Transmission Media - Transmission Media This chapter is a...

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Transmission Media This chapter is a précis of Chapter 4 of Doug Comer's book [Comer 2004] and covers the basics of data transmission. Copper Wires Conventional computer networks use copper wire because it is inexpensive, easy to install, and has low resistance to electrical current. Unfortunately, copper wire is prone to interference in the form electromagnetic energy emitted by neighbouring wires, especially those running in parallel. To minimise interference, twisted pair wiring, as used in telephone systems, can be used as illustrated in Figure 1. Figure 1: Twisted pair wiring A plastic coating on each wire prevents the copper in one wire from touching the copper in another. The twist helps reduce interference by preventing electrical signals on the wire radiating energy (causing interference) and by preventing signals on other wires interfering with the pair. A second type of copper wire is coaxial cable , similar to that used for TV aerials. The coaxial cable provides better protection from interference by providing a metal shield as illustrated in Figure 2. Figure 2: Cross-section of a coaxial cable
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Transmission Media - Transmission Media This chapter is a...

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