure C. Near a distance of 1420m along the length of fiber F, the temporal variation of the strain amplitude distribution along the length of fiber F is discontinuous, exhibiting almost no strain amplitude (step S13, no). This is because fiber F does not contact the ground G within manhole M2, and does not use closure C, but only passes through...

[0057] Therefore, the underground equipment location comparison unit 23 can estimate the underground equipment state of the optical fiber F as the interval of manhole M1 where the closure member C exists, approximately 1340m along the length direction of the optical fiber F (step S14), so that the position of manhole M1 where the closure member C exists corresponds to the interval of the optical fiber F at approximately 1340m along the length direction of the optical fiber F (step S16). Furthermore, the underground equipment location comparison unit 23 can estimate the underground equipment state of the optical fiber F as the interval of manhole M2 through which the optical fiber F passes, approximately 1420m along the length direction of the optical fiber F (step S14), so that the position of manhole M2 through which the optical fiber F passes corresponds to the interval of the optical fiber F at approximately 1420m along the length direction of the optical fiber F (step S16).

[0058] In this way, it is possible to determine whether the time variation of the strain amplitude distribution along the length of the fiber F is continuous or discontinuous along the length of the fiber F, so that the positions of the intervals of manholes M1 and M2 and the intervals of pipeline T correspond to the length distance of the fiber F.

[0059] Industrial applicability

[0060] The optical communication underground equipment location matching system, optical communication underground equipment location matching method, and optical communication underground equipment location matching device disclosed herein can reduce the manual utilization rate by utilizing seismic vibrations when aligning the location of the optical fiber underground equipment with the distance along the length of the optical fiber.

[0061] Explanation of reference numerals in the attached figures

[0062] S: Underground equipment location reference system

[0063] F: Fiber optic cable

[0064] B: Optical Communication Central Building

[0065] G: Ground

[0066] M, M1, M2: Manholes

[0067] C: Closure

[0068] T: Piping

[0069] 1: Scattered light intensity distribution measurement device

[0070] 2: Underground equipment location reference device

[0071] 21: Scattered Light Intensity Distribution Acquisition Unit

[0072] 22: Strain Response Distribution Measurement Unit

[0073] 23: Location reference section for underground equipment.

Claims

1. A location tracking system for underground optical communication equipment, characterized in that, have: A device for measuring the intensity distribution of scattered light is used to measure the temporal change of the intensity distribution of scattered light along the length of an underground optical fiber when seismic vibrations are applied to the fiber. and, The underground equipment location comparison device measures the temporal change of the vibration frequency distribution along the length of the optical fiber based on the temporal change of the scattered light intensity distribution along the length of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the temporal change of the vibration frequency distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the location of the underground equipment corresponds to the distance along the length of the optical fiber.

2. A location tracking system for underground optical communication equipment, characterized in that, have: A device for measuring the intensity distribution of scattered light is used to measure the temporal change of the intensity distribution of scattered light along the length of an underground optical fiber when seismic vibrations are applied to the fiber. and, The underground equipment location comparison device measures the time change of the strain amplitude distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the time change of the strain amplitude distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the location of the underground equipment in the optical fiber corresponds to the distance along the length of the optical fiber.

3. A method for determining the location of underground optical communication equipment, characterized in that, In order to have: The step of obtaining the scattered light intensity distribution involves acquiring information on the temporal change of the scattered light intensity distribution along the length direction of the optical fiber when seismic vibration is applied to the underground optical fiber. The strain response distribution measurement step involves measuring the time change of the strain response distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber. and, The underground equipment location comparison step involves measuring the time change of the vibration frequency distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber, and estimating the underground equipment status of the optical fiber based on whether the time change of the vibration frequency distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the location of the underground equipment corresponds to the distance along the length of the optical fiber.

4. A method for determining the location of underground optical communication equipment, characterized in that, In order to have: The step of obtaining the scattered light intensity distribution involves acquiring information on the temporal change of the scattered light intensity distribution along the length direction of the optical fiber when seismic vibration is applied to the underground optical fiber. The strain response distribution measurement step involves measuring the time change of the strain response distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber. and, The underground equipment location comparison step involves measuring the time change of the strain amplitude distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber, and estimating the underground equipment status of the optical fiber based on whether the time change of the strain amplitude distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the location of the underground equipment corresponds to the distance along the length of the optical fiber.

5. A location matching device for underground optical communication equipment, characterized in that, have: The scattered light intensity distribution acquisition unit acquires information on the temporal change of the scattered light intensity distribution along the length direction of the optical fiber when seismic vibration is applied to the underground optical fiber; The strain response distribution measurement unit measures the time change of the strain response distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber. and, The underground equipment location reference unit measures the time change of the vibration frequency distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the time change of the vibration frequency distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the location of the underground equipment of the optical fiber corresponds to the distance along the length of the optical fiber.

6. A location matching device for underground optical communication equipment, characterized in that, have: The scattered light intensity distribution acquisition unit acquires information on the temporal change of the scattered light intensity distribution along the length direction of the optical fiber when seismic vibration is applied to the underground optical fiber; The strain response distribution measurement unit measures the time change of the strain response distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber. and, The underground equipment location reference unit measures the time change of the strain amplitude distribution along the length of the optical fiber based on the time change of the scattered light intensity distribution along the length of the optical fiber, and estimates the underground equipment status of the optical fiber based on whether the time change of the strain amplitude distribution along the length of the optical fiber is continuous or discontinuous along the length of the optical fiber, so that the location of the underground equipment of the optical fiber corresponds to the distance along the length of the optical fiber.

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