Apparatus and method for identifying the position of an optical fiber facility

Abstract

The purpose of the present disclosure is to enable identification of the position of equipment in which an optical fiber is disposed.　The present disclosure is a device (10) for identifying the position of equipment in which an optical fiber (100) is disposed, wherein: Brillouin-scattered light in the optical fiber is measured using test light with a pulse width that will result in a spatial resolution larger than the equipment; and the position of the equipment in the longitudinal direction of the optical fiber is identified using the Brillouin gain bandwidth of the measured Brillouin-scattered light.

Description

Technical Field

[0001] The present disclosure relates to a technique for identifying the location of a facility where an optical fiber is arranged.

Background Art

[0002] Optical fiber measurement techniques using Brillouin scattering include BOTDA (Brillouin Optical Time Domain Analysis) and BOTDR (Brillouin optical time domain reflectometer), and changes in temperature and strain can be measured by observing changes in the Brillouin frequency shift (BFS) (see, for example, Non-Patent Document 1). These spatial resolutions are represented by Δz = νW / 2. ν is the speed of light in the optical fiber, and W is the pulse width of the test light. Generally, it is difficult to detect changes in longitudinal events shorter than the spatial resolution Δz.

[0003] When constructing an optical cable used for optical communication, the length information of the optical cable is recorded based on the length described on the outer sheath of the constructed optical cable. However, when identifying the failure location of an optical cable by an optical fiber measurement technique such as OTDR (Optical Time Domain Reflectometer) measurement during a failure of the optical cable or a problem such as closure flooding, the actual length measurement result is obtained instead of the total length. Therefore, the failure location needs to be searched on-site while matching the total length information at the time of construction and the actual length measurement result of the OTDR measurement. Inside facilities such as closures and manholes, the difference between the total length and the actual length may be large due to the extra length of the optical cable or optical core wire, making it difficult to identify the location of the facility.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure aims to enable identification of the location of facilities where optical fibers are arranged.

Means for Solving the Problems

[0006] The present disclosure is made in view of the above problems. For characteristic points within a period shorter than the spatial resolution Δz existing or occurring in the longitudinal direction of the optical fiber, by measuring the change in the Brillouin gain bandwidth using an optical fiber measurement technique using Brillouin scattering, the locations of facilities such as manholes and overhead closures are identified.

[0007] Specifically, the apparatus and method according to the present disclosure are an apparatus and method for identifying the location of facilities where optical fibers are arranged, using a test light with a pulse width whose spatial resolution is larger than that of the facility to measure the Brillouin scattered light in the optical fiber, and identifying the location of the facility in the longitudinal direction of the optical fiber using the Brillouin gain bandwidth of the measured Brillouin scattered light.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to identify the location of facilities where optical fibers are arranged.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These examples are merely illustrative, and the present disclosure can be implemented in various modified forms based on the knowledge of those skilled in the art. In the present specification and drawings, components having the same reference numerals indicate the same components as each other.

[0011] (System Configuration) FIG. 1 shows an example of the system configuration of the present disclosure. The facility location identification device 10 of the present disclosure includes a BOTDR or BOTDA 11 connected to an optical fiber 100, and an arithmetic processing unit 12 that performs arithmetic processing using the measurement results of the BOTDR or BOTDA.

[0012] The optical fiber 100 is arranged in any facility specified in the present disclosure. Examples of the facility include pipelines, manholes, handholes, and underground enclosures if it is underground infrastructure facilities. Examples of overhead infrastructure facilities include overhead optical cables, overhead enclosures, and utility poles.

[0013] BOTDR or BOTDA 11 measures the Brillouin scattered light in the optical fiber 100 using a test light having a pulse width W according to the equipment. In BOTDR or BOTDA 11, by setting the pulse width W, the spatial resolution Δz for measuring the Brillouin scattered light can be determined. Therefore, in the present disclosure, by setting the pulse width W, the section length at each measurement point is set.

[0014] The arithmetic processing unit 12 identifies the position of the equipment in the optical fiber 100 using the Brillouin gain bandwidth of the Brillouin scattered light measured by BOTDR or BOTDA 11. The arithmetic processing unit 12 of the present disclosure can also be realized by a computer and a program, and it is also possible to record the program on a recording medium or provide it through a network.

[0015] The BOTDR or BOTDA 11 of the present disclosure measures two or more Brillouin scattered lights with different BFSs existing within the spatial resolution Δz using a pulse width W corresponding to a spatial resolution Δz larger than the event to be detected. By this measurement, the arithmetic processing unit 12 can acquire a waveform in which two or more Brillouin gain spectra (BGSs) of different BFSs included in the spatial resolution Δz are synthesized.

[0016] By measuring the change in the Brillouin gain bandwidth ΔG of this synthesized BGS, it can be determined whether a change has occurred in the longitudinal direction of the optical fiber 100. For this reason, for an underground optical cable section where most sections in the longitudinal direction are underground pipelines, the arithmetic processing unit 12 can identify the position of the manhole that becomes a characteristic change point. Also, for an aerial optical cable section, the arithmetic processing unit 12 can identify the position of the aerial closure that becomes a characteristic change point.

[0017] FIG. 2 shows an example of underground infrastructure facilities that house an underground optical cable. The equipment section S1 and the equipment section S3 are pipelines 101, and the equipment section S2 is a manhole 102. In the present embodiment, the case of detecting the position of the manhole 102 in the longitudinal direction of the optical fiber 100 will be described.

[0018] The facility location identification method of the present disclosure has the following steps. Step 1: Set the measurement spatial resolution Δz to a value that is up to about 300% larger than the same as that of the manhole (2 m). Step 2: For each equipment section S1 to S3, measure with BOTDR or BOTDA using a pulse width W corresponding to the measurement spatial resolution Δz. Step 3: Analyze the BGS width obtained as a result of the measurement. Step 4: Identify the position where the BGS width changes steeply (a spike is observed). Step 5: Record the distance between the spikes in Step 4 as the actual length of the cable.

[0019] Regarding Step 1. Generally, the length of the manhole body is about 3 m, and the optical fiber 100 with a total length of 5 m to 10 m including the extra length is accommodated in the section of the manhole 102. In the present embodiment, in order to obtain a waveform in which a plurality of different BWGSs of BFSs from different equipment sections are synthesized within the same measurement point M2, BOTDR or BOTDA with a pulse width such that the measurement spatial resolution Δz is 2 m or more is used.

[0020] Here, the upper limit of the pulse width W is arbitrary. For example, the measurement spatial resolution Δz can be set to a value that is about 300% larger than the length of the manhole body. For example, when the equipment is a manhole, the pulse width W can be set such that the measurement spatial resolution Δz is 6 m or less.

[0021] In Step 2, by measuring the Brillouin scattered light generated by the test light, Brillouin gain spectra corresponding to BFS1 in the equipment section S1, BFS2 in the equipment section S2, and BFS3 in the equipment section S3 are obtained. The BFSs of the equipment sections S1 and S3 may be the same. Although it is known that the BFS also changes depending on temperature, the strain applied to the optical cable, the type and design parameters of the optical fiber 100, and the manufacturing lot, it can be considered to be substantially constant within the spatial resolution Δz of one optical cable in a general cable laying state.

[0022] In Step 2, the measurement points M1 to M3 are different points measured with a spatial resolution Δz, have the same interval length with each other according to the pulse width W, and all have a length of 1 m or more. The measurement points M1 and M3 measure only the pipeline section, and the measurement point M2 is set to straddle the pipeline section and the manhole section.

[0023] FIG. 3 shows an example of the BGS obtained at each measurement point. As shown in FIGS. 3(a) and 3(c), at the measurement points M1 and M3, since the BFS is invariant within the spatial resolution Δz, a sharp BGS with narrow Brillouin gain bandwidths ΔG1 and ΔG3 is obtained. On the other hand, as shown in FIG. 3(b), at the measurement point M2, three different Brillouin gain spectra of the BFS from the equipment sections S1, S2, and S3 are synthesized, and ΔG2 becomes wider than ΔG1 and ΔG3.

[0024] Also, when BFS2 has a value close to BFS1 and BFS3, during the measurement at the measurement point M2, the Brillouin scattered light is effectively measured by dividing it into three measurement points M2-1, M2-2, and M2-3. In this case, within the same pulse width W, probe lights with a pulse width W shorter than that of the measurement point M2 corresponding to the interval lengths of the measurement points M2-1, M2-2, and M2-3 respectively generate BGS 2-1 , BGS 2-2 , BGS 2-3 with different BFSs, and ΔG2 of the synthesized BGS becomes wider. This is synonymous with the fact that in BOTDA and BOTDR measurement results using a narrow pulse width W of the probe light, the BGS becomes wider due to the broadening of the frequency spectrum of the probe light.

[0025] FIG. 4 shows an example of the field test results according to this embodiment. L BGS shows an example of the distance distribution of the BGS width according to the present disclosure. In FIG. 4, the full width at half maximum (FWHM) is shown as an example of the BGS width. The occurrence of spikes due to the broadening of the BGS width indicates the position of the manhole 102, and the interval between the spikes corresponds to the actual length of the optical fiber cable laid between the manholes 102.

[0026] L BFS is a comparative example of the present disclosure and shows the BFS measurement results. L BFS In the BFS measurement results shown in, the BFS may or may not change even if the equipment section is different. Therefore, it is difficult to identify the manhole position. For this reason, when using BFS, it is necessary to distinguish the equipment section. On the other hand, when using the BGS width of the present disclosure, L BGS As shown in, spikes due to the clear widening of the BGS width at the manhole position are collectively observed.

[0027] Therefore, in the present disclosure, in step 3, L BGS obtain the distance distribution of the BGS width as shown in. Then, in step 4, identify the spike position. Thereby, the manhole position can be identified. The interval between the spikes corresponds to the actual length of the cable laid between the manholes. For this reason, in step 5, record the distance between the spikes as the cable actual length. Thereby, the present disclosure can collectively identify the positions of manholes, which are characteristic points of the equipment, in underground optical equipment.

[0028] Although an example of underground infrastructure equipment is described in this embodiment example, the present disclosure is not limited thereto. For example, in overhead optical equipment, it is possible to identify the position of an optical closure having a connection point. In this case, use BOTDR or BOTDA with a pulse width W such that the measurement spatial resolution Δz is equal to or greater than the length of the optical closure. Thereby, the present disclosure can collectively identify the positions of overhead closures having connection points in overhead optical equipment.

[0029] As described above, the present disclosure detects whether a change has occurred in the longitudinal direction of the optical fiber 100 by observing a change in the Brillouin gain bandwidth ΔBGS using BOTDA or BOTDR. Thereby, the present disclosure can collectively identify the positions of any facilities such as manholes and aerial closures. For example, using a pulse width with a measurement spatial resolution Δz of 2 m or more, the positions of handholes, underground closures, aerial closures, and utility poles can be collectively identified. Therefore, according to the present disclosure, since the position (actual length) to the facility can be identified, the actual failure position can be identified from the measurement result of the failure position by OTDR.

Industrial Applicability

[0030] The present disclosure can be applied to the information and communication industry.

Explanation of Signs

[0031] 10: Facility position identification device 11: BOTDR or BOTDA 12: Arithmetic processing unit 100: Optical fiber 101: Pipeline 102: Manhole

Claims

1. An apparatus for identifying the location of a facility in which an optical fiber is disposed, using a test light with a pulse width having a spatial resolution greater than that of the facility to measure Brillouin scattered light in the optical fiber, and identifying the location of the facility in the longitudinal direction of the optical fiber using the Brillouin gain bandwidth of the measured Brillouin scattered light. Apparatus.

2. The facility is at least one of a handhole, an underground closure, an overhead closure, and a utility pole, using a test light with a pulse width having a spatial resolution of 2 m or more to measure Brillouin scattered light in the optical fiber, The apparatus according to claim 1.

3. The Brillouin gain bandwidth is the full width at half maximum of the Brillouin gain spectrum with respect to the longitudinal distance of the optical fiber, identifying the position where the full width at half maximum of the Brillouin gain spectrum is wide as the position of the facility, The apparatus according to claim 1 or 2.

4. A method for identifying the location of a facility in which an optical fiber is disposed, using a test light with a pulse width having a spatial resolution greater than that of the facility to measure Brillouin scattered light in the optical fiber, and identifying the location of the facility in the longitudinal direction of the optical fiber using the Brillouin gain bandwidth of the measured Brillouin scattered light. Method.

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