Editing Duplex (telecommunications) (section)

==Simplex==
[[File:Locale_RS6_Simplex.jpg|thumb|Simplex wireless communication]] 

'''Simplex communication''' is a [[communication channel]] that sends information in one direction only.<ref name="IEEE">"Simplex" ''The IEEE Authoritative Dictionary of Standard Terms, 7th Ed.'', 2000, Inst. of Electrical and Electronic Engineers, p.1053</ref>

The [[International Telecommunication Union]] definition is a communications channel that operates in one direction at a time, but that may be reversible; this is termed ''[[half duplex]]'' in other contexts. 

For example, in TV and radio [[broadcasting]], information flows only from the transmitter site to multiple receivers. A pair of [[walkie-talkie]] [[two-way radio]]s provide a simplex circuit in the ITU sense; only one party at a time can talk, while the other listens until it can hear an opportunity to transmit. The transmission medium (the radio signal over the air) can carry information in only one direction. 

The [[Western Union]] company used the term ''simplex'' when describing the half-duplex and simplex capacity of their new [[transatlantic telegraph cable]] completed between [[Newfoundland (island)|Newfoundland]] and the [[Azores]] in 1928.<ref>Milnor, J.W. and G.A. Randall. "The Newfoundland-Azores High-Speed Duplex Cable". ''A.I.E.E. Electrical Engineering''. May 1931</ref> The same definition for a simplex radio channel was used by the [[National Fire Protection Association]] in 2002.<ref>''Report of the Committee on Public Emergency Service Communication''. NFPA 1221, May, 2002.</ref>