Principles Digital Communication System & Computer Networks (Charles River Media Computer Engineering)

3.1 TWISTED PAIR

Twisted pair gets its name because a pair of copper wires is twisted to form the transmission medium. This is the least expensive transmission medium and hence the most widely used. This medium is used extensively in the local underground telephone network, in Private Branch Exchanges (PBX's), and also in local area networks (LANs).

As the electrical signal traverses the medium, it becomes attenuated, that is, the signal level will go down. Hence, a small electronic gadget called a repeater is used every 2 to 10 kilometers. A repeater amplifies the signal to the required level and retransmits on the medium.

The data rate supported by the twisted pair depends on the distance to be covered and the quality of the copper. Category 5 twisted pair supports data rates in the range of 10Mbps to 100Mbps up to a distance of 100 meters.

The twisted pair of copper wires is a low-cost transmission medium used extensively in telephone networks and local area networks.