Global Maritime Distress and Safety System GMDSS

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Global Maritime Distress and Safety System (GMDSS)

• By S. M. Challo, Radiocommunication Bureau 2000

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General concept of GMDSS
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Application

• The GMDSS applies to vessels subject to the SOLAS
  Convention - that is
• Commercial vessels of 300 Gross Registered Tons
  (GRT) and above and all passenger vessels,
  engaged on international voyages.
• The GMDSS became mandatory for such vesselsas
  from February 1, 1999.
• Commercial vessels under 300 GRT, or those above
  300 GRT engaged on domestic voyages only are
  subject to the requirements of their Flag State.
  Some Flag States have incorporated GMDSS
  requirements into their domestic marine radio
  legislation - however many have not.

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GMDSS Implementation Calendar

• 1.7.1991 Entry into force of the Radio
  Regulations (gradual implementation of GMDSS)
• 1.2.1992 Entry into force of the 1988 Amendments
  to SOLAS Convention (IMO) specifying (for SOLAS
  ships)
• new ships built after 1.2.1992 SART and two-way
  VHF RTF apparatus for survival craft
• After 1.8.1993 all ships with NAVTEX receiver
  and S-EPIRB

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• After 1.8.1993 all ships with NAVTEX receiver
  and S-EPIRB
• After 1.2.1995 all ships will have to carry at
  least one radar capable of operating in the 9 GHz
  band, and SART and two-way VHF RTF apparatus for
  survival craft
• new ships built after 1.2.1995 must comply with
  all applicable GMDSS requirements
• After 1.2.1999 all ships must comply with the
  GMDSS

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Functional requirements

• The GMDSS regulations (chapter IV of the
  International SOLAS Convention), require that
  every GMDSS equipped ship shall be capable of
• transmitting ship-to-shore Distress Alerts by at
  least two separate and independent means, each
  using a different radio communication service
• receiving shore-to-ship Distress Alerts
  transmitting and receiving ship-to-ship Distress
  Alerts
• transmitting and receiving search and rescue
  co-coordinating communications
• transmitting and receiving on-scene
  communications

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• transmitting and receiving locating and homing
  signals
• receiving maritime safety information
• transmitting and receiving general
  radiocommunications relating to the management
  and operation of the vessel
• transmitting and receiving bridge-to-bridge
  communications.

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Equipment vs. Operational requirements

• The major difference between the GMDSS and its
  predecessor systems is that the radio
  communications equipment to be fitted to a GMDSS
  ship is determined by the ship's area of
  operation, rather than by its size.
• Because the various radio systems used in the
  GMDSS have different limitations with regards to
  range and services provided, the new system
  divides the world's oceans into 4 areas

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• Area A1 lies within range of shore-based VHF
  coast stations (up to about 50 nautical miles)
• Area A2 lies within range of shore based MF coast
  stations (excluding A1 areas) (up to about 150
  nautical miles)
• Area A3 lies within the coverage area of Inmarsat
  communications satellites (excluding A1 and A2
  areas - approximately between latitude 70 degrees
  north to latitude 70 degrees south) and
• Area A4 comprises the remaining sea areas outside
  areas A1, A2 and A3 (the polar regions).

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GMDSS communication systems

• The GMDSS utilizes both satellite and terrestrial
  radio systems as appropriate
• Sea Area A1 (short range) - VHF is used to
  provide 1) DSC alerting on CH-70, 2) Distress
  and Safety voice communications on CH-16.
• Sea Area A2 (medium range) MF Frequencies are
  used to provide 1) DSC alerting, 2) Distress
  and safety communications on voice and NBDP.
• Sea Areas A3 and A4 (long range) - HF /or SES
  are used to provide 1) alerting, 2) Distress and
  Safety communications both voice and NBDP.

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GMDSS Ship equipment carriage requirements

• VHF equipment
• S-EPIRB or VHF EPIRB
• MSI receiver

A1

• VHF and MF equipment
• S-EPIRB
• MSI receiver

A2

• VHF, MF and HF or satellite equipment
• S-EPIRB
• MSI receiver

A3

• VHF, MF and HF equipment
• 406 MHz S-EPIRB
• MSI receiver

A4
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Shore infrastructure

• Each signatory country to the SOLAS Convention
  (basically, all of the world's major shipping
  nations) is obliged to enforce the appropriate
  carriage of GMDSS radio equipment and service
  documents by vessels sailing under their national
  flag and also to provide suitable GMDSS
  shore-based infrastructure, including Coast radio
  stations, RCC and Search and Rescue units.
• However, the shore based infrastructure may be
  provided in conjunction with neighboring states,
  as appropriate.

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Maritime Mobile Service Identities (MMSI)

• All DSC equipment is programmed with a unique
  nine digit identification number, known as a
  Maritime Mobile Service Identity (MMSI).
• The MMSI is sent automatically with each and
  every DSC transmission made.

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Maritime Identification Digits (MID)

• Maritime Identification Digits (MID)
• The first three digits of the MMSI are known as
  the Maritime Identification Digits (MID). The MID
  represents the country of registration (FLAG) of
  the vessel. MID's are allocated on an
  international basis by the ITU, in much the same
  way as the international series of call-sign
  prefixes are.

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N A V T E X

• Introduction
• The NAVTEX system is used for the automatic
  broadcast of localized Maritime Safety
  Information (MSI) using Radio Telex, NBDP.
• The system operates on the Medium wave Frequency
  band. The system range is generally about 200 or
  so nautical miles from the transmitter.

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• Major service areas of NAVTEX coverage include
  the Mediterranean Sea, the North Sea, coastal
  areas around Japan and areas around the North
  American continent.
• The NAVTEX system is designed to be used in GMDSS
  Sea Area A2, and is utilized mainly by those
  countries with relatively small areas of
  coastline and/or sea areas to cover.

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Frequency of operation

• The NAVTEX system has been allocated three
  broadcast frequencies
• 518 kHz - the main NAVTEX channel
• 490 kHz - used for broadcasts in local languages
  (i.e. non-English)
• 4209.5 kHz - allocated for NAVTEX broadcasts in
  tropical areas - not used at the moment.

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• In real terms, 518 kHz is the only NAVTEX channel
  used - this means that all broadcasts from
  stations within the same NAVAREA must be
  coordinated (IMO) on a time sharing basis to
  eliminate interference.
• In addition, power outputs from each station are
  adjusted to control the range of each broadcast.
  This is particularly important during night-time
  hours, as Medium Frequencies tend to travel
  further after dark.

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CONCLUSIONS

• Unprecedented international cooperation over a
  period of about 10 years, involving IMO, ITU,
  IHO, WMO, INMARSAT and the COSPAS-SARSAT
  partners, has resulted in the maritime community
  being provided with an integrated distress and
  safety system
• The provision of appropriate international
  regulations concerning the operation and
  implementation of the system has been
  successfully completed

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• The implementation of the system and its
  efficient operation would considerably depend
  upon the establishment of shore based facilities
  by the Members and proper network arrangements
  that will include
• maritime satellite and terrestrial radio
  services between the coast and ships,
• connections between coast stations and CES and
  RCCs,
• telecommunication interconnections between RCCs.

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