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TDM channel:
The Inmarsat system uses different TDM channels, each transmitted on an unique
frequency. The TDM channels are used for system control and message transfer to
MESs. See LES TDM Channel and NCS Common Channel.
Time slot:
Basic unit into which one time frame of a TDM channel is divided.
TX ......................................................................................................... Transmit/Transmitter
U
User defined area
A temporary geographic area, either circular or rectangular, to which maritime safety
information is addressed.
UTC .......................................................................................... Coordinated Universal Time
Universal Coordinated Time. A term, which for practical purpose has the same meaning
as Greenwich Mean Time (GMT).
V
VCXO .............................................................................. Voltage Control Crystal Oscillator
W
WMO ............................................................................ World Meteorological Organization
Others
5-bit packed (also known as telex format or ITA2):
A format based on 5-bit codes used for sending alphanumeric characters to and from
telex terminals.
7-bit ASCII:
A format based on 7-bit codes used for sending the alphanumeric characters of the
ASCII character set.
8-bit data:
A format based on 8-bit codes used for encoding information such as text, national
character sets and numerical information.