Optical line facility location identification method

Abstract

The objective of the present invention is to provide a location identification method and a data processing device capable of identifying, with a high degree of accuracy, the location of a desired utility pole on a distance axis from an incident end, in three-dimensional vibration data.　The optical line facility location identification method according to the present invention is characterized by: acquiring three-dimensional vibration data obtained by measuring the propagation state, through an optical fiber, of vibrations generated by exciting a utility pole; and either detecting the timing at which vibrations starts to occur at each point on the distance axis of the three-dimensional vibration data, and setting the point having the earliest timing as the location of the excited utility pole, or detecting the intensity of vibrations at each point on the distance axis of the three-dimensional vibration data, acquiring a change in the intensity with respect to distance, and setting the point at which the intensity suddenly attenuates as the location of the utility pole adjacent to the excited utility pole.

Description

Optical line equipment location identification method

[0001] The present disclosure relates to a method and apparatus for locating utility poles in an optical fiber installation in which optical fibers are strung across multiple utility poles.

[0002] Distributed vibration sensing using installed optical fiber can obtain three-dimensional information: measurement time [s], distance [m] from the incident end, and vibration amplitude [ε]. This three-dimensional information is referred to as "three-dimensional vibration data" in this specification. By analyzing this three-dimensional vibration data, it is possible to estimate the environment around the optical fiber.

[0003] When analyzing three-dimensional vibration data from a section where optical fiber is laid across utility poles to estimate the environment, it is important to map with high accuracy the distance position of the utility pole from the input end (one end of the optical fiber connected to the optical fiber sensing device) in the three-dimensional vibration data. Specifically, in order to correctly estimate the installation status of the optical fiber cable laid across utility poles and the conditions of wind and rain blowing on the cable, it is first necessary to accurately determine the location of the utility pole.

[0004] JP 2020-52030 A JP 2020-127094 A

[0005] T. Okamoto, D. Iida, Y. Koshikiya and N. Honda, “Deployment Condition Visualization of Aerial Optical Fiber Cable By Distributed Vibration Sensing Based On Optical Frequency Domain Reflectometry”, in Journal of Lightwave Technology, vol. 39, no. 21, pp. 6942-6951, 1 Nov. 1, 2021, doi: 10.1109 / JLT. 2021.3107855.

[0006] However, methods for mapping utility pole positions with high accuracy on the distance axis from the incident end in three-dimensional vibration data have not been fully explored. For example, Non-Patent Document 1 describes that, when analyzing how vibrations propagate on a space-time plane of the measurement time and the distance from the incident end, the vibration propagation pattern changes with the utility pole position as the boundary. However, it does not describe in detail how utility pole positions are mapped. Furthermore, changes in the vibration propagation pattern differ for each utility pole, and there are utility poles for which it is difficult to extract changes. Therefore, even if there is a target utility pole, it is not necessarily possible to map that utility pole.

[0007] Patent Documents 1 and 2 disclose methods for mapping the position of a manhole on a distance axis from the input end of three-dimensional vibration data for an optical fiber in an underground section. Specifically, the methods involve exciting the iron cover of a target manhole to vibrate, causing the vibration to propagate to an optical fiber passing through the manhole, measuring the optical fiber using a distributed vibration sensing device at the time the optical fiber is vibrating, and mapping the distance from the input end at which the excited vibration is detected as the position of the manhole in the three-dimensional vibration data obtained by the measurement. The methods of Patent Documents 1 and 2 have the advantage that they facilitate mapping of the target manhole because they artificially vibrate the manhole.

[0008] However, even if one were to simply apply this technique to mapping utility poles, there was a problem in that the vibrations generated by vibrating the utility pole easily propagated to the left and right sides of the pole via the optical fiber, making it difficult to map the utility poles with high accuracy.

[0009] Therefore, in order to solve the above-mentioned problems, the present invention aims to provide a position identification method and a data processing device that can identify the position of a desired utility pole on the distance axis from the incident end with high accuracy in three-dimensional vibration data.

[0010] In order to achieve the above object, the position specifying method according to the present invention analyzes three-dimensional vibration data focusing on the propagation of vibrations when a utility pole is vibrated.

[0011] Specifically, the position identification method according to the present invention is a position identification method for identifying the position of a plurality of utility poles in an optical fiber line facility in which optical fibers are strung across the utility poles, and is characterized in that the state in which vibrations caused by excitation of one of the utility poles propagate through the optical fiber is measured as three-dimensional vibration data of the measurement time, the distance from one end of the optical fiber, and the vibration amplitude, and an analysis process is performed on the three-dimensional vibration data to detect a point on the distance axis of the optical fiber.

[0012] Furthermore, the data processing device according to the present invention is a data processing device for identifying the position of a plurality of utility poles in an optical fiber line facility in which optical fibers are strung across the utility poles, and is characterized by comprising: a measurement unit that measures the state in which vibrations caused by excitation of one of the utility poles propagate through the optical fiber as three-dimensional vibration data of the measurement time, the distance from one end of the optical fiber, and the vibration amplitude; and an analysis unit that performs an analysis process on the three-dimensional vibration data and detects a point on the distance axis of the optical fiber.

[0013] Here, the analysis process detects the time when the vibration occurred for each distance, and the point at which the vibration occurred earliest within the distance is set as a point on the distance axis of the optical fiber, and this point can be set as the position of the vibrated utility pole.

[0014] Furthermore, the analysis process may detect the intensity of the vibration for each distance, and the point at which the attenuation of the intensity of the vibration is greatest within the distance may be set as a point on the distance axis of the optical fiber, and this point may be set as the position of the utility pole next to the vibrated utility pole.

[0015] In the present invention, three-dimensional vibration data is obtained by measuring how vibrations generated by exciting a utility pole propagate through an optical fiber, the timing at which vibrations begin to occur at each point on the distance axis of the three-dimensional vibration data is detected, and the point at which this timing is earliest is taken as the location of the vibrating utility pole. Alternatively, in the present invention, three-dimensional vibration data is obtained by measuring how vibrations generated by exciting a utility pole propagate through an optical fiber, the intensity of vibrations at each point on the distance axis of the three-dimensional vibration data is detected, the change in the intensity with respect to distance is obtained, and the point at which the intensity rapidly attenuates is taken as the location of the utility pole adjacent to the vibrating utility pole.

[0016] With this method, the position of the desired utility pole can be identified even if the vibration propagates to the left and right of the utility pole through the optical fiber. Therefore, the present invention can provide a position identification method and a data processing device that can identify the position of the desired utility pole on the distance axis from the incident end with high accuracy in three-dimensional vibration data.

[0017] The data processing device of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0018] Furthermore, the above inventions can be combined as much as possible.

[0019] The present invention can provide a position identification method and a data processing device that can identify the position of a desired utility pole on the distance axis from the incident end with high accuracy in three-dimensional vibration data.

[0020] FIG. 1 is a diagram illustrating a data processing device and a position identification system according to the present invention. FIG. 2 is an image diagram illustrating three-dimensional vibration data acquired by a data processing device according to the present invention. FIG. 3 is a diagram illustrating a vibration waveform calculated from three-dimensional vibration data by a data processing device according to the present invention. FIG. 4 is a graph illustrating the distance dependence of vibration start time created by a data processing device according to the present invention. FIG. 5 is a diagram illustrating an analysis method performed by a data processing device according to the present invention. FIG. 6 is a graph illustrating the distance dependence of vibration start time created by a data processing device according to the present invention. FIG. 7 is a diagram illustrating an analysis method performed by a data processing device according to the present invention.

[0021] The following description of the preferred embodiments of the present invention will be given with reference to the accompanying drawings. The preferred embodiments described below are examples of the present invention, and the present invention is not limited to the preferred embodiments. In this specification and the drawings, components having the same reference numerals are intended to represent the same components.

[0022] 1 is a diagram illustrating a data processing device 20 and a position identification system 301 according to this embodiment. The data processing device 20 is a data processing device that identifies the positions of a plurality of utility poles 10 in an optical fiber line facility in which optical fibers 50 are strung across the utility poles, and is characterized by comprising: a measurement unit 21 that measures the state in which vibrations caused by excitation of one of the utility poles 10 propagate through the optical fiber 50 as three-dimensional vibration data including the measurement time, the distance from one end 50 a of the optical fiber 50, and the vibration amplitude; and an analysis unit 22 that performs an analysis process on the three-dimensional vibration data to detect one point on the distance axis of the optical fiber 50.

[0023] The position identification method using the data processing device 20 is a position identification method for identifying the position of a utility pole 50 in an optical line facility in which optical fibers 50 are strung across a plurality of utility poles 10, and is characterized in that the state in which vibrations caused by excitation of one of the utility poles 50 propagate through the optical fibers 50 is measured as three-dimensional vibration data of the measurement time, the distance from one end 50a of the optical fibers 50, and the vibration amplitude, and an analysis process is performed on the three-dimensional vibration data to detect a point on the distance axis of the optical fibers 50.

[0024] In this embodiment, the property that vibrations caused by excitation propagate most quickly to the target utility pole 10 is utilized. A specific operation procedure will be described.

[0025] [Step 1] Vibration is applied to the target utility pole 10 (for example, utility pole 10-2). The vibration may be an impulse-type impact vibration. The vibration may be applied by an operator directly hitting the utility pole with a hammer or by a vibrator attached to the utility pole. The vibration may also be applied by remotely operating the vibrator.

[0026] [Step 2] Simultaneously with Step 1, the measurement unit 21 of the data processing device 20 measures the propagation of vibrations due to excitation through the optical fiber 50 to acquire three-dimensional vibration data. The measurement unit 21 is, for example, a distributed acoustic sensor (DAS), which acquires three-dimensional vibration data by irradiating an optical pulse Lp onto one end 50a of the optical fiber 50 and detecting changes in the intensity and phase of the backscattered light Lb. Note that, although a data processing device using backscattered light is used in this embodiment, any measurement principle may be used as long as three-dimensional vibration data can be acquired. Figure 2 is an image diagram of the acquired three-dimensional vibration data. It can be observed that the amplitude of vibration at each point decreases over time.

[0027] 5 is a diagram illustrating the data processing steps performed by the analysis unit 22. [Procedure 3] Three-dimensional vibration data is input to the analysis unit 22 from the measurement unit 21 (step S01). The analysis unit 22 calculates the timing (referred to as T) at which vibration begins to occur at point P on the distance axis from the incident end 50a from the three-dimensional vibration data (step S02). FIG. 3 shows the vibration waveform at point P in FIG. 2. The analysis unit 22 detects the timing T from the waveform. Then, the analysis unit 22 detects the timing T at all points.

[0028] [Procedure 4] The analysis unit 22 creates a graph (see FIG. 4) in which the horizontal axis represents the distance from the entrance end 50a to each point P and the vertical axis represents the time T at each point (step S03).

[0029] [Step 5] The analysis unit 22 finds the point P ０ (Step S04), and point P ０ is set as the position of the target utility pole 10-2 (step S05).

[0030] That is, in this embodiment, the analysis process detects the time when the vibration occurred for each distance, and the point at which the vibration occurred earliest among the distances is set as one point on the distance axis of the optical fiber, and the point is set as the position P of the vibrated utility pole 10. ０ The present invention is characterized in that:

[0031] (Variation of the first embodiment) (v １ If it is possible to estimate the timing at which vibrations begin to occur, the vibrations to be applied may not be impulse-like impact vibrations, but may be appropriately coded. ２ As a pre-processing step for step 3, filtering may be applied in the distance direction or time direction depending on the characteristics of the vibration to remove natural vibrations caused by wind and rain. ３ ) Vibration may be applied multiple times, and the timing T calculated in step 3 may be averaged or the median value may be used to improve accuracy, and then steps 4 and beyond may be performed. ４ ) In step 5, simply select the earliest timing point as P ０ However, the accuracy can be improved by performing appropriate fitting. For fitting, fitting is performed assuming a quadratic function with a minimum value, and the point that gives the minimum value can be set as P. In this case, ax of the quadratic function ２ The three parameters a, b, and c in +bx+c are variables. However, they are constrained to have a minimum value. (v ５ In step 5, fitting may be performed using two straight lines with an intersecting point. The two straight lines have a negative slope in an area closer to the incident end than the intersecting point, and a positive slope in an area farther from the incident end than the intersecting point. Fitting is performed using the two straight lines, and the intersecting point is defined as point P ０ In this case, the four parameters of the coordinates of the intersection and the slope of each line are variables. However, there are constraints on whether the slope is positive or negative. (v ６ ) The steps from step 3 onwards may be changed as follows: The three-dimensional data acquired in step 2 is visually confirmed on a waterfall diagram with the horizontal axis representing the distance from the incident end, the vertical axis representing the measurement time, and the vibration amplitude represented by a color bar, and the point where the excitation vibration arrives earliest is designated as P. ０ If impact vibration is applied multiple times, the average or median value of the distance from the incident end to the point determined for each impact vibration can be used.

[0032] (Embodiment 2) The configuration of this embodiment is the same as the data processing device 20 and the positioning system 301 described in Fig. 1. The positioning method using the data processing device 20 is also a positioning method for identifying the position of a utility pole 50 in an optical line facility in which optical fibers 50 are strung across a plurality of utility poles 10, and is characterized in that the state in which vibration caused by excitation of one of the utility poles 50 propagates through the optical fiber 50 is measured as three-dimensional vibration data of the measurement time, the distance from one end 50a of the optical fiber 50, and the vibration amplitude, and the three-dimensional vibration data is analyzed to detect one point on the distance axis of the optical fiber 50.

[0033] However, in this embodiment, the vibration caused by the excitation propagates from the vibrating utility pole to the left and right, and when it propagates to the utility poles on the left and right of the vibrating utility pole, the vibration suddenly attenuates.

[0034] [Step 1] Vibration is applied to the utility pole 10 (for example, utility pole 10-2) adjacent to the target utility pole 10 (for example, utility pole 10-3). The vibration may be an impulse-type impact vibration. The vibration may be applied by an operator directly hitting the utility pole with a hammer or the like, or by a vibrator attached to the utility pole. The vibration may also be applied by remotely operating the vibrator.

[0035] [Step 2] Simultaneously with Step 1, the measuring unit 21 of the data processing device 20 measures the propagation of vibrations due to excitation through the optical fiber 50 to obtain three-dimensional vibration data. The measuring unit 21 is the same as that described in the first embodiment. The three-dimensional vibration data obtained by the measuring unit 21 is illustrated in the same way as in FIG. 2 .

[0036] 7 is a diagram illustrating the data processing steps performed by the analysis unit 22. [Procedure 3] The analysis unit 22 receives three-dimensional vibration data from the measurement unit 21 (step S11). The analysis unit 22 calculates the vibration intensity (denoted as I) at each point on the distance axis from the incident end 50a from the three-dimensional vibration data (step S12). For example, the vibration intensity I may be the sum of the absolute values ​​of the amplitudes over the time the vibrations are sustained.

[0037] [Step 4] The analysis unit 22 creates a graph (see FIG. 6) in which the horizontal axis represents the distance from the incident end 50a and the vertical axis represents the vibration intensity I at each point (step S13).

[0038] [Step 5] The analysis unit 22 determines the point P ０ (Step S14), and point P ０ The analysis unit 22 determines the point where the attenuation of the vibration intensity I is maximum as the point P ０ The analysis unit 22 may also calculate the attenuation rate of the vibration intensity I and determine the point at which the attenuation rate is maximum as the point P ０ It may also be possible to use the following.

[0039] That is, in this embodiment, the analysis process detects the intensity of the vibration for each distance, and the point at which the attenuation of the intensity of the vibration is greatest within the distance is set as one point on the distance axis of the optical fiber, and this point is set as the position P ０ The present invention is characterized in that:

[0040] (Variation of the second embodiment) １ If it is possible to detect whether or not vibration is propagating at each point, the vibration to be applied may be appropriately coded. ２ As a pre-processing step for step 3, filtering may be applied in the distance direction or time direction depending on the characteristics of the vibration to remove natural vibrations caused by wind and rain. ３ ) Vibration may be applied multiple times, and the vibration intensity I calculated in step 3 each time may be averaged or the median value may be used to improve accuracy, and then steps 4 and beyond may be performed. ４ ) Information other than intensity may be used to determine how far the vibration propagates. For example, a method such as visual confirmation on a waterfall diagram with the horizontal axis representing the distance from the incident end, the vertical axis representing the measurement time, and the vibration amplitude represented by a color bar may be used. ５) The pole position estimated by striking a pole farther from the target pole and the pole position estimated by striking a pole closer to the target pole may be combined. For example, the average of the two estimated values ​​may be used as the final pole position.

[0041] (Embodiment 3) The position of a utility pole may be identified by combining the position identification method described in embodiment 1 and the position identification method described in embodiment 2. For example, when it is difficult to determine the position of a utility pole using the position identification method described in embodiment 1, the position identification method described in embodiment 2 can be implemented.

[0042] <Specific Procedure> [Task 1] A target utility pole is struck and the position identification method described in embodiment 1 is implemented. If this method fails to accurately identify the utility pole position, the next task is implemented. [Task 2] A utility pole one step ahead of the target utility pole is struck and the position identification method described in embodiment 2 is implemented. If this method fails to accurately identify the utility pole position, the next task is implemented. [Task 3] A utility pole one step behind the target utility pole is struck and the position identification method described in embodiment 2 is implemented.

[0043] Note that the position identification method described in embodiment 2 may be tried first, and then the position identification method described in embodiment 1 may be implemented. Alternatively, the order of hitting may be such that the utility pole immediately before the target utility pole is hit and the position identification method described in embodiment 2 is implemented, the target utility pole is hit and the position identification method described in embodiment 2 is implemented, and the utility pole immediately behind the target utility pole is hit and the position identification method described in embodiment 2 is implemented, and so on, starting from the nearest utility pole. In other words, the order in which the utility poles are hit can be changed according to the convenience of the worker. It is also possible to improve accuracy by averaging the utility pole positions estimated by these three actions.

[0044] 10, 10-1, 10-2, 10-3, 10-4, ...: utility poles 20: data processing device 21: measurement unit 22: analysis unit 50: optical fiber 301: position identification system

Claims

1. A method for locating the position of a plurality of utility poles in an optical fiber line facility in which optical fibers are strung across the utility poles, the method comprising: measuring the state in which vibrations caused by excitation of one of the utility poles propagate through the optical fiber as three-dimensional vibration data of the measurement time, distance from one end of the optical fiber, and vibration amplitude; and analyzing the three-dimensional vibration data to detect a point on the distance axis of the optical fiber.

2. The method of determining a location according to claim 1, characterized in that the analysis process detects the time when the vibration occurred for each distance, and the point at which the vibration occurred earliest among the distances is designated as one point on the distance axis of the optical fiber, and this point is designated as the position of the vibrated utility pole.

3. The method of determining a location according to claim 1, characterized in that the analysis process detects the strength of the vibration for each distance, and the point on the distance axis of the optical fiber at which the attenuation of the strength of the vibration is greatest within the distance is taken as one point, and this point is taken as the position of the utility pole next to the vibrated utility pole.

4. A data processing device for identifying the position of a plurality of utility poles in an optical fiber line facility in which optical fibers are strung across the utility poles, comprising: a measurement unit that measures the state in which vibrations caused by excitation of one of the utility poles propagate through the optical fiber as three-dimensional vibration data of the measurement time, distance from one end of the optical fiber, and vibration amplitude; and an analysis unit that performs analysis processing on the three-dimensional vibration data and detects a point on the distance axis of the optical fiber.

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