The present disclosure provides ribbed and grooved sheath for optical fiber cables. An optical fiber cable (100) comprises one or more optical transmission elements (118) and a sheath (102) surrounding the one or more optical transmission elements (118). An outer surface of the sheath (102) has a plurality of ribs (104, 106, 108) and a plurality of grooves (110, 112) such that at least one groove has unequal groove width and/or at least one rib has unequal rib width. The plurality of ribs (104, 106, 108) is continuous and parallel on the outer surface. Alternatively, the plurality of ribs (104, 106, 108) is discontinuous.

An integrated transmission line installation system includes a transmission line conveying system that operates to install a transmission line within a conduit by advancing the transmission line through the conduit. The conduit includes at least a first segment and a second segment. The segments are evaluated to determine a full route including the routes of the first and second segments, and an installation plan is generated based at least in part on the full route. The transmission line conveying system includes two or more transmission line conveying apparatuses, a first that controls the advancement of the transmission line through the first segment, and a second that controls the advancement of the transmission line through the second segment. The transmission line conveying system controls and synchronizes the operation of the transmission line conveying apparatuses according to the installation plan so that the transmission line can be continuously installed through the full length of the conduit in a single pass.

An integrated transmission line installation system includes a transmission line conveying system that operates to install a transmission line within a conduit by advancing the transmission line through the conduit. The conduit includes at least a first segment and a second segment. The segments are evaluated to determine a full route including the routes of the first and second segments, and an installation plan is generated based at least in part on the full route. The transmission line conveying system includes two or more transmission line conveying apparatuses, a first that controls the advancement of the transmission line through the first segment, and a second that controls the advancement of the transmission line through the second segment. The transmission line conveying system controls and synchronizes the operation of the transmission line conveying apparatuses according to the installation plan so that the transmission line can be continuously installed through the full length of the conduit in a single pass.

Systems, assemblies and methods for deploying an optical fiber through a duct to a customer premises. A blowable section of the optical fiber is blown through the duct. A non-blowable section of the optical fiber is coupled to a trail end of the duct. The non-blowable section can be terminated with a hardened or ruggedized connector. The optical fiber, including both the blowable and non-blowable sections, can be wound around a spool for easy payout of the blowable section.

Systems, assemblies and methods for deploying an optical fiber through a duct to a customer premises. A blowable section of the optical fiber is blown through the duct. A non-blowable section of the optical fiber is coupled to a trail end of the duct. The non-blowable section can be terminated with a hardened or ruggedized connector. The optical fiber, including both the blowable and non-blowable sections, can be wound around a spool for easy payout of the blowable section.

An optical fiber cable includes: a plurality of optical fibers or a plurality of optical fiber ribbons; a cable sheath inside which a plurality of the optical fibers or a plurality of the optical fiber ribbons are housed; and four or more tensile strength member units which are provided so as to be embedded inside the cable sheath, and in which two or more tensile strength members are paired with each other, in which the four or more tensile strength member units are respectively provided at locations facing each other with a center of the optical fiber cable interposed therebetween in a cross section in a radial direction of the optical fiber cable, and in which a cable outer diameter of the optical fiber cable is 6 mm or more and 16 mm or less.

In at least one general aspect, a cable assembly adapted to be installed into a duct by a combination of blowing and mechanical feeding. The cable assembly can include at least one flexible signal transmitting member for transmitting optical signals, a first layer surrounding the at least one flexible signal transmitting member such that at least one signal transmitting member is in touching contact with the first layer, and a second layer arranged outwardly of the first layer. The second layer is a non-thermoplastic layer made of a composition comprising a base material of polyethylene adapted to be cross-linked, whereby the second layer comprises crosslinked polyethylene.

Method for installing an elongated element, in a submarine duct, the submarine duct having an entry port and an exit port located in outer liquid (OL) at a second depth,

the method comprising the steps of: introducing the elongated element into the entry port, introducing propelling liquid (PL) into the entry port,
characterized in that the method comprises a step of sucking propelling liquid (PL) out of the exit port of the duct with an immerged suction pump being operated at a predetermined suction pressure drop (ΔP.sub.pump) of propelling liquid (PL) so that the predetermined suction pressure drop (ΔP.sub.pump) applied to propelling liquid (PL) is smaller than a hydrostatic pressure (P.sub.hydro) of the outer liquid (OL) at the second depth.

Method for installing an elongated element, in a submarine duct, the submarine duct having an entry port and an exit port located in outer liquid (OL) at a second depth,

the method comprising the steps of: introducing the elongated element into the entry port, introducing propelling liquid (PL) into the entry port,
characterized in that the method comprises a step of sucking propelling liquid (PL) out of the exit port of the duct with an immerged suction pump being operated at a predetermined suction pressure drop (ΔP.sub.pump) of propelling liquid (PL) so that the predetermined suction pressure drop (ΔP.sub.pump) applied to propelling liquid (PL) is smaller than a hydrostatic pressure (P.sub.hydro) of the outer liquid (OL) at the second depth.

It is disclosed an optical fibre unit for air-blown installations comprising: a first group of optical fibres embedded in a resin layer; a sheath arranged in a radially outer position with respect to the resin layer so that an annular space is formed between resin layer and sheath; and a second group of optical fibres arranged in the annular space. Also disclosed are an apparatus and a method for manufacturing such optical fibre unit.