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Twisted-pair cabling was invented by Alexander Graham Bell in 1881. [4] By 1900, the entire American telephone network was either twisted pair or open wire with transposition to guard against interference. Today, most of the twisted pairs in the world are outdoor landlines, owned and maintained by telephone companies, used for voice service.
Telephone cable containing multiple twisted-pair lines. The primary line constants are parameters that describe the characteristics of conductive transmission lines, such as pairs of copper wires, in terms of the physical electrical properties of the line.
For cables, the swapping is gradual and continuous; that is the two or three conductors are twisted around each other. For communication cables, this is called twisted pair . For overhead power lines or open pair communication lines, the conductors are exchanged at pylons, for example at transposition towers or at utility poles , respectively.
The wire pairs are referenced directly by their color combination, or by the pair number. For example, pair 9 is also called the red-brown pair. In technical tabulations, the colors are often suitably abbreviated. Violet is the standard name in the telecommunications and electronics industry, but it is sometimes referred to as purple.
In North America no adapter is needed for certain uses: With ports wired in the preferred standard T568A pattern, for the 6P2C plugs most commonly used for single-line phone equipment (e.g. with RJ11), and 6P4C plugs used for two-line phones without power (e.g. with RJ14) and single-line phones with power (again RJ11), telephone connections are ...
Category 5 cable that is partially stripped and showing its four twisted pairs (eight wires). Category 5 cable (Cat 5) is a twisted pair cable for computer networks.Since 2001, the variant commonly in use is the Category 5e specification (Cat 5e).
Crosstalk can be reduced by ensuring that twisted-pair wiring is tightly twisted and is not crushed, and by ensuring that connectors between wire and cable media are properly rated and installed. [3] Positive ACR calculations mean that transmitted signal strength is stronger than that of near-end crosstalk. [4]
The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. The pair of conductors can be wires in a twisted-pair or ribbon cable or traces on a printed circuit board. Electrically, the two conductors carry voltage signals which are equal in magnitude, but of opposite polarity. The receiving ...