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List of Terms
AC Alternating Current
ACB Antenna Control Board
ADE Above Deck Equipment
ALC Automatic Level control
ANT Antenna
AOR-E Atlantic Ocean Region East.
AOR-W Atlantic Ocean Region West.
ASIC Application Specific Integrated Circuit
AU Antenna Unit, major part of MiniPhone
AUX Auxiliary
BDE Below Deck Equipment
BPSK Binary Phase Shift Keying
Bulletin Board system status information for MES
C Band band of radio frequencies from about 4.0 GHz to
6.0 GHz, used by Inmarsat links for the satellite/LES link.
CCITT International Telegraph and Telephone Consulta-
tive Committee
CES Coast Earth Station
Codec speech encoder/decoder
CPU Central Processing Unit
CRC Cyclic Redundancy Check
CTS Clear To Send
DAC Digital-Analogue Converter
dBW deciBels relative to 1 Watt
DC Direct current
DCD Data Carrier Detect
DI Destination Identification digits
Downlink radio link from the satellite down to stations on
Earth.
DSP Digital Signal Processor
DSR Data Set Ready
DSUB Data Sub-band, SCPC sub-band signalling.
DSUB Data Subminiature
DTE Data Terminal Equipment
DTR Data Terminal Ready
EEPROM Electrically Erasable Programmable Read Only
Memory
EIRP Equivalent Isotropically Radiated Power
EPROM Erasable Programmable Read Only Memory
FDMA Frequency Division Multiple Access
FIO Fax Interface Unit
GPS Global Positioning System, a satellite navigation
system.
HPA High Power Amplifier
40
Hz Hertz
ID Identification Digit(s)
IMN Inmarsat Mobile Number, a unique 9-digit number.
Inmarsat International Maritime Satellite Organisation
IOR Indian Ocean Region.
ISDN Integrated Services Digital Network, digital national
and international telecommunications network.
ITU International Telecommunications Union, international
organisation that oversees and compiles standards for
telecommunications.
KBPS KiloBits Per Second
L Band band of radio frequencies from about 1.5 GHz to
1.6 GHz, used by Inmarsat for the MES/satellite link.
Latitude distance north or south of the equator, measured
in degrees.
LED Light-Emitting Diode, semiconductor element that
emits light.
LES Land Earth Station, a station that interconnects fixed
telecommunications networks with the Inmarsat system;
may also be called a CES (Coast Earth Station) or a GES
(Ground Earth Station).
LES-SIG LES Signalling, SCPC mode for in-band signal-
ling.
LESA Land Earth Station Assignment Channel
LESD LES Data, SCPC mode for data communications
LESI LES Interstation Signalling Channel, TDM channel
carrying signalling information to NCS.
LESV LES Voice, SCPC mode for voice communications
LHCP Left Hand Circular Polarization
LNA Low Noise Amplifier
LONG longitude
Longitude distance east or west of Greenwich meridian,
measured in degrees.
MCB Main Control Board
MCC Mobile Country Code
MCU Main Control Unit, major part of terminal; performs
all signal processing and message handling functions.
MES Mobile Earth Station, a user terminal for an Inmarsat
system; the Saturn M terminal is an MES for the Inmarsat-
M system; MES may also be called SES (Ship Earth
Station) or, if on aircraft, AES (Aeronautical Earth Station).
MES-SIG MES Signalling, SCPC mode for in-band signal-
ling.
MESCA MES Call Acknowledgement, random access
(Slotted Aloha) burst mode channel carrying acknowl-
edgement messages for fixed-originated simplex calls.
MESD MES Data, SCPC mode for data communications
MESRP MES Response, TDMA channel carrying the
response information required for a fixed-originated call.
MESRQ MES Request, random access (Slotted Aloha)
burst mode channel carrying access request messages to
LESs for initiation of mobile-originated calls.
MESRR MES Registration channel, random access
(Slotted Aloha) burst mode channel carrying the Ocean
Registration messages required to route fixed-originated
calls.
MESV MES Voice, SCPC mode for voice communications
MHz MegaHertz
MID Maritime Identification Digits
NCRA Network Coordination Registration Acknowledge-
ment, TDM channel carrying responses to registration
messages transmitted by MESs.
NCS Network Coordination Station, station that super-
vises all messages and signals sent in the Inmarsat
system; one in each Ocean Region.
NCSA NCS Assignment, TDM channel carrying channel
assignment messages.
NCSC NCS Common, TDM channel carrying signalling
messages including call announcements, Bulletin Board
and forced channel clearing.
NCSI NCS Inter-station channel used by NCS to carry
signalling information to the LES.
NCSS NCS Spotbeam, TDM channel carrying spotbeam
identification numbers.
NMEA National Marine Electronics Association, US
industrial organisation whose activities include stipulating
standards for marine navigation systems.
O-QPSK Offset Quadrature Phase Shift Keying.
OCC Operation Control Centre, Inmarsat centre that
monitors entire Inmarsat system.
Ocean Region area of coverage of a single Inmarsat
satellite, from 70°N to 70°S; there are four: Atlantic East,
Atlantic West, Pacific, Indian.
OI Originating Identification digits
OSC Oscillator
PC Personal Computer
PCM Pulse Code Modulation, analogue-to-digital signal
conversion method.
PCU Pedestal Control Unit
PLL Phase Locked Loop
POR Pacific Ocean Region
Prefix service in Inmarsat-M, two-digit prefix to number
called, keyed in to stipulate special service, such as credit-
card call.
PROM Programmable Read Only Memory
Protocol the internal rules in the system that enable
communications.
PSDN Packet Switched Data Network, terrestrial network
for packet data communications.
S e r v i c e
S e r v i c e
S e r v i c e
PSTN Public Switched Telephone Network, terrestrial
network for telephone, telefax and data modem services.
QUART Quad Universal Asynchronous Receiver/Trans-
mitter, provides four interfaces between parallel data
circuits and serial data circuits.
RF Radio Frequency
RHCP Right Hand Circular Polarization
ROM Read-Only Memory, microchip memory that stores
programs and/or data.
RS 232 Serial Data Interface
RS 422 Serial Data Interface
RTS Request To Send
RX IF Receiver Intermediate Frequency
Rx Receive
RXD Receive Data
SAMBA TX/RX Up/down conversion between intermedi-
ate frequency and base band.
SCC Satellite Control Centre
SCPC Single Channel per Carrier
SDM (Inmarsat-M) System Definition Manual
SES Ship Earth Station
Spot Beam (Inmarsat-M) service that divides each Ocean
Region into sub-regions, each "spotlighted" by a beam
from the region satellite; permits increasing capacity of
system.
SU Signalling Unit, 96-bit data packets transmitted on
SCPC sub-band signalling channels, to conduct system
signalling.
SU Signalling Unit, data packets
TDM Time Division Multiplexing, method of allowing
several users to share the same channel.
TDMA Time Division Multiple Access
Terrestrial Network a fixed telecommunications network,
such as a telephone network or a data network, which
connects to the Inmarsat-M system at an LES.
TUP Telephone User Part of CCITT Signalling System No 7.
TX IF Transmitter Intermediate Frequency
Tx Transmit
TXD Transmit Data
UART Universal Asynchronous Receiver/Transmitter,
provides interface between parallel data circuits and serial
data circuits.
Uplink radio link from a station on Earth up to the satellite.
UTC Coordinated Universal Time, referenced to Green-
wich Mean Time (GMT)
UW Unique Word
VSUB Voice Sub-band, SCPC sub-band signalling.
WMO World Meteorological Organization
Saturn Bp Portable – Technical Manual
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