 Câblage de fibre optique
General FAQ
Fiber Testing FAQ
General FAQ
5. Principle of operation
There are two types of optical fiber: singlemode and multimode. Multimode fiber has a much larger core than SingleMode fiber, allowing hundreds of rays of light to propagate through the fiber simultaneously (High Order Mode). Multimode fiber may have a typical core diameter of 50 to 100 µm with a refractive index that is graded or stepped. It allows the use of inexpensive LED light sources and connector alignment and coupling is less critical than single mode fiber. Singlemode fiber, on the other hand, has a much smaller core that allows only one mode of light to propagate through the core (Low Order Mode). The fiber has a very small core diameter of approximately 8 µm. It permits signal transmission at extremely high bandwidth and allows very long transmission distances. It might appear that Multimode fibers have higher information carrying capacity, where the Singlemode fibers retain the integrity of each light pulse over longer distances, allowing more information to be transmitted. This high bandwidth has made Single Mode fiber the ideal transmission medium for many applications. Multimode fiber today is used primarily in premise applications, where transmission distances are less than two kilometers.
Single Mode Fiber
Multimode Fiber
6. Types of Cable
Breakout Cable
Breakout cables are designed with alldielectric construction to insure EMI immunity. It is basically several simplex fibers packaged individually inside one jacket. The design of the breakout-style cable adds strength to the cable,Breakout cable is suitable for riser and plenum applications such as routing within buildings, in riser shafts, and under computer room floors. The Breakout design enables the individual reinforced; you can divide the cable into individual fiber lines. In addition to the standard duty 2.4 mm subunit design, a 2.9 mm heavy duty and a 2.0 mm lite duty design are also available.
Interconnect Cable
Interconnect cable is use in dielectric construction and aims to provides EMI immunity. This type of cable is usually used as “jumper” for intra-building distribution. Interconnect Cable can be design in single mode and multimode fiber and this cable can be ordered for riser environments.
Lose Tube Cable
In loose-tube construction the fiber is laid helically into semi-rigid tubes, allowing the cable to stretch without stretching the fiber itself. This protects the fiber from tension during laying and due to temperature changes, therefore these are usually suitable for outdoor duct, aerial, and direct buried installations.
Low Smoke, Zero Halogen Cable
Low smoke zero halogen (LSZH or LSOH) is a type of cable jacketing used in the manufacture of industrial and network cabling. LSZH cable jacketing is composed of thermoplastic or thermoset compounds that emit limited smoke and no halogens when exposed to high sources of heat. It is designed to replace standard polyethylene jacketed fiber optic cables in environments where public safety is of great concern.
Most network cables are insulated with PVC plastic. In fires, this plastic material releases chlorine, a poisonous gas, which forms caustic hydrochloric acid when it comes in contact with water. Halogen-free cable, on the other hand, is made of a different material called polypropylene, which doesn't produce a dangerous gas/acid combination.
Low smoke zero halogen cable reduces the amount of toxic and corrosive gases emitted during combustion. Typically used in poorly ventilated areas, low smoke zero halogen is becoming very popular where the protection of people and equipment from toxic and corrosive gasses is critical.
Low smoke zero halogen cable is available with any optical fibers, both singlemode and multimode, in loose tube, tight buffer or breakout constructions. Attenuations as low as 0.4 dB/km, and bandwidths as high as 1000 MHZ/km, can be supplied.
LXE Light Guide Express Entry Cable
The LXE (Lightguide Express Entry) sheath system is designed with the loop distribution market in mind, where express entry (accessing fibers in the middle of a cable span) is a common practice.
The LXE sheath system achieves a 600 pound (2670 N) tensile rating through the use of linearly applied strength members placed 180 degrees opposite each other.
High density polyethylene (HDPE) is used for the cable jacket to provide both faster installation, through a lower coefficient of friction, and optimum cable core protection in hostile environments.
LXE Light Guide Express Entry Cable is the standard Non-Metallic (Dielectric) Lightguide Express Entry (LXE) cable, containing Multimode fiber.
Lightpack Cable
A cable core design that allows bundles of optical fibers in a cable core without central strength members. The LightPack cable features an easy-to-install, compact design that protects your network in outside plant environments. The LightPack cable core is a bundle of 2 to 12 fibers (up to 8 bundles, 96 fibers) held together loosely with two helically applied binders. Positive identification of each fiber is provided by color coding both the fibers and the binders.
Indoor/Outdoor Loose Tube Cable
Indoor/outdoor stranded loose tube combines the robust mechanical and environmental characteristics of an outside plant cable with the flexibility of an inside plant riser cable. They meet or exceed Article 770 of the NEC and UL Subject 1666 (Type OFNR). They also meet CSA C22.2 No. 232M1988 Type OFNFT4.
All of the RLT products utilize a proprietary ChromaTek 3 jacketing system that is designed for resistance to moisture, sunlight and flame for use both indoors and outdoors By installing indoor/outdoor stranded loose tube, costly splice locations entering into a building are avoided, being routed directly from the outside plant to telecommunications closets, or main distribution frames (MDF) through the riser of a building and eliminating the “50-foot rule.”
Main Features:
- Building interconnections
- Telecommunications and data trunk
- Long haul networking
- Direct burial and aerial lashing
- Applications requiring good ozone, moisture, weather resistance
Tactical/Military Cable
Tactical cable utilizes a tight buffer configuration in an all dielectric construction. The tight buffer design offers increased ruggedness, ease of handling and connectorization. Tactical fiber optic cable designed to be quickly deployed across the ground for communications in battlefield conditions - can survive being run over by tanks, trucks and armored Humvees.
Simplex and Zip Cord
Simplex cables are one fiber, tight-buffered (coated with a 900 micron buffer over the primary buffer coating) with Kevlar (aramid fiber) strength members and jacketed for indoor use. The jacket is usually 3mm (1/8 in.) diameter. Zipcord is simply two of these joined with a thin web. It's used mostly for patch cord and backplane applications, but zipcord can also be used for desktop connections.
Distribution Cables
They contain several tight-buffered fibers bundled under the same jacket with Kevlar strength members and sometimes fiberglass rod reinforcement to stiffen the cable and prevent kinking. These cables are small in size, and used for short, dry conduit runs, riser and plenum applications. The fibers are double buffered and can be directly terminated, but because their fibers are not individually reinforced, these cables need to be broken out with a "breakout box" or terminated inside a patch panel or junction box.
Ribbon Cable
This cable offers the highest packing density, since all the fibers are laid out in rows, typically of 12 fibers, and laid on top of each other. This way 144 fibers only has a cross section of about 1/4 inch or 6 mm! Some cable designs use a "slotted core" with up to 6 of these 144 fiber ribbon assemblies for 864 fibers in one cable! Since it's outside plant cable, it's gel-filled for water blocking.
Armored Cable
Cable installed by direct burial in areas where rodents are problems usually have metal armoring between two jackets to prevent rodent penetration. This means the cable is conductive, so it must be grounded properly.
Aerial cable
Aerial cables are for outside installation on poles. They can be lashed to a messenger or another cable (common in CATV) or have metal or aramid strength members to make them self supporting.
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