A data link is the means of
connecting one location to another for the purpose of transmitting and receiving digital information (
data communication
Data transmission and data reception or, more broadly, data communication or digital communications is the transfer and reception of data in the form of a digital bitstream or a digitized analog signal transmitted over a point-to-point or p ...
). It can also refer to a set of electronics assemblies, consisting of a transmitter and a receiver (two pieces of
data terminal equipment) and the interconnecting data
telecommunication circuit
A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved over time from generally being built on physical connections between individual hardware cables, as in an analog phone swi ...
. These are governed by a
link protocol enabling digital data to be transferred from a data source to a
data sink In computing, a sink, or data sink generally refers to the destination of data flow.
The word sink has multiple uses in computing. In software engineering, an event sink is a class or function that receives events from another object or function, ...
.
Types
There are at least three types of basic data-link configurations that can be conceived of and used:
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Simplex communication
Simplex communication is a communication channel that sends information in one direction only."Simplex" ''The IEEE Authoritative Dictionary of Standard Terms, 7th Ed.'', 2000, Inst. of Electrical and Electronic Engineers, p.1053
The Internationa ...
s, most commonly meaning all communications in one direction only.
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Half-duplex communications, meaning communications in both directions, but not both ways simultaneously.
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Duplex communications, communications in both directions simultaneously.
Aviation
In civil
aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes airplane, fixed-wing and helicopter, rotary-wing types, morphable wings, wing-less lifting bodies, as well as aerostat, lighter- ...
, 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 airsp ...
lers for example when an aircraft is too far from the ATC to make voice radio communication and
radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...
observations possible. Such systems are used for aircraft crossing the
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
and
Pacific oceans. One such system, used by
Nav Canada 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), commonly known as a drone, is an aircraft without any human pilot, crew, or passengers on board. UAVs are a component of an unmanned aircraft system (UAS), which includes adding a ground-based controlle ...
, land vehicles, boats, and spacecraft, a two-way (
full-duplex or
half-duplex) 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'', "remote", an ...
.
See also
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ACARS
In aviation, ACARS (; an acronym for Aircraft Communications Addressing and Reporting System) is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. The protocol was des ...
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Deep Space Network
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Space probe
A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; o ...
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Tactical Data Links
A tactical data link (TDL) uses a data link standard in order to provide communication via radio waves or cable used by NATO nations. All military C3 systems use standardized TDL to transmit, relay and receive tactical data.
Multi-TDL netw ...
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Terminal (telecommunication)
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Timex Datalink
Timex Datalink or Timex Data Link is a line of early smartwatches manufactured by Timex and is considered a wristwatch computer. It is the first watch capable of downloading information wirelessly from a computer. As the name implies, datalink ...
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Unmanned Aircraft System
Sources
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Data transmission
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