Abstract: A cable for digital transmission, said cable (1) being constituted by a plurality of twisted quads (6) each of which has a particular pitch length (A . . . N), the quads being grouped together in one or several layers bundles (2,3,4 and 5) and four bundles being grouped together in the cable. With a view to reducing cross-talk, especially at the high frequencies used for digital transmission, it is recommended to use identical twist lengths only under certain conditions. This produces a simpler cable in which the circuits can be completely filled with digital signals. Application to PCM transmission.

Abstract: An electric cable and in particular a coaxial cable, said cable having at least one conductor surrounded by electrical insulation and at least one longitudinal strength member formed by a cord of aromatic polyamide fibres, disposed parallel to the conductor or twisted in a helix therearound. Various kinds of cords are described: twisted; non-twisted; in one or in several layers; embedded in insulation or constituting the insulation.

Abstract: A circular wave guide for transmitting the TE.sub.11 mode of propagation is manufactured such that it is suitable for winding on a drum. During manufacture, a flexible thin-walled conductive tube is reinforced by an outer protective covering of plastic material and by an inner reinforcing member also of plastic material. The inner reinforcing member may be of tubular cross-section as shown, or may have some other cross-section, e.g. cruciform. The inner reinforcing member may be made of a material which shrinks on heating so that it can be removed once the wave guide has been unwound from the drum employed during transport. The conductor tube may be periodically intended to improve its flexibility.

Abstract: The expansion joint includes a first component and a second component which have the same inside dimensions as the wave guide and are free to move longitudinally with respect to each other, the first component having exclusively a wave guide structure, the second component including a trap positioned at least partially between said components and outside the first component, the electric length of said trap being equal to half the wavelength of the central frequency transmitted by the wave guide, said components being separated longitudinally at the trap by a distance which varies when the length of the wave guide varies. The trap can be folded to reduce its bulk.Application to long wave guides.

Abstract: Sealed power cables (e.g. for underground or submarine use) are often equipped with a metal sheath. A problem with some such cables is that their insulation is subject to greater thermal expansion of the cable during use than the metal sheath is capable of following. According to the present invention the metal sheath (5) is longitudinally corrugated either when the metal sheath is manufactured or by pressing a metal sheet which is originally plane over resilient ribs disposed longitudinally on the cable.

Abstract: A helical circular wave guide which reduces loss around curves. It includes contiguous turns of copper wire coated with a thermoplastic material, said helical turns being surrounded by a first tube made of aluminium in contact with the helix and by a second tube made of steel held centered in relation to said first tube by supports made of plastic material.

Abstract: The device includes a moving mould 2 which defines a cylindrical mould cavity 12 closed on one side and open on the other. The repair material 10 is brought through an annular orifice, the pressure of the material drives the slidable mould towards the right (closed side) and the hardening material completes the closing of the mould which, while moving, can cover any distance and the length of the packing to be effected is therefore not limited, while the volume of the tooling is small. A fixed sleeve 3 is used to prime the operation.

Abstract: A mechanical device for connecting optical fibres together by single or multiple connections with little attenuation loss. The connector has a body in the form of a cylinder, end pieces which support three cylindrical rods enclosing the fibre and disposed in guiding V-grooves, covers associated with the end pieces by spring washers which enable the cover to be longitudinally snap-fitted onto the body and a deformable blade which presses transversally against the rods.

Abstract: Connector for simultaneous end-to-end connection of groups of seven optical fibres. The ends of the groups of fibres to be connected are brought into mutual radial contact in a centered hexagonal configuration, e.g. by a guide structure (8) and associated clamping device (9), and their end faces of two groups are then brought into contact with each other. Particularly intended for on site connections of optical cables.

Abstract: Coating for optical fibres comprising at least one layer of a resinous composition which hardens in the cold and in a few seconds upon contact with a gaseous catalyst applicable more particularly to optical fibres intended to be assembled together in a cable.

Abstract: A method and device enabling simplified connection of two circular wave guides and reduction of the manufacturing price. The method consists of expanding the outer steel casings so as to form flanges on the end of sleeves having a larger diameter than the remainder of the casing. The inner guides are connected together by hoops and possibly a clamp ring. The flanges are then welded together. Application to electromagnetic wave guides.

Abstract: A device for connecting optical fibres comprises two identical units fitted to the respective ends to be joined. Each unit has an alinement structure in which the end portion of the fibre is held resiliently by a bend in the fibre leading to the clamp. The units are mated with their alinement structures alined and face to face with their respective fibre end portions meeting end to end substantially half way along the alinement structures.

Abstract: A connection device allowing optical fibres manufactures in a factory to be connected together in the field by end pieces. Each end piece comprises a fibre clamped between three cylindrical rods which lie tangential to each other in pairs and encompass a fibre in their central clamed. The end pieces are disposed on either side of a mounting assembly comprising alignment structures constituted by V-shaped grooves in which the fibre and the rods are inserted. Means are provided to press on the rods transversally. According to one variant, this function is fulfilled by elastomer cylinders compressed by clamping the plates of the mounting assembly. Application : Optical fibres for telecommunications.

Abstract: A multiple optical fibre cable in which the fibres can be used separately for long distance signal transmission comprises a central core round which the optical conductors are concentically disposed. Each optical conductor is constituted by an optical fibre protected by a first layer or covering of polyamide and a second layer or sheath of polyethylene. In order to avoid distortion of the optical fibre, the second layer or sheath is stretched. Application: Optical telecommunications cables.

Abstract: A covering of thermoplastic material applied to a bare portion of optical fibre by pressure molding.The device for performing the pressure molding includes a micro injection cylinder and a mold having a distribution chamber with injection holes distributed over the fibre to be covered.

Abstract: A welding device for joining optical fibres together with a low loss joint. It comprises a microplasma blow torch with central and tubular electrodes and central and peripheral nozzles supplied with pure and hydrogenated argon. The torch is used in conjunction with a clamping frame for aligning the fibres and holding them in position during welding.

Abstract: A machine for manufacturing circular section helical wave-guides and providing simultaneous calibration of the bore of the helix and snug fitting of the screen around the helix. The helix is loosely fitted in an enveloping tube and both tube and helix are drawn through a reducing die for drawing the tube down onto the helix. The bore of the helix is established by a mandrel and the outer surface of the helix is softened just before entering the die whereby the helix is welded to the inner surface of the tube.

Abstract: A taping device permitting tension-free winding of tapes. It comprises guide hooks between which the tape passes disposed as close as possible to the product to be taped. Applications: manufacture of optical fibre telecommunications cables and special cables.

Abstract: A helical wave guide comprising a hollow conductor coated on its outside with an electrically conductive screen and formed by an electrically conductive wire coated with a thermoplastic insulator, wound in a helix and welded turn by turn by surface melting of the thermoplastic insulator. It is applicable to signal transmission.

Abstract: The invention concerns the centering and the fixing of a long thin object inside a tubular body. It has as its object a means consisting in a filling in of the space left free by the long thin object inside the tubular body with a granular substance at least a part of which is agglomerated by means of a resinous isocure compound hardening when cold in a very short time on coming into contact with a gaseous catalyst. It applies more particularly to the centering of a wave guide in a metallic tube.