Simplex communication
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Simplex communication is a name for a type of communication circuit. There are two (contradictory) definitions that have been used for the term. In both cases, the other definition is referred to as half duplex.
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[edit] One way at a time
According to the ITU-T definition, a simplex circuit is one where all signals can flow in only one direction at a time. This was also the way Western Union used the term when describing the duplex and simplex capacity of their new transatlantic telegraph cable completed between Newfoundland and the Azores in 1928[1]. The same definition for a simplex radio channel was used by the National Fire Protection Association in 2002[2]. Note that this is sometime also refer as Half duplex.
[edit] One way only
According to the ANSI definition, a simplex circuit is one where all signals can flow in only one direction. These systems are often employed in broadcast networks, where the receivers do not need to send any data back to the transmitter/broadcaster.
To put it simply, you won't find your radio receiver actually sending out any information. All it does is receive. Thus then, information moves one way only from the radio broadcasting station to your radio receiver.
[edit] Examples according to ANSI definition
- Television broadcast
- Commercial radio broadcast (not CB, etc.)
- Internet simulcast
[edit] References
- ^ Milnor, J.W. and G.A. Randall. "The Newfoundland-Azores High-Speed Duplex Cable". A.I.E.E. Electrical Engineering. May 1931
- ^ Report of the Committee on Public Emergency Service Communication. NFPA 1221, May, 2002.
