Abstract: There is disclosed a submarine cable grapnel which is tied to the two rope of a cable ship and is dragged on the bottom of the sea, one grappling unit and at least one attitude stabilizer is connected while this assembly is connected at one end the two rope of the cable ship and at the other end a chain. In this instance, front and rear coupling portions of the grappling element and the attitude stabilizer are positioned so that the center of gravity of each element under the water stays nearer the seabed than a straight line joining the coupling centers of the coupling portions of the elements when the grapnel lands in the normal attitude on the bottom of the sea.

Abstract: An anchor for hooking and cutting a submarine cable comprises an anchor body part, a cable-hooking part and a connecting part, these parts being connected together into a form like a fishing hook. A cable-sensing device is provided on the inner side of the connecting part and spring-biased in the floating-up direction. A cutting device is provided for cutting and holding the submarine cable by being advanced from the anchor body part by hydraulic pressure making use of a force such as sea water pressure or a tugging force for raising the submarine cable externally applied to the anchor body part when the cable-sensing device is caused to sink against the biasing force in the floating-up direction by receiving the tension in the cable hooked on the inner side of the connecting part.

Abstract: An anchoring structure is disclosed for connecting to a casing of an optical submarine repeater or a cable joint box an optical submarine cable which is composed of a cylindrical pressure proof layer formed by a combination of three deformed metal wires of the same sectorial cross-section and disposed inside an insulator so that the pressure proof layer has centrally thereof a circularly-sectioned optical fiber unit housing space for housing an optical fiber unit formed by at least one optical fiber, a cable tensile-strength member formed by a plurality of tensile-strength wires disposed concentrically with the cylindrical pressure proof layer on the outside thereof and a metallic tape layer disposed in a cylindrical form outside the tensile-strength member to extend in its axial direction, the seam of the metallic tape layer being welded and the insulator being disposed outside the metallic tape layer.

Abstract: An optical fiber hermetic fixing structure of a feedthrough for an optical submarine repeater in which at least one optical fiber is introduced into a fluid-tight pressure-resistant housing of an optical marine repeater. Optical fibers are introduced and disposed in a through opening defined between a metal fiber-supporting guide and a metal sealing sleeve circumferentially of the fiber-supporting guide. The guide has a somewhat reduced diameter adjacent an end of the through opening so that the through opening has a greater transverse dimension along this part adjacent a seawater end of the feedthrough. This part of the through opening is filled with a low temperature melting metal about and between the optical fibers extending therethrough. The low melting temperature metal extends out of the through opening with a generally conical cross section configuration. A protective cover cap is disposed coaxial with the sleeve and fiber-supporting guide and through which the optical fibers extend longitudinally.

Abstract: Elongation distortion at any location of an optical fiber cable is measured by using the principle of the stimulated Raman effect in which a stokes beam with a little frequency difference from that of a pumping beam is generated when a pumping beam and a seed beam with the same frequency as that of the stokes beam meet in a Raman material like an optical fiber cable. Due to the fact that the group refractive index of an optical fiber cable for a pumping beam is different from that for a stokes beam, elongation of a cable is measured by observing time difference of the arrival of pumping beam and stokes beam. The location that the pumping beam meets with the stokes beam can be adjusted merely by shifting the pumping pulse, then, elongation distortion at any location can be measured. According to the invention, the pumping pulse is applied to the cable to be tested from both the ends of the cable with one of the pumping pulse delayed according to the desired location for meeting of two pulses.

Abstract: In the connection of the opposed ends of two optical fibers, a method and apparatus for core alignment of the optical fibers, comprises placing the two optical fibers being connected so that their ends face each other, and illuminating at least the facing ends with a beam of ultraviolet light thereby causing the illuminated ends of the cores of the optical fibers which are doped with germanium (Ge) to emit light of a wavelength in the visible region and enabling the core alignment to be directly monitored visually with the aid of the visible light so emitted from the cores during the course of the core alignment.

Abstract: A spliced portion housing structure for an optical fiber in an optical submerged repeater, characterized in that, in order to splice together in a joint ring an optical fiber and a power-supplying feeder from the optical submerged repeater to an optical fiber and a power-supplying feeder of a tail cable from a cable coupling of an optical submarine cable, respectively, a joint chamber is provided on an end plate of a housing of the optical submerged repeater in such a manner that the end plate forms a part of the joint chamber; the optical fiber and the power-supplying feeder from the submerged repeater are introduced into the joint chamber through a first feedthrough provided in the end plate for hermetically introducing the optical fiber and the power-supplying feeder; the tail cable from the cable coupling is hermetically introduced into the joint chamber through a second feedthrough provided in the wall of the joint chamber so that the tail cable is insulated from the joint chamber, the optical fibers and

Abstract: An optical fiber submarine cable, which is provided with at least one coated optical fiber, a power supplying, pressure resisting layer of a pipe-like configuration, a tension resisting wire layer formed of a conductive material of relatively low conductivity and disposed in close contact with the power supplying, pressure resisting layer of the pipe-like configuration, and an insulator layer disposed around the tension resisting wire layer. The power supplying, pressure resisting layer is formed as at least one inner layer and an outer layer.

Abstract: An optical fiber unit for optical submarine cables, in which glass portions formed by a plurality of optical fibers each having at least one coating layer and twisted together at a required pitch are embedded in a resin layer. Adjacent two layers of the coating layer and the resin layer are formed of the same material or materials which satisfy the following condition; ##EQU1## where E.sub.1 is the Young's modulus of the inner one of the two layers, E.sub.2 is the Young's modulus of the outer one of the two layers, .nu..sub.1 is the Poisson's ratio of the inner one of the two layers and .nu..sub.2 is the Poisson's ratio of the outer one of the two layers, the thus coated portion being formed over the entire length of the optical fibers or at desired intervals.

Abstract: An optical fiber submarine cable, in which a multilayer, cylindrical pressure resisting layer is prepared so as to have a construction in that at least one optical fiber layer is successively covered by a cushion layer and a rounded layer of a first tape of a good electric conductor member, a longitudinal joint of side edges of the first tape is welded, at least one second tape of a good electric conductor material is closely coated on the layer of the first tape by the use of an adhesive binder layer therebetween, and a longitudinal joint of the side edges of the second tape is welded.

Abstract: A submarine optical fiber cable using a low-loss optical fiber as a transmission medium, which is provided with a cylindrical pressure resisting layer composed of an assembly of three equally divided long pressure resisting segments of fan-shaped sections with flat contact planes and having at least one optical fiber in an optical fiber housing space formed in the center of the assembly so as to protect the optical fiber from a high water pressure.

Abstract: A feedthrough terminal for optical fiber cables (12), particularly for use in an underwater repeater, comprises a rod (22) received snugly in a tube (21) and having grooves (24), which are filled by a mass of solder (26) with the optical fiber cables placed in the respective grooves. The grooves may be formed along the tube inside surface or on opposing portion of the tube and the rod. The tube and/or the rod may be possessed of a recessed surface to provide a gap for the solder mass.

Abstract: An optical fiber introducing equipment for an optical submerged repeater, in which for introducing an optical fiber for optical communication into an optical submerged repeater housing through an introducing hole, the coating of the portion of the optical fiber to be disposed in the introducing part is entirely removed for a suitable length; the coated optical fiber having the exposed fiber portion is inserted into a small-diametered metal cylinder having an insertion hole which has an inner diameter more than several times as large as the outer diameter of the coated optical fiber; an adhesive whose volume remains substantially unchanged even if hardened is filled between the optical fiber and the insertion hole to unite the optical fiber and the metal cylinder; seawater preventing means is provided on the outside of the adhesive for preventing the adhesive from making direct contact with seawater; and the metal cylinder is disposed in the introducing hole provided at a part of the repeater housing.

Abstract: A feedthrough for optical submerged repeater, in which a clad part of an optical fiber to be introduced into the feedthrough is given a metal coating; the coated part is inserted into a small-diametered metal pipe to be hermetically fixed between the optical fiber and the small-diametered metal pipe as by soft solder; and the small-diametered metal pipe is inserted into a disc sleeve to hermetically fix them as by brazing. Between the disc sleeve and a metal body housing the disc sleeve, polyethylene is molded for electrical insulation therebetween and for holding air-tightness against seawater, and at the side of the disc sleeve facing toward seawater or at both sides of the disc sleeve, an insulator of the optical fiber cable and polyethylene of the abovesaid molding are molded to be contiguous to each other. The abovementioned metal body is fixedly attached to the end face plate of the pressure resisting casing in a manner to provide an air-tight structure.

Abstract: An optical fiber submarine cable, in which a high viscosity material of good wettability containing air gaps is filled in a space between an optical fiber cord having housed therein at least one coated optical fiber and a pressure resisting material layer having housed therein the optical fiber cord for protecting it from seawater pressure. The air gaps and the high viscosity material are arranged alternately with each other in the space at suitable intervals in the lengthwise direction of the cable. Alternatively, the air gaps are contained in the form of bubbles in the high viscosity material.

Abstract: A digital signal repeater selecting system for a digital signal transmission system equipped with a plurality of digital signal repeaters disposed on a transmission line at desired intervals, in which there are provided in each of the repeaters a delay circuit having a particular delay time corresponding to an integral multiple of the unit code length of a digital signal and assigned to the repeater and having its input terminal connected to the transmission line, and a code comparator for comparing the input signal to and the output signal from the delay circuit with each other to produce a predetermined output signal when the both signals are decided to be substantially identical with each other, and in which when a repeater selecting code train repeating in synchronism with the delay time is applied to the transmission line, the repeater to which the delay time is assigned produces the predetermined output signal from the code comparator to allow an operation of selecting the repeater.