JPS60151905A - Optical fiber cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to optical fiber cables, particularly optical fiber cables used in submarine couple transmission systems. It is progressing.

Optical submarine cables, which are currently being put into practical use in many countries, have a central structure consisting of several optical fibers bundled together and housed in a pressure-resistant pipe made of metal such as aluminum or copper as an optical fiber unit, with a tensile strength member on the outside. It has a structure in which the outside is narrowed down with a pipe at the extra end.

FIG. 1 shows an example of the structure of a conventional optical fiber cable. In this cable, a fiber unit 1, a copper pipe 2 that protects it from seawater pressure, a tensile strength member (@ wire) 3 that provides tensile strength to the cable, and a copper pipe 4 that suppresses the tensile strength member form the central part. Configure. The copper pipes 2 and 4 are usually also used as a DC power supply path to a submarine repeater, and since they have a potential with respect to seawater, they are thickly coated with low-density polyethylene as an insulator 5 from the seawater. Finally, in order to mine the entire couple from external friction, it is covered with a layer of jacket 6 of high-density polyethylene, resulting in a deep-sea unarmored cable. Armored cable for shallow water.

It is constructed by winding one or two layers of iron wire as necessary on the outside of the outer sheath 6 in the order of the seat floor and the exterior iron wire.

In the conventional coaxial cable transmission system, in the event that the cable is cut, the break point of the couple can be estimated by measuring DC resistance, pulse echo measurement, and measuring the output of the repeater's built-in oscillator. In the case of open-failure oils where the cutting point is electrically open, the tit measurement method and the d-pulse echo measurement method, which measure the capacitance between the inner and outer conductors of the couple, are highly accurate and effective means. this is,
This method takes advantage of the characteristics that the dielectric constant of the polyethylene insulator that exists between the shapes and dimensions of the inner and outer conductors of a coaxial cable is extremely accurate, and the linearity of capacitance versus line length is extremely good.

However, the optical fiber cable shown in Figure 1 does not have a component that shows such an accurate capacity, so it has the disadvantage that it is not possible to estimate the failure point by measuring the capacity of a coaxial couple or by measuring pulse echoes. be.

Of course, there are methods that utilize the unique characteristics of optical fiber systems, such as utilizing light reflection at fault points, but these methods cannot search for fault points farther away than the submarine repeater.

[Object of the Invention] An object of the present invention is to provide an optical fiber cable that enables the fault point search method established in the coaxial cable transmission system.

[Structure of the invention]

The optical fiber cable of the present invention includes a fiber unit,
A central portion having a first conductor pipe provided on the outside thereof, a tensile strength member provided on the outside thereof, and a second conductor pipe provided on the outside thereof, and a primary coating covering this central portion;
This secondary coating is characterized by having a conductor layer formed in the shape of a pipe, and a secondary coating covering this conductor layer.

[Principle and operation]

According to the above configuration, a pseudo coaxial cable structure is created between the conductor layer such as aluminum between the secondary storage and the secondary coating and the metal pipe of the original optical fiber submarine cable.
It can be used for various purposes. One of them is to make it possible to search for failure points by measuring capacity. In other words, the conductor layer between the secondary and secondary coatings forms a cylindrical capacitor with the primary coating insulator as a shield between it and the metal pipe. The length of the capacitor, that is, the line length, can be calculated. This so-called pseudo-coaxial structure is not a coaxial cable in the strict sense of the word, so its line length vs. capacity characteristic is not necessarily strictly linear, but it is linear enough for the purpose of searching for fault points. have sex.

Furthermore, using the quasi-coaxial structure, low-frequency or high-frequency pulse echo tests can be performed.

[Embodiments of the invention]

Next, specific embodiments of the present invention will be described using the drawings. In FIG. 2, numerals 1 to 4 are the same as those shown in FIG. A conductor layer 9 is sandwiched between the primary polyethylene coating 7 and the secondary polyethylene coating 8. This conductor layer 9 can be easily constructed by using, for example, a laminated aluminum tape shown in FIG. The laminated aluminum tape is made by applying a polyethylene coating layer 11 to an aluminum tape 10, and the laminated aluminum tape is wrapped vertically over the primary coating polyethylene.

Subsequently, by extruding the secondary coating polyethylene onto it, the polynyte on the surface of the aluminum tag melts, and the aluminum layer is fused to the primary and secondary coating polyethylene. As a result, copper pipe 4. Primary coverage by Bollier, Chishi/7. The conductor layer 9 constitutes a pseudo-coaxial structure. By using this quasi-coaxial structure, it becomes possible to (1) locate a couple fault by capacitance measurement, and (2) locate a fault by pulse echo testing.

When carrying out the above search (1) (21) beyond the submarine repeater, it goes without saying that the conductor layers of the couple on both sides of the repeater must be connected within the submarine repeater.

The search technology of g4(tl(21) has been established for coaxial cable transmission systems, and it is clear that it is possible to locate faults with sufficiently high accuracy. Conventionally, the extrusion process of Bolietere/ is divided into two steps, so it is clear that the goople according to the present invention can be easily realized by adding a vertical alignment process of the laminated aluminum tape between the two steps.

〔Effect of the invention〕

According to the present invention, various fault detection methods established in the coaxial couple transmission system can be applied to optical fiber cable breakage accidents, which is advantageous in terms of system maintenance.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the structure of a conventional optical fiber cable, Fig. 2 is a sectional view showing an embodiment of the present invention, and Fig. 3 is a sectional view showing the structure of a conventional optical fiber cable.
It is a perspective view which shows the laminated aluminum tag used to form the conductor layer in a figure. l...Fiber unit, 2...Copper pipe, 3...Tensile strength body, 4...Copper pipe, 1 Old...Insulator, 6... ...Outer cover, 7...
...-Next employee, 8...Mark/Secondary coating, 9...Conductor layer, 10...Aluminum tape, 11°
゛°°°°Polyethylene coating/yte. 4th elocution ± 1.ヮ Meng j l・1, Go. Kaya 1fl Kaya 3 monks

Claims (1)

[Claims] A fiber unit, a central portion having a first conductor pipe provided on the outside thereof, a tensile strength member provided on the outside thereof, a second conductor pipe provided on the outside thereof, a primary covering covering this central portion; - An optical fiber cable characterized by having a conductor layer formed in a pipe shape on a secondary sheath, and a secondary sheath covering the conductor layer.