Data communications can be carried from one location to another through a variety of communications channels. These communications media include telephone lines (twisted pairs), coaxial cable, fiber-optic cable, microwave, and satellite. In general, there can be two ways of connecting microcomputers with each other and with other equipment: guided and radiated media.

• Guided Media: Refer to channels that allow the transmission of data and information through a physical media such as a twisted pair wire, coaxial cable, or fiber optic cable.

• Radiated media: Refer to those that transmit data and information through the air such as microwave, or satellite.

Twisted Pair

The telephone lines used to carry most of the voice and data communications consist of a pair of thin-diameter insulated copper wires (called twisted pairs). The wires are twisted around each other to minimize interference from other twisted pairs in the cable. Twisted pairs have fewer bandwidth than coaxial cable or optical fiber. They have been the standard communication channels for voice, data and information, but are now diminishing because of more reliable media such as coaxial cable, optical fibers, microwave, or satellite.

Bandwidth

Refers to transmission capacity of a communications channel. It is the difference between the lowest and highest frequencies transmitted. It is expressed in cycles per second (Hertz).