22 February, 2014
Twisted Pair cable
Twisted pair is the ordinary copper wire that connects home and many business computers to the telephone company. To reduce crosstalk or electromagnetic induction between pairs of wires, two insulated copper wires are twisted around each other. Each connection on twisted pair requires both wires. Since some telephone sets or desktop locations require multiple connections, twisted pair is sometimes installed in two or more pairs, all within a single cable. For some business locations, twisted pair is enclosed in a shield that functions as a ground. This is known as shielded twisted pair (STP). Ordinary wire to the home is ...view middle of the document...
Fiber optic wire carries much more information than conventional copper wire and is far less subject to electromagnetic interference. Most telephone company long-distance lines are now fiber optic.
Transmission on fiber optic wire requires repeating at distance intervals. The glass fiber requires more protection within an outer cable than copper. For these reasons and because the installation of any new wiring is labor-intensive, few communities yet have fiber optic wires or cables from the phone company's branch office to local customers (known as local loop).
Coaxial cable is the kind of copper cable used by cable TV companies between the community antenna and user homes and businesses. Coaxial cable is sometimes used by telephone companies from their central office to the telephone poles near users. It is also widely installed for use in business and corporation Ethernet and other types of local area network.
Coaxial cable is called "coaxial" because it includes one physical channel that carries the signal surrounded (after a layer of insulation) by another concentric physical channel, both running along the same axis. The outer channel serves as a ground. Many of these cables or pairs of coaxial tubes can be placed in a single outer sheathing and, with repeaters, can carry information for a great distance.
Coaxial cable was invented in 1929 and first used commercially in 1941. AT&T established its first cross-continental coaxial transmission system in 1940. Depending on the carrier technology used and other factors, twisted pair copper wire and optical fiber are alternatives to coaxial cable.
A patch cord (sometimes called a patch cable) is a length of cable with connectors on the ends that is used to connect an end device to something else, such as a power source. One of the most common uses is connecting a laptop, desktop or other end device to a wall outlet.
Typically, a patch cord is a copper cable that has an RJ45, TERA or GG45 connector on both ends, although hybrid versions exist that have different types of connectors on the ends. Fiber patch cords are typically called fiber jumpers and are either standard jumpers or mode conditioning jumpers.
A patch cord may also be used to connect a switch port or a server to the structured cabling system. Although the new standards do not recommend doing so, sometimes a patch cord is used to connect a server directly to a switch port.
When cabling channel is tested, it is a called channel test if patch cords are included, but a permanent link test otherwise. Special connectors are required to test patch cords, which should not be tested using other test methods.
Ethernet is a family of computer networking technologies for local area networks (LANs). Ethernet was commercially introduced in 1980 and standardized in 1983 as IEEE 802.3. Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI, and...