Optical Fiber Real-Space Distribution Calculation System, Real-Space Distribution Calculation Method, and Program

Abstract

This optical fiber real space distribution calculation system comprises: a propagated signal outputting means for outputting a propagated signal that propagates contactlessly through a vibrating medium to an optical fiber in which a plurality of measurement points have been set at prescribed length segments; a reception time difference calculating means for calculating a reception time difference for the propagated signal from the propagated signal outputting means between adjacent measurement points; a coordinate information acquiring means for acquiring coordinates of a measurement point of the optical fiber and coordinates of the propagated signal outputting means; and a measurement point calculating means for calculating the coordinates of each of the measurement points on the optical fiber by recurrently repeating calculation on the basis of the reception time difference for the propagated signal calculated by the reception time difference calculating means, the intersection between a circle centered on the coordinates of the measurement point with a radius equal to the distance between the prescribed length segments and a circle centered on the coordinates of the propagated signal outputting means being the next measurement point on the optical fiber adjacent to the measurement point.

Description

Technical Field

[0001] The present invention relates to a system for calculating the in-space distribution of an optical fiber, a method for calculating the in-space distribution, and a computer-readable medium, which calculate the distribution of the optical fiber in the actual space.

Background Art

[0002] A system for calculating the in-space distribution of an optical fiber that calculates the distribution of the optical fiber in the actual space is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above system, since the linearity of the optical fiber is not considered, it has been difficult to accurately obtain the distribution of an optical fiber with high linearity.

[0005] An object of the present disclosure is to provide a system for calculating the in-space distribution of an optical fiber, a method for calculating the in-space distribution, and a computer-readable medium that solve the above-described problems.

Means for Solving the Problems

[0006] One aspect of the present invention for achieving the above object is propagation signal output means for outputting a propagation signal that propagates non-contact via a vibration medium to an optical fiber in which a plurality of measurement points are set for each predetermined length section; reception time difference calculation means for calculating a reception time difference of the propagation signal from the propagation signal output means between adjacent measurement points; Coordinate information acquisition means for acquiring the coordinates of the measurement points on the optical fiber and the coordinates of the propagation signal output means; Calculating the intersection points of a circle centered on the coordinates of the measurement point with the distance of the predetermined length interval as the radius and a circle centered on the coordinates of the propagation signal output means, and gradually repeating the calculation based on the reception time difference of the propagation signal calculated by the reception time difference calculation means to calculate the coordinates of each measurement point on the optical fiber. The measurement point calculation means for calculating; Comprising; Real-space distribution calculation system for optical fiber It is. One aspect of the present invention for achieving the above object is For an optical fiber in which a plurality of measurement points are set for each predetermined length interval, obtaining the coordinates of the propagation signal output means that outputs a propagation signal that propagates non-contact via a vibration medium and the coordinates of the measurement points on the optical fiber; Calculating the intersection points of a circle centered on the coordinates of the measurement point with the distance of the predetermined length interval as the radius and a circle centered on the coordinates of the propagation signal output means, and gradually repeating the calculation based on the reception time difference of the propagation signal from the propagation signal output means between the measurement point and the next measurement point to calculate the coordinates of each measurement point on the optical fiber. Steps; Including; Real-space distribution calculation method for optical fiber It is. One aspect of the present invention for achieving the above object is For an optical fiber in which a plurality of measurement points are set for each predetermined length interval, a process of obtaining the coordinates of the propagation signal output means that outputs a propagation signal that propagates non-contact via a vibration medium and the coordinates of the measurement points on the optical fiber; By gradually repeating the process of calculating the coordinates of each measurement point on the optical fiber by using, as the radius, the distance of the predetermined length interval and centering on the coordinates of the measurement point, the intersection of the circle centered on the coordinates of the measurement point and the circle centered on the coordinates of the propagation signal output means, and calculating based on the reception time difference of the propagation signal from the propagation signal output means between the measurement point and the next measurement point, as the next measurement point on the optical fiber adjacent to the measurement point, Causing a computer to execute A non-transitory computer-readable medium storing a program is provided.

Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a system for calculating the real-space distribution of an optical fiber, a method for calculating the real-space distribution, and a computer-readable medium that solve the above-described problems.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 10

Figure 11

Mode for Carrying Out the Invention

[0009] Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an optical fiber according to this embodiment. The real-space distribution calculation system of the optical fiber according to this embodiment calculates the distribution in the real space of the optical fiber 1.

[0010] In the optical fiber 1, a plurality of measurement points are set for each predetermined length interval (gauge length interval). Time synchronization is completed between adjacent measurement points. Therefore, adjacent measurement points can be regarded as adjacent acoustic sensors that are synchronized.

[0011] At the end of the optical fiber 1, an optical fiber sensor 2 is provided. The optical fiber sensor 2 measures the strain ΔL of the optical fiber 1 through the phase difference Δφ of the backscattered light in the gauge length interval. The optical fiber 1 operates as an independent vibration / acoustic sensor in each gauge length interval.

[0012] From the relationship between the acoustic signal detected on the optical fiber 1 and the real-space distribution information of the optical fiber 1, for example, the position and direction of a vibration source such as a drone can be estimated. Here, although vibration can be detected in an arbitrary section on the optical fiber 1 by optical fiber sensing, as described above, in order to estimate the position and direction of the vibration source in the real space, the real-space distribution of the optical fiber 1 is required. The real-space distribution calculation system according to this embodiment calculates the real-space distribution of the optical fiber 1 as follows.

[0013] FIG. 2 is a block diagram showing a schematic system configuration of the real-space distribution calculation system according to the present embodiment. The real-space distribution calculation system 10 according to the present embodiment calculates each measurement point on the optical fiber 1 and calculates the real-space distribution of the optical fiber 1 as described later.

[0014] Note that the real-space distribution calculation system 10 has a hardware configuration of a normal computer including, for example, a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), an internal memory such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), an input / output I / F for connecting peripheral devices such as a display, and a communication I / F for communicating with devices outside the apparatus.

[0015] The real-space distribution calculation system 10 according to the present embodiment includes a propagation signal output unit 11 that outputs a propagation signal, a reception time difference calculation unit 12 that calculates a reception time difference of the propagation signal, a coordinate information acquisition unit 13 that acquires coordinate information, and a measurement point calculation unit 14 that calculates the coordinates of each measurement point on the optical fiber 1. The real-space distribution calculation system 10 calculates the real-space distribution of the optical fiber 1 based on the reception time difference of the propagation signal from the propagation signal output unit 11 between the measurement points on the optical fiber 1.

[0016] The propagation signal output unit 11 is a specific example of the propagation signal output means. The propagation signal output unit 11 outputs a propagation signal that propagates non-contact with respect to the optical fiber 1 via a vibrating medium. For example, two propagation signal output units 11 are provided at arbitrary positions.

[0017] The propagation signal is a signal that has little attenuation during the propagation process and propagates over a wide area with respect to the optical fiber 1, and is a signal in which a arrival time difference of the signal due to the difference in the distance from the signal source to the signal measurement point occurs.

[0018] By using the characteristics of the propagation signal as described above, as will be described later, the real-space distribution of the wide-range optical fiber 1 can be obtained non-contact with respect to the optical fiber 1. Further, when the propagation speed of the propagation signal is high, the real-space distribution of the optical fiber 1 can be obtained in a short time. Therefore, for example, the distribution of the optical fiber 1 laid in a difficult-to-access place such as the seabed can be easily obtained.

[0019] The propagation signal is, for example, sound propagating in the air, seismic waves propagating on the ground, etc. The propagation signal is preferably a burst sound (for example, the sound of a balloon bursting) that spreads over a wide band with a large sound pressure. This is because the sampling frequency of the optical fiber sensor 2 is inversely proportional to the total length of the optical fiber 1.

[0020] When using a narrow-band propagation signal, it is preferable to select so as to satisfy the measurement point interval > wavelength of sound wave / 2. This is because it becomes easy to evaluate the reception time difference (TDOA: Time Difference Of Arrival) between each measurement point.

[0021] The reception time difference calculation unit 12 is a specific example of the reception time difference calculation means. The reception time difference calculation unit 12 calculates the reception time difference of the propagation signal from the propagation signal output unit 11 between adjacent measurement points.

[0022] The optical fiber sensor 2 outputs an optical signal to the optical fiber 1 at a predetermined cycle, for example, and receives the reflected signal. The reception time difference calculation unit 12 calculates the reception time when each measurement point on the optical fiber 1 receives the propagation signal based on the reflected signal received by the optical fiber sensor 2. Then, the reception time difference calculation unit 12 calculates the reception time difference between adjacent measurement points, thereby calculating the reception time difference of the propagation signal between each of the above-described measurement points. Here, the reception time difference calculation unit 12 may store the calculated reception time difference of the propagation signal between each measurement point in the internal memory or the like.

[0023] The coordinate information acquisition unit 13 is a specific example of the coordinate information acquisition means. The coordinate information acquisition unit 13 acquires the coordinates of one measurement point on the optical fiber 1 and the coordinates of the two propagation signal output units 11. As the coordinates of one measurement point on the optical fiber 1, the coordinate information acquisition unit 13 acquires, for example, the coordinates of the optical fiber sensor 2 connected to the end of the optical fiber 1. These coordinates may be input to the coordinate information acquisition unit 13 via, for example, an input device, or may be set in advance in an internal memory or the like.

[0024] Incidentally, since the optical fiber 1 is distributed one-dimensionally and cannot be bent, it has a highly linear property. Therefore, based on the coordinates of a certain measurement point on the optical fiber 1, the coordinates of the next measurement point adjacent to that measurement point can be easily obtained.

[0025] In the present embodiment, paying attention to the characteristics of the optical fiber 1 described above, as shown in FIG. 3, the measurement point calculation unit 14 uses the distance d of a predetermined length interval as the radius and the coordinates (x0, y0) of the measurement point as the center, and the coordinates of the two propagation signal output units 11 as the centers of the two circles, and calculates the intersection points of the two circles as the next measurement point (x1, y1) on the optical fiber 1 adjacent to the measurement point (x0, y0). By gradually repeating the calculation based on the reception time difference of the propagation signals from the propagation signal output unit 11 between the measurement point (x0, y0) and the next measurement point (x1, y1), the coordinates of each measurement point on the optical fiber 1 are calculated.

[0026] In this way, by considering the linearity of the optical fiber 1 and gradually obtaining the coordinates of adjacent measurement points from the coordinates of known measurement points, the distribution of the highly linear optical fiber 1 can be obtained with high accuracy.

[0027] Here, the method for calculating the coordinates of each measurement point on the optical fiber 1 described above will be described more specifically. FIG. 4 is a flowchart showing the flow of the method for calculating the coordinates of each measurement point on the optical fiber 1 described above.

[0028] The distance d between adjacent measurement points (predetermined length interval) of the optical fiber 1 is assumed to be a straight line. Let the coordinates of the measurement points of the optical fiber 1 be (xi , y i (i = 0, 1, 2, 3, ···). Let the coordinates of the two propagation signal output units 11 be (x α s , y α s )(α = 1, 2). Each propagation signal output unit 11 outputs a propagation signal to each measurement point on the optical fiber 1 (step S101).

[0029] The measurement point calculation unit 14 is a specific example of the measurement point calculation means. The measurement point calculation unit 14 calculates geometrically the intersection points of a circle with a radius of the distance d of a predetermined length interval centered on the coordinates (x0, y0) of the measurement point and two circles centered on the coordinates (x α and, y α s , y α s ) of each propagation signal output unit 11 (Figure 3).

[0030] Here, r α = r 0α + ct 1、0、α and, r iα is the distance from the origin (x i , y i ) to each propagation signal output unit 11. Let t i、i-1、α be the reception time difference between the measurement point i and the measurement point i - 1 in the propagation signal from each propagation signal output unit 11. Let c be the signal propagation speed.

[0031] Specifically, the measurement point calculation unit 14 calculates the straight lines L1 and L2 connecting the two intersection points of a circle with a radius of the distance d of a predetermined length interval centered on the coordinates (x0, y0) of the measurement point and two circles centered on the coordinates (x α and, y α s , y α s ) of each propagation signal output unit 11, respectively (step S102). Note that r α = {(x0 - x α s ) 2 + (y0 - y α s ) 2 )}1 / 2 +ct 1、0、α be set as

[0032] The measurement point calculation unit 14 calculates the coordinates of the intersection of the two straight lines L1 and L2. The measurement point calculation unit 14 sets the calculated coordinates of the intersection as the radius d, and uses the circle centered on the coordinates (x0, y0) of the measurement point and the radius r α and sets the coordinates (x α s , y α s ) of each propagation signal output unit 11 as the centers respectively, and estimates the intersection as the intersection of two circles. The measurement point calculation unit 14 sets the estimated coordinates as the coordinates (x1, y1) of the next measurement point (step S103).

[0033] The measurement point calculation unit 14 replaces (x0, y0) with (x1, y1), and gradually repeats the above-described process until the distribution of the measurement points on the optical fiber 1 is obtained (step S104). Note that r is also updated simultaneously with the update of (x0, y0). That is, the measurement point calculation unit 14 gradually calculates (x1, y1), (x2, y2), (x3, y3),... using the above-described calculation method based on the coordinates (x0, y0) of the known measurement points acquired by the coordinate information acquisition unit 13. 0α is also updated. That is, the measurement point calculation unit 14 gradually calculates (x1, y1), (x2, y2), (x3, y3),... using the above-described calculation method based on the coordinates (x0, y0) of the known measurement points acquired by the coordinate information acquisition unit 13. (x0, y0) ⇒ (x1, y1), (x1, y1) ⇒ (x2, y2), (x2, y2) ⇒ (x3, y3),...

[0034] Note that when the first known measurement point is, for example, the coordinates of the optical fiber sensor 2 at the starting end point of the optical fiber 1, the measurement point calculation unit 14 gradually calculates each measurement point from the starting end point to the ending point of the optical fiber 1 in one stroke based on the above-described calculation method.

[0035] On the other hand, when the first known measurement point is, for example, the midpoint of the optical fiber 1, the measurement point calculation unit 14 may calculate from the midpoint of the optical fiber 1 to the starting end point and then calculate from the midpoint to the ending point based on the above-described calculation method.

[0036] In the above description, the measurement point calculation unit 14 calculates the coordinates of each measurement point on the optical fiber 1 based on the coordinates of one measurement point acquired by the coordinate information acquisition unit 13 and the coordinates of two propagation signal output units 11, but it is not limited to this. The measurement point calculation unit 14 may calculate the coordinates of each measurement point on the optical fiber 1 in the same manner as above based on the coordinates of one measurement point acquired by the coordinate information acquisition unit 13 and the coordinates of three or more propagation signal output units 11.

[0037] Also, in the above description, the measurement point calculation unit 14 calculates the two-dimensional real space distribution of the optical fiber 1 by calculating the two-dimensional coordinates of each measurement point on the optical fiber 1. However, the measurement point calculation unit 14 may calculate the three-dimensional real space distribution of the optical fiber 1 by calculating the three-dimensional coordinates of each measurement point on the optical fiber 1 in the same manner as when calculating the two-dimensional coordinates of each measurement point on the optical fiber 1.

[0038] In this case, the measurement point calculation unit 14 geometrically calculates the intersection points of a sphere with a radius of the distance d of a predetermined length interval centered on the coordinates (x0, y0, z0) of the measurement point and three spheres centered on the coordinates (x α (α = 1, 2, 3) and the coordinates (x α s , y α s , z α s ) of each propagation signal output unit 11, respectively.

[0039] Specifically, the measurement point calculation unit 14 calculates planes S1, S2, and S3 that each contain the intersection lines of a sphere with a radius of the distance d of a predetermined length interval centered on the coordinates (x0, y0, z0) of the measurement point and three spheres centered on the coordinates (x α and the coordinates (x α s , y α s , z α s ) of each propagation signal output unit 11, respectively.

[0040] The measurement point calculation unit 14 calculates the coordinates of the intersection points of the above three planes S1, S2, and S3. The measurement point calculation unit 14 estimates the coordinates of the calculated intersection points as the coordinates (x1, y1, z1) of the next measurement point.

[0041] The measurement point calculation unit 14 replaces (x0, y0, z0) with (x1, y1, z1) and repeatedly performs the above-described similar processing step by step until the distribution of the measurement points on the optical fiber 1 is obtained. That is, the measurement point calculation unit 14 gradually calculates (x1, y1, z1), (x2, y2, z2), (x3, y3, z3),... using the above-described calculation method based on the coordinates (x0, y0, z0) of the known measurement points acquired by the coordinate information acquisition unit 13.

[0042] Note that the measurement point calculation unit 14 may gradually calculate the three-dimensional coordinates (x1, y1, z1), (x2, y2, z2), (x3, y3, z3),... of each measurement point on the optical fiber 1 using the above-described similar calculation method based on the three-dimensional coordinates (x0, y0, z0) of one known measurement point acquired by the coordinate information acquisition unit 13 and the three-dimensional coordinates of four or more propagation signal output units 11.

[0043] Next, a comparison between the measurement points estimated by the real-space distribution calculation system 10 according to the present embodiment and the actual measurement points will be described with reference to FIG. 5. Here, two smartphones are used as the propagation signal output units 11, and a recording of applause is output as the propagation signal. As shown in the upper part of FIG. 5, each smartphone is installed at positions A and B, respectively. Microphones are installed at measurement points 0, 1, 2, and 3 on the optical fiber 1, respectively.

[0044] The coordinates of the microphone measurement points 0 to 3 are (0, 0), (0.5, 0), (1.0, 0), and (1.5, 0), respectively. The coordinates of the microphone measurement points 0 to 3 are the coordinates of the actual measurement points. The coordinates of the positions A and B of the smartphones are (0.5, 1.0) and (1.0, 1.0), respectively. The coordinates of the smartphones are the coordinates of the propagation signal output unit 11.

[0045] As shown in the lower part of FIG. 5, the measurement points estimated by the real space distribution calculation system 10 according to the present embodiment and the actual measurement points (solid lines) slightly differ at the measurement point 2 but are substantially in agreement. Thus, it can be seen that according to the real space distribution calculation system 10 according to the present embodiment, the distribution of the optical fiber 1 can be obtained with high accuracy.

[0046] Subsequently, the real space distribution calculation method according to the present embodiment will be described. FIG. 6 is a flowchart showing the flow of the real space distribution calculation method according to the present embodiment.

[0047] The two propagation signal output units 11 respectively output propagation signals that propagate non - contactingly with respect to the optical fiber 1 via a vibration medium (step S201).

[0048] The reception time difference calculation unit 12 calculates the reception time difference of the propagation signals from each propagation signal output unit 11 between adjacent measurement points (step S202).

[0049] The coordinate information acquisition unit 13 acquires the coordinate of one first measurement point on the optical fiber 1 and the coordinates of the two propagation signal output units 11, and outputs the acquired coordinates to the measurement point calculation unit 14 (step S203).

[0050] The measurement point calculation unit 14 calculates the intersection points of a circle with a radius equal to the distance of a predetermined - length interval centered on the coordinate of the first measurement point and circles centered on the coordinates of the two propagation signal output units 11 respectively, as the next second measurement point on the optical fiber 1 adjacent to the first measurement point, based on the reception time difference of the propagation signals from each propagation signal output unit 11 between the first measurement point and the second measurement point (step S204).

[0051] The measurement point calculation unit 14 calculates the coordinates of the third measurement point, the fourth measurement point, the fifth measurement point, ··· the Nth measurement point on the optical fiber 1 by gradually repeating the above calculation (step S205).

[0052] As described above, the real-space distribution calculation system 10 according to the present embodiment calculates the intersection points of a circle with the distance of a predetermined length interval as the radius and the coordinates of the measurement point as the center, and two circles with the coordinates of the two propagation signal output units 11 as the centers respectively, as the next measurement point on the optical fiber 1 adjacent to the measurement point, and gradually repeats calculating based on the reception time difference of the propagation signal from the propagation signal output unit 11 between the measurement point and the next measurement point, thereby calculating the coordinates of each measurement point on the optical fiber 1. Thereby, considering the linearity of the optical fiber 1, by gradually obtaining the coordinates of adjacent measurement points from the coordinates of known measurement points, the distribution of the highly linear optical fiber 1 can be obtained with high accuracy.

[0053] Embodiment 2 In the present embodiment, the measurement point calculation unit 14 may perform curve regression of four dimensions or less on the reception time difference of the propagation signal calculated by the reception time difference calculation unit 12 to calculate the coordinates of each measurement point on the optical fiber 1. In this way, by utilizing the linearity of the optical fiber 1 and performing curve regression of four dimensions or less on the reception time difference of the propagation signal, the variation in the reception time difference of the propagation signal can be suppressed. Thereby, each measurement point on the optical fiber 1 can be calculated with higher accuracy, and the real-space distribution of the optical fiber 1 can be calculated with higher accuracy.

[0054] In the above Embodiment 1, there is an error upper limit in the reception time difference of the propagation signal. Specifically, a circle with the distance d of a predetermined upper interval as the radius and the coordinates (x i-1 , y i-1 ) of the (i - 1)-th measurement point as the center needs to have an intersection with a circle with the radius r α and the coordinates (x α s , y α s ) as the center, and the reception time difference of the propagation signal calculated from the i-th measurement point needs to satisfy |t i、i-1、α | ≦ d / c. When the reception time difference of the propagation signal does not satisfy the above conditions due to measurement errors or the like, the above two circles do not have an intersection. Also, as described above, since the measurement points are calculated gradually, an accumulation error is likely to occur.

[0055] In contrast, in the present embodiment, by utilizing the linearity of the optical fiber 1, as described above, the measurement point calculation unit 14 performs curve regression of four dimensions or less on the reception time difference of the propagation signal calculated by the reception time difference calculation unit 12.

[0056] For example, in FIG. 7, the reception time differences of the propagation signals calculated by the reception time difference calculation unit 12 actually vary as indicated by points. In FIG. 7, the horizontal axis represents the distance from the optical fiber sensor 2, and the vertical axis represents the reception time difference. When obtaining the coordinates of each measurement point of the optical fiber based on the reception time difference of the propagation signal, with d = 1 m and c = 340 m / sec, the reception time difference needs to fall within the range of ±1 / 340 seconds as depicted by the upper and lower lines in FIG. 7.

[0057] However, by performing curve regression of four dimensions or less on the reception time difference of this propagation signal to obtain a regression line and correcting the reception time difference of the propagation signal based on this regression line, the variation can be suppressed. The reason why two regression lines are generated is that curve regression is performed respectively on the reception time differences of the propagation signals from the two propagation signal output units 11.

[0058] As a correction of each measurement point based on the above regression line, the measurement point calculation unit 14, for example, corrects the reception time difference of each propagation signal to a point on the above regression line. Alternatively, the measurement point calculation unit 14 may exclude those that deviate significantly from the regression line by a predetermined value or more among the reception time differences of the propagation signals calculated by the reception time difference calculation unit 12.

[0059] Embodiment 3 FIG. 8 is a block diagram showing a schematic system configuration of the real space distribution calculation system according to the present embodiment. The real space distribution calculation system 20 according to the present embodiment may further include a shape estimation unit 15 that estimates the general shape of the optical fiber 1 by utilizing the continuity of the optical fiber 1.

[0060] Using the outline of the optical fiber 1 estimated by the outline estimation unit 15, each measurement point on the optical fiber 1 can be calculated with higher accuracy, and the real space distribution of the optical fiber 1 can be calculated with higher accuracy. The outline estimation unit 15 is a specific example of outline estimation means.

[0061] As shown in FIG. 9, the propagation signal output unit 11 may be arranged at the starting point of the optical fiber 1. For example, the propagation signal output unit 11 is arranged at the same position as the optical fiber sensor 2.

[0062] Here, let |TDOA| be the reception time difference of the propagation signal between the propagation signal output unit 11 and each measurement point. Let l be the distance from the propagation signal output unit 11 to the measurement point on the optical fiber 1.

[0063] The outline estimation unit 15 can estimate the outline of the optical fiber 1 as follows in (1) to (3) below by utilizing the continuity of the optical fiber 1. (1) When |TDOA| = l / c, the outline estimation unit 15 estimates that the optical fiber 1 is linearly distributed from the propagation signal output unit 11.

[0064] (2) When |TDOA| < l / c, the outline estimation unit 15 estimates that the optical fiber 1 is distributed in a bent state from the propagation signal output unit 11.

[0065] (3) The outline estimation unit 15 estimates that the optical fiber 1 turns back toward the propagation signal output unit 11 at the point where |TDOA| reaches the maximum value.

[0066] The measurement point calculation unit 14 compares the coordinates of each measurement point on the calculated optical fiber 1 with the outline of the optical fiber 1 estimated by the outline estimation unit 15. When the measurement point calculation unit 14 determines that there is a large deviation of a predetermined value or more between the coordinates of each measurement point on the calculated optical fiber 1 and the outline of the optical fiber 1 estimated by the outline estimation unit 15, the coordinates of each measurement point on the calculated optical fiber 1 may be corrected.

[0067] For example, the measurement point calculation unit 14 corrects the coordinates of each measurement point on the optical fiber 1 calculated to the points on the approximate shape of the optical fiber 1 estimated by the approximate shape estimation unit 15. Alternatively, the measurement point calculation unit 14 may exclude points that deviate significantly from the approximate shape of the optical fiber 1 estimated by the approximate shape estimation unit 15 by more than a predetermined value from among the coordinates of each measurement point on the optical fiber 1 calculated.

[0068] Embodiment 4 In this embodiment, the optical fiber 1 may be linearly arranged along a linear member. For example, as shown in FIG. 10, the optical fiber 1 is linearly arranged along a linear fence.

[0069] The coordinate information acquisition unit 13 acquires, for example, the point that takes the maximum amplitude value as the coordinates of the end point of the fence on the optical fiber 1 when the end point portion of the fence is vibrated by a vibrator or the like. The measurement point calculation unit 14 gradually calculates each measurement point on the optical fiber 1 using the above calculation method based on the coordinates of the above end points acquired by the coordinate information acquisition unit 13.

[0070] Here, since the optical fiber 1 is linearly arranged along a linear fence, originally, each of the calculated measurement points should also be linear. However, as shown in the upper part of FIG. 11, large variations may occur in each measurement point.

[0071] In contrast, in this embodiment, the measurement point calculation unit 14 calculates the deflection angles of the lines connecting the calculated adjacent measurement points with respect to the linear direction of the optical fiber 1 respectively. The measurement point calculation unit 14 may exclude the measurement points whose absolute values of the calculated deflection angles are equal to or greater than a predetermined angle from the calculated measurement points as shown in the lower part of FIG. 11.

[0072] Further, the measurement point calculation unit 14 may correct the measurement points whose absolute values of the calculated deflection angles are equal to or greater than a predetermined angle to the points on the line in the linear direction of the optical fiber 1. Thereby, the variation of the above measurement points can be suppressed, each measurement point on the optical fiber 1 can be calculated with higher accuracy, and the real space distribution of the optical fiber 1 can be calculated with higher accuracy.

[0073] The measurement point calculation unit 14 may calculate the average value of the absolute values of the deflection angles of each measurement point, and set this average value to the predetermined angle.

[0074] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

[0075] The present invention can also be realized, for example, by causing a processor to execute a computer program for the processing shown in FIG. 4 or FIG. 6.

[0076] The program can be stored using various types of non-transitory computer readable media and supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROM (Read Only Memory), CD-R, CD-R / W, semiconductor memories (e.g., mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)).

[0077] The program may be supplied to a computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer readable media can supply the program to the computer via wired communication paths such as electric wires and optical fibers, or wireless communication paths.

[0078] Each part constituting the real space distribution calculation systems 10 and 20 according to the above-described embodiments can be realized not only by a program but also by dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array) for some or all of them.

Description of Reference Numerals

[0079] 1 Optical fiber 2 Optical fiber sensor 10 Real space distribution calculation system 11 Propagation signal output unit 12 Reception time difference calculation unit 13 Coordinate information acquisition unit 14 Measurement point calculation unit 15 Outline estimation unit 20 Real space distribution calculation system

Claims

1. Propagation signal output means for outputting a propagation signal that propagates non - contact via a vibrating medium to an optical fiber in which a plurality of measurement points are set for each predetermined length interval; Receiving time difference calculation means for calculating the reception time difference of the propagation signal from the propagation signal output means between adjacent measurement points; Coordinate information acquisition means for acquiring the coordinates of the measurement points on the optical fiber and the coordinates of the propagation signal output means; Measurement point calculation means for calculating the coordinates of each measurement point on the optical fiber by gradually repeating the calculation of the intersection of a circle centered on the coordinates of the measurement point with the radius of the distance of the predetermined length interval and a circle centered on the coordinates of the propagation signal output means as the next measurement point on the optical fiber adjacent to the measurement point, based on the reception time difference of the propagation signal calculated by the reception time difference calculation means; Comprising: An actual space distribution calculation system for an optical fiber.

2. The actual space distribution calculation system for an optical fiber according to claim 1, wherein the measurement point calculation means performs curve regression of four dimensions or less on the reception time difference of the propagation signal calculated by the reception time difference calculation means to calculate the coordinates of each measurement point on the optical fiber. An actual space distribution calculation system for an optical fiber.

3. The actual space distribution calculation system for an optical fiber according to claim 1 or 2, wherein the propagation signal output means is arranged at an end point of the optical fiber, assuming |TDOA| as the reception time difference of the propagation signal, l as the distance from the propagation signal output means to the measurement point on the optical fiber, and c as the speed of sound, (1) when |TDOA| = l / c, it is estimated that the optical fiber is linearly distributed from the propagation signal output means, (2) when |TDOA| < l / c, it is estimated that the optical fiber is distributed in a bent state from the propagation signal output means, and (3) at the point where |TDOA| reaches a maximum value, it is estimated that the optical fiber turns back toward the propagation signal output means, further comprising approximate shape estimation means for estimating the approximate shape of the optical fiber, wherein the measurement point calculation means compares the calculated coordinates of each measurement point on the optical fiber with the approximate shape of the optical fiber estimated by the approximate shape estimation means. An actual space distribution calculation system for an optical fiber.

4. The actual space distribution calculation system for an optical fiber according to any one of claims 1 to 3, when the optical fiber is linearly arranged along a linear member, The measurement point calculation means calculates, for each line connecting the calculated adjacent measurement points, the deflection angle of the line with respect to the linear direction of the optical fiber, and excludes a measurement point where the absolute value of the calculated deflection angle is equal to or greater than a predetermined angle from the calculated measurement points, or corrects the point to a point on the line in the linear direction of the optical fiber. Optical fiber real-space distribution calculation system.

5. A step of obtaining the coordinates of a propagation signal output means that outputs a propagation signal that propagates non-contact via a vibration medium, and the coordinates of measurement points on the optical fiber, for an optical fiber in which a plurality of measurement points are set for each predetermined length interval; A step of calculating the coordinates of each measurement point on the optical fiber by gradually repeating the calculation of the intersection of a circle centered on the coordinates of the measurement point with a radius equal to the distance of the predetermined length interval and a circle centered on the coordinates of the propagation signal output means as the next measurement point on the optical fiber adjacent to the measurement point, based on the reception time difference of the propagation signal from the propagation signal output means between the measurement point and the next measurement point; comprising Optical fiber real-space distribution calculation method.

6. A process of obtaining the coordinates of a propagation signal output means that outputs a propagation signal that propagates non-contact via a vibration medium, and the coordinates of measurement points on the optical fiber, for an optical fiber in which a plurality of measurement points are set for each predetermined length interval; A process of calculating the coordinates of each measurement point on the optical fiber by gradually repeating the calculation of the intersection of a circle centered on the coordinates of the measurement point with a radius equal to the distance of the predetermined length interval and a circle centered on the coordinates of the propagation signal output means as the next measurement point on the optical fiber adjacent to the measurement point, based on the reception time difference of the propagation signal from the propagation signal output means between the measurement point and the next measurement point; to be executed by a computer Program.

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