Editing Telecommunication circuit

{{Short description|Line, conductor, or other conduit by which information is transmitted}}
{{Redirect|Communications circuit|the concept in information science|Robert Darnton}}
{{refimprove|date=March 2017}}

A '''telecommunication circuit''' is a path in a [[telecommunications network]] used to [[Transmission (telecommunications)|transmit information]]. Circuits have evolved from generally being built on physical connections between individual hardware cables, as in an analog phone switch, to [[Virtual circuit|virtual circuits]] established over [[packet switching]] networks.

==Definitions==
A telecommunication circuit may be defined as follows:{{cn|date=September 2019}}

* The complete path between two terminals over which one-way or two-way communications may be provided.
* An electronic path between two or more points, capable of providing a single or multiple [[channel (communications)|communication channels]].
* An electronic closed-loop path among two or more points used for [[signal]] transfer.
* The [[transmission media]] and any intermediate equipment between [[data terminal equipment]].<ref>{{cite standard |institution=[[Institute for Telecommunication Sciences]] |number=[[Federal Standard 1037C]] |url=https://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm |archive-url=https://web.archive.org/web/20220122224547/https://www.its.bldrdoc.gov/fs-1037/fs-1037c.htm |archive-date=22 January 2022 |title=Data transmission circuit}}</ref>

In operational terms, a telecommunication circuit may be capable of transmitting information in only one direction (''simplex'' circuit), or it may be bi-directional (''duplex'' circuit). Bi-directional circuits may support half-[[Duplex (telecommunications)|duplex operation]], when only one end of the channel transmits at any one time, or they may support full-duplex operation where independent simultaneous transmission occurs in both directions.<ref name=freeman>{{Cite book|title=Fundamentals of Telecommunications|last=Freeman|first=Roger L.|publisher=John Wiley & Sons, Inc.|year=1999|isbn=0471296996|url-access=registration|url=https://archive.org/details/fundamentalsofte0000free}}</ref>

==Applications==
Originally, telecommunication circuits transmitted [[analog signal]]s. [[Radio station]]s used them as [[studio transmitter link]]s (STLs) or as [[remote pickup unit]] (RPU) for [[sound reproduction]], sometimes as a backup to other means.  Later lines were [[Digital data|digital]], used in pair-gain applications, such as [[carrier system]]s, or in enterprise [[data network]]s.

A [[leased line]], ''private circuit'', or ''dedicated circuit'', is a circuit that is dedicated to only one use and is typically not switched at a central office. The opposite is a '''switched circuit''', which can be connected to different paths in a switching center or telephone exchange. [[Plain old telephone service]] (POTS) and [[ISDN]] telephone lines are switched circuits.

On certain [[packet switching]] telecommunication circuits, a [[virtual circuit]] may be created, while sharing the physical circuit.

==References==
{{reflist}}
{{FS1037C MS188}}

==Further reading==
*{{cite book|title=Telecommunication Circuit Design|author=Patrick D. van der Puije|year=2002|publisher=John Wiley & Sons|location=New York}}

[[Category:Telecommunications equipment]]