5.2 Other transmission media

Wires are still used to carry electrical signals over short distances. At the time of writing, for example, most connections between telephones in private houses and the local telephone exchange still use wires. The telephone networks within office buildings are mostly connected with wires, and so are many computer networks (local area networks, LANs) within single buildings. However, all longer-distance communication, between towns, cities or countries, uses either optical fibre or microwave systems. Increasingly, even shorter distances use either optical fibres or wireless links of one sort or another.

Many of the concepts described in the previous section for signal transmission on electrical wires also apply to wireless systems (such as microwave) or optical fibres. Pulses are still attenuated and distorted, for example. It is worth, however, briefly looking at some of the characteristics particular to these other transmission media.