A telecommunication circuit is a path in a
telecommunications network
A telecommunications network is a group of Node (networking), nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit ...
used to
transmit information. Circuits have evolved from generally being built on physical connections between individual hardware cables, as in an analog phone switch, to
virtual circuits established over
packet switching
In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consi ...
networks.
Definitions
A telecommunication circuit may be defined as follows:
* 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
communication channels.
* An electronic closed-loop path among two or more points used for
signal
A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology.
In ...
transfer.
* The
transmission media and any intermediate equipment between
data terminal equipment.
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 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.
Applications
Originally, telecommunication circuits transmitted
analog signals.
Radio station
Radio broadcasting is the broadcasting of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based rad ...
s used them as
studio transmitter links (STLs) or as
remote pickup unit (RPU) for
sound reproduction, sometimes as a backup to other means. Later lines were
digital, used in pair-gain applications, such as
carrier systems, or in enterprise
data networks.
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
Plain old telephone service (POTS), or publicly offered telephone service, is basic Voice band, voice-grade telephone service. Historically, POTS has been delivered by Analog signal, analog signal transmission over copper loops, but the term also d ...
(POTS) and
ISDN telephone lines are switched circuits.
On certain
packet switching
In telecommunications, packet switching is a method of grouping Data (computing), data into short messages in fixed format, i.e. ''network packet, packets,'' that are transmitted over a digital Telecommunications network, network. Packets consi ...
telecommunication circuits, a
virtual circuit
A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is first established across the network between two endpoints. The network, rather than having a fixed data rate reser ...
may be created, while sharing the physical circuit.
References
Further reading
*{{cite book, title=Telecommunication Circuit Design, author=Patrick D. van der Puije, year=2002, publisher=John Wiley & Sons, location=New York
Telecommunications equipment