Simplex communication
Encyclopedia
Simplex communication refers to communication that occurs in one direction only. Two definitions have arisen over time: a common definition, which is used in ANSI standard and elsewhere, and an ITU-T definition. The ITU definition of simplex is termed "half duplex" in other contexts.
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.
is one where signals can flow in only one direction at a time. At other times communications can flow in the reverse direction. A more common term for this application is half-duplex.
The old Western Union
company used the term simplex when describing the half-duplex
and simplex capacity of their new transatlantic telegraph cable
completed between Newfoundland and the Azores
in 1928. The same definition for a simplex radio channel was used by the National Fire Protection Association
in 2002.
ANSI definition: One way signaling
According to the ANSIAmerican National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
definition, a simplex circuit
Simplex circuit
In telecommunication, the term simplex circuit has the following meanings:#A circuit that provides transmission in one direction only.#Deprecated definition: A circuit using ground return and affording communication in either direction, but in only one direction at a time.The above two definitions...
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.
Examples
- Commercial radioRadioRadio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
broadcastBroadcastBroadcast or Broadcasting may refer to:* Broadcasting, the transmission of audio and video signals* Broadcast, an individual television program or radio program* Broadcast , an English electronic music band...
(not walkie-talkies, etc.) - TelevisionTelevisionTelevision is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
broadcast - Keyboard to CPU communication
- Internet multicastIP MulticastIP multicast is a method of sending Internet Protocol datagrams to a group of interested receivers in a single transmission. It is often employed for streaming media applications on the Internet and private networks. The method is the IP-specific version of the general concept of multicast...
- One-way communications from a launcher to a guided missileGuided MissileGuided Missile is a London based independent record label set up by Paul Kearney in 1994.Guided Missile has always focused on 'the underground', preferring to put out a steady flow of releases and developing the numerous GM events around London and beyond....
, where the launcher (airplane, ship, etc.) sends commands to the missile, but does not receive any information sent back.
ITU-T definition: One way signaling at a time
According to the ITU-T definition, a simplex circuitSimplex circuit
In telecommunication, the term simplex circuit has the following meanings:#A circuit that provides transmission in one direction only.#Deprecated definition: A circuit using ground return and affording communication in either direction, but in only one direction at a time.The above two definitions...
is one where signals can flow in only one direction at a time. At other times communications can flow in the reverse direction. A more common term for this application is half-duplex.
The old Western Union
Western Union
The Western Union Company is a financial services and communications company based in the United States. Its North American headquarters is in Englewood, Colorado. Up until 2006, Western Union was the best-known U.S...
company used the term simplex when describing the half-duplex
Duplex (telecommunications)
A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions. The term multiplexing is used when describing communication between more than two parties or devices....
and simplex capacity of their new transatlantic telegraph cable
Transatlantic telegraph cable
The transatlantic telegraph cable was the first cable used for telegraph communications laid across the floor of the Atlantic Ocean. It crossed from , Foilhommerum Bay, Valentia Island, in western Ireland to Heart's Content in eastern Newfoundland. The transatlantic cable connected North America...
completed between Newfoundland and the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
in 1928. The same definition for a simplex radio channel was used by the National Fire Protection Association
National Fire Protection Association
The National Fire Protection Association is a United States trade association that creates and maintains private, copywrited, standards and codes for usage and adoption by local governments...
in 2002.