INMARSAT
SYATEM
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What is the Inmarsat System?
The
basic components of the Inmarsat system include the Inmarsat space segment, Land Earth Stations (LES), also referred to as Coast Earth Stations (CES), and mobile
Ship Earth Stations (SES).
How many ocean regions are there for
INMARSAT satellite communication?
What are they?
The
ocean region is divided in to four with overlapping area for maritime satellite communication purpose
Atlantic
Ocean - East (AOR-E)
Atlantic
Ocean - West (AOR-W)
Pacific
Ocean (POR)
Indian
Ocean (IOR)
What is the function of LES?
LES
is the gateway between the maritime satellite network and the
national/International telecommunication network.
What is the gateway between ship
station and land network in satellite communication?
LES
What
are the priorities in the Inmarsat network communication?
0
for routine calls
1
for safety calls
2
for urgent calls
3
for distress calls
What is the satellite foot print?
It covers between 76 deg North and 76 deg South
What does ‘satellite foot
print’ means?
Satellite
coverage area is called satellite foot print
What is the drawback in
sea area A4?
Sea
area A4 is not in INMARSAT coverage.
No satellite communication is possible outside the satellite
coverage area. In that area, Terrestrial communication is used.
What is space segment?
Space segment consists of INMARSAT satellites
What is ground segment?
Ground segment consists of CES, NCS and NOC (Network Operation
Centre)
What are the positions of
satellites?
AOR-E 15.5 deg
West
POR 178 deg
East
IOR 64 deg East
AOR-W 54 deg West
What is Geo stationary satellite?
Inmarsat
satellite is placed in the geo stationary orbit.
What is Geo synchronous satellite?
Inmarsat
satellite is synchronized with the speed and direction of the earth’s rotation
Where the inmarsat satellite is
placed?
Approximately
36000 KM above earth’s equator
How many satellites are used in this Inmarsat network?
Four
satellites. (and four back up satellites)
What are the uplink and down link
frequencies of SES? (SES – SATELLITE)?
Uplink
frequency - 1.6 GHZ (1626.5 MHz –
1660.5 MHz)
Downlink
frequency – 1.5 GHZ (1525.0 MHz -
1559.0 MHz)
What are the uplink and down link
frequencies of LES/CES? (LES/CES – SATELLITE)?
Uplink
frequency – 6 GHZ
Downlink
frequency – 4 GHZ
What is up link frequency?
Transmitting
frequency
What is down link frequency?
Receiving
frequency
What type of antenna is used in CES?
SIZE?
At CES, antenna which is used is Parabolic Antenna 11 to 14 meters
in dia. Same aerial or another aerial for 1.6 GHz/1.5GHz (L band Transmission)
What is the function of Network Co-ordination Station (NCS)?
NCS
monitor and control communications through the INMARSAT Satellite for which it
is responsible.
NCS provides a common signaling channel to the stations for
communication when we log in to NCS.
How many NCS are there?
There are 4 NCS, one in each ocean region.
What are telephone and
telex access codes used in satellite communication?
Telephone
and Telex access codes in 4 ocean regions
Telex - Telephone
AOR-E - 581 - 870
PQR
- 582
- 870
IOR
-
583 - 870
AOR-W
- 584 - 870
SNAC (Single Network Access Code)
What is SNAC?
Same telephone access code
is used in all four ocean regions.
That is called single network access code.
What are the INMARSAT
ID/IMN?
INMARSAT A1 Seven (7) digits beginning
with 1
INMARSAT B Nine (9) digits beginning with 3
INMARSAT C Nine (9) digits beginning with 4
INMARSAT mini-C Nine (9) digits beginning
with
4
INMARSAT Fleet F77 Nine (9) digits
beginning with 76 (voice) or 60 (data)2
Non-GMDSS
Terminals:
INMARSAT M Nine (9) digits beginning
with 6
INMARSAT mini-M Nine (9) digits beginning
with 76 (voice and/or data)
INMARSAT Fleet F33 Nine (9) digits
beginning with 76 (voice) or 60 (data)
INMARSAT Fleet F55 Nine (9) digits
beginning with 76 (voice) or 60 (data)
What are the 2 digit
special access codes?
URGENCY
/ SAFETY by Satellite Communication:
By using 2 digit special access code
32 - Medical advice - connected to shore hospital/doctor
38 - Medical assistance - connected to associated RCC
39 - Maritime assistance -
connected to associated RCC
42 – navigational
Hazards
VASUDEVAN PONDICHERRY PH:91 96299 80476
What is SIM?
Subscriber
Identity Module
1
byte = 8 bits = 1 character
1
kilobit = 1024 bits = 128 characters = approx 25 words
INMCC = Indian Mission Control Centre
ISRO/MCC – ISTRAC Dept of Space INMCC
Bangalore
Who is the LES operator in India?
TATA
communications
