[0001]The present invention relates to an optical communication system using a submarine cable.
Background technology
[0002]

　The submarine communication cable system is widely used as a means for realizing communication between land and land across the sea. The medium for transmitting the signal is an optical fiber, and the transmission loss is compensated by the optical amplifier in the repeater for relay transmission. The power that drives the optical amplifier is supplied from the land stations at both ends of the cable through the feeder lines in the cable.
[0003]
　In submarine cable laying work, it is common to separate the process of cable landing work and offshore laying work. Landing cable (ShoreEnd cable) is a name for a section of submarine cable constructed in cable landing work, and is a submarine cable from the landing point to the offshore construction section.
[0004]
　At the landing point, what constitutes a demarcation point called a beach manhole is generally installed. The landing cable is pulled to the beach manhole and connected to the land cable. A land cable connects the beach manhole and the Cable Landing Station.

　As the demand for submarine cables continues to grow, landing work becomes difficult and costs are high. The main reasons for this are described below.
(1) Submarine cable congestion. The landing of submarine cables is concentrated on the coast near the big city, and multiple submarine cables are drawn into one landing station building, so the submarine cables have to approach each other and become crowded. Considering the repair of submarine cables, a certain distance is required between the submarine cables, but it becomes difficult when it is crowded. Crossing between submarine cables is also a problem. Cables underneath the new cable will not be able to be lifted.
(2) Decrease in places suitable for landing. A shallow sandy beach that is not privately owned is ideal as a landing site for submarine cables. However, in recent years, the number of such places has decreased, and a method of forming a pipeline under the coastline by a horizontal excavation (HDD: Horizontal Directional Drilling) method is also used. A dedicated excavator is required for the HDD method. In addition, since the HDD construction method has a high risk of failure depending on the geology, it is necessary to design a route based on a preliminary boring survey. Therefore, the HDD method is expensive.
[0005]
　In addition, even in places where a simple landing method could be applied on a sandy beach in the past, the HDD method may be required when a new submarine cable is additionally landed due to the construction of a seawall after that.
(3) Coordination with fishermen. The sea is a public common land, and it is necessary to obtain the consent of fishermen and other concurrent parties involved in the construction area for cable landing. In addition, during the cable landing work period, it is necessary to have nets and baskets avoided from around the cable route, which limits fishing. Therefore, the period during which landing work can be carried out is often limited to the season when fishing is inactive. Furthermore, the construction period is required to be shortened as much as possible.
(4) Necessity of cable protection work. In shallow waters of rocky areas, a resin protective tube is generally attached to the cable and then bolted by a diver of the resin protective tube in order to prevent damage to the submarine cable due to fishing activities such as bottom trawling and anchoring of ships. Further, in the case of sediment bottom sediment, simultaneous burying by a cable laying ship is generally performed from the landing point to a water depth of about 1000 to 1500 m. When laying a sufficiently deep sea area, the laying work of the landing cable is much more time-consuming than the construction method of simply placing the submarine cable on the seabed. Therefore, the construction cost per distance for laying the landing cable is significantly higher than the construction cost for laying in the open ocean and the deep sea.
(5) Protection of the natural environment. The number of cases where the coast is designated as a nature conservation area is increasing, and it is difficult to obtain a permit for construction that changes the landscape even a little.
(6) Territorial waters construction license regulation. Generally, construction work within the territorial waters of each country (12 nautical miles, about 22.2 km) can only be carried out by a licensed contractor under the Construction Business Act of that country, and the construction vessel is also required to be registered in that country (cabotage). (Cabotage) regulation). Even if these conditions are met, the processing of construction permit applications often does not proceed easily, which may have a serious impact on the construction plan of the entire cable system. Therefore, when constructing a submarine cable system that connects multiple countries, it is necessary to manage the construction work in the territorial waters and the high seas of each country separately, and to contract with a different contractor for each landing country. This point is also a factor of high cost.
A
　general submarine cable for optical communication is a composite cable having a plurality of (about 6 to 16) optical fibers and one feeder line. The feeder is a conductor for feeding to a submarine repeater or the like. The optical fiber is housed in a pipe-shaped structure to protect it from high water pressure.
[0006]
　The number of optical fiber cores (optical fiber cores) per cable (the number of optical fiber cores) has been generally about 1000 for backbone transmission on land since the 1990s. On the other hand, in the submarine cable, the number of optical fiber cores is restricted mainly for the following two reasons. (1) Since there is an upper limit to the number of optical amplification repeaters that can be mounted to compensate for the transmission loss of the optical fiber due to the limitation of the power supply from the landing station, there is an upper limit to the number of optical fiber core wires that can be used as a result. (2) There is an upper limit to the number of optical fiber cores that can be accommodated inside the pipe-shaped structure.

　A method called streaming-off, which is often used in submarine cable laying work, will be described. Streaming off occurs, for example, when a submarine cable laying vessel needs to temporarily release the cable at sea. Streaming-off is a construction method in which the end point of the submarine cable, which is the resumption point of construction, is temporarily laid on the seabed by adding a rope with a wire for exploration and an unnecessary submarine cable in order to make it easier to pull up at the time of resumption.
[0007]
　At streaming off, the end points of the submarine cable are watertightly sealed with a water pressure resistant cap and connected to the streaming cable. In this connection, the optical fiber core wire inside the streaming cable is not connected to the optical fiber core wire of the submarine cable, and only the mechanical tensile strength between the streaming cable and the submarine cable is secured.
[0008]
　When pulling up the cable, a small anchor called a Grapnel anchor is dropped from the ship to the seabed, the anchor is run so as orthogonal to the cable as much as possible, and the streaming cable is hooked and pulled up. If the anchor is hooked too close to the tip of the streaming cable, the streaming cable will slip off due to the imbalance of the left and right weights of the streaming cable during lifting, so hook the anchor not too close to the tip.
[0009]
　The route for temporary laying of the streaming cable is set in consideration of the area where the Grapnel anchor runs at the time of withdrawal.
The streaming off
　has been described in the case where the end point of the cable in the middle of laying is temporarily released from the laying ship and placed on the seabed. However, among the submarine cables extending from the device installed on the seabed, streaming off is also used in cases where the submarine cable is not connected at the time of installation and is extended or expanded by connecting the submarine cable to the end in the future.
[0010]
　In that case, make sure that the real submarine cable that extends from the device installed on the seabed is long enough, and then connect a streaming cable to be hooked at the time of withdrawal.
[0011]
　In general, it is much more difficult to lift a submarine device such as a repeater or a branching device from the seabed than to lift a submarine cable because of the following risks. Submarine equipment is heavy due to its hydraulically resistant housing structure. Furthermore, since the shape of submarine equipment is special compared to cables, it is difficult to pull it up while winding it around a drum like a cable. Therefore, in order to lift the submarine equipment on board, it must be lifted by a crane. Therefore, at that time, the cables before and after the submarine equipment are easily damaged. Therefore, submarine equipment should be designed so that it does not need to be lifted as much as possible unless it fails. Therefore, streaming off is effective and is often used.

　Today, a submarine branching device (BU: Branching Unit) for branching a cable and landing it on a plurality of grounds is widely used.
[0012]
　There are several types of branching. First, regarding the branching of light, there are those that branch in units of optical fiber core wires and those that branch in units of wavelengths (groups) that pass through one optical fiber core wire, and their band distribution and directions are fixed. It can be classified into those that are targeted and those that are variable by remote control.
[0013]
　As for the branching of the feeder, it is more complicated than the branching of light, including the configuration of grounding at the branching point, and various types are used.

　There are two main purposes for installing a cable branching device on the seabed.
(1) Branching of Communication Route A
　typical form of a submarine cable network connecting a plurality of landings will be described with reference to FIGS. 11 and 12.
[0014]
　FIG. 11 is a conceptual diagram showing the form of a network using a seafloor branching device (BU). The individual branches are shown in FIG. At a highway interchange, vehicles for different grounds are routed to different directions on the seabed so that they branch or merge. The destination of an optical signal is divided according to the optical fiber core wire through which it is flowing and the wavelength group in wavelength division multiplexing.
[0015]
　If there is a possibility of adding a route in the future, a method of attaching a streaming cable to the branch submarine cable extending from the submarine branch device and placing it on the seabed as shown in FIG. 14 is also used.
[0016]
　On the other hand, FIG. 12 is a conceptual diagram showing a form of a network called Festoon. In this form, it is not necessary to place the branch on the seabed, but the number of landing cables increases. Each landing point has a structure as shown in FIG.
[0017]
　These two landing forms may coexist in one submarine cable network.
(2) Improvement of fault tolerance by route redundancy
　FIG. 15 is a conceptual diagram showing the configuration of a submarine cable system that makes landing cables redundant. Since the submarine cable is easily damaged by fishing activities, ship anchors, etc., especially in shallow seas, techniques for providing a redundant configuration with a plurality of landing cables are disclosed in, for example, Patent Documents 1 and 2.

　Construction work may be carried out to land multiple submarine cables at one landing site. This is the above-mentioned network form called Festoon, and is generally used. In this case, the method of first landing the first one, laying it offshore, streaming off, and then landing the second one is used. The first submarine cable will be streamed off after laying, at least to areas that do not require coordination with fishermen.
[0018]
　Landing without a gap is a great advantage because it makes it possible to set up heavy machinery at the landing site and coordinate with fishermen at once. However, by landing two submarine cables, it becomes necessary to add steps of cutting, streaming off, recovery, and connection to the first landing cable.
[0019]
　The composition of a plurality of landings is as shown in FIG.

Today, the connection part of the submarine cable is realized by the Universal Joint specified and supplied by the Universal Jointing (UJ) consortium, which is an industry group, or a Joint having a similar configuration. .. In English, Universal Joint refers to a universal joint, but UJ here is the name given by the UJ consortium, not a universal joint.
[0020]
　The main requirements for the connection are (1) connection between optical fiber cores and feeders, (2) electrical insulation, (3) water pressure resistance, and (4) tensile strength equivalent to that of cables. Is. Various measures have been taken to realize this. The optical fiber is fused and connected, and the reinforcing sleeve and the extra length of the optical fiber are wound around the center and accommodated. The entire core of the connection is molded with polyethylene (polyethylene, hereinafter abbreviated as PE) to obtain insulation. The mold allows the connection to have a compact shape with bumps in the middle of the cable, allowing the connection to be wound integrally with the submarine cable.
[0021]
　UJ jointium also qualifies connection technicians, and a qualified person called UJ Jointer can board a laying vessel together with a connection jig to enable high-quality submarine cable connection even at sea.

　A device equipped with an electric circuit, such as an optical amplification repeater, is housed in a metal pressure-resistant container capable of radiating heat, covered with a pressure-resistant lid, sealed by welding, and shipped from the factory. For the connection portion between such a device and the submarine cable, what is called a cable coupling portion is used. The structure is described, for example, in Non-Patent Document 1.
[0022]
　The core of the cable coupling has a structure similar to the UJ Joint, but the basic difference is that one of the optical wires is called a tail cable. The tail cable is described in p. 123, 129.
[0023]
　The tail cable is a flexible wire that combines an optical fiber and a feeder, made to withstand the high water pressure of the deep sea. Since it is a wire used for wiring inside the housing structure (but outside the pressure resistant container), tensile strength is not required. The end of the tail cable on the pressure resistant container side is integrated with a component called a feedthrough, and the optical fiber and the feeder are connected to the inside of the housing via the feedthrough. The feedthrough has the ability to prevent water from entering the housing even if water should enter the tail cable.
[0024]
　At the end of the tail cable on the coupling part side, a metal fitting called a chip, which acts like a feedthrough, is integrated, and the optical fiber and the feeder are connected to the center of the coupling part via the chip. ..
[0025]
　The core of the connection, including the chip, is PE-molded to achieve electrical insulation. In this way, both the cable coupling and the UJ have a PE-molded cocoon ball-like appearance at the core of the connection.
[0026]
　The cable coupling connection work is done at the submarine cable factory before loading on the laying vessel. Since cable couplings do not need to be connected on board, they have not yet been standardized in the industry and are based on manufacturer-specific specifications.
Since
　the load of several thousand meters of submarine cable and submarine equipment from the laying ship on the sea surface to the sea floor is several tons, the submarine cable is designed and manufactured with strict specifications of tensile strength. ing. Therefore, the cable connection portion also needs to have the same tensile strength. The cable contains a tensile strength wire, which provides tension strength. The connection portion requires a tensile strength wire retaining portion having a structure for firmly retaining the tensile strength wire. The tensile strength wire retaining portion is described in p. 89, p. It is described in 129.
[0027]
　The basic structure is a structure in which the tensile strength wire in the cable is separated and unfolded, and the separated tensile strength wire is sandwiched between the funnel-shaped metal fitting and the pin to be pushed into the funnel-shaped metal fitting. There are these fasteners at both ends of the cable connection, which are tightly connected to the connection structure. Due to this structure, tensile strength comparable to that of the cable itself is realized.
[0028]
　In the above-mentioned UJ, the core portion including the tensile strength wire retaining portion is entirely molded with polyethylene.
[0029]
　Submarine cables include basic structural cables and armored cables with exterior iron wires wrapped around them for protection. There are various types of exteriors depending on the degree of protection. The above-mentioned tensile strength wire is inside the non-exterior cable, but it is also necessary to retain the exterior iron wire when connecting the exterior cable, and it is realized with the same structure.
Next, the technological advances of submarine communication cables and the accompanying technological obsolescence will be explained. In particular, the field of telecommunications equipment is known for its rapid technological progress and the accompanying technological obsolescence. Even after the shift from coaxial cables to optical fiber cables for communication submarine cables, technological advances continue, and the performance of submarine cable systems that have been laid and in operation continues to be inferior to the latest models.
[0030]
　Today, optical fiber transmission using wavelength division multiplexing technology is commonly used in backbone transmission lines. One of the features of wavelength division multiplexing technology is that the overall transmission capacity can be increased in response to increasing demand by adding or updating optical transmitters and receivers at both ends of the cable. Even with such expandability, the expansion is technically severe, and the situation of migrating from old cable systems to new cable systems continues. The reasons are as follows. (1) Optical characteristics of optical fiber. As the modulation speed of the transmission signal is increased, the demand for optical characteristics such as wavelength dispersion and polarization mode dispersion becomes stricter, and there are restrictions in the direction of increasing the transmission speed. (2) Band of optical amplification repeater, number of optical fiber cores that can be amplified. Advances in technology have further widened the amplification band, and improvements in power efficiency have increased the number of optical fiber cores that can be amplified, and repeaters that have been manufactured for many years are inferior in performance to the latest models. However, for example, in the trans-Pacific communication cable, more than 200 repeaters are connected in a row, and it is not economically feasible to replace many of these repeaters with the latest ones at sea, so a new communication cable system Is selected to be installed.

　Next, the technical obsolescence tendency of communication submarine cables in recent years will be additionally explained. The optical characteristics (wavelength dispersion and polarization mode dispersion) of optical fibers, which were one of the factors that made the technology obsolete, were alleviated at once by the digital coherent technology that was put into practical use in the early 2010s. Digital coherent technology has put into practical use the equalization of analog-to-digital converted signal waveforms by real-time arithmetic processing. As a result, even a slightly old optical fiber cable can be used as a transmission line for cutting-edge large-capacity transmission with almost no problem.
[0031]
　On the other hand, the technological progress of parts other than optical fibers, such as optical amplifier repeaters and submarine branching devices, continues to be remarkable, and the performance tends to gradually deteriorate over the years.
[0032]
　For these reasons, the rate of technical obsolescence has slowed down only in the submarine cable section, and it is becoming possible to use it as a part of the most advanced communication system even after many years have passed. In particular, reuse is of great significance for landing cables, which have high installation costs and are difficult to obtain permits.

　In the Faston configuration, it has been practiced to land multiple cables at one point. However, laying landing cables for future expansion in advance, such as long streaming cables, has been rarely done so far because the cost reduction effect was uncertain despite the high cost.
[0033]
　However, these days, as mentioned at the beginning, the laying work of the landing cable tends to be difficult, the construction period and cost of the section are increasing, there is little deterioration over time, and it is technically difficult to become obsolete. The situation is such that economic benefits can be expected.
Prior art literature
Patent documents
[0034]
Patent Document 1: Japanese Patent No. 4526168
Patent Document 2: US Pat. No. 6,731,879
Patent Document 3: Japanese Patent Application Laid-
Open No. 07-087013 Patent Document 4: Japanese Patent Application Laid-Open No. 2002-124141
Non-patent literature
[0035]
Non-Patent Document 1: "Optical Submarine Cable Communication", Noboru Oyama, Supervised by Moriji Kuwahara, Published by KDD Engineering and Consulting Foundation, (1991)
Outline of the invention
Problems to be solved by the invention
[0036]
　As explained at the beginning of the background technology, cable landing work has become more and more difficult in recent years. To solve this problem, it is effective to reduce the number of cable landing works. For that purpose, it is effective to lay a landing cable including a reserve capacity for future expansion.
[0037]
　However, it has been economically and technically difficult to install a submarine cable system having a large number of optical fiber core wires for expansion in the future. Since a cable system with many optical fiber cores is naturally expensive, the initial capital investment is limited to the extent that there is a concrete expansion plan. The technical reason is that if the number of optical fiber cores is increased, it is necessary to increase the number of optical amplification repeaters. be.
[0038]
　An object of the present invention is to provide a landing cable or the like that can suppress the occurrence of landing work.
Means to solve problems
[0039]
　The landing cable of the present invention is a landing cable installed offshore from the cable landing point, and is an optical fiber core wire used from the beginning of communication by the landing cable. In addition to the initially used power supply line which is a more used power supply line, a spare optical fiber core wire which is a spare optical fiber core wire is provided, and the spare optical fiber core wire is the preliminary optical fiber from the end point on the cable landing point side. It is connected to the boundary point with the cable section not including the fiber core wire, and at the boundary point, the spare optical fiber core wire end point, which is the end point of the preliminary optical fiber core wire, is held in a state where it can be used in the future.
Effect of the invention
[0040]
　The landing cable or the like of the present invention can suppress the occurrence of landing work.
A brief description of the drawing
[0041]
[Fig. 1] Fig. 1 is a conceptual diagram showing a configuration example of the submarine cable system of the first embodiment.
FIG. 2 is a conceptual diagram showing a configuration example of a cable coupling portion on the land side of the first repeater of the first embodiment.
[Fig. 3] Fig. 3 is a conceptual diagram showing a configuration example of the submarine cable system of the second embodiment.
FIG. 4 is a conceptual diagram showing a first configuration example of the landing cable of the second embodiment.
FIG. 5 is a conceptual diagram showing a second configuration example of the landing cable of the second embodiment.
FIG. 6 is a cross-sectional conceptual diagram showing a third configuration example of the landing cable of the second embodiment.
FIG. 7 is a conceptual diagram showing a first configuration example of a branch portion of a second embodiment.
FIG. 8 is a conceptual diagram showing a second configuration example of a branch portion of the second embodiment.
FIG. 9 is a conceptual diagram showing a third configuration example of the branch portion of the second embodiment.
FIG. 10 is a wiring conceptual diagram showing a configuration example of a submarine cable system of an embodiment to which optical fiber sensing is applied.
[Fig. 11] Fig. 11 is a diagram illustrating a submarine network form using a device for branching a cable.
[Fig. 12] Fig. 12 is a diagram illustrating a form of a submarine network called Festoon.
[Fig. 13] Fig. 13 is a diagram illustrating an example of use of a seafloor branch.
[Fig. 14] Fig. 14 is a diagram illustrating a method of providing a streaming cable for connecting to a seafloor branching device and a landing cable in advance.
[Fig. 15] Fig. 15 is a diagram illustrating an example of a general technique for making a landing cable redundant.
[Fig. 16] Fig. 16 is a diagram illustrating a general technique for landing multiple submarine cables at the same point.
FIG. 17 is a conceptual diagram showing the minimum configuration of the landing cable of the embodiment.
Embodiment for carrying out the invention
[0042]
　In the following embodiment, an example of a landing cable used in a submarine optical transmission system (submarine cable system) that realizes a communication line with a foreign country beyond the sea will be described.
In
　the submarine cable system of the present embodiment, a spare optical fiber core wire (spare optical fiber core wire) for expansion is provided in the landing cable. The spare optical fiber core wire is provided assuming that more optical fiber core wires will be used in the future in the submarine cable ahead of the cable boundary point (offshore side). By providing the spare optical fiber core wire, even if the number of optical fiber core wires used increases in the future, the laid landing cable can be continuously used. Therefore, the submarine cable system of the present embodiment has the effect of suppressing the occurrence of cable landing work.
[Configuration and Operation]
　FIG. 1 is a conceptual diagram showing the configuration of a submarine cable system 100, which is an example of the submarine cable system of the present embodiment. The submarine cable system 100 connects the landing station building 16 and the oncoming landing station (not shown) via the seabed. The landing cable 121 is a part of the submarine cable system 100, and is a submarine cable landed at the landing station building 16 via the land cable 18.
[0043]
　Next, the configuration around the landing point 97 will be described in detail. At the landing point 97, a beach manhole 17 that forms a demarcation point is installed. In the beach manhole 17, the landing cable 121 and the land cable 18 are connected. In some cases, the landing cable 121 is directly pulled into the landing station building 16 without going through the land cable 18. However, since the landing cable is made strong, it lacks flexibility and is difficult to handle. Therefore, in general, the land section is connected by the land cable 18 having a high flexibility.
[0044]
　The first repeater 11 is the first repeater when the landing cable 121 is traced offshore from the landing point 97. In some cases, the submarine equipment such as BU explained in the background technology section appears before the repeater, but including those submarine equipment, they will be collectively referred to as the first repeater here. ..
[0045]
　The landing cable 121 includes an optical fiber having 48 optical fiber core wires (not shown) and a feeder line. This feeder is for supplying power to the repeaters in the submarine cable system 100 including the first repeater 11. Sixteen of the above-mentioned 48 optical fiber core wires are used for communication with other countries from the beginning of communication by the submarine cable system 100. The remaining 32 optical fiber cores are spare optical fiber cores that are not used at the beginning and are to be expanded when the number of optical fiber cores used in the future increases.
[0046]
　At the end point on the land side of the landing cable 121, at least 16 optical fiber core wires used from the beginning are guided to the landing station building 16 by the land cable 18 together with the feeder line. These are connected to communication equipment (not shown) installed in the landing station building 16. In addition, some or all of the end points of the 32 spare optical fiber core wires for expansion are stored in the beach manhole 17 at the landing point, or are introduced to the landing station building 16 by the land cable 18. , Stored in the landing station building 16.
[0047]
　The 32 spare optical fiber core wires for these expansions are connected to the boundary point 119 in the sea through the landing cable 121. In the present embodiment, as will be described later, the boundary point 119 is set in the cable coupling on the landing point side of the first repeater 11. That is, the preliminary optical fiber core wire is not guided to the inside of the main body portion that performs optical amplification of the first repeater, and is not connected to the submarine cable beyond that.
[0048]
　The boundary point 119 is set outside the territorial waters line (12 nautical miles (22.2 km) from the coast). Since the distance from the coastline to the first repeater 11 is generally about 30 to 50 km, it can be expected to cross the territorial waters line. Therefore, it is desirable that the boundary point 119 is set near the first repeater 11.
[0049]
　Further, the boundary point 119 is any of a range beyond the section where the cable burial method is required, a range beyond the section where the HDD method is required, and a range beyond the section where permission for installation work is required. Is set to.
[0050]
　FIG. 2 is a conceptual diagram showing a configuration example of the first repeater 11 shown in FIG. In the following, first, the structure of a general repeater will be described. Then, the mounting configuration of what constitutes the boundary point 119 in this embodiment will be described.
[0051]
　The first repeater 11 includes a cable coupling portion 24 on the land side, a repeater housing 37, and a cable coupling portion on the offshore side (not shown). The cable coupling portion 24 includes a boot 38, a storage portion 35, and a bellows portion 36. The same applies to the cable coupling portion on the offshore side.
[0052]
　The boot 38 is a conical member that protects the vicinity of the cable connection. The bellows portion 36 has a bellows shape, and the relative angle between the main body of the cable coupling portion and the repeater housing 37 can be changed.
[0053]
　The storage unit 35 includes a mold unit 34. The mold portion 34 is, for example, one molded from polyethylene. Molding with polyethylene ensures electrical insulation.
[0054]
　The mold portion 34 is provided with a tensile strength wire retaining portion 33 and an optical fiber extra length storage portion 31 inside. The landing cable 121 is fixed to the inside of the mold portion 34 by the tensile strength wire retaining portion 33. The optical fiber core wire in the landing cable 121 and the tail cable 23 extending from the inside of the repeater housing 37 are fusedly connected and accommodated in the mold portion 34. These structures are also described in the background art section.
[0055]
　Next, the mounting configuration of the boundary point 119 shown in FIG. 1 in the present embodiment will be described. In short, the present mounting configuration is to store the end points of the preliminary optical fiber core wires connected from the landing point 97 in the mold portion, for example, in a wound state.
[0056]
　The landing cable 121 is the same as that shown in FIG. 1, and includes 48 optical fiber core wires and a feeder line. Although not shown, 48 optical fiber core wires are exposed to the right by a predetermined length from the end fixed to the tensile strength wire retaining portion 33 of the landing cable 121.
[0057]
　Of these 48 optical fiber cores, 16 optical fiber cores used from the beginning of communication are connected to the tail cable 23 and further offshore via an optical amplifier (not shown) inside the repeater housing 37. It is connected to the optical fiber core of the submarine cable to which it is heading. On the other hand, 32 of these 48 optical fiber core wires are stored in the optical fiber extra length storage unit 31 by, for example, being rolled up. In the spare 32 optical fiber core wires, 16 pairs of optical fiber core wires may be looped back connected to each other. As a result, the number of test executions in the continuity monitoring from land of these 32 spare optical fiber core wires is half that in the case where the loopback connection is not made. Therefore, it becomes easy to monitor the continuity of these 32 spare optical fiber core wires from land.
[0058]
　In the above explanation, the total number of optical fiber cores included in the landing cable is 48, of which 16 are the optical fiber cores (initially used optical fiber cores) used from the beginning of communication. An example of the case where the number of preliminary optical fiber cores is 32 has been described. However, the total number of optical fiber cores, the number of initially used optical fiber cores, and the number of spare optical fiber cores included in the landing cable of the present embodiment are not limited to these numbers.
[Effect]
　The landing cable of the present embodiment includes a spare optical fiber core wire. The spare fiber optic core is pre-included in the landing cable to be laid in case the number of fiber optic cores used increases due to future renewal of the submarine cable beyond the boundary point. When the number of optical fiber cores used increases, by using this spare optical fiber core as well, it is possible to suppress the occurrence of new cable landing work.
[0059]
　Here, a supplementary explanation will be given of when expansion is performed to increase the number of optical fiber cores used in the submarine cable (the number of optical fiber cores used). There are two main reasons why the number of optical fiber cores used at the beginning of cable installation may be less than the maximum number of cores that can be accommodated in the cable. One is when there is a limit to the power that the amplification repeater can receive. Since there is an upper limit to the power supply from the landing station to the submarine cable, there is a limit to the power that can be used by each amplification repeater. An amplification repeater for each core wire is stored in the amplification repeater main body, and as the number of core wires increases, the number of amplifiers increases and the required power increases. Therefore, if the power limit per repeater is strict, the number of core wires that can be amplified and relayed is limited. The other is when the maximum number of optical fiber cores that can be accommodated is not required when predicting future increases in communication demand at the beginning of installation. In that case, the number of optical fiber cores is selected to be smaller than the maximum number of optical fiber cores that can be accommodated in order to minimize the investment required.
[0060]
　In the former case, it is assumed that the energy conversion efficiency of the optical amplifier in the repeater is improved by the future technological improvement, and the power required for the optical amplification relay per optical fiber core wire is reduced. In that case, in the landing cable of the present embodiment, by using the spare optical fiber core wire already provided, it is possible to increase the number of optical fiber core wires used without updating the landing cable. It will be possible.
[0061]
　In the latter case, it is assumed that the communication demand has increased more rapidly than expected. In that case, the number of optical fiber cores will be insufficient, and the submarine communication system including the landing cable will be renewed. However, even in that case, the landing cable of the present embodiment can reuse the communication ground as a communication line for a new communication route changed from the original communication ground.
[0062]
　Even with the landing cable of the present embodiment, if the number of optical fiber core wires used in the submarine cable is to be increased, it is necessary to re-lay the submarine cable and the repeater beyond the boundary point. However, when the landing cable of the present embodiment is used, a spare optical fiber core wire is included in the landing cable in advance. Therefore, the landing cable of the present embodiment can be used as a part of the new optical submarine cable system without laying a new landing cable.
[0063]
　The boundary point, which is the end point on the offshore side of the preliminary fiber optic core wire, is also set outside the territorial waters, that is, on the high seas. As explained in part in the background technology section, each country enforces the law of the license system for civil engineering and construction. The license system applies to the territorial waters covered by the sovereignty of the country. Therefore, construction work carried out in the territorial waters can only be carried out by a contractor with a civil engineering license in that country. In addition, construction work in the territorial waters is an economic activity within the country, so it is necessary to comply with the tax system of that country. Therefore, construction work in the territorial waters is laborious and costly, and it is desirable to avoid it if possible. On the other hand, outside the territorial waters, the law of the country generally does not apply. Therefore, since the spare optical fiber core wire is laid in advance to the outside of the territorial waters, the benefit of labor and cost reduction can be enjoyed.
[0064]
　The boundary point is also set in a range beyond the section where the cable burial method or the horizontal excavation method is required. Since the cable burial method is for burying the submarine cable, it is more costly than the method of simply placing the submarine cable on the seabed. The horizontal excavation method is more costly because it requires a dedicated excavator and a route design based on a preliminary boring survey, as described in the background technology section. If the boundary point is set to a range beyond the section where the cable burial method or horizontal excavation method is required, the method of simply placing it on the seabed can be applied, and the benefit of cost reduction can be enjoyed. Can be done.
[0065]
　The boundary point is also set in a range beyond the section requiring the acquisition of a permit for installation work. As a result, even if the country is overseas or the law of the country is applied, it is not necessary to obtain a permit, and the benefit of labor and cost reduction can be enjoyed.
[0066]
　In the above, the example in which the boundary point is in the cable coupling portion on the land side of the first repeater has been described, but the installation position of the boundary point is not limited to the inside of the cable coupling portion. For example, a boundary point may be set in the submarine cable connection portion provided in the middle of the coastline and the first repeater. However, since it is possible to reuse up to the relevant connection when expanding to increase the number of optical fiber cores used, it is desirable that the spare optical fiber cores be connected as close to the first repeater as possible.
[0067]
　Further, the boundary point may be set offshore from the first repeater. However, in that case, the first repeater also needs to be equipped with an optical amplifier for the spare optical fiber core wire. Therefore, the price of the first repeater increases because it is a special product having different specifications from many other repeaters. In the submarine cable system, in order to quickly recover from a failure, spare products (spare machines) for repairing repeaters and submarine cables that require a long time to manufacture are stored in a warehouse on land and shipped. Perform repair work. Since this spare machine needs to be prepared for each type of repeater, as the number of types increases, the cost for manufacturing and holding the spare machine also increases.

　The landing cable of the first embodiment has only an extra optical fiber core wire as a spare for future expansion, and does not have a spare feeder line (spare feeder line). Therefore, in the landing cable of the first embodiment, a new submarine cable cannot be additionally connected to the landing cable.
[0068]
　On the other hand, in the landing cable of the second embodiment, since there is only one landing cable, the cable landing work can be done only once. Nevertheless, the landing cable of the present embodiment includes a configuration in which a spare branch submarine cable for connecting a new submarine cable is installed on the seabed in advance. Here, the branched submarine cable refers to a branched submarine cable. Therefore, the landing cable of the present embodiment can suppress the occurrence of landing work when a new submarine cable is added in the future.
[Configuration and Operation]
　FIG. 3 is a conceptual diagram showing the configuration of the submarine cable system 200, which is an example of the submarine cable system of the present embodiment. The landing cable 221 of the submarine cable system 200 includes a spare optical fiber core wire and a spare feeder line that are not initially used. The preliminary optical fiber core wire is branched at the branch portion 41, and the end points of the branched optical fiber core wire and the preliminary feeding line form the boundary point 219.
[0069]
　The landing cable 221 has the same number of optical fibers as the sum of the number of optical fiber cores of the four branched submarine cables 21a to 21d and the same number of optical fiber cores as the number of power supply lines of each branched submarine cable. It is equipped with a power supply line. The landing cable 221 is one landing cable. The number of optical fiber cores to be distributed to each branched submarine cable is arbitrary, but here, an example in the case of 16 cables will be described.
[0070]
　At the land-side end of the landing cable 221, at least 16 optical fiber core wires used from the beginning of communication by the landing cable 221 are connected to the feeder line used from the beginning, for example, via a land cable. It is led to the landing station building 16. These are connected to communication equipment (not shown) installed in the landing station building 16. In addition, at the end, part or all of the land end of the spare optical fiber core wire and feeder for expansion to connect the new submarine cable to the offshore side is in the beach manhole at the landing point. It is stored at, or it is introduced to the landing station building 16 and stored there.
[0071]
　The branch portion 41 branches the optical fiber core wire group and the feeder line provided in the landing cable 221 to each branch submarine cable.
[0072]
　In the present embodiment, the boundary point 219, which is the boundary between the cable section including the spare optical fiber core wire and the spare feeder line and the cable section not included, is composed of the branch portion 41 and the branch submarine cables 21a to 21d. However, what constitutes the boundary point in the narrow sense is the branch portion 41.
[0073]
　Of the branched submarine cables, only the branched submarine cable 21c is used from the beginning of communication by the submarine cable system 200. The first repeater 11 is a general one similar to many other repeaters in the submarine cable system 200, and the number of optical fiber cores of the cable before and after the repeater is also the same as that of other repeaters.
[0074]
　The branched submarine cables 21a, 21b and 21d are expansion reserves that are not initially used. The offshore ends of the bifurcated submarine cables 21a, 21b and 21d are watertightly sealed and streamed-off. Streaming-off is a method of mechanically adding a streaming cable and laying it on the seabed in order to make it easier to pull up the submarine cable end point, which is the construction restart point, as explained in the background technology section. (The optical fiber core wire and the feeding line are not connected.) Although not
　shown, the branched submarine cable 21c is connected to other countries via a plurality of repeaters beyond the branch submarine cable 21c. Communication between one's own country and another country is performed by an optical fiber core wire included in the branched submarine cable 21c.
[0075]
　The branch portion 41 and the branch submarine cables 21a to 21d constituting the boundary point 219 are, of course, set between the coastline and the first repeater 11.
[0076]
　The branch portion 41 and the branch submarine cables 21a to 21d constituting the boundary point 219 are also set outside the territorial waters, that is, on the high seas. As explained in part in the background technology section, each country enforces the law of the license system for civil engineering and construction. The license system applies to the territorial waters covered by the sovereignty of the country. Therefore, construction work carried out in the territorial waters can only be carried out by a contractor with a civil engineering license in that country. In addition, construction work in the territorial waters is an economic activity within the country, so it is necessary to comply with the tax system of that country. Therefore, construction work in the territorial waters is laborious and costly, and it is desirable to avoid it if possible. On the other hand, outside the territorial waters, the law of the country generally does not apply. Therefore, by setting the boundary point 219 outside the territorial waters, the benefit of labor and cost reduction can be enjoyed.
[0077]
　The branch portion 41 and the branch submarine cables 21a to 21d constituting the boundary point 219 are also set in a range beyond the section where the cable burial method or the horizontal excavation method is required. Since the cable burial method is for burying the submarine cable, it is more costly than the method of simply placing the submarine cable on the seabed. The horizontal excavation method is more costly because it requires a dedicated excavator and a route design based on a preliminary boring survey, as described in the background technology section. If the boundary point 219 is set in a range beyond the section where the cable burial method or horizontal excavation method is required, the method of simply placing it on the seabed can be applied, and the benefit of cost reduction can be enjoyed. Can be done.
[0078]
　The branch portion 41 and the branch submarine cables 21a to 21d constituting the boundary point 219 are also set in a range beyond the section requiring the acquisition of a permit for installation work. As a result, even if the country is overseas or the law of the country is applied, it is not necessary to obtain a permit, and the benefit of labor and cost reduction can be enjoyed.
[0079]
　Next, a configuration example of the landing cable 221 shown in FIG. 3 will be described.
[0080] [0080]
　FIG. 4 is a conceptual diagram showing the landing cable 21 which is the first configuration example of the landing cable 221 of FIG. The landing cable 21 shown in FIG. 4 is a bundle of a plurality of minimum basic units of a submarine cable called a LW (Light Weight Cable) core cable and decorated with an exterior. Hereinafter, the LW core cable may be abbreviated as LW core. FIG. 4A is a cross-sectional view of the landing cable 21.
FIG. 4B is a cross-sectional view showing the configuration of the LW core cable 51n, which is a configuration example of the LW core cables 51a to 51d shown in FIG. 4A.
[0081]
　The exterior iron wire 52 of the landing cable 21 shown in FIG. 4 is for protecting the cable from fishing activities in shallow water, anchoring of a ship, contact with a cable burying machine during landing work, and the like.
[0082]
　The landing cable 21 has a structure in which four LW core cables 51a to 51d are gently wound around an interposition 53 and filled with inclusions such as resin.
[0083]
　The LW core cable 51n shown in FIG. 4B is a basic unit of a general submarine cable. As shown in FIG. 4B, the LW core cable 51n includes an optical fiber accommodating pipe 56, a plurality of tensile strength wires 562 arranged so as to surround the optical fiber accommodating pipe 56, and a pipe-shaped feeder line 54 covering the outside thereof. And the outside thereof is covered with an insulating coating material 57. The tensile strength wire 562 is a steel wire for holding and withstanding when tension is applied to the cable. The optical fiber accommodating pipe 56 is a strong steel pipe that withstands the optical fiber so as not to apply water pressure, and accommodates the optical fiber core wire.
[0084]
　There is a degree of freedom in the number of LW core cables included in the landing cable 21. FIG. 5 is a conceptual diagram showing a cross section of a landing cable 21 which is a second configuration example of the landing cable 221 shown in FIG. 3 including six LW core cables 51a to 51f. Each LW core cable has the same configuration as the LW core cable 51n shown in FIG. 4 (b).
[0085]
　FIG. 6 is a cross-sectional conceptual diagram showing the landing cable 21 which is the third configuration example of the landing cable 221 shown in FIG. Unlike the first and second configuration examples, the landing cable 21 shown in FIG. 6 is not an aggregate of the basic unit structure (LW core) of the submarine cable, but is configured as one cable. FIG. 6A is a cross-sectional view of the landing cable 21, and FIG. 6B is a cross-sectional view showing a feeder line 62 which is a configuration example of each feeder shown in FIG. 6A.
[0086]
　The landing cable 21 shown in FIG. 6 has a tensile strength wire 61 at the center, and feeder lines 62a to 62e with an insulating coating are arranged concentrically around the tensile strength wire 61. In the landing cable 21, the optical fiber accommodating pipes 63a to 63e are further arranged in the valley where the feeder lines are in contact with each other, and the structure up to this point is resin-molded. The landing cable 21 is further wound with a protective exterior iron wire 52 on the outside thereof.
[0087]
　The tensile strength wire 58 is for realizing the tension performance of the cable, and serves as a central interposition during cable manufacturing. As shown in FIG. 6B, the feeder line 62 is formed by covering the feeder conductor 621 with a feeder line coating 622 which is an insulating material such as resin. The fiber optic accommodation pipe 63 does not have to be as strong as that used for LW core cables. The configuration shown in FIG. 6 includes optical fiber accommodating pipes for the number of branches. However, the optical fiber core wires may be put together in one pipe. In that case, it is necessary to distribute the optical fiber core wire correctly at the branch portion described later. The exterior iron wire 52 is the same as that shown in FIGS. 4 and 5.
[0088]
　Since the above-mentioned first and second configuration examples are collective cables of LW cores, they have the advantage that general connection parts and connection techniques can be used by disassembling the landing cable 21 to the LW core, but they are slightly thicker. There is a disadvantage that it will end up. On the other hand, in the third configuration example, the structure can be simplified, the diameter can be reduced, the weight can be reduced, etc. However, there is a drawback that special connection parts are required.
[0089]
　Next, a configuration example of the branch portion 41 shown in FIG. 3 will be described. The branch portion 41 shown in FIG. 3 is described with an example of four branches, but in the following description, in order to avoid complication of the drawing, the branch portion 41 will be described with an example of three branches.
[0090]
　FIG. 7 is a conceptual diagram showing a first configuration example of the branch portion 41. The branch portion 41 shown in FIG. 7 is used when the landing cable 21 is a collective cable of a plurality of LW core cables as in the structure shown in FIGS. 4 and 5.
[0091]
　The branch portion 41 shown in FIG. 7 includes boots 45a and 46a to 46c and a housing 47. The housing 47 includes an exterior wire fastening portion 42 and mold portions 44a to 44c. The mold portions 44a to 44c include tensile strength wire retaining portions 43a to 43c.
[0092]
　The exterior iron wire of the landing cable 21 (corresponding to the exterior iron wire 52 in FIG. 4) is fixed to the housing 47 by the exterior wire fastening portion 42. The LW core cables 51a to 51c of the landing cable 21 are guided to the inside of the mold portions 44a to 44c in the housing 47. The LW core cables 51a to 51c are UJ compliant. UJ is described in the Background Techniques section.
[0093]
　The branched submarine cables 21a to 21c also comply with the UJ specifications. The branched submarine cables 21a to 21c are fixed to the mold portions 44a to 44c by the tensile strength wire retaining portions 43a to 43c. Although not shown, since the mold portions 44a to 44c are fixed to the housing 47, the branched submarine cables 21a to 21c are fixed to the housing 47. As a result, the branched submarine cables 21a to 21c are fixed to the exterior iron wire provided in the landing cable 21 via the housing 47.
[0094]
　The optical fiber core wire and feeder of the optical fiber (not shown) included in the LW core cable guided to each mold portion are the optical fiber core wire and feeder of the optical fiber included in the branched submarine cable fixed to the mold member. Be connected. The connection is made by the method disclosed in the UJ specifications. UJ is described in the Background Techniques section.
[0095]
　The mold portions 44a to 44c are internally molded with, for example, polyethylene. It is generally known that by molding with polyethylene, it is possible to secure connection between optical fiber core wires and feeder wires, electrical insulation, water pressure resistance, and tensile strength equivalent to that of a cable.
[0096]
　FIG. 8 is a conceptual diagram showing a second configuration example of the branch portion 41. The branch portion 41 shown in FIG. 8 is used when the landing cable 21 is specially designed as shown in FIG. 6 and does not include an LW core cable. FIG. 7 shows that the branch portion 41 shown in FIG. 8 is a tail cable 48a to 48c instead of the LW core cables 51a to 51c of the landing cable 21 as the optical wiring from the landing cable 21 drawn into each mold portion. Different from the one. Tail cables are described in the Background Techniques section.
[0097]
　The tail cables 48a to 48c are also fixed to the mold portions 44a to 44c by the tips 39a to 39c. Chips are described in the Background Techniques section.
[0098]
　The branch portion 41 shown in FIG. 8 also uses the same configuration as the cable coupling to connect between the optical fiber core wires and the feeder lines between the tail cables 48a to 48c and the branch submarine cables 21a to 21c. The points to be performed are different from those shown in FIG. Cable coupling is described in the Background Techniques section.
[0099]
　Except for the above, the description of the branch portion 41 shown in FIG. 8 is the same as that shown in FIG. 7.
[0100]
　FIG. 9 is a conceptual diagram showing a third configuration example of the branch portion 41. In the branch portion 41 shown in FIG. 9, the housings 47a to 47c provided with the mold portions 44a to 44c are provided outside the housing 47 and are connected to the housing 47 by universal joints 49a to 49c. 7 or different from that shown in FIG. Further, the branch portion 41 shown in FIG. 9 is different from that shown in FIG. 7 or FIG. 8 in that the boots 46a to 46c cover the housings 47a to 47c.
[0101]
　The optical wirings 50a to 50c shown in FIG. 9 are any of the LW core cables 51a to 51c shown in FIG. 7 and the tail cables 48a to 48c shown in FIG. When the optical wirings 50a to 50c are the LW core cables 51a to 51c shown in FIG. 7, the optical wirings 50a to 50c are connected to the branched submarine cables 21a to 21c by a method conforming to, for example, UJ specifications. On the other hand, when the optical wirings 50a to 50c are the tail cables 48a to 48c shown in FIG. 8, the optical wirings 50a to 50c are connected to the branched submarine cables 21a to 21c, for example, by the cable coupling described above.
[Effect]
　In the submarine cable system of the present embodiment, the landing cable is provided with a spare optical fiber core wire and a spare feeder line in case it becomes necessary to add a new submarine cable in the future. These spare lines connect to a streamed-off branched submarine cable. Therefore, the submarine cable system enables the addition of submarine cables without performing new landing work by connecting a new submarine cable to the streamed off branch submarine cable. Therefore, the submarine cable system can suppress the occurrence of new landing work.

　The preliminary optical fiber core wire of the landing cable of the first and second embodiments cannot be used for communication because it is not connected to the communication ground. However, the preliminary fiber optic core wire can be applied to vibration and temperature sensing applications in the section where the landing cable is laid. This will be described as the third embodiment.
[0102]
　First, optical fiber sensing will be briefly described. An optical fiber, which is originally a medium for transmitting a signal, can also carry information on the temperature and vibration of the environment in which the optical fiber is placed on the light transmitted therein. Therefore, the optical fiber core wire has come to be used for sensing applications as well.
[0103]
　FIG. 10 is a wiring conceptual diagram showing a configuration example in which optical fiber sensing is applied to the configuration of the submarine cable system 100 shown in FIG.
[0104]
　The interrogator 70 periodically sends the pulsed light to the optical fiber core wire of the landing cable 121. Then, weak light returns from the optical fiber core wire to the interrogator 70 due to the backscattered light phenomenon in the optical fiber core wire. By analyzing this light, it is possible to obtain information on the temperature and vibration of various parts of the optical fiber core wire at the moment when the pulsed light passes.
One of the features of optical fiber sensing is that only one optical fiber core wire is required, and no electric wire for power or signal transmission is required. Therefore, it is possible to apply fiber optic sensing to the preliminary fiber optic core wire of the landing cable of any embodiment, whereby the landing cable 121 monitors the temperature and vibration of the seabed in the section up to the boundary point 119. It can be used to do.
[0105]
　The optical fiber core wire for optical fiber sensing may be allocated for provisional use until it is used for communication in the future, or may be assigned as a core wire dedicated to sensing.

　FIG. 17 is a conceptual diagram showing the configuration of the landing cable 321x, which is the minimum configuration of the landing cable of the embodiment.
[0106]
　The landing cable 321x is a landing cable installed offshore from the cable landing point. The landing cable 321x also includes an initially used optical fiber core wire 56ax, which is an optical fiber core wire used from the beginning of communication by the landing cable 321x, and an initially used feeder line 54x, which is a feeder used from the beginning. In addition, the landing cable 321x includes a spare optical fiber core wire 56bx, which is a spare optical fiber core wire.
[0107]
　The preliminary optical fiber core wire 56bx is connected from the end point on the cable landing point side to the boundary point with the cable section not including the preliminary optical fiber core wire 56bx. Further, at the boundary point, the end point of the spare optical fiber core wire 56bx, which is the end point of the spare optical fiber core wire 56bx, is held in a state where it can be used in the future.
[0108]
　The arrangement of the initially used optical fiber core wire 56ax, the spare optical fiber core wire 56bx, and the initially used feeder line 54x is not limited to the case shown in FIG. 17, and is arbitrary.
[0109]
　The spare fiber optic core wire 56bx is spare and its ends are kept ready for future use. Therefore, when the number of optical fiber core wires of the submarine cable connected to the landing cable 321x increases, a new optical fiber core wire straddling the coastline can be newly connected by the preliminary optical fiber core wire 56bx. Therefore, the landing cable 321x can suppress the occurrence of new landing work of the submarine cable.
[0110]
　Therefore, the landing cable 321x exhibits the effects described in the section [Effects of the Invention] by the above configuration.
[0111]
　Here, the landing cable 321x shown in FIG. 17 is, for example, the landing cable 21 shown in FIG. 1 or FIG.
[0112]
　Further, the initially used feeder line 54x is, for example, the feeder line shown in FIG. 4, the feeder line included in the LW core cables 51a to 51f shown in FIG. 5, or the feeder line 54a to 54e shown in FIG. It has been used since the beginning of communication.
[0113]
　Further, the initially used optical fiber core wire 56ax is, for example, an optical fiber included in the landing cable 21 connected to the optical fiber included in the submarine cable 22 shown in FIG. The initially used optical fiber core wire 56ax is, for example, connected to the optical fiber core wire included in the tail cable 23 among the optical fiber core wires included in the landing cable 121 shown in FIG. The initially used optical fiber core wire 56ax is, for example, an optical fiber core wire included in the optical fiber included in the landing cable 21 connected to the optical fiber core wire provided in the optical fiber included in the branched submarine cable 21c shown in FIG. be.
[0114]
　Further, the landing point is, for example, the landing point 97 shown in FIG. 1 or FIG.
[0115]
　Further, the preliminary optical fiber core wire 56bx is, for example, an optical fiber core wire included in the optical fiber included in the landing cable 21, which is not connected to the optical fiber core wire provided in the submarine cable 22 shown in FIG. The spare optical fiber core wire 56bx is, for example, an optical fiber in which the vicinity of the end thereof is stored in the optical fiber extra length accommodating portion 31 shown in FIG. The spare optical fiber core wire 56bx is, for example, the optical fiber included in the landing cable 21 connected to the optical fiber core wire group included in the optical fiber included in the branched submarine cables 21a, 21b and 21d shown in FIG. It is a fiber core wire.
[0116]
　Further, the boundary point is, for example, the boundary point 119 shown in FIG. 1 or FIG. 10 or the boundary point 219 shown in FIG.
[0117]
　Further, the preliminary optical fiber core wire end point is, for example, the end point of the optical fiber core wire included in the optical fiber included in the landing cable 21 housed in the optical fiber extra length storage portion 31 shown in FIG. The preliminary optical fiber core wire end point is, for example, an optical fiber core wire included in the optical fiber included in the landing cable 21 connected to the optical fiber core wire group included in the branched submarine cables 21a, 21b and 21d shown in FIG. It is the end point of.
[0118]
　Although each embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and further modifications, substitutions, and adjustments can be made without departing from the basic technical idea of ​​the present invention. Can be added. For example, the composition of the elements shown in each drawing is an example for facilitating the understanding of the present invention, and is not limited to the composition shown in these drawings.
[0119]
　Further, a part or all of the above-described embodiment may be described as in the following appendix, but is not limited to the following.
(Appendix 1)
　Cable A landing cable installed offshore from the landing point, which
　is an optical fiber core wire used from the beginning of communication by the landing cable, and an initially used optical fiber core wire and used from the beginning. In addition to the initially used power supply line which is a power supply line, a spare optical fiber core wire which is a spare optical fiber core wire is provided, and the
　spare optical fiber core wire is the spare optical fiber core wire from an end point on the cable landing point side. A landing cable that is connected to a boundary point with a cable section that does not include the above, and at the
　boundary point, the preliminary optical fiber core wire end point, which is the end point of the preliminary optical fiber core wire, is held in a state where it can be used in the future.
(Appendix 2)
　The boundary point is the landing cable described in Appendix 1 located on the land side of the cable coupling portion on the land side of the first repeater or submarine equipment when traced from the landing point.
(Appendix 3)
　The landing cable described in Appendix 1 or Appendix 2 whose boundary point is outside the territory.
(Appendix 4)
　The boundary point is within the range beyond the area where the cable burial method is required, the area where the horizontal excavation method is required, and the area where the installation work permit is required. The landing cable according to any one of Supplementary note 1 to Supplementary note 3, which is at least one of them.
(Appendix 5)
　A spare feeding line is further provided at the end point on the side of the landing point, and the
　preliminary optical fiber core wire and the preliminary feeding line are connected to the boundary point, and at the
　boundary point, with the preliminary optical fiber core wire end point. The end point of the preliminary power supply line, which is the end point of the preliminary power supply line, is kept in a state where it can be used in the future, is bundled into one, and is equipped with a cable branching device at the tip on the offshore side thereof
　. The initially used submarine cable including the fiber core wire and the initially used feeding line, and a plurality of spare submarine cables having the spare optical fiber core wire and the spare feeding line are branched into the
　spare submarine cable. At the seabed end point, the spare fiber core wire end point and the spare power supply line end point are kept available in the future, and the
　boundary point and the spare seabed cable are the first to be traced from the landing point. It is the range on the land side from the cable coupling part on the land side of the repeater or the first submarine equipment, it is outside the territory, and it is the range beyond the area where the cable burial method is required, and the horizontal excavation method is required. The landing cable according to any one of Supplementary note 1 to Supplementary note 4, which is in a range exceeding the area where the installation work is required to obtain a license.
(Appendix 6)
　A streaming cable is connected to the seabed end of the spare submarine cable.
　The boundary point, the spare submarine cable, and the streaming cable are in the range on the land side of the cable coupling portion, are outside the territory, and are in the range beyond the area where the cable burial method is required. The landing cable according to Appendix 5, which is in a range beyond the area where the horizontal excavation method is required and is in a range beyond the area where the license acquisition is required.
(Appendix 7)
A composite submarine cable formed by combining a plurality of non-exterior submarine cables, the non-exterior submarine cable includes an optical fiber core wire and a feeding line, and the
　cable brancher is the non-exterior submarine cable. The landing cable according to Appendix 5 or Appendix 6 in which a plurality of combined cables are separated into units of the non-exterior submarine cable and connected by using existing submarine cable connection parts and connection technology.
(Supplementary Note 8)
　The landing cable according to any one of Supplementary note 1 to Supplementary note 7, wherein the spare optical fiber core wire is loopback-connected to the other spare optical fiber core wire at the boundary point.
(Supplementary note 9)
　The landing cable according to any one of Supplementary note 1 to Supplementary note 8, wherein a part of the optical fiber core wires connected to the boundary point is used for optical fiber sensing applications.
(Appendix 10)
　Of Appendix 1 to Appendix 9, where the boundary point is assumed to be outside the territory of the country where the landing point is set, or outside the territory of the country. A partial landing cable that is all part of the area of ​​the submarine cable described in any one.
(Appendix 11)
　It is equipped with an optical fiber core wire group consisting of a plurality of optical fiber core wires and a feeding line group consisting of a feeding wire, and is installed from the
　landing point. It is either in the first repeater, which is the repeater of the above, or between the landing point and the first repeater, and the
　optical fiber core wire group is the first optical fiber core wire group and the second. The optical fiber core wire of
　the first optical fiber core wire group including the optical fiber core wire group is the optical fiber connected to the submarine cable after the first repeater which is the submarine cable ahead of the first repeater. It is a fiber core wire, and the
　optical fiber core wire of the second optical fiber core wire group is a spare optical fiber core wire that is not connected to the submarine cable after the first repeater, and is
　the second optical fiber core wire. A
　landing cable in which the core end of the optical fiber core of the wire group is kept available .
(Appendix 12)
　The landing cable according to Appendix 11, wherein the end of the core wire is in a range beyond the territorial waters.
(Appendix 13)
　Whether the end of the core wire is in a range exceeding the area where the cable burial method is required, or the area where the horizontal excavation method is required exceeds the area where the horizontal excavation method is required, or is installed. The landing cable according to Appendix 11 or Appendix 12, which is at least one of the areas beyond the area requiring a work permit.
(Appendix 14)
　The landing cable according to any one of Supplementary note 11 to Supplementary note 13, wherein the optical fiber core wires included in the second optical fiber core wire group are loopback-connected.
(Appendix 15)
　The second optical fiber core is held by the optical fiber extra length accommodating portion at the end of the optical fiber on the sea side of the optical fiber including the optical fiber core wire of the second optical fiber core wire group. The landing cable according to any one of Supplementary note 11 to Supplementary note 14, wherein the optical fiber core wire of the wire group is kept in the available state.
(Appendix 16)
　The optical fiber core wire of the second optical fiber core wire group is used when the number of submarine cable optical fiber core wires after the first repeater included in the submarine cable after the first repeater increases. The landing cable described in Appendix 15, which is supposed to be used.
(Appendix 17)
　The end of the core wire on the sea side of the optical fiber core wire group of the first optical fiber core wire group is connected to the submarine cable after the first repeater by a connecting device, and the optical fiber extra length. The storage unit is the landing cable described in Appendix 16 included in the connection device.
(Appendix 18)
　The landing cable according to Appendix 17, wherein the optical fiber extra length storage portion is molded with a resin.
(Appendix 19)
　The landing cable according to Appendix 18, wherein the resin is polyethylene.
(Appendix 20)
　The landing cable according to any one of Supplementary note 17 to Supplementary note 19, wherein the connecting device is provided in the first repeater.
(Appendix 21)
　A branch portion is provided, the portion on the sea side from the branch portion is divided into a second plurality of branch submarine cables, and some of the branch submarine cables are submarine cables after the first repeater. The optical fiber core wire connected to the other branch seabed cable and included in the other branch seabed cable is the optical fiber core wire of the second optical fiber core wire group. The listed landing cable.
(Appendix 22)
　The optical fiber core wire of the second optical fiber core wire group is described in Appendix 21, which is assumed to be used when another submarine cable is added in the future. Landing cable.
(Appendix 23)
　The branch submarine cable end, which is the end not connected to the branch of the branch submarine cable, is streamed off, and the streaming off causes the branch of the part. The landing cable according to Appendix 21 or Appendix 22, wherein the core end of the optical fiber core of the second optical fiber core group included in the submarine cable is kept in the available state.
(Appendix 24)
　The landing cable according to Appendix 23, wherein the streaming off is a connection of a dummy submarine cable or rope to the end of the branch submarine cable and a sealing of the end of the branch submarine cable.
(Appendix 25)
　The landing cable according to any one of Supplementary note 21 to Supplementary note 24, wherein the number of feeding lines is the plurality of lines.
(Appendix 26)
　The landing cable according to any one of Appendix 21 to Appendix 25, which comprises a configuration in which a second plurality of non-exterior submarine cables without an exterior are bundled.
(Appendix 27)
　Corresponds to the combination of the submarine cable optical fiber core wire after the first repeater of the submarine cable after the first repeater and the submarine cable power supply line after the first repeater of the submarine cable after the first repeater. The landing cable according to any one of Supplementary note 21 to Supplementary note 25, comprising a third plurality of combinations of the optical fiber core wire and the feeding line.
(Appendix 28)
　The core end on the sea side is installed outside the area of ​​the country where the core end on the land side is installed, or the core end on the land side is installed. A partial landing cable that is all part of the area of ​​the landing submarine cable according to any one of Supplements 11 to 27, which is intended to be installed outside the territory of the country.
[0120]
　The present invention has been described above by using the above-described embodiment as a model example. However, the invention is not limited to the embodiments described above. That is, the present invention can apply various aspects that can be understood by those skilled in the art within the scope of the present invention.
[0121]
　This application claims priority on the basis of Japanese Application Japanese Patent Application No. 2019-110497 filed on June 13, 2019 and incorporates all of its disclosures herein.
Code description
[0122]
　100, 200 Submarine cable system
　11 First repeater
　16 Landing station building
　17 Beachman hall
　18 Land cable 119,
　219 Boundary point 121,
　221 Landing cable
　321x Landing cable
　21a, 21b, 21c, 21d Branch submarine cable
　23 Tail cable
　24 Cable cup Ring part
　31 Optical fiber extra length storage part
　33, 43a, 43b, 43c Tensile wire fastening part
　34 Mold part
　35 Storage part
　36 Bellows part
　37 Repeater housing
　38, 45a, 46a, 46b, 46c Boots
　39a, 39b, 39c Chip
　41 Branch
　42 Exterior wire fastening
　44a, 44b, 44c Molded
　47, 47a, 47b, 47c Housing
　48a, 48b, 48c Tail cable
　49a, 49b, 49c Flexible joint
　51 LW core cable
　51a, 51b, 51c, 51d, 51e, 51n LW core cable
　52 Exterior iron wire
　54 Power supply line
　54x Initially used power supply line
　56 Optical fiber accommodation pipe
　56ax Initially used optical fiber core wire
　56bx Spare Optical fiber core wire
　61 Tensile wire
　62, 62a, 62b, 62c, 62d, 62e Feeding line
　621 Feeding conductor
　622 Feeding wire coating
　63, 63a, 63b, 63c, 63d, 63e Optical fiber accommodating pipe
　70 Interrogator
　97 Landing point

WE CLAIMS

Cable A landing cable installed offshore from the landing point, which
　is an optical fiber core wire used from the beginning of communication by the landing cable, an initially used optical fiber core wire, and a feeding line used from the beginning. In addition to a certain initially used power supply line, a spare optical fiber core wire, which is a spare optical fiber core wire, is provided, and the
　spare optical fiber core wire is a cable that does not include the spare optical fiber core wire from an end point on the cable landing point side. A landing cable that is connected to a boundary point with a section and in which
　the end point of the preliminary optical fiber core wire, which is the end point of the preliminary optical fiber core wire, is held at the boundary point so that it can be used in the future.
[Claim 2]
　The landing cable according to claim 1, wherein the boundary point is located on the land side of the cable coupling portion on the land side of the first repeater or the submarine equipment when traced from the landing point.
[Claim 3]
　The landing cable according to claim 1 or 2, wherein the boundary point is outside the territory.
[Claim 4]
　The boundary point is at least one of a range beyond the area where the cable burial method is required, a range where the horizontal excavation method is required, and a range where the installation work license is required. The landing cable according to any one of claims 1 to 3.
[Claim 5]
　A spare feeding line is further provided at the end point on the side of the landing point, and the
　preliminary optical fiber core wire and the preliminary feeding line are connected to the boundary point, and at the
　boundary point, with the preliminary optical fiber core wire end point. The end point of the preliminary power supply line, which is the end point of the preliminary power supply line, is kept in a state where it can be used in the future, is bundled into one, and is equipped with a cable branching device at the tip on the offshore side thereof
　. The initially used submarine cable including the fiber core wire and the initially used feeding line, and a plurality of spare submarine cables having the spare optical fiber core wire and the spare feeding line are branched into the
　spare submarine cable. At the seabed end point, the spare fiber core wire end point and the spare power supply line end point are kept available in the future, and the
　boundary point and the spare seabed cable are the first to be traced from the landing point. It is the range on the land side from the cable coupling part on the land side of the repeater or the first submarine equipment, it is outside the territory, and it is the range beyond the area where the cable burial method is required, and the horizontal excavation method is required. The landing cable according to any one of claims 1 to 4, which is in a range beyond the area to which the installation work is required to be licensed.
[Claim 6]
　A streaming cable is connected to the submarine end of the spare submarine cable, and the
　boundary point, the spare submarine cable and the streaming cable are in the range on the land side of the cable coupling portion, and are outside the territory. The present invention is described in claim 5, which is a range beyond the area where the cable burial method is required, a range beyond the area where the horizontal excavation method is required, and a range beyond the area where the license acquisition is required. Landing cable.
[Claim 7]
It is a composite submarine cable formed by compounding a plurality of
　non-exterior submarine cables. The landing cable according to claim 5 or 6, wherein the cable is separated into units of the non-exterior submarine cable and connected by using existing submarine cable connection parts and connection techniques.
[Claim 8]
　The landing cable according to any one of claims 1 to 7, wherein the spare optical fiber core is loopback-connected to the other preliminary optical fiber core at the boundary point.
[Claim 9]
　The landing cable according to any one of claims 1 to 8, wherein a part of the optical fiber core wires connected to the boundary point is used for optical fiber sensing applications.
[Claim 10]
　One of claims 1 to 9, wherein the boundary point is outside the territory of the country in which the landing point is set, or is assumed to be outside the territory of the country. Partial landing cables that are all parts of said area of ​​the submarine cable described in 1.
[Claim 11]
　It is equipped with an optical fiber core wire group consisting of a plurality of optical fiber core wires and a feeding line group consisting of a feeding wire, and is installed from the
　landing point. It is either in the first repeater, which is the repeater of the above, or between the landing point and the first repeater, and the
　optical fiber core wire group is the first optical fiber core wire group and the second. The optical fiber core wire of the first optical fiber core wire group , including the
　optical fiber core wire group, is the optical fiber connected to the submarine cable after the first repeater, which is the submarine cable ahead of the first repeater. It is a fiber core wire, and the
　optical fiber core wire of the second optical fiber core wire group is a spare optical fiber core wire that is not connected to the submarine cable after the first repeater, and is
　the second optical fiber core wire. A
　landing cable in which the core end of the optical fiber core of the wire group is kept available .
[Claim 12]
　The landing cable according to claim 11, wherein the end of the core wire is in a range beyond the territorial waters.
[Claim 13]
　Whether the end of the core wire is in a range beyond the area where the cable burial method is required, or the area where the horizontal excavation method is required exceeds the area where the horizontal excavation method is required, or the installation work permit is obtained. The landing cable according to claim 11 or 12, which is at least one of the areas beyond the required area.
[Claim 14]
　The landing cable according to any one of claims 11 to 13, wherein the optical fiber cores included in the second optical fiber core group are loopback-connected.
[Claim 15]
　The end of the optical fiber on the sea side of the optical fiber including the optical fiber core wire of the second optical fiber core wire group is held by the optical fiber extra length storage portion, whereby the second optical fiber core wire group is said. The landing cable according to any one of claims 11 to 14, wherein the optical fiber core wire is kept in an available state.
[Claim 16]
　It is assumed that the optical fiber core wire of the second optical fiber core wire group is used when the number of submarine cable optical fiber core wires after the first repeater provided in the submarine cable after the first repeater increases. The landing cable according to claim 15, which has been made.
[Claim 17]
　The end of the core on the sea side of the optical fiber core of the first optical fiber core group is connected to the submarine cable after the first repeater by a connecting device, and the optical fiber extra length storage portion is described. The landing cable according to claim 16, which is included in the connecting device.
[Claim 18]
　The landing cable according to claim 17, wherein the optical fiber extra length storage portion is molded with a resin.
[Claim 19]
　The landing cable according to claim 18, wherein the resin is polyethylene.
[Claim 20]
　The landing cable according to any one of claims 17 to 19, wherein the connecting device is provided in the first repeater.
[Claim 21]
　A branch portion is provided, and the portion on the sea side from the branch portion is divided into a second plurality of branch submarine cables, and some of the branch submarine cables are connected to the submarine cables after the first repeater. The present invention is described in any one of claims 11 to 14, wherein the optical fiber core wire included in the other branched submarine cable is the optical fiber core wire of the second optical fiber core wire group. Landing cable.
[Claim 22]
　The landing cable according to claim 21, wherein the optical fiber core wire of the second optical fiber core wire group is assumed to be used when another submarine cable is added in the future.
[Claim 23]
　The end of the branch submarine cable, which is the end not connected to the branch of the part of the branch submarine cable, is streamed off, and is included in the part of the branch submarine cable due to the streaming off. The landing cable according to claim 21 or 22, wherein the core wire end portion of the optical fiber core wire of the second optical fiber core wire group is kept in the available state.
[Claim 24]
　23. The landing cable according to claim 23, wherein the streaming off is the connection of a dummy submarine cable or rope to the end of the branch submarine cable and the sealing of the end of the branch submarine cable.
[Claim 25]
　The landing cable according to any one of claims 21 to 24, wherein the number of feeding lines is the plurality.
[Claim 26]
　The landing cable according to any one of claims 21 to 25, comprising a configuration in which a second plurality of non-exterior submarine cables without an exterior are bundled.
[Claim 27]
　The optical fiber core corresponding to the combination of the submarine cable optical fiber core wire after the first repeater of the submarine cable after the first repeater and the submarine cable feeding line after the first repeater of the submarine cable after the first repeater. The landing cable according to any one of claims 21 to 25, comprising a third plurality of combinations of wires and the feeding line.
[Claim 28]
　The sea-side core end is located outside the region of the country where the land-side core end is installed, or the land-side core end is located in the region of the country where the core end is installed. A partial landing cable that is all part of the area of ​​the landing submarine cable according to any one of claims 11 to 27, which is assumed to be installed outside of.