Glossary A
A
ARQ Automatic Repetition reQuest. An error-control method for data
transmission that uses acknowledgements and timeouts to
achieve reliable data transmission over an unreliable service. If
the sender does not receive an acknowledgment before the
timeout, it usually re-transmits the frame/packet until the sender
receives an acknowledgment or exceeds a predefined number of
re-transmissions.
C
CAN Controller-Area Network. A message based protocol designed to
allow microcontrollers and devices to communicate with each
other within a vehicle without a host computer.
D
DE A command used in a telex message to insert an answer-back
string identifying the sender of the message. The string should
normally contain the call sign.
DSC Digital Selective Calling. Primarily intended to initiate ship-to-
ship, ship-to-shore and shore-to-ship radiotelephone and MF/HF
radiotelex calls. Each DSC-equipped ship, shore station and group
is assigned a unique 9-digit Maritime Mobile Service Identity. DSC
distress alerts, which consist of a preformatted distress message,
are used to initiate emergency communication with ships and
rescue coordination centers.
F
FEC Forward Error Correction. A system of error control for data
transmission, whereby the sender adds redundant data to its
messages, also known as an error-correcting code. This allows
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