JP7406768B2 - Optical fiber cable sensing device, optical fiber cable sensing method, and program - Google Patents

Description

The present disclosure relates to an optical fiber cable sensing device, an optical fiber cable sensing method, and a program for estimating the position of a laid optical fiber cable.

A laid optical fiber cable can be expressed as a curved locus in three-dimensional space. The locus of a curve in three-dimensional space can be analyzed by obtaining the curvature κ and torsion τ and using the Frenet-Séret formula. Here, the curvature κ is a value expressing how much and in which direction the curve is curved. The torsion coefficient τ is a value that expresses how much the object rotates with respect to the initial coordinates (absolute coordinates based on the earth's top and bottom) that serve as a reference for the bending direction. In addition, "absolute coordinates" are, for example, coordinates where a plane parallel to an arbitrary tangential surface when the earth is a sphere is expressed by the orthogonal x and z axes, and a perpendicular to the xz plane is expressed by the y axis. be.

By substituting the curvature κ and torsion τ obtained at an arbitrary position of the curve into the Frenet-Celet formula, the position vector T(s) at an arbitrary position can be obtained, and by integrating the position vector T(s), the curve The trajectory vector r(s) of can be obtained.

FIG. 1 is an image explaining a method for estimating the position of an optical fiber cable. As shown in FIG. 1, if the "rotation Ω due to twisting" and the "direction vector r due to bending" are known, the position of the optical fiber cable can be estimated. Here, "rotation Ω due to twisting" means rotation by Ω about the z-axis (direction of the central axis of the optical fiber cable) with respect to the initial position _r0 . "Direction vector r due to bending" is the trajectory vector r(s). Moreover, r _j (j is an integer of 0 or more) in FIG. 1 means a position in the longitudinal direction of the optical fiber cable, and L _j means a section of the optical fiber cable. The x'-axis and y'-axis are reference axes of the optical fiber cable, and are rotated by Ω with respect to the absolute coordinate x-axis and y-axis.

When analyzing a curve trajectory in this way, there is a known method of calculating the curvature κ and torsion τ using a multi-core optical fiber provided with FBG (Fiber Bragg Grating) (for example, Non-Patent Documents 1 and 2). ). Since the wavelength of reflected light changes due to fiber bending due to FBG (Bragg wavelength shifts), the strain distribution in the longitudinal direction of each core is measured using OFDR (Optical Frequency Domain Reflectometry). Then, the curvature κ and torsion rate τ are calculated based on the strain distribution in the cross-sectional direction obtained from the strain of each core at the same point.

“Shape sensing using multi-core fiber optical cable and parametric curve solution”, Optics Express, Vol. 20, No. 3, pp. 2967-2973 “Bend measurement using Bragg gratings in multicore fiber”, Electronics letters, vol. 36, no. 2, pp. 120-121

The conventional method of using a multi-core optical fiber provided with FBG as a sensor medium has the following problems.
First, multi-core optical fibers provided with FBG have a special structure and are difficult to lengthen, making it difficult to analyze long-distance curve trajectories using conventional methods.
Furthermore, in order to improve the sensitivity to distortion, it is necessary to increase the core pitch of a multi-core optical fiber provided with an FBG, but it is difficult to increase the core pitch from the viewpoint of ensuring mechanical strength and transmission characteristics. At present, the core pitch is limited to several tens of μm. In other words, it is difficult to improve measurement accuracy with conventional methods.
Furthermore, OFDR, which is a measurement means, has a short measurement distance (several tens of meters to hundreds of meters), making it difficult to measure long distances.

On the other hand, the installed optical fiber cable is not a multi-core optical fiber, but a general-purpose single mode optical fiber. For this reason, there is also the problem that it is difficult to perform curve locus analysis using a multi-core optical fiber as described above.

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an optical fiber cable sensing device, an optical fiber cable sensing method, and an optical fiber cable sensing method that can easily estimate the installation route of an optical fiber cable made of a general-purpose single mode optical fiber. The purpose is to provide programs.

In order to achieve the above object, an optical fiber cable sensing device according to the present invention identifies a point where an optical fiber cable is bent from longitudinal strain distribution light obtained using light, and detects a point where an optical fiber cable is bent. We decided to correct the direction in which the optical fiber cable is facing by correlating it with the position information of the equipment (manholes, etc.) it is passing through.

Specifically, the optical fiber cable sensing device according to the present invention includes:
a measuring device that injects test light into a single mode optical fiber included in a laid optical fiber cable and measures the longitudinal distribution of physical quantities for each single mode optical fiber;
Detecting the bending position of the single mode optical fiber from the longitudinal distribution of the physical quantity, and comparing the bending position with the position of a specific point described in a database to determine the installation route of the optical fiber cable. an arithmetic unit that estimates
Equipped with.

Further, the optical fiber cable sensing method according to the present invention includes:
a measurement step of injecting test light into a single mode optical fiber included in the laid optical fiber cable and measuring the longitudinal distribution of physical quantities for each single mode optical fiber with a measuring device;
Detecting the bending position of the single mode optical fiber from the longitudinal distribution of the physical quantity, and comparing the bending position with the position of a specific point described in a database to determine the installation route of the optical fiber cable. a calculation step for estimating
I do.

This optical fiber cable sensing device and method detects the position where bending occurs from the longitudinal strain distribution of a single mode optical fiber, and compares it with a specific point (equipment such as a manhole) on a database. Estimate the installation route. Therefore, the present invention can provide an optical fiber cable sensing device and an optical fiber cable sensing method that can easily estimate the installation route of an optical fiber cable made of a general-purpose single mode optical fiber.

The specific estimation method is as follows.
The arithmetic unit is
The installation direction of the optical fiber cable from the measuring device to a specific point position _p1 corresponding to the bending position _z1 closest to the measuring device is already known;
Calculating the distance between the bending position z _n (n is a natural number of 2 or more) and the bending position z _n-1 ,
Find from the database a position p _n of the specific point located at a distance of the specific point p _n-1 corresponding to the bending position z _n-1 ;
Between the bending position zn _-1 and the bending position _zn , the installation direction of the optical fiber cable is estimated to be from the specific point pn _-1 to the specific point _pn . and repeating the estimation work until the n reaches the number N of all the bends.

The present invention is a program for causing a computer to function as the route estimating device. The optical fiber cable sensing device according to the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.

In other words, the device of the present invention can estimate the passing area and route of the optical fiber cable routed from the communication building.

Note that the above inventions can be combined as much as possible.

The present invention can provide an optical fiber cable sensing device, an optical fiber cable sensing method, and a program that can easily estimate the installation route of an optical fiber cable made of a general-purpose single mode optical fiber.

This is an image explaining a method for estimating the position of an optical fiber cable. FIG. 1 is a diagram illustrating an optical fiber cable sensing device according to the present invention. FIG. 3 is a diagram showing one of the single mode optical fibers included in the optical fiber cable being measured using the optical fiber cable sensing device according to the present invention. FIG. 2 is a diagram illustrating the position of a single mode optical fiber within an optical fiber cable cross section measured by the optical fiber cable sensing device according to the present invention. It is an example of cable cross-sectional strain distribution calculated by the optical fiber cable sensing device according to the present invention. It is a figure explaining the definition of a "bending axis." FIG. 3 is a diagram illustrating calculations performed by the optical fiber cable sensing device according to the present invention. 1 is a flowchart illustrating an optical fiber cable sensing method according to the present invention. FIG. 1 is a diagram illustrating an optical fiber cable sensing system according to the present invention. FIG. 1 is a diagram illustrating an optical fiber cable sensing device according to the present invention. FIG. 3 is a diagram illustrating the longitudinal distribution of strain acquired by the optical fiber cable sensing device according to the present invention. FIG. 3 is a diagram illustrating the operation of the optical fiber cable sensing device according to the present invention. FIG. 2 is a diagram illustrating an optical fiber cable sensing method according to the present invention. FIG. 1 is a diagram illustrating an optical fiber cable sensing device according to the present invention.

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

(Embodiment 1)
FIG. 2 is a diagram illustrating the optical fiber cable sensing device 10 of this embodiment. Moreover, FIG. 3 is a diagram in which one of the single mode optical fibers included in the optical fiber cable 20 is measured using the optical fiber cable sensing device 10. The optical fiber cable 20 is of a tape slot type, and five sets of four-core optical fiber ribbons 23 are inserted into the grooves 22 of the slots 21. The optical fiber ribbon 23 has four single mode optical fibers 24 arranged in parallel. In this embodiment, the tape slot type optical fiber cable 20 will be described, but the optical fiber cable that can be measured by the optical fiber cable sensing device 10 is not limited to the tape slot type.
Note that the single mode optical fiber means an optical fiber in which light propagates in a single mode at the wavelength of the test light.

The optical fiber cable sensing device 10 includes:
Inject the test light into any N single mode optical fibers 24 (N is an integer less than M) among the M single mode optical fibers 24 (M is an integer of 3 or more) stored in the optical fiber cable 20. and a measuring device 11 that measures the longitudinal distribution of physical quantities representing bending for each of the N single mode optical fibers 24;
At an arbitrary point in the longitudinal direction of the optical fiber cable 20, the curvature κ at the arbitrary point of the optical fiber cable 20 can be calculated by formula 1 from the respective positions of the N single mode optical fibers 24 in the cross section of the optical fiber cable 20 and the physical quantity. an arithmetic unit 12 that calculates the torsion coefficient τ at the arbitrary point of the optical fiber cable 20 using equation 2;
Equipped with.
In the example of FIG. 3, M=160.
Further, Equation 1 and Equation 2 will be described later.

The fiber optic cable sensing device 10 does not have to measure all single mode optical fibers 24. FIG. 4 is a diagram illustrating the position of the single mode optical fiber 24 measured by the optical fiber cable sensing device 10. The optical fiber cable sensing device 10 measures the four single-mode optical fibers 24 at the outermost circumference and the four single-mode optical fibers 24 at the innermost circumference for each groove 22. That is, in the example of FIG. 4, N=64. Note that the x-axis and y-axis shown in FIGS. 4 and 5 are shown assuming that the central axis of the optical fiber cable 20 is x=0 and y=0.

The measuring device 11 is characterized in that it measures the amount of distortion, bending loss, or polarization fluctuation as the physical quantity. In the following description, a case will be explained in which the amount of strain is measured as the physical quantity, but the curvature κ and torsion τ can be similarly calculated even when other physical quantities are measured. The measuring device 11 measures the amount of strain at position z for each single mode optical fiber 24 in the optical fiber cable 20 by measuring the strain distribution in the longitudinal direction. Examples of such means include OFDR and B-OFDR (OFDR that measures strain distribution by observing Brillouin scattered light). Note that if B-OTDR (OTDR that measures strain distribution by observing Brillouin scattered light) is used as the means, long-distance measurement becomes possible compared to the above-mentioned OFDR.

The computing unit 12 maps the strain amount of each single mode optical fiber 24 at an arbitrary position z of the optical fiber cable 20 on three-dimensional spatial coordinates (the center position of the cable corresponds to coordinate 0), and calculates the cable cross-sectional strain distribution. do. FIG. 5 is an example of cable cross-sectional strain distribution. In the example of FIG. 5, it can be seen that the single mode optical fiber 24 in the first quadrant is contracted and the single mode optical fiber 24 in the third quadrant is extended. From this, it is predicted that the optical fiber cable 20 is bent toward the positive side of the x-axis and the positive side of the y-axis at an arbitrary position z.

Here, the definition of "bending axis" is shown in FIG. The "bending axis" is a "neutral axis", which is a straight line Ax that passes perpendicularly through the center Ce of a circle having a radius of curvature R at the point of contact of a tangent line tangent to the central axis of the optical fiber cable 20 at an arbitrary position z. It is a straight line Nx that is parallel and passes through the center O of the optical fiber cable 20 at an arbitrary position z.

ただし、
ｉ：シングルモード光ファイバの番号
ε_ｉ：シングルモード光ファイバのうちｉ番目のシングルモード光ファイバの任意地点ｚにおける物理量
ｒ_ｉ：断面におけるｉ番目のシングルモード光ファイバと前記曲げ軸との距離
θ_ｉ：断面におけるｉ番目のシングルモード光ファイバのｘ軸に対する角度オフセット
ａｎｇｌｅ（ｖ）：ベクトルｖのｘ軸に対する角度
θ：任意位置ｚにおける曲率κのベクトルのｘ軸に対する傾き
θ’（ｓ）：前記θの、光ファイバケーブルの中心弧長ｓに関する微分
である。 The computing unit 12 extracts the strain amount for each position of the single mode optical fiber from the cable cross-sectional strain distribution in FIG. 5, calculates the curvature κ using Equation 1 as shown in FIG. Calculate the rate τ.

however,
i: Number of single-mode optical fiber ε _i : Physical quantity at arbitrary point z of the i-th single-mode optical fiber among the single-mode optical fibers r _i : Distance θ between the i-th single-mode optical fiber and the bending axis in the cross section _i : Angle offset with respect to the x-axis of the i-th single mode optical fiber in the cross section angle (v): Angle θ of the vector v with respect to the x-axis: Inclination of the vector of curvature κ with respect to the x-axis at an arbitrary position z θ' (s): This is the differential of θ with respect to the central arc length s of the optical fiber cable.

数１のΣの中の式は、各シングルモード光ファイバの歪を「ケーブル中心からの方向θを持ち、歪の大きさεを持つ歪ベクトル」として考え、その歪ベクトルの各成分を曲げ軸Ｎｘからの距離ｒで規格化したもの、といえる。なお、光ファイバケーブル断面中心Ｏ（ｒ＝０）では歪がなく、軸Ａｘ側で縮む歪が発生し、軸Ａｘの反対側で伸びる歪が発生する。 The amount of strain ε _i can be expressed as ε _i =r _i /R using the radius of curvature R at an arbitrary position and the distance r _i from the center of the cross section of the optical fiber cable to the single mode optical fiber. Here, since the bending radius R of the optical fiber cable 20 is 1/κ and the strain difference Δε is proportional to (distance difference)/R, ε _i ∝κr _i holds true if the bending axis is used as a reference.

The equation in Σ of Equation 1 considers the strain in each single-mode optical fiber as a "strain vector with direction θ from the cable center and strain magnitude ε", and each component of the strain vector is defined as the bending axis. It can be said that it is normalized by the distance r from Nx. Note that there is no strain at the optical fiber cable cross-sectional center O (r=0), a shrinking strain occurs on the axis Ax side, and an elongating strain occurs on the opposite side of the axis Ax.

ただし、
Ｔ（ｓ）：位置ベクトル
ｒ_０：初期位置
ｅ_１：単位接ベクトル
ｅ_２：単位主法線ベクトル
ｅ_３：単位従法線ベクトル
ｄ／ｄｓ：単位弧長当たりの変化量
である。 The calculator 12 calculates the central axis trajectory r(s) of the optical fiber cable 20 by substituting the curvature κ and the torsion rate τ into Equation 3 (Frenet-Celet formula), thereby determining the length of the installed optical fiber. The location of the cable can be estimated.

however,
T(s): Position vector r ₀ : Initial position e ₁ : Unit tangent vector e ₂ : Unit principal normal vector e ₃ : Unit binormal vector d/ds: Amount of change per unit arc length.

The computing unit 12 takes at least two of the amount of distortion, bending loss, and polarization fluctuation as the physical quantities, and calculates a value obtained by statistically processing the curvature κ calculated for each physical quantity, and a value obtained by statistically processing the curvature κ calculated for each physical quantity, and the torsion factor τ calculated for each physical quantity. The values obtained by statistically processing the above are respectively set as the new curvature κ and the new torsion τ. Here, statistical processing means averaging the values measured by each measurement technique or taking the median value. The accuracy of bend estimation can be improved by using various measurement techniques.
The calculator 12 causes the measuring device 11 to measure not only the amount of distortion of the single mode optical fiber 24 but also the bending loss and polarization fluctuation, and substitutes these physical quantities into Equations 1 and 2 to obtain the curvature κ and torsion τ. can be calculated. By averaging or taking the median value of the curvature κ and torsion rate τ calculated from a plurality of physical quantities in this way, more accurate curvature κ and torsion rate τ can be obtained.

FIG. 8 is a flowchart illustrating an optical fiber cable sensing method performed by the optical fiber cable sensing device 10. The optical fiber cable sensing method is
Inject the test light into any N single mode optical fibers 24 (N is an integer less than M) among the M single mode optical fibers 24 (M is an integer of 3 or more) stored in the optical fiber cable 20. to do (step S01),
Measuring the longitudinal distribution of physical quantities representing bending for each of the N single mode optical fibers 24 (step S02); and From each position of the single mode optical fiber 24 and the physical quantity, the curvature κ at the arbitrary point of the optical fiber cable 20 is calculated by equation 1, and the torsion coefficient τ at the arbitrary point of the optical fiber cable 20 is calculated by equation 2. That (step S03),
I do.

(Embodiment 2)
FIG. 9 is a diagram illustrating an example of the optical fiber cable sensing system 301 of this embodiment. The optical fiber cable sensing system 301 includes the optical fiber cable sensing device 10 and the optical fiber cable 20 described above. The optical fiber cable 20 is buried under a road 51 in a city area 50. One of the single mode optical fibers 24 is branched from the optical fiber cable 20 and is led into the home of a user who has signed an optical communication contract. Alternatively, it may be brought into the user's home via an optical splitter connected to the single mode optical fiber 24.

The optical fiber cable sensing system 301 is a system for estimating the position of the communication optical fiber cable 20 buried underground in this way from the communication company's office building 15 side. The optical fiber cable 20 for communication uses a general-purpose single-mode optical fiber instead of a multi-core optical fiber, and the conventional 3D sensing technology using multi-core optical fibers cannot be applied as is. Furthermore, since the optical fiber cable 20 is often buried over a long distance, it is required to be able to measure the position of the optical fiber cable 20 over its entire length.

Therefore, the optical fiber cable system 301 includes the optical fiber cable sensing device 10 described above. However, the optical fiber cable sensing device 10 of this embodiment has the following characteristics. FIG. 10 is a functional block diagram illustrating the optical fiber cable sensing device 10. The optical fiber cable sensing device 10 includes:
A measuring device 11 that inputs test light into a single mode optical fiber 24 included in a laid optical fiber cable 20 and measures the longitudinal distribution of physical quantities for each single mode optical fiber 24;
Detecting the bending position of the single mode optical fiber 24 from the longitudinal distribution of the physical quantity, and comparing the bending position with the position of a specific point (equipment such as a manhole) described in the database 13. a computing unit 12 that estimates the installation route of the optical fiber cable 20;
Equipped with.

The measuring device 11 measures the longitudinal distribution of the amount of distortion, bending loss, or polarization fluctuation as the longitudinal distribution of the physical quantity. In this embodiment, an example will be explained in which a longitudinal distribution of strain is measured as a physical quantity.
The measuring device 11 makes the test light enter each single mode optical fiber in the optical fiber cable 20 and measures the strain distribution in the longitudinal direction of the optical fiber (the amount of strain at the distance z) by receiving the backscattered light. The measuring device 11 includes B-OTDR (OTDR (Optical Time Domain Reflectometer) that measures strain distribution by observing Brillouin scattered light), OFDR (Optical Frequency Domain Reflectometer), and B-OFDR (Optical Frequency Domain Reflectometer). Observing Brillouin scattered light (OFDR), which measures the strain distribution.

Here, the measuring device 11 needs to measure the bending of the single mode optical fiber 24 over a long distance. The strain caused by bending the single mode optical fiber 24 increases the intensity of backscattered light compared to the strain caused by twisting or twisting. Furthermore, the strain caused by bending the single mode optical fiber 24 continues for several meters. For this reason, the measuring instrument 11 only needs to measure the strain due to bending of the single-mode optical fiber 24 over a long distance, so it measures with lowering the measurement resolution and distance resolution (lowering the measurement sensitivity and widening the measurement interval).

Specifically, for example, in the case of B-OTDR, the pulse width is about 100 ns and the resolution is 10 m.

The computing unit 12 identifies the point where the optical fiber cable 20 is bent from the strain distribution measured by the measuring instrument 11, and obtains position information (database 13) of the equipment (such as a manhole) through which the optical fiber cable 20 passes. ), the bending direction of the optical fiber cable 20 is corrected.

As shown in FIG. 10, the calculator 12 includes a strain distribution acquisition section 31, a discontinuous strain position acquisition section 32, a direction calculation section 33, and a cable route calculation section 34. The strain distribution acquisition unit 31 acquires a strain distribution from the measuring device 11. FIG. 11 is an example of the strain distribution acquired by the strain distribution acquisition section 31. There are multiple peaks of strain values in the strain distribution. The discontinuous strain position acquisition unit 32 determines that this peak is a strain caused by bending the optical fiber cable 20, and detects the position _zn of the peak. For example, the discontinuous strain position acquisition unit 32 may determine a position where the amount of strain is larger than a threshold value as a peak. Note that the position z _n is the distance from the optical fiber cable sensing device 10 of the optical fiber cable 20 to each peak. n is a natural number, and the total number of peaks is N.

The direction calculation unit 33 compares the distance z _n detected by the discontinuous strain position acquisition unit 32 with the equipment position information stored in the database 13 .
First, the installation direction of the optical fiber cable 20 from the measuring device 10 to the position p ₁ of the specific point (equipment) corresponding to the bending position z ₁ (n=1) closest to the measuring device 10 is already known. do.
The direction calculation unit 33
Calculating the distance between the bending position z _n (n is a natural number of 2 or more) and the bending position z _n-1 ,
finding from the database 13 a position p _n of the specific point located at a position separated by the distance from the position p _n-1 of the specific point corresponding to the bending position z _n-1 ;
It is estimated that the installation direction of the optical fiber cable 20 is from the specific point position p _{n -1 to the specific point position p n between the bending position z n-1 and} the bending position z _n . and repeating the estimation work until the n reaches the number N of all the bends.

A specific calculation method will be explained using FIG. 12. The database 13 stores a map and the installation positions of the equipment _pn . The direction calculation unit 33 searches the database 13 for a facility whose distance from the facility p ₁ is z ₂ −z ₁ , and sets this as facility p ₂ . On the other hand, the direction calculation unit 33 determines that the equipment p _x and the equipment p _y are not the equipment p ₂ because the distance from the equipment p ₁ is not z ₂ −z ₁ . Then, the cable route calculation unit 34 estimates that the optical fiber cable 20 passes from the equipment p ₁ to the equipment p ₂ . The direction calculation unit 33 and the cable route calculation unit 34 repeat the same estimation work based on the distance z ₃ −z ₂ from the equipment p ₂ to the equipment p ₃ to estimate the route of the optical fiber cable 20. The direction calculation section 33 and the cable route calculation section 34 repeat this estimation work until n=N. Thereby, the route of the communication optical fiber cable 20 using the single mode optical fiber 24 in the urban area 50 can be estimated.
Note that when the distance z _n is detected from each of the plurality of single mode optical fibers 24 , it is preferable to use an averaged value as the distance z _n .

FIG. 13 is a diagram illustrating an optical fiber cable sensing method performed by the optical fiber cable sensing device 10. The optical fiber cable sensing method is
A measurement step (steps S01 and S02) of injecting test light into the single mode optical fiber 24 included in the laid optical fiber cable 20 and measuring the longitudinal distribution of physical quantities for each single mode optical fiber 24 with the measuring device 11; ,
Detecting the bending position (distance z _n ) of the single mode optical fiber 24 from the longitudinal distribution of the physical quantity, and detecting the position of the specific point (equipment p _n ) and the bending position (distance) described in the database 13 z _n ) to estimate the installation route of the optical fiber cable 20 (step S03);
I do.

Then, in the calculation step (step S03),
Knowing the installation direction of the optical fiber cable 20 from the measuring device 11 to the specific point position p1 corresponding to the bending position _z1 closest to the measuring device ₁₁ (step S31);
Calculate the distance between the bending position z _n (n is a natural number of 2 or more) and the bending position z _n-1 ,
Find from the database 13 a specific point position p _n that is a distance (z _n -z _{n-1 )} away from the specific point position p n-1 corresponding to the bending position z _n-1 ;
Between the bending position zn _-1 and the bending position _zn, an estimation process is performed to estimate that the installation direction of the optical fiber cable 20 is from the specific point position pn _-1 to the specific point position _pn . (step S32), and repeating the estimation work until the number n reaches the number N of all bends.

(Embodiment 3)
The position of the optical fiber cable may be estimated by combining the optical fiber cable estimation methods described in Embodiment 1 and Embodiment 2. Specifically, it is performed as follows. First, the position of the optical fiber cable installed as described in the first embodiment is estimated. In the estimation method of the first embodiment, the position error of the optical fiber cable 20 increases as the distance from the optical fiber cable sensing device 10 increases. Therefore, the position error is corrected using the estimation method described in the second embodiment.

(Embodiment 4)
The arithmetic unit 12 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided through a network.
FIG. 14 shows a block diagram of system 100. System 100 includes computer 105 connected to network 135.

Network 135 is a data communications network. Network 135 may be a private network or a public network, such as (a) a personal area network covering, for example, a room; (b) a local area network, e.g., covering a building; (c) a local area network, e.g. (d) a metropolitan area network, which covers, for example, a city; (e) a wide network, which covers an area that spans, for example, urban, regional, or national boundaries or (f) the Internet. Communication occurs via electronic and optical signals via network 135.

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

Processor 110 is an electronic device comprised of logic circuitry that responds to and executes instructions.

Memory 115 is a tangible computer readable storage medium having a computer program encoded thereon. In this regard, memory 115 stores data and instructions, or program codes, readable and executable by processor 110 to control the operation of processor 110. Memory 115 may be implemented as random access memory (RAM), a hard drive, read only memory (ROM), or a combination thereof. One of the components of memory 115 is program module 120.

Program modules 120 include instructions for controlling processor 110 to perform the processes described herein. Although operations are described herein as being performed by computer 105 or a method or process or subprocess thereof, those operations are actually performed by processor 110.

The term "module" is used herein to refer to functional operations that can be implemented either as a stand-alone component or as an integrated arrangement of multiple subcomponents. Accordingly, program module 120 may be implemented as a single module or as multiple modules operating in concert with each other. Further, although program modules 120 are described herein as being installed in memory 115 and thus being implemented in software, program modules 120 may be implemented in hardware (e.g., electronic circuitry), firmware, software, or any combination thereof. It is possible to implement either of these methods.

Although program modules 120 are shown as already loaded into memory 115, they may be configured to reside on storage device 140 for later loading into memory 115. Storage device 140 is a tangible computer readable storage medium that stores program modules 120 . Examples of storage devices 140 include compact disks, magnetic tape, read-only memory, optical storage media, memory units composed of a hard drive or multiple parallel hard drives, and Universal Serial Bus (USB) flash drives. It will be done. Alternatively, storage 140 may be random access memory or other type of electronic storage device located in a remote storage system, not shown, and connected to computer 105 via network 135.

System 100 further includes a data source 150A and a data source 150B, collectively referred to herein as data sources 150, and communicatively connected to network 135. In fact, data sources 150 may include any number of data sources, ie, one or more data sources. Data sources 150 include unstructured data and may include social media.

System 100 further includes a user device 130 operated by user 101 and connected to computer 105 via network 135. User device 130 may include an input device, such as a keyboard or voice recognition subsystem, for allowing user 101 to convey information and command selections to processor 110. User device 130 further includes a display device or an output device such as a printer or a speech synthesizer. A cursor control, such as a mouse, trackball, or touch-sensitive screen, allows user 101 to manipulate a cursor on the display to convey additional information and command selections to processor 110.

Processor 110 outputs results 122 of execution of program module 120 to user device 130. Alternatively, processor 110 may provide output to storage 125, such as a database or memory, or via network 135 to a remote device not shown.

For example, the program module 120 may be a program that performs the flowchart in FIG. System 100 can be operated as computing unit 12.

The term "comprising" or "comprising" specifies that the recited feature, integer, step, or component is present, but one or more It should not be interpreted as excluding the presence of other features, integers, steps or components or groups thereof. The terms "a" and "an" are indefinite articles and therefore do not exclude embodiments having a plurality of them.

(Other embodiments)
Note that the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the gist of the present invention. In short, the present invention is not limited to the higher-level embodiment as it is, but can be embodied by modifying the constituent elements within the scope of the gist at the implementation stage.

Moreover, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components from different embodiments may be combined as appropriate.

10: Optical fiber cable sensing device 11: Measuring device 12: Computing unit 13: Database 20: Optical fiber cable 21: Slot 22: Groove 23: Optical fiber tape core 24: Single mode optical fiber 31: Strain distribution acquisition section 32: Discontinuous strain position acquisition section 33: Direction calculation section 34: Cable route calculation section 50: Urban area 51: Road 100: System 101: User 105: Computer 110: Processor 115: Memory 120: Program module 122: Result 125: Storage device 130 : User device 135 : Network 140 : Storage device 150 : Data source 301 : Optical fiber cable sensing system

Claims (5)

A test light is incident on one end of a single mode optical fiber for communication included in a laid optical fiber cable, and from the scattered light returning to the one end of the single mode optical fiber, a physical quantity is determined for each single mode optical fiber. a measuring device for measuring directional distribution;
Detecting the bending position of the single mode optical fiber from the longitudinal distribution of the physical quantity, and comparing the bending position with the position of a specific point described in a database to determine the installation route of the optical fiber cable. an arithmetic unit that estimates
Equipped with
An optical fiber cable sensing device, wherein the position of the bend is a distance from the measuring device of the optical fiber cable to a peak appearing in the longitudinal distribution of the physical quantity . The arithmetic unit is
The installation direction of the optical fiber cable from the measuring device to a specific point position _p1 corresponding to the bending position _z1 closest to the measuring device is already known;
Calculating the distance between the bending position z _n (n is a natural number of 2 or more) and the bending position z _n-1 ,
Find from the database a position p _n of the specific point located at a distance of the specific point p _n-1 corresponding to the bending position z _n-1 ;
Between the bending position zn _-1 and the bending position _zn , the installation direction of the optical fiber cable is estimated to be from the specific point pn _-1 to the specific point _pn . 2. The optical fiber cable sensing device according to claim 1, further comprising: performing an estimating operation to determine the number of bends; and repeating the estimating operation until the n reaches the number N of all the bends. A test light is incident on one end of a single-mode optical fiber for communication included in a laid optical fiber cable, and a physical quantity of longitudinal length is determined for each single-mode optical fiber from the scattered light that returns to the one end of the single-mode optical fiber. a measurement step of measuring the directional distribution with a measuring device;
Detecting the bending position of the single mode optical fiber from the longitudinal distribution of the physical quantity, and comparing the bending position with the position of a specific point described in a database to determine the installation route of the optical fiber cable. a calculation step for estimating
and
An optical fiber cable sensing method, wherein the position of the bend is a distance from the measuring device of the optical fiber cable to a peak appearing in the longitudinal distribution of the physical quantity . In the calculation step,
knowing the installation direction of the optical fiber cable from the measuring device to a position _p1 of a specific point corresponding to the bending position _z1 closest to the measuring device;
Calculating the distance between the bending position z _n (n is a natural number of 2 or more) and the bending position z _n-1 ,
Find from the database a position p _n of the specific point located at a distance of the specific point p _n-1 corresponding to the bending position z _n-1 ;
Between the bending position zn _-1 and the bending position _zn , the installation direction of the optical fiber cable is estimated to be from the specific point pn _-1 to the specific point _pn . 4. The optical fiber cable sensing method according to claim 3, further comprising performing an estimating operation to determine the number of bends, and repeating the estimating operation until the n reaches the number N of all the bends. A program for causing a computer to function as the optical fiber cable sensing device according to claim 1 or 2.

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