PHYSICAL AND WIRELESS TRANSMISSION MEDIA
PHYSICAL TRANSMISSION MEDIA Physical transmission media used in communications include twisted-pair cable, coaxial cable, and fiber-optic cable. These cables typically are used within or underground between buildings. Ethernet and token ring LANs often use physical transmission media. Twisted-Pair Cable One of the more commonly used transmission media for network cabling and telephone systems is twisted-pair cable. Twisted-pair cable consists of one or more twisted-pair wires bundled together (Figure 8-24). Each twisted-pair wire consists of two separate insulated copper wires that are twisted together. The wires are twisted together to reduce noise. Noise is an electri- cal disturbance that can degrade communications. Coaxial Cable Coaxial cable , often referred to as coax (pronounced KO-ax), consists of a single copper wire surrounded by at least three layers: (1) an insulating material, (2) a woven or braided metal, and (3) a plastic o...