Optical fiber installation vehicle, optical fiber sensing system, optical fiber sensing method, and program

Abstract

To provide an optical fiber installation vehicle capable of accurately determining an installation position of optical fiber.SOLUTION: An optical fiber vehicle is provided with: a transmitter transmitting pinger signals into water; DAS interrogator acquiring acoustic data showing acoustics caused by the pinger signals detected at each of a plurality of positions on the optical fiber installed on the seabed; and an estimation part estimating a shape of the optical fiber using each of the acoustic data at the plurality of positions.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to an optical fiber laying vehicle, an optical fiber sensing system, an optical fiber sensing method, and a program. [Background technology]

[0002] A Distributed Acoustic Sensing (DAS) interrogator uses backscattered light received from an optical fiber to obtain information about vibrations and acoustics applied to the optical fiber. Recently, underwater optical fiber sensing systems using DAS interrogators have been researched and developed.

[0003] Patent Document 1 discloses an optical fiber sensing system that uses a DAS interrogator to acquire underwater environmental information that indicates the environment around an optical fiber laid on the seabed. Patent Document 2 discloses an optical fiber sensing system that uses a DAS interrogator to acquire underwater environmental information including information in higher frequency bands. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 153142 [Patent Document 2] International Publication No. 2021 / 111691 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in order to detect targets underwater or on the sea surface using the optical fiber sensing systems disclosed in Patent Documents 1 and 2, it is necessary to use optical fibers laid on the seabed. However, it is difficult to accurately determine the location of the optical fiber, which has been a factor in reducing the accuracy of detecting the target position in the optical fiber sensing system.

[0006] In view of the above-mentioned problems, an object of the present disclosure is to provide an optical fiber installation vehicle, an optical fiber sensing system, an optical fiber sensing method, and a program that are capable of more precisely determining the installation position of an optical fiber. [Means for solving the problem]

[0007] An optical fiber installation vehicle according to one aspect includes: a transmitter that transmits a pinger signal underwater; a Distributed Acoustic Sensing (DAS) interrogator for acquiring acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on an optical fiber laid on the seabed; and an estimation unit that estimates the shape of the optical fiber using the acoustic data from each of the plurality of points.

[0008] An optical fiber sensing system according to one aspect includes: an optical fiber installation vehicle; a land-based device; The optical fiber laying vehicle comprises: A transmitter is provided to transmit a pinger signal underwater, The land-based device is a Distributed Acoustic Sensing (DAS) interrogator for acquiring acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on an optical fiber laid on the seabed; and an estimation unit that estimates the shape of the optical fiber using the acoustic data from each of the plurality of points.

[0009] An optical fiber sensing method according to one aspect includes: 1. A fiber optic sensing method performed by an optical fiber installation vehicle, comprising: transmitting a pinger signal underwater; acquiring, for each of a plurality of points on an optical fiber laid on the seabed, acoustic data indicating the acoustics caused by the pinger signal detected at each of the points; and estimating a shape of the optical fiber using the acoustic data at each of the plurality of points.

[0010] In one aspect, the program comprises: On the computer, The procedure for sending a pinger signal underwater; acquiring, for each of a plurality of points on an optical fiber laid on the seabed, acoustic data indicating the acoustics caused by the pinger signal detected at each of the points; and a procedure of estimating the shape of the optical fiber using the acoustic data at each of the plurality of points. [Effects of the Invention]

[0011] According to the above-described aspects, it is possible to provide an optical fiber installation vehicle, an optical fiber sensing system, an optical fiber sensing method, and a program that are capable of determining the installation position of an optical fiber more precisely. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a schematic configuration example of an optical fiber sensing system according to the present disclosure. [Figure 2] FIG. 1 is a diagram showing an example of an image of laying optical fiber on the seabed using an underwater unmanned vehicle according to the present disclosure. [Figure 3] 1A and 1B illustrate example transmit signals generated by a pinger transmitter according to the present disclosure. [Figure 4] FIG. 1 illustrates an example of processing performed by a DAS interrogator and a signal processing computer according to the present disclosure. [Figure 5]1A and 1B illustrate example locations where acoustic data is acquired by a DAS interrogator according to the present disclosure. [Figure 6] FIG. 10 is a diagram illustrating an example of a process for calculating a distance from a transmitting point of a pinger signal by a signal processing computer according to the present disclosure. [Figure 7] 10 is a diagram illustrating an example of a process for calculating the arrival direction of a pinger signal by a signal processing computer according to the present disclosure. FIG. [Figure 8] FIG. 10 is a diagram illustrating an example of processing for estimating the shape of an optical fiber by a signal processing computer according to the present disclosure. [Figure 9] 1 is a diagram illustrating a schematic configuration example of an optical fiber sensing system according to the present disclosure. [Figure 10] 1 is a diagram illustrating a schematic configuration example of an optical fiber sensing system according to the present disclosure. [Figure 11] 1 is a diagram illustrating a schematic configuration example of an optical fiber sensing system according to the present disclosure. [Figure 12] FIG. 1 is a diagram illustrating an example of the hardware configuration of a computer that realizes the underwater unmanned vehicle and the land device according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description and drawings have been omitted and simplified as appropriate for clarity of explanation. In addition, in the following drawings, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0014] <First Embodiment> FIG. 1 is a diagram showing a schematic configuration example of an optical fiber sensing system 1. As shown in FIG. The optical fiber sensing system 1 includes an underwater vehicle 101 .

[0015] The underwater vehicle 101 is a vehicle used to lay optical fiber 114F included in the optical cable 114 on the seabed, and is an example of an optical fiber laying vehicle.

[0016] The underwater vehicle 101 includes a GPS (Global Positioning System) unit 102, a communication device 103, a control computer 104, an INS (Inertial Navigation System) unit 105, a rudder 106, a propeller 107, a signal processing computer 108, a pinger transmitter 109, an altimeter 110, a pinger transmitter 111, a DAS interrogator 112, and an optical cable storage / retraction device 113. A mooring mechanism 115 is attached to the end of an optical cable 114.

[0017] When the underwater vehicle 101 is deployed and while traveling on the water, the underwater vehicle 101 calculates its own position using the GPS unit 102. While traveling underwater, the underwater vehicle 101 calculates its own position using the INS unit 105. The underwater vehicle 101 transmits information indicating its current position to the control computer 104.

[0018] The altimeter 110 is a sensor that can detect the distance between the underwater vehicle 101 and the seabed as the altitude from the seabed. The altimeter 110 transmits information indicating the current altitude to the control computer 104.

[0019] The control computer 104 controls the rudder 106 and the propeller 107 based on the current position and altitude information of the underwater unmanned vehicle 101, thereby causing the underwater unmanned vehicle 101 to navigate a pre-programmed route or a route according to the route information received by the communication device 103.

[0020] The optical cable storage / reeling device 113 reels out the optical cable 114. Then, first, the end point of the optical cable 114 is fixed to the seabed by a mooring mechanism 115 attached to the end point of the optical cable 114. Then, as the underwater vehicle 101 moves, the optical fiber 114F included in the optical cable 114 is laid on the seabed.

[0021] At this time, the optical cable storage / payout device 113 may pay out the optical cable 114 from a position where the altitude is equal to or lower than a threshold, i.e., from a position close to the seabed, based on information about the current altitude of the underwater vehicle 101. This makes it possible to reduce errors in the laying position of the optical fiber 114F.

[0022] The DAS interrogator 112 is connected to the end point of the optical cable 114 on the underwater vehicle 101 side. The DAS interrogator 112 inputs pulsed light into an optical fiber 114F included in the optical cable 114, and receives backscattered light from the optical fiber 114F that is generated as the pulsed light is transmitted through the optical fiber 114F. The DAS interrogator 112 acquires DAS data indicating the sound detected at each point on the optical cable 114 using the backscattered light received from the optical fiber 114F.

[0023] The DAS interrogator 112 selects a plurality of arbitrary points on the optical cable 114 as points from which acoustic data is to be acquired. At this time, the DAS interrogator 112 can select an arbitrary point by changing software parameters. The DAS interrogator 112 acquires DAS data from each of the selected points as acoustic data. The DAS interrogator 112 transmits the acoustic data from each of the multiple points to the signal processing computer 108.

[0024] The signal processing computer 108 performs signal processing on the acoustic data from each of the multiple points on the optical cable 114. The details of this signal processing will be described later. The signal processing computer 108 transmits the results of the signal processing to the control computer 104.

[0025] Pinger transmitter 109 operates under the control of control computer 104 and generates a transmission signal. Pinger transmitter 111 transmits the transmission signal generated by pinger transmitter 109 into the water as a pinger signal, which is an acoustic signal.

[0026] The DAS interrogator 112 acquires DAS data indicating the sound caused by the pinger signal transmitted by the pinger transmitter 111 and detected at each point on the optical cable 114 .

[0027] Fig. 2 is a diagram showing an example of an image when optical fiber 114F is laid on the seabed by the underwater vehicle 101. Fig. 2 shows the seabed as viewed from the sea surface. The underwater vehicle 101 lays an optical fiber 114F on the seabed. However, a difference occurs between the planned laying position 201 and the actual laying position 202 of the optical fiber 114F.

[0028] Fig. 3 is a diagram showing an example of a transmission signal generated by pinger transmitter 109. In Fig. 3, the horizontal axis represents time, and the vertical axis represents frequency. The waveform of the transmission signal generated by pinger transmitter 109 is a waveform that combines the waveform of the ranging signal and the waveform of the data transmission signal. This transmission signal is transmitted in all directions as a pinger signal from pinger transmitter 111. The data transmission signal contains information about the transmission time of the pinger signal and the self-position of underwater vehicle 101 at that transmission time.

[0029] FIG. 4 illustrates an example of the processing performed by the DAS interrogator 112 and the signal processing computer 108. First, the DAS interrogator 112 uses the backscattered light received from the optical fiber 114F to acquire DAS data indicating the sound caused by the pinger signal transmitted by the pinger transmitter 111 and detected at each point on the optical cable 114 (S101).

[0030] Next, the DAS interrogator 112 selects a plurality of points on the optical cable 114 and acquires DAS data from each of the selected points as acoustic data (S102). Next, the signal processing computer 108 executes signal processing for the acoustic data of each of the plurality of points (S103).

[0031] In the signal processing of S103, first, the signal processing computer 108 separates the acoustic data of each point into a positioning signal and a data transmission signal (S104).

[0032] Next, the signal processing computer 108 performs a data decoding process on the data transmission signal (S106), which decodes information included in the data transmission signal, such as the time of transmission of the pinger signal and the self-position of the underwater vehicle 101 at that time (i.e., the point of transmission of the pinger signal).

[0033] Furthermore, the signal processing computer 108 performs replica correlation processing on the positioning signal (S105). Next, the signal processing computer 108 calculates the distance from the transmission point of the pinger signal and the arrival direction of the pinger signal (S107, S108).

[0034] Thereafter, the signal processing computer 108 estimates the shape of the optical fiber 114F using information on the distance from the transmitting point of the pinger signal and the direction of arrival of the pinger signal calculated for each of the multiple points on the optical cable 114, and information decoded from the data transmission signal (S109).

[0035] FIG. 5 shows an example of locations where acoustic data is acquired by the DAS interrogator 112. In the example of Fig. 5, the DAS interrogator 112 selects five points A to E and acquires acoustic data at three points for each of the selected five points. For example, for point A, the DAS interrogator 112 acquires acoustic data at point A and at point A, which is a distance a from point A. - and Point A + Acquire acoustic data.

[0036] Fig. 6 is a diagram showing an example of processing for calculating the distance from the transmission point of the pinger signal by the signal processing computer 108. In Fig. 6, the horizontal axis represents time, and the vertical axis represents the acoustic intensity at each point. In Fig. 6, the time when the pinger signal was transmitted is time 0. In the example of FIG. 6, for each of the five points A to E, the distance from the point where the pinger signal was transmitted to that point is calculated.

[0037] The signal processing computer 108 obtains information on the transmission time and transmission position of the pinger signal by performing data decoding processing on the data transmission signal of point X (X=A, B, C, D, E; the same applies below). Furthermore, the signal processing computer 108 derives the time when a peak occurs in the acoustic intensity of the signal after replica correlation processing of the positioning signal at point X. Then, the signal processing computer 108 calculates the time difference t between the time when the peak occurred and the time when the pinger signal was transmitted. X Derive and derive t X is used to calculate the distance from the point where the pinger signal is transmitted.

[0038] FIG. 7 is a diagram showing an example of processing performed by the signal processing computer 108 to calculate the arrival direction of a pinger signal. In the example of FIG. 7, the arrival direction of the pinger signal at each of the five points A to E is calculated.

[0039] The signal processing computer 108 detects a point X at a distance a from the point X. - The signal after replica correlation processing for the positioning signal of point X and point X at a distance a from point X. + The phase difference between the signal obtained by replica correlation processing for the positioning signal and the signal obtained by replica correlation processing for the positioning signal is derived. Then, the signal processing computer 108 uses the phase difference derived for the point X to calculate the arrival direction θ of the pinger signal at that point X.

[0040] FIG. 8 is a diagram showing an example of processing performed by the signal processing computer 108 to estimate the shape of the optical fiber 114F. 8, information on the distance from the transmitting point of the pinger signal and the direction of arrival is obtained for each of five points A to E on the optical cable 114. Information on the transmitting point of the pinger signal is also obtained.

[0041] Therefore, the signal processing computer 108 estimates the shape of the optical fiber 114F using information on the transmission point of the pinger signal and information on the distance and arrival direction from the transmission point of the pinger signal for the five points A to E. Specifically, first, the signal processing computer 108 uses the above information to estimate the positions of each of the five points A to E on the optical cable 114. Then, the signal processing computer 108 uses the positions of each of the five points A to E on the optical cable 114 to estimate the shape of the optical fiber 114F.

[0042] After the optical fiber 114F is laid, underwater monitoring is performed using the optical fiber 114F by the signal processing computer 108 and DAS interrogator 112 mounted on the underwater vehicle 101. When a target is detected by the underwater monitoring, the detection of the target is notified to the outside by means of the communicator 103 or the like under the control of the control computer 104.

[0043] As described above, according to the first embodiment, the pinger transmitter 111 transmits a pinger signal underwater. The DAS interrogator 112 acquires acoustic data indicating the acoustics caused by the pinger signal detected at each of a plurality of points on the optical fiber 114F laid on the seabed. The signal processing computer 108 uses the acoustic data from each of the plurality of points to estimate the shape of the optical fiber 114F.

[0044] As shown in FIG. 2, when laying the optical fiber 114F, a difference occurs between the planned laying position 201 and the actual laying position 202. However, according to the first embodiment, after the optical fiber 114F is laid, the shape of the optical fiber 114F is estimated using acoustic data from each of a plurality of points on the optical fiber 114F, thereby making it possible to more precisely grasp the laying position of the optical fiber 114F.

[0045] The altimeter 110 detects the altitude of the underwater vehicle 101 from the seabed, and the optical cable retracting / retracting device 113 can use the detected altitude to retract the optical cable 114 from a position close to the seabed. This makes it possible to reduce errors in the laying position of the optical fiber 114F.

[0046] The DAS interrogator 112 also selects multiple locations from which acoustic data is acquired. At this time, the DAS interrogator 112 can select any location by changing software parameters. Therefore, even if the location is different from the location used for underwater monitoring, which is its original purpose, it is possible to select a location suitable for estimating the shape of the optical fiber 114F and acquire acoustic data from that location.

[0047] <Embodiment 2> FIG. 9 is a diagram showing a schematic configuration example of an optical fiber sensing system 1A. The optical fiber sensing system 1A includes an underwater vehicle 301 and a land-based device 302, which is a land-based facility.

[0048] The underwater vehicle 301 includes a GPS unit 102, a control computer 303, an INS unit 105, a rudder 106, a propeller 107, a pinger transmitter 109, an altimeter 110, a pinger transmitter 111, and an optical cable storage and payout device 113. The land-based device 302 comprises a communicator 103 , a control computer 104 , a signal processing computer 108 , and a DAS interrogator 112 .

[0049] That is, in the optical fiber sensing system 1A, the communicator 103, the control computer 104, the signal processing computer 108, and the DAS interrogator 112 that are provided in the underwater vehicle 101 are provided in the land device 302.

[0050] In the optical fiber sensing system 1A, it is necessary to synchronize the time between the underwater vehicle 301 and the signal processing computer 108 in the land device 302 in order to estimate the shape of the optical fiber 114F. On the other hand, underwater monitoring can be performed using only the land-based equipment 302, which is a land-based facility, and therefore the optical fiber sensing system 1A can be constructed simply.

[0051] Other than the above, the configuration of the present embodiment 2 is the same as that of the above-described embodiment 1. Therefore, the present embodiment 2 can obtain the same effects as those of the above-described embodiment 1.

[0052] <Third Embodiment> The third embodiment corresponds to an embodiment that is a higher-level concept of the first embodiment described above. FIG. 10 is a diagram showing a schematic configuration example of an optical fiber sensing system 1B. The optical fiber sensing system 1B includes an underwater vehicle 401. The underwater vehicle 401 is an example of an optical fiber laying vehicle.

[0053] The underwater vehicle 401 comprises a transmitter 402 , a DAS interrogator 403 , and an estimator 404 . The wave transmitter 402 transmits a pinger signal into the water. The wave transmitter 402 corresponds to the pinger transmitter 109 and the pinger wave transmitter 111.

[0054] The DAS interrogator 403 acquires acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on the optical fiber 114F laid on the seabed. The DAS interrogator 403 corresponds to the DAS interrogator 112.

[0055] The estimation unit 404 estimates the shape of the optical fiber 114 F using the acoustic data from each of a plurality of points on the optical fiber 114 F. The estimation unit 404 corresponds to the signal processing computer 108.

[0056] As described above, according to the third embodiment, after the optical fiber 114F is laid, the shape of the optical fiber 114F is estimated using acoustic data from each of a plurality of points on the optical fiber 114F, thereby making it possible to more precisely grasp the laying position of the optical fiber 114F.

[0057] The underwater unmanned vehicle 401 may further include a position calculation unit that calculates the position of the underwater unmanned vehicle 401. This position calculation unit corresponds to the GPS unit 102 and the INS unit 105. In this case, the pinger signal may include a ranging signal and a data transmission signal. The data transmission signal may include information about the transmission time of the pinger signal, and may also include the position of the underwater unmanned vehicle 401 at the transmission time of the pinger signal as information about the transmission point of the pinger signal.

[0058] The estimation unit 404 may also separate, for each of a plurality of points on the optical fiber 114F, a ranging signal and a data transmission signal from the acoustic data of that point. Furthermore, for each of a plurality of points on the optical fiber 114F, the estimation unit 404 may decode the data transmission signal to acquire information on the transmission point and transmission time of the pinger signal, and perform replica correlation processing on the ranging signal at that point. Furthermore, for each of a plurality of points on the optical fiber 114F, the estimation unit 404 may estimate the position of that point using the ranging signal after replica correlation processing and the transmission point and transmission time of the pinger signal, and estimate the shape of the optical fiber 114F using the positions of each of the plurality of points.

[0059] The estimation unit 404 may also calculate, for each of a plurality of points on the optical fiber 114F, the distance from the transmitting point of the pinger signal to that point using the ranging signal after replica correlation processing for that point and the transmitting point and transmitting time of the pinger signal, and may also calculate the arrival direction of the pinger signal at that point. Furthermore, the estimation unit 404 may estimate, for each of a plurality of points on the optical fiber 114F, the position of that point using the transmitting point of the pinger signal and the distance and arrival direction calculated for that point.

[0060] The underwater vehicle 401 may further include an optical cable storage and payout device that stores the optical cable 114 including the optical fiber 114F and pays out the optical cable 114 underwater to lay the optical fiber 114F on the seabed. This optical cable storage and payout device corresponds to the optical cable storage and payout device 113.

[0061] The underwater vehicle 401 may further include an altimeter that detects the distance between the underwater vehicle 401 and the seabed as altitude. This altimeter corresponds to the altimeter 110. In this case, the optical cable retraction / reeling device may reel out the optical cable 114 underwater when the altitude of the underwater vehicle 401 is equal to or lower than a predetermined threshold.

[0062] Furthermore, when the optical fiber 114F is laid on the seabed by the optical cable storage and payout device, the transmitter 402 may transmit a pinger signal underwater, the DAS interrogator 403 may acquire acoustic data from each of multiple points on the optical fiber 114F, and the estimation unit 404 may estimate the shape of the optical fiber 114F.

[0063] <Fourth Embodiment> The fourth embodiment corresponds to an embodiment that is a higher-level concept of the first embodiment described above. FIG. 11 is a diagram showing a schematic configuration example of an optical fiber sensing system 1C. The optical fiber sensing system 1C includes an underwater vehicle 501 and a land-based device 502 that is a land-based facility.

[0064] The underwater vehicle 501 is equipped with a transmitter 402 . The land-based device 502 comprises a DAS interrogator 403 and an estimator 404 . That is, in the optical fiber sensing system 1C, the DAS interrogator 403 and the estimation unit 404 that were provided in the underwater vehicle 401 are provided in the land device 302, which is a land facility.

[0065] Other than the above, the configuration of the present embodiment 4 is the same as that of the above-mentioned embodiment 3. Therefore, the present embodiment 4 can obtain the same effects as those of the above-mentioned embodiment 3.

[0066] <Other embodiments> In each of the above-described embodiments, an example has been described in which the optical fiber laying vehicle is the underwater vehicle 101, but the present invention is not limited to this. The optical fiber laying vehicle may be an underwater vehicle, a manned ship, a submarine, or the like.

[0067] In addition, in each of the above-described embodiments, the shape of the optical fiber 114F is estimated when the optical fiber 114F is laid, but this is not limiting. The shape of the optical fiber 114F may be estimated again when a certain time has elapsed since the laying of the optical fiber 114F in order to correct a positional deviation of the optical cable 114.

[0068] <Hardware configuration of underwater drone and land device> 12 is a diagram showing an example of the hardware configuration of a computer 900 that realizes the functions of the underwater unmanned aerial vehicles 101, 301, 401, 501 and the land devices 302, 502. The computer 900 may realize all of the functions of the underwater unmanned aerial vehicles 101, 301, 401, 501 and the land devices 302, 502, or may realize only some of the functions. The computer 900 includes a processor 901 and a memory 902. The processor 901 and the memory 902 are coupled to each other.

[0069] The processor 901 may be, for example, a microprocessor, a microprocessing unit (MPU), or a central processing unit (CPU). The processor 901 may include multiple processors.

[0070] The memory 902 is configured by a combination of volatile memory and non-volatile memory. The memory 902 may include storage located remotely from the processor 901. In this case, the processor 901 may access the memory 902 via an I (Input) / O (Output) interface (not shown).

[0071] The memory 902 may store software modules (computer programs) including instructions and data for performing processing by the underwater vehicle 101, 301, 401, 501 and land-based device 302, 502 described above.

[0072] In addition, in some implementations, the processor 901 may be configured to read and execute software modules from the memory 902 to perform the processing of the underwater vehicle 101, 301, 401, 501 and the land-based device 302, 502 described above.

[0073] The above-described programs may also be stored on non-transitory computer-readable media or tangible storage media. By way of example and not limitation, computer-readable media or tangible storage media include random access memory (RAM), read-only memory (ROM), flash memory, solid-state drives (SSD) or other memory technologies, compact discs (CD)-ROMs, digital versatile discs (DVDs), Blu-ray discs or other optical disc storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices. The programs may also be transmitted on transitory computer-readable media or communication media. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0074] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0075] Furthermore, each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessarily required to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0076] Furthermore, some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes. (Appendix 1) a transmitter that transmits a pinger signal underwater; a Distributed Acoustic Sensing (DAS) interrogator for acquiring acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on an optical fiber laid on the seabed; an estimation unit that estimates a shape of the optical fiber using the acoustic data at each of the plurality of points, Optical fiber laying vehicle. (Appendix 2) a position calculation unit that calculates a position of the optical fiber laying vehicle; the pinger signal includes a ranging signal and a data transmission signal; the data transmission signal includes information on the transmission time of the pinger signal, and also includes the position of the optical fiber laying vehicle at the transmission time of the pinger signal as information on the transmission point of the pinger signal; 10. The optical fiber installation vehicle according to claim 1. (Appendix 3) The estimation unit Separating the ranging signal and the data transmission signal from the acoustic data of each of the plurality of points; For each of the plurality of locations, the data transmission signal of the location is decoded to obtain information on the transmission location and transmission time of the pinger signal; performing a replica correlation process on the ranging signal for each of the plurality of points; For each of the plurality of points, estimating a position of the point using the ranging signal after the replica correlation process and the transmitting point and transmitting time of the pinger signal; estimating a shape of the optical fiber using the positions of each of the plurality of points; 1. An optical fiber installation vehicle as described in Appendix 2. (Appendix 4) The estimation unit calculating, for each of the plurality of points, a distance from the transmitting point of the pinger signal to the point in question using the ranging signal after the replica correlation process of the point in question and the transmitting point and transmitting time of the pinger signal, and calculating an arrival direction of the pinger signal at the point in question; For each of the plurality of points, a position of the point is estimated using the point from which the pinger signal was transmitted and the distance and the arrival direction calculated for the point. 10. An optical fiber installation vehicle as described in Appendix 3. (Appendix 5) The optical fiber cable may further include an optical cable storage and payout device that stores an optical cable including the optical fiber and pays out the optical cable underwater to lay the optical fiber on the seabed. 10. The optical fiber installation vehicle according to claim 1. (Appendix 6) an altimeter that detects the distance between the optical fiber laying vehicle and the seabed as an altitude; The optical cable storage and payout device pays out the optical cable underwater when the altitude is equal to or lower than a predetermined threshold. 6. An optical fiber installation vehicle as described in Appendix 5. (Appendix 7) When the optical fiber is laid on the seabed by the optical cable storage / reel-out device, the wave transmitter transmits the pinger signal underwater, the DAS interrogator acquires the acoustic data for each of the plurality of points, and the estimation unit estimates the shape of the optical fiber. 6. An optical fiber installation vehicle as described in Appendix 5. (Appendix 8) The optical fiber laying vehicle is an underwater unmanned aerial vehicle, a surface unmanned aerial vehicle, a manned ship, or a manned submarine. 10. The optical fiber installation vehicle according to claim 1. (Appendix 9) an optical fiber installation vehicle; a land-based device; The optical fiber laying vehicle comprises: A transmitter is provided to transmit a pinger signal underwater, The land-based device is a Distributed Acoustic Sensing (DAS) interrogator for acquiring acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on an optical fiber laid on the seabed; an estimation unit that estimates a shape of the optical fiber using the acoustic data at each of the plurality of points, Fiber optic sensing system. (Appendix 10) 1. A fiber optic sensing method performed by an optical fiber installation vehicle, comprising: transmitting a pinger signal underwater; acquiring, for each of a plurality of points on an optical fiber laid on the seabed, acoustic data indicating the acoustics caused by the pinger signal detected at each of the points; and estimating a shape of the optical fiber using the acoustic data at each of the plurality of points. Fiber optic sensing methods. (Appendix 11) On the computer, The procedure for sending a pinger signal underwater; acquiring, for each of a plurality of points on an optical fiber laid on the seabed, acoustic data indicating the acoustics caused by the pinger signal detected at each of the points; and a procedure of estimating a shape of the optical fiber using the acoustic data at each of the plurality of points. program.

[0077] Note that some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Notes 1 may also be dependent on Supplementary Notes 9 to 11 in the same dependency relationship as Supplementary Notes 2 to 8. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0078] 1,1A,1B,1C Optical Fiber Sensing System 101,301,401,501 Underwater drone 102 GPS unit 103 Communication Device 104,303 Control computer 105 INS unit 106 Rudder 107 Propulsion device 108 Signal Processing Computer 109 Pinger Transmitter 110 Altimeter 111 Pinger Transmitter 112 DAS Interrogator 113 Optical cable storage and payout device 114 Optical Cable 114F optical fiber 115 Mooring mechanism 302,502 Land equipment 900 Computers 901 processor 902 memory

Claims

1. a transmitter that transmits a pinger signal underwater; a Distributed Acoustic Sensing (DAS) interrogator for acquiring acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on an optical fiber laid on the seabed; an estimation unit that estimates a shape of the optical fiber using the acoustic data at each of the plurality of points, Optical fiber laying vehicle.

2. a position calculation unit that calculates a position of the optical fiber laying vehicle; the pinger signal includes a ranging signal and a data transmission signal; the data transmission signal includes information on the transmission time of the pinger signal, and also includes the position of the optical fiber laying vehicle at the transmission time of the pinger signal as information on the transmission point of the pinger signal; 2. The optical fiber laying vehicle according to claim 1.

3. The estimation unit Separating the ranging signal and the data transmission signal from the acoustic data of each of the plurality of points; For each of the plurality of locations, the data transmission signal of the location is decoded to obtain information on the transmission location and transmission time of the pinger signal; performing a replica correlation process on the ranging signal for each of the plurality of points; For each of the plurality of points, estimating a position of the point using the ranging signal after the replica correlation process and the transmitting point and transmitting time of the pinger signal; estimating a shape of the optical fiber using the positions of each of the plurality of points; 3. The optical fiber laying vehicle according to claim 2.

4. The estimation unit calculating, for each of the plurality of points, a distance from the transmitting point of the pinger signal to the point in question using the ranging signal after the replica correlation process of the point in question and the transmitting point and transmitting time of the pinger signal, and calculating an arrival direction of the pinger signal at the point in question; For each of the plurality of points, a position of the point is estimated using the point from which the pinger signal was transmitted and the distance and the arrival direction calculated for the point.

4. The optical fiber laying vehicle according to claim 3.

5. an optical cable storage and payout device that stores an optical cable including the optical fiber and pays out the optical cable underwater to lay the optical fiber on the seabed; 2. The optical fiber laying vehicle according to claim 1.

6. an altimeter that detects the distance between the optical fiber laying vehicle and the seabed as an altitude; The optical cable storage / reeling device reels out the optical cable into the water when the altitude is equal to or lower than a predetermined threshold.

6. The optical fiber laying vehicle according to claim 5.

7. When the optical fiber is laid on the seabed by the optical cable storage / reel-out device, the wave transmitter transmits the pinger signal underwater, the DAS interrogator acquires the acoustic data for each of the plurality of points, and the estimation unit estimates the shape of the optical fiber.

6. The optical fiber laying vehicle according to claim 5.

8. an optical fiber installation vehicle; a land-based device; The optical fiber laying vehicle comprises: A transmitter is provided to transmit a pinger signal underwater, The land-based device is a Distributed Acoustic Sensing (DAS) interrogator for acquiring acoustic data indicating the acoustics caused by the pinger signals detected at each of a plurality of points on an optical fiber laid on the seabed; an estimation unit that estimates a shape of the optical fiber using the acoustic data at each of the plurality of points, Fiber optic sensing system.

9. 1. A fiber optic sensing method performed by an optical fiber installation vehicle, comprising: transmitting a pinger signal underwater; acquiring, for each of a plurality of points on an optical fiber laid on the seabed, acoustic data indicating the acoustics caused by the pinger signal detected at each of the points; and estimating a shape of the optical fiber using the acoustic data at each of the plurality of points. Fiber optic sensing methods.

10. On the computer, The procedure for sending a pinger signal underwater; acquiring, for each of a plurality of points on an optical fiber laid on the seabed, acoustic data indicating the acoustics caused by the pinger signal detected at each of the points; and a procedure of estimating a shape of the optical fiber using the acoustic data at each of the plurality of points. program.

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