gmdss paper work
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T H E G L O B A L M A R I T I M E D I S T R E S S A N D S A F E T Y S Y S T E MG M D S S
Student: Constantin Gabriel
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INTRODUCTIONThe Global Maritime Distress and Safety System is the
technical, operational and administrative structure formaritime distress and safety communications worldwide. Itwas established in 1988 by the International MaritimeOrganization (IMO) which adopted a revised text of Chapter IVof the International Convention for the Safety of Life at Sea,1974, (SOLAS) - dealing with Radiocommunications - and wasimplemented globally between 1992 and 1997. The GMDSSestablishes the radiocommunications equipment that ships arerequired to carry, how this equipment shall be maintained and
how it is used, and provides the context within whichgovernments should establish the appropriate shore-basedfacilities to support GMDSS communications.
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GMDSS EQUIPMENT:
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VHF RADIO
Marine VHF radio refers to the radio frequency range
between 156.0 and 162.025 MHz, inclusive. In the official language
of the ITU the band is called the VHF maritime mobile band.
It's installed on all large ships and most seagoing small
craft. It is also used, with slightly different regulation, on rivers and
lakes. It is used for a wide variety of purposes, including
summoning rescue services and communicating with harbours,
locks, bridges and marinas, and operates in the very high
frequency (VHF) range, between 156 and 162.025 MHz. Although it
is widely used for collision avoidance, its use for that purpose iscontentious and is strongly discouraged by some countries,
including the UK
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VHF RADIO
A marine VHF set is a combined transmitter andreceiver and only operates on standard, international
frequencies known as channels. Channel 16 (156.8 MHz) is
the international calling and distress channel. Transmission
power ranges between 1 and 25 watts, giving a maximum
range of up to about 60 nautical miles (111 km) between
aerials mounted on tall ships and hills, and 5 nautical miles (9
km; 6 mi) between aerials mounted on small boats at sea
level. Frequency modulation (FM) is used, with vertical
polarization, meaning that antennas have to be vertical in
order to have good reception.
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VHF RADIO
Modern-day marine VHF radios not onlyoffer basic transmit and receive capabilities.
Permanently mounted marine VHF radios on
seagoing vessels are required to have certification
of some level of "Digital Selective Calling" (DSC)
capability, to allow a distress signal to be sent with
a single button press.
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VHF RADIO
Marine VHF mostly uses "simplex" transmission, where
communication can only take place in one direction at a time. A
transmit button on the set or microphone determines whether it is
operating as a transmitter or a receiver. The majority of channels,
however, are set aside as "semi-duplex" transmission channels
where communication can take place in both directionssimultaneously. Each semi-duplex channel has two frequency
assignments. Semi-Duplex channels can be used to place calls on
the public telephone system for a fee via a marine operator. This
facility is still available in some areas, though its use has largelydied out. Marine VHF radios can also receive weather radio
broadcasts, where they are available.
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SART
A Search And Rescue Transponder (SART) is a self-
contained, waterproof transponder intended for emergency use
at sea. These devices may be either a radar-SART, or a GPS-
based AIS-SART (automatic identification system SART).
The radar-SART is used to locate a survival craft ordistressed vessel by creating a series of dots on a rescuing
ship's radar display. A SART will only respond to a 9 GHz X-band
(3 cm wavelength) radar. It will not be seen on S-band (10 cm) or
other radar. Shipboard Global Maritime Distress Safety System
(GMDSS) include one or more search and rescue locating
devices.
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SART
The radar-SART may be triggered by any X-bandradar within a range of approximately 8 nautical miles (15
kilometers). Each radar pulse received causes the SART
to transmit a response which is swept repetitively across
the complete radar frequency band. When interrogated, itfirst sweeps rapidly (0.4 microsecond) through the band
before beginning a relatively slow sweep (7.5
microseconds) through the band back to the starting
frequency.
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SART
This process is repeated for a total of twelvecomplete cycles. At some point in each sweep, the
radar-SART frequency will match that of the
interrogating radar and be within the pass band of
the radar receiver. If the radar-SART is within
range, the frequency match during each of the 12
slow sweeps will produce a response on the radar
display, thus a line of 12 dots equally spaced byabout 0.64 nautical mile (1.2 km) will be shown.
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SART
When the range to the radar-SART is reduced toabout 1 nautical mile (2 km), the radar display may show
also the 12 responses generated during the fast sweeps.
These additional dot responses, which also are equally
spaced by 0.64 nautical mile (1.2 km), will be interspersedwith the original line of 12 dots. They will appear slightly
weaker and smaller than the original dots.
SARTs are typically cylindrical, about the size of a
person's forearm, and brightly coloured.
GMDSS EQUIPMENT
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GMDSS EQUIPMENT:
Portable VHF Transceiver
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PORTABLE VHF TRANSCEIVER
Usual portable VHF transreceiver specifications:
Built-in Parallel 12 Channel GPS Receiver
SC-101 DSC Distress Call Automatically BroadcastsLat/Lon and Vessel ID
6 Watt Transmit power
Volume & Squelch indication on display
DSC Position Request
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PORTABLE VHF TRANSCEIVER
NMEA output of DSC, DSE, GLL, RMC, GSA, GSV andGGAChannel names on display
SOS Strobe light
Submersible Speaker Microphone Jack 1150 mAh Rechargeable Li-Ion battery
AC and 12 VDC Chargers included
Position information shown on the display
GMDSS EQUIPMENT
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GMDSS EQUIPMENT:
NAVTEX Receiver
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NAVTEX RECEIVER
NAVTEX (Navigational Telex) is an international automated
medium frequency direct-printing service for delivery of
navigational and meteorological warnings and forecasts, as well as
urgent marine safety information to ships.Navtex was developed to
provide a low-cost, simple, and automated means of receiving this
information aboard ships at sea within approximately 370 km (200nautical miles) off shore.
There are no user fees associated with receiving NAVTEX
broadcasts, as the transmissions are typically transmitted from the
National Weather Authority (Italy) or Navy or Coast Guard (as inthe US) or national navigation authority (Canada).
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NAVTEX RECEIVER
Where the messages contain weather forecasts, anabbreviated format very similar to the shipping forecast is
used.
NAVTEX is a component of the International
Maritime Organization/International HydrographicOrganization Worldwide Navigation Warning Service
(WWNWS). NAVTEX is also a major element of the Global
Maritime Distress Safety System (GMDSS). International
Convention for the Safety of Life at Sea (SOLAS) mandatedcertain classes of vessels must carry NAVTEX, beginning
August 1, 1993
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NAVTEX RECEIVER
NAVTEX transmissions are also called narrow-band direct
printing (NBDP). The transmissions are layered on top of SITOR
collective B-mode. SITOR-B is a forward error correcting (FEC) broadcast
that uses the CCIR 476 character set.
SITOR-B is also used in amateur radio, where it is known as
AMTOR-B or AMTOR-FEC. NAVTEX / SITOR / AMTOR broadcasts use100 baud FSK modulation with a frequency shift of 170 Hz.
NAVTEX broadcasts are primarily made on the Medium
frequencies of 518 kHz and 490 kHz. The international NAVTEX
frequency is 518 kHz, and these broadcasts should always be in English.National transmission of NAVTEX uses 490 kHz specifically for
broadcasts in local languages.
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NAVTEX RECEIVER
A NAVTEX message is built on SITOR collective B-mode and consists
of:
a phasing signal of at least ten seconds;
the four characters "ZCZC" that identify the end of phasing;
a single space; four characters B1, B2, B3and B4;
a carriage return and a line feed;
the information;
the four characters "NNNN" to identify the end of information;
a carriage return and two line feeds;
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NAVTEX RECEIVER
B1
is an alpha character identifying the station, and B2
is an
alpha character used to identify the subject of the message.
Receivers use these characters to reject messages from certain
stations or if the message contains subjects of no interest to the
user.
B3 and B4 are two-digit numerics identifying individual
messages, used by receivers to keep already received messages
from being repeated.
For example, a message containing B1
B2
B3
B4
characters of
'FE01' from a U.S. NAVTEX Station indicates a weather forecast
message from Boston MA.
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GMDSS EQUIPMENT
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GMDSS EQUIPMENT:
INMARSAR EGC Receiver
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INMARSAT EGC RECEIVER
The company was originally founded in 1979 asthe International Maritime Satellite Organization
(Inmarsat), a not-for-profit international organization, set
up at the behest of the International Maritime Organization
(IMO), a UN body, for the purpose of establishing asatellite communications network for the maritime
community. Originally, the model was that of Intelsat, an
international consortium which provided satellite
communications among the member countries
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INMARSAT EGC RECEIVER
The founding member of Intelsat, and the USAmember, was Communications Satellite Corporation
(COMSAT). Comsat also took the lead in the founding of
Inmarsat. Inmarsat began trading in 1982. From the
beginning, the acronym "Inmarsat" was used. The intentwas to create a self-financing body which would improve
safety of life at sea.
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INMARSAT EGC RECEIVER
The founding member of Intelsat, and the USAmember, was Communications Satellite Corporation
(COMSAT). Comsat also took the lead in the founding of
Inmarsat. Inmarsat began trading in 1982. From the
beginning, the acronym "Inmarsat" was used. The intentwas to create a self-financing body which would improve
safety of life at sea.
BIBLIOGRAPHY
http://www.gmdss.com/http://www.gmdss.com/ -
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BIBLIOGRAPHY
http://www.gmdss.comhttp://www.wikipedia.com
http://www.imso.org
http://www.inmarsat.com
http://www.icomamerica.com
http://www.icomuk.co.uk
http://www.gmdss.com/http://www.gmdss.com/http://www.wikipedia.com/http://www.imso.org/http://www.inmarsat.com/http://www.icomamerica.com/http://www.icomuk.co.uk/http://www.icomuk.co.uk/http://www.icomamerica.com/http://www.inmarsat.com/http://www.imso.org/http://www.wikipedia.com/http://www.gmdss.com/http://www.gmdss.com/http://www.gmdss.com/ -
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END!
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