ABSTRACT
Telecommunication transmission media are the facilities for the transmission by wire or radio of all types of messages or information in analog or digital forms, including voice, telegraph data at various rates, facsimile data, videophone, television, and visual display. There are two main categories: physical lines and radio. The former includes open wires, paired cables and coaxial cables, optical fibers, while the latter includes microwave, troposcatter, and communication satellites. Submarine coaxial cable was introduced for transmission in bodies of water, particularly across oceans, before the use of satellite communication. Communication satellites provide coverage and a line-of-sight mode of transmission similar to microwave transmission. The twisted-wire pair has been the most common type of transmission media for analog signals. Coaxial and twinaxial cable are used for high frequencies, digital information, and wide-bandwidth applications. A main source of competition with coaxial systems is the microwave radio system. The basic function of a microwave repeater is to amplify and redirect microwave signals.
