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| Twisted pair |
| Multiwire twisted pair is the
simplest transmission technique. It I also the most familiar, because it
is the trasmission medium used in commercial PBX telephone systems. The
most common type used is two-pair wire, which consists of two pairs of plastic-sheathed
copper wire twisted around one another, then wrapped with a protective outer
sheath. Twisted wire is the least expensive medium. Bandwith varies depending on the distance between repeaters, signaling technique, and quality of the wire. Data rates up to 1.5 Mbps can be achieved; However, today's typical PBX systems operate at 56-K or 64-Kbps, with end user devices communicating at 9600 bps over point-to-point connections, or 1200 bps over multipoint connections. |
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