Science Fair Project Encyclopedia
Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. The number of twists per metre make up part of the specification for a given type of cable. The greater the number of twists, the more crosstalk is reduced. Twisting wires decreases interference because:
- The loop area between the wires (which determines the magnetic coupling into the signal) is reduced as much as physically possible.
- The directions of current generated by a uniform coupled magnetic field is reversed for every twist, cancelling each other out.
Shielded Twisted Pair (STP) has an outer conductive braided casing similar to coaxial cable and theoretically offers the best protection from interference. It was commonly used for token ring networks.
Foiled Twisted Pair (FTP) ...
In telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T. A typical subset of these colors (white/blue, blue/white, white/orange, orange/white) shows up in most UTP cables.
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