Bending state estimation device, bending state estimation method, and program
Patent Information
- Application Number
- JP2021186947
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-11-17
- Publication Date
- 2025-06-02
- Estimated Expiration
- 2041-11-17
AI Technical Summary
Existing methods, such as the OTDR, only estimate the presence or absence of bending in optical fiber transmission lines but fail to provide quantitative information about the bending state.
A system that measures bending loss using multiple wavelengths, calculates the ratio of bending losses, and estimates the bending curvature and angle based on the relationship between these losses and the curvature, utilizing a curvature estimation unit and a bending angle estimation unit.
Enables the estimation of quantitative information about the bending state of optical fiber transmission lines, including curvature and angle, improving accuracy and reliability in assessing potential damage.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a bending state estimation device, a bending state estimation method, and a program.
Background Art
[0002] Bending occurring in the transmission path of an optical fiber may lead to deterioration of communication quality and damage or disconnection of the optical fiber. Therefore, grasping the bending state and position of the optical fiber is important in the inspection of optical communication equipment. For example, in Non-Patent Document 1, in order to grasp the bending state and position of an optical fiber, an OTDR (optical time-domain reflectometer) that can measure the loss of the transmission path using a plurality of different wavelengths is used, and when the difference in losses corresponding to different wavelengths is 10 dB or more, it is described that it is determined that bending has occurred in the transmission path.
Prior Art Documents
Non-Patent Documents
[0003]
Non-Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, the invention described in Non-Patent Document 1 only estimates the presence or absence of bending, and cannot estimate a quantitative value regarding bending. An object of the present invention is to provide a bending state estimation device that estimates quantitative information regarding bending of a transmission path.
Means for Solving the Problems
[0005] One aspect of the present invention is a bending state estimation device comprising: bending loss caused by bending of a transmission line measured using two or more light of different wavelengths; and a curvature estimation unit that estimates the curvature of the bending of a transmission line based on the relationship between the ratio of bending losses corresponding to different wavelengths and the curvature of the bending of the transmission line.
[0006] One aspect of the present invention is a bending state estimation method comprising: a bending loss caused by bending of a transmission line measured using two or more light sources of different wavelengths; and a curvature estimation step of estimating the curvature of the bending of a transmission line based on the relationship between the ratio of bending losses corresponding to different wavelengths and the curvature of the bending of the transmission line. [Effects of the Invention]
[0007] According to the present invention, quantitative information regarding the bending of the transmission line can be estimated. [Brief explanation of the drawing]
[0008] [Figure 1] This figure shows the configuration of the bending state estimation system according to the first embodiment. [Figure 2A] This figure shows the measurement results from a loss measuring device when there is no bending in the transmission line. [Figure 2B] This figure shows the measurement results from a loss measuring device when bending occurs in the transmission line. [Figure 3] This figure shows the configuration of the bending state estimation device according to the first embodiment. [Figure 4] This is an example of a table stored in the loss ratio curvature relationship storage unit according to the first embodiment. [Figure 5] This is an example of a table stored in the loss coefficient storage unit according to the first embodiment. [Figure 6] This is a flowchart showing the operation of the bending state estimation device according to the first embodiment. [Figure 7] This is an example of a table stored by the loss ratio curvature relationship storage unit according to the second embodiment. [Figure 8] This figure shows a bending state estimation device according to the third embodiment. [Figure 9] This is a flowchart showing an example of the operation of the bending state estimation device according to the third embodiment. [Modes for carrying out the invention]
[0009] Embodiments of the present invention will be described in detail below with reference to the drawings.
[0010] <First Embodiment> Figure 1 shows the configuration of the bending state estimation system 1 according to the first embodiment. The bending state estimation system 1 comprises a transmission line 11, a loss measuring device 12, a bending state estimation device 13, and a display device 14.
[0011] The transmission line 11 is, for example, an optical fiber and transmits optical signals. The transmission loss of the transmission line 11 is measured by a loss measuring device 12, and the bending state is estimated by a bending state estimation device 13.
[0012] The loss measuring device 12 measures the transmission loss of the transmission line 11 using light. The loss measuring device 12 is, for example, an OTDR, which sends pulsed light into the transmission line 11 and measures the light that is backscattered from the transmitted light and returns to the transmission line to measure the transmission loss of the transmission line 11. FIG. 2A is a diagram showing the measurement result by the loss measurement device 12 when no bending occurs in the transmission line. FIG. 2B is a diagram showing the measurement result by the loss measurement device 12 when bending occurs in the transmission line. In FIG. 2A, the pulse intensity of the reflected light measured by the loss measurement device 12 decreases linearly as the position of reflection is farther from the loss measurement device 12. However, in FIG. 2B, the pulse intensity of the reflected light measured by the loss measurement device 12 decreases sharply at the position where bending occurs because the reflected light from beyond that position decreases, and a step is confirmed. The difference between the magnitude of the pulse intensity before it decreases sharply and the magnitude of the pulse intensity after it decreases sharply is called the "bending loss". The loss measurement device 12 determines that the pulse intensity has decreased sharply when, for example, the rate of decrease of the reflected light pulse intensity with respect to the distance from the loss measurement device 12 is greater than or equal to a predetermined value.
[0013] The loss measurement device 12 can measure the bending loss of the transmission line 11 by sending light of different wavelengths. The bending loss measured by the loss measurement device 12 varies depending on the wavelength of the light sent. This is because the propagation characteristics of light change with wavelength, and generally, the bending loss increases as the wavelength becomes longer.
[0014] The bending loss measured by the loss measurement device 12 depends on the curvature and angle of the bending that occurs in the transmission line 11. The bending loss has a linear relationship with the bending angle. The bending loss can be expressed by Equation (1).
[0015]
Equation
[0016] Here, L is the bending loss. k is the loss coefficient, which is a number determined by the wavelength of the light sent by the loss measurement device 12 and the curvature of the bending that occurs in the transmission line 11. θ is the angle of the bending that occurs in the transmission line 11.
[0017] The bending state estimation device 13 estimates the bending state in the transmission line 11 based on the measurement results from the loss measurement device 12.
[0018] The display device 14 displays values related to the bending state based on the output from the bending state estimation device 13.
[0019] Figure 3 shows the configuration of the bending state estimation device 13 according to the first embodiment. The bending state estimation device 13 includes a transmission loss acquisition unit 130, a loss ratio calculation unit 131, a curvature estimation unit 132, a loss ratio-curvature relationship storage unit 133, a bending angle estimation unit 134, a loss coefficient storage unit 135, and an output unit 136.
[0020] The transmission loss acquisition unit 130 acquires data indicating the bending loss measured by the loss measuring device 12.
[0021] The loss ratio calculation unit 131 calculates the ratio of bending losses for two wavelengths (loss ratio) based on the bending losses measured for each wavelength of light emitted by the loss measuring device 12. For example, the loss ratio calculated by the loss ratio calculation unit 131 is expressed by equation (2).
[0022]
number
[0023] Here, α is the loss ratio, L1 is the bending loss corresponding to the wavelength λ1 of the light emitted by the loss measuring device 12, and L2 is the bending loss corresponding to the wavelength λ2 of the light emitted by the loss measuring device 12. When the bending losses L1 and L2 follow equation (1), the loss ratio α is a number that depends on the loss coefficient and does not depend on the bending angle. In other words, if the wavelengths λ1 and λ2 are fixed, there is a one-to-one relationship between the loss ratio and the curvature of the bending. Wavelengths λ1 and λ2 are, for example, the wavelengths of optical pulses that a typical OTDR can emit, for example, λ1 is 1310 nm and λ2 is 1550 nm.
[0024] The curvature estimation unit 132 estimates the curvature of the bend occurring in the transmission line 11 based on the loss ratio calculated by the loss ratio calculation unit 131 and the relationship between the loss ratio and curvature stored in the loss ratio-curvature relationship storage unit 133. The relationship between the loss ratio and curvature is, for example, the relationship formula between the loss ratio and curvature, and is the relationship formula between the loss ratio and curvature when the wavelengths of the light emitted by the loss measuring device 12 are λ1 and λ2. The relationship formula stored in the loss ratio-curvature relationship storage unit 133 is a formula created by measuring the loss ratio by changing the curvature of the bend occurring in the transmission line using a device that can measure the transmission loss of the transmission line by emitting light of the same wavelength as the light emitted by the loss measuring device 12, and a transmission line that exhibits the same transmission loss as the transmission line 11, and applying a method such as the least squares method. Since the loss ratio is not an angle-dependent value, the bending angle does not need to be kept constant when changing the curvature of the bend occurring in the transmission line. The curvature estimation unit 132 estimates the curvature by substituting the loss ratio calculated by the loss ratio calculation unit 131 into the relationship formula between the loss ratio and curvature.
[0025] The relationship between the loss ratio and curvature may be represented by a table showing the relationship between the loss ratio and curvature. Figure 4 is an example of a table stored in the loss ratio-curvature relationship storage unit 133 according to the first embodiment. The table shown in Figure 4 is created by measuring the loss ratio by changing the curvature of the bend occurring in the transmission line using a device equivalent to the loss measuring device 12 and a transmission line equivalent to the transmission line 11.
[0026] The curvature estimation unit 132 may find the loss ratio value closest to the loss ratio calculated by the loss ratio calculation unit 131 from the table stored in the loss ratio-curvature relationship storage unit 133, and estimate the curvature corresponding to the found loss ratio as the curvature of the bend occurring in the transmission line 11.
[0027] The bending angle estimation unit 134 estimates the bending angle based on the bending loss measured by the loss measuring device 12, the curvature of the bending estimated by the curvature estimation unit 132, and the relationship between curvature and the loss coefficient stored in the loss coefficient storage unit 135. The relationship between curvature and the loss coefficient is, for example, a relationship formula between curvature and the loss coefficient, which is the relationship formula between curvature and the loss coefficient when the wavelength of the light transmitted by the loss measuring device 12 is λ1. The relationship formula stored in the loss coefficient storage unit 135 is a formula created by measuring the bending loss and bending angle using a device equivalent to the loss measuring device 12 and a transmission line equivalent to the transmission line 11, setting the wavelength of the transmitted light to λ1 and changing the curvature of the bending occurring in the transmission line, and applying a method such as the least squares method. The bending angle estimation unit 134 estimates the loss coefficient by substituting the curvature of the bending estimated by the curvature estimation unit 132 into the relationship formula between curvature and the loss coefficient. Subsequently, the bending angle estimation unit 134 substitutes the estimated loss coefficient and the bending loss measured by the loss measuring device 12 into equation (1) to estimate the bending angle.
[0028] The output unit 136 outputs data to the display device 14 showing the curvature of the bend estimated by the curvature estimation unit 132 and the bending angle estimated by the bending angle estimation unit 134.
[0029] The relationship between curvature and loss coefficient may be represented by a table showing the relationship between curvature and loss coefficient. Figure 5 is an example of a table stored in the loss coefficient storage unit 135 according to the first embodiment. The table shown in Figure 5 shows the relationship between bending curvature and loss coefficient when the wavelength of the light transmitted by the loss measuring device 12 is λ1. The table shown in Figure 5 was created by measuring bending loss and bending angle using a device equivalent to the loss measuring device 12 and a transmission line equivalent to the transmission line 11, setting the wavelength of the transmitted light to λ1 and changing the curvature of the bending that occurs in the transmission line.
[0030] The bending angle estimation unit 134 may estimate the loss coefficient by finding the value of curvature closest to the curvature estimated by the curvature estimation unit 132 from a table stored in the loss coefficient storage unit 135.
[0031] Figure 6 is a flowchart showing the operation of the bending state estimation device 13 according to the first embodiment. The transmission loss acquisition unit 130 acquires data indicating the bending loss measured by the loss measuring device 12 (step S10). The loss ratio calculation unit 131 calculates the loss ratio, which is the ratio of the bending losses measured separately according to the wavelength of the light transmitted by the loss measuring device 12 (step S11). The curvature estimation unit 132 estimates the curvature of the bending occurring in the transmission line 11 based on the loss ratio calculated by the loss ratio calculation unit 131 and the relationship between the loss ratio and curvature stored in the loss ratio-curvature relationship storage unit 133 (step S12). The bending angle estimation unit 134 estimates the bending angle based on the bending loss measured by the loss measuring device 12, the bending curvature estimated by the curvature estimation unit 132, and the relationship between curvature and loss coefficient stored in the loss coefficient storage unit 135 (step S14). The output unit 136 outputs the bending curvature and bending angle as estimation results to the display device 14 (step S16).
[0032] The bending state estimation device 13, with the above configuration, can estimate the curvature and bending angle of the transmission line, that is, quantitative values related to bending.
[0033] <Second Embodiment> The loss measuring device 12 according to the second embodiment measures the bending loss of the transmission line 11 using light of three different wavelengths. In other words, the loss measuring device 12 according to the second embodiment measures three different bending losses depending on the wavelength of light used.
[0034] The loss ratio calculation unit 131 according to the second embodiment calculates two loss ratios based on three losses measured by the loss measuring device 12. For example, the loss ratio calculation unit 131 according to the second embodiment calculates the ratio of the bending loss corresponding to wavelength λ1 to the bending loss corresponding to wavelength λ2, and further calculates the ratio of the bending loss corresponding to wavelength λ1 to the bending loss corresponding to wavelength λ3.
[0035] The curvature estimation unit 132 according to the second embodiment estimates two curvatures based on two loss ratios calculated by the loss ratio calculation unit 131. The loss ratio-curvature relationship storage unit 133 according to the second embodiment stores different relational formulas or tables depending on which wavelength the loss ratio corresponds to the bending loss. Figure 7 is an example of a table stored by the loss ratio-curvature relationship storage unit 133 according to the second embodiment. The loss ratio-curvature relationship storage unit 133 according to the second embodiment stores relational formulas or tables showing the relationship between the loss ratio and curvature when the loss ratio is the ratio of the bending loss corresponding to wavelength λ1 to the bending loss corresponding to wavelength λ2, and further stores relational formulas or tables showing the relationship between the loss ratio and curvature when the loss ratio is the ratio of the bending loss corresponding to wavelength λ1 to the bending loss corresponding to wavelength λ3. The curvature estimated based on the relational formulas or tables stored in the loss ratio-curvature relationship storage unit 133 is called a curvature sample.
[0036] The curvature estimation unit 132 further estimates the curvature based on the curvature samples. For example, the curvature estimation unit 132 determines the mean of two curvature samples as the final estimated curvature.
[0037] The bending state estimation device 13 according to the second embodiment calculates two loss ratios based on three bending losses measured using three wavelengths, estimates two curvature samples, and finally determines the curvature to be estimated based on the two curvature samples. As a result, the bending state estimation device 13 according to the second embodiment can improve the accuracy of the estimated curvature.
[0038] The loss ratio calculation unit 131 is not limited to two loss ratios; it may calculate three or more. In this case, the loss measuring device 12 measures three or more losses. The loss ratio curvature relationship storage unit 133 stores a table of wavelengths corresponding to the loss ratios calculated by the loss ratio calculation unit 131, and the curvature estimation unit 132 may estimate the same number of curvature samples as the loss ratios calculated by the loss ratio calculation unit 131 and determine the final estimated curvature based on the multiple curvature samples.
[0039] <Third Embodiment> Figure 8 shows a bending state estimation device 13 according to the third embodiment. The bending state estimation device 13 according to the third embodiment includes a bending presence / absence estimation unit 137 in addition to the bending state estimation device 13 according to the first embodiment. The bending presence / absence estimation unit 137 estimates whether or not there is a bend in the transmission line 11 based on the loss ratio calculated by the loss ratio calculation unit 131.
[0040] The bending state estimation device 13 according to the third embodiment estimates that there is no bending in the transmission line 11 and that the resulting loss is due to another factor when the loss ratio calculated by the loss ratio calculation unit 131 is not within a specified range. The lower limit of the specified range is, for example, the loss ratio when the difference between two losses measured by the loss measuring device 12 is the smallest loss difference (e.g., 10 dB) that can estimate the bending of the transmission line. The upper limit of the specified range is, for example, the loss ratio at an acceptable curvature of the transmission line 11 (the limit of curvature at which the transmission line 11 will not be damaged due to bending).
[0041] When the bending presence / absence estimation unit 137 estimates that there is no bending in the transmission line 11, the curvature estimation unit 132 does not need to estimate the curvature, and the bending angle estimation unit 134 does not need to estimate the bending angle.
[0042] Figure 9 is a flowchart showing an example of the operation of the bending state estimation device 13 according to the third embodiment. The transmission loss acquisition unit 130 acquires data indicating bending loss (step S30). The loss ratio calculation unit 131 calculates the loss ratio (step S31). The bending presence / absence estimation unit 137 estimates whether or not there is a bend in the transmission line 11 based on the loss ratio calculated by the loss ratio calculation unit 131 (step S32). Subsequently, if the bending presence / absence estimation unit 137 estimates that there is a bend in the transmission line 11 (step S34: YES), the curvature estimation unit 132 estimates the curvature (step S36), and the bending angle estimation unit 134 estimates the bending angle (step S38). The output unit 136 outputs the curvature and bending angle of the bend as estimation results (step S40), and the operation ends. If the bending presence estimation unit 137 estimates that there is no bending in the transmission line 11 (step S34: NO), the output unit 136 outputs that there is no bending as the estimation result (step S40), and the operation ends.
[0043] In the third embodiment, the bending state estimation device 13 has a bending presence / absence estimation unit 137 that estimates whether or not there is a bend in the transmission line 11. This allows the bending state estimation device 13 to avoid estimating the bending state based on losses due to factors other than bending, such as losses due to wavelength-dependent devices such as optical filters.
[0044] <Other Embodiments> Although one embodiment of this invention has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the spirit of this invention.
[0045] The bending state estimation device 13 in the above-described embodiment may be implemented using a computer. In that case, the program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. Here, "computer system" includes hardware such as an OS and peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, and storage devices such as hard disks built into a computer system. Moreover, "computer-readable recording medium" may also include those that dynamically hold programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and those that hold programs for a certain period of time, such as volatile memory inside a computer system that acts as a server or client in such cases. Furthermore, the above-mentioned program may be for realizing a part of the above-mentioned function, or it may be a program that can realize the above-mentioned function in combination with a program already recorded in the computer system, or it may be implemented using a programmable logic device such as an FPGA (Field Programmable Gate Array). [Explanation of Symbols]
[0046] 1 Bending state estimation system, 11 Transmission line, 12 Loss measuring device, 13 Bending state estimation device, 14 Display device, 130 Transmission loss acquisition unit, 131 Loss ratio calculation unit, 132 Curvature estimation unit, 133 Loss ratio-curvature relationship storage unit, 134 Bending angle estimation unit, 135 Loss coefficient storage unit, 136 Output unit, 137 Bending presence / absence estimation unit
Claims
1. a curvature estimation unit that estimates the curvature of the bending of the transmission line based on a bending loss caused by bending of the transmission line measured using two or more lights with different wavelengths, a ratio of the bending losses corresponding to the different wavelengths, and a relationship between the curvature of the bending of the transmission line; A bending state estimation device comprising:
2. a loss ratio calculation unit that calculates a loss ratio indicating a ratio of bending losses for each wavelength based on bending losses caused by bending of the transmission line measured using two or more lights having different wavelengths; Furthermore, The curvature estimation unit estimates the curvature of the bend of the transmission line based on the relationship between the loss ratio and the curvature of the bend of the transmission line. The bending state estimation device according to claim 1 .
3. a bending angle estimating unit that estimates the bending angle based on the bending loss, the curvature estimated by the curvature estimating unit, and a loss coefficient that indicates the bending loss per bending angle at the bending curvature and the bending curvature; Further provided with The bending state estimation device according to claim 2 .
4. the loss ratio calculation unit calculates a plurality of loss ratios based on a combination of losses associated with different wavelengths from the bending losses measured using light of three or more different wavelengths; The curvature estimation unit estimates a plurality of curvature samples related to the curvature based on the plurality of loss ratios, and estimates the curvature based on the plurality of curvature samples. The bending state estimation device according to claim 2 or 3.
5. a bend presence / absence estimation unit that estimates whether or not there is a bend in the transmission line based on the loss ratio calculated by the loss ratio calculation unit; The bending state estimation device according to claim 2 , further comprising:
6. a curvature estimation step of estimating the curvature of the bending of the transmission line based on a bending loss caused by bending of the transmission line measured using two or more lights having different wavelengths, and a relationship between a ratio of the bending losses corresponding to the different wavelengths and the curvature of the bending of the transmission line; A bending state estimation method comprising:
7. A program for causing a computer to function as the bending state estimation device according to any one of claims 1 to 5.