A data link is a means of connecting one location to another for the purpose of transmitting and receiving digital information (

data communication Data communication, including data transmission and data reception, is the transfer of data, transmitted and received over a point-to-point or point-to-multipoint communication channel. Examples of such channels are copper wires, optic ...

). It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of

data terminal equipment Data terminal equipment (DTE) is an end instrument that converts user information into signals or reconverts received signals. It is also called data processing terminal equipment or tail circuit. A DTE device communicates with the data cir ...

) and the interconnecting data

telecommunication circuit A telecommunication circuit is a path in a telecommunications network 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 v ...

. These are governed by a link protocol enabling digital data to be transferred from a data source to a data sink.

Types

There are at least three types of basic data-link configurations that can be conceived of and used: *

Simplex communication A duplex communication system is a Point-to-point (telecommunications), point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many commu ...

s, most commonly meaning all communications in one direction only. *

Half-duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

communications, meaning communications in both directions, but not both ways simultaneously. * Duplex communications, communications in both directions simultaneously.

Aviation

In civil

aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' include fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air aircraft such as h ...

, a data-link system (known as Controller Pilot Data Link Communications) is used to send information between aircraft and

air traffic control Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled air ...

lers for example when an aircraft is too far from the ATC to make voice radio communication and

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

observations possible. Such systems are used for aircraft crossing the

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

and Indian oceans. One such system, used by

Nav Canada Nav Canada (styled as NAV CANADA) is a privately run, non-profit corporation that owns and operates Canada's civil air navigation system (ANS). It was established by statute in accordance with the ''Civil Air Navigation Services Commercializati ...

and NATS over the North Atlantic, uses a five-digit data link sequence number confirmed between air traffic control and the pilots of the aircraft before the aircraft proceeds to cross the ocean. This system uses the aircraft's flight management computer to send location, speed and altitude information about the aircraft to the ATC. ATC can then send messages to the aircraft regarding any necessary change of course. In

unmanned aircraft An unmanned aerial vehicle (UAV) or unmanned aircraft system (UAS), commonly known as a drone, is an aircraft with no human Aircraft pilot, pilot, crew, or passengers onboard, but rather is controlled remotely or is autonomous.De Gruyter H ...

, land vehicles, boats, and spacecraft, a two-way (

full-duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

half-duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...

) data-link is used to send control signals, and to receive

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', 'far off', an ...

Sources

* * {{Authority control Data transmission

Types

Aviation

See also

Sources