xv
N
NAVAREA.................................................................................................. Navigational Area
A geographical sea area established for the purpose of co ordinating the broadcast of
navigational warnings.
NAVTEX .......................................................................MF Navigational Broadcast Service
The system for The broadcast and automatic reception of Maritime Safety information
by means of narrow-band direct-printing telegraphy.
NCS........................................................................................ Network Coordination Station
A fixed land station in the Inmarsat satellite communications system which controls
channel assignments and provides network management functions in each satellite ocean
region. NCSs also transmit EGC messages on the NCS common channel.
NCS Common Signaling Channel:
Also known as the NCS Common Channel. A TDM channel used by the NCS to
transmit system information and message announcements to MESs.
NMEA................................................................... National Marine Electronics Association
N/S.........................................................................................................................North/South
O
OCC.......................................................................INMARSAT Operations Control Centre
Ocean region:
The coverage area of an Inmarsat satellite within which an MES may send and receive
messages.
OSC........................................................................................................................... Oscillator
P
Packet:
An envelope or block of data sent over a network; each packet contains addressing
information as well as the data being sent.
PC .............................................................................................................Personal Computer
PEP ................................................................................................. Packet Error Probability
PER.............................................................................................................Packet Error Rate
PIN.......................................................................................Personal Identification Number
Polling:
The facility whereby an operational center sends an instruction (a polling command) to
selected MESs to perform a defined task, such as returning a pre-assigned data report or
performing a SCADA operation.
POR .......................................................................................................Pacific Ocean Region
Presentation code:
A code included in a transmission (ship-to-shore or shore-to-ship), indicating to the
recipient the presentation or formatting of the data contained in the message.
Protocol:
A defined set of communications standards, which lay down the parameters to which all
users must abide. Protocols in general use are X.25 and X.400.
PROM........................................................................... Programmable Read Only Memory
PSA ................................................................................................ Point of service activation
PSDN ....................................................................................Packet Switched Data Network
PSPDN......................................................................Packet Switched Public Data Network
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