Global Maritime Distress and Safety System

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The Global Maritime Distress And Safety System (GMDSS) is used for rescue, and it is essential for the safety of life at sea. It has been embraced by the government at the international convention SOLAS '74 (SAFETY OF LIFE AT SEA) and it was developed to guarantee a greater efficiency in carrying out rescue operations, taking in consideration new technologies such as Digital Selective Call (DSC), Narrow Band Data Print (NBDP) and the use of geostationary/polar satellites.

The system was developed to give to the vessel in need of assistance the ability to send distress signals to the control centers and to other vessels. The primary objective of the system is to notify coastal authorities and send the request for immediate assistance. The MRCC (Maritime Rescue Coordination Center) coordinates the operations of rescue while other ships in the surrounding area are obliged to give assistance.
This operative ability was obtained respecting several functional requirements that were considered essential to guarantee safety at sea; All these functional requirements are satisfied by a combination of the following radio-communication services/systems:

• INMARSAT system using geostationary satellites.
• COSPAS-SARSAT system using satellites in polar orbit.
• Maritime radio service in VHF band (156-174 MHz).
• Maritime radio service in MF band (1.6-4.0 MHz).
• Maritime radio service in HF band (4-27.5 MHz).

The type of radio communication service depends on the geographic location in which the vessel operates. The following areas are defined as follows:

AREA A1	Area covered by a VHF coastal radio station with continuous DSC service.
AREA A2	Area covered by a MF-HF coastal radio station with continuous DSC service (excluding area A1).
AREA A3	Area covered by stationary satellites IMMARSAT (excluded areas A1 and A2).
AREA A4	Area not covered by any of the above (A1, A2, A3).

The emergency call procedures are divided by area. The DSC is part of the GMDSS, and it is essentially a system that allows "selective calls" ship-ship and ship-land with automatic identification of the vessel from the coastal station. In fact, every "call" has a digital packet in one of the four preset standards: Distress, Safety, Routine, Urgency.

The "Distress" messages are automatically transmitted to all stations in the maritime bands: MF
(2187.5 kHz), HF (4207.5, 6312, 8414.5, 12577, 16804.5 kHz), VHF (Ch.70 - 156.525 MHz). 
The GMDSS proposed by ELMAN is composed by the following units:

• N. 2 VHF/FM transceivers (MST-11124) in marine band with DSC module (one in working mode and one for redundancy) complete of antennas.;
• N. 1 MF-HF Receiver (+1 Optional) with encoder/decoder DSC (mod.MSR-1097);
• N. 2 Power supply for MST-11124 115 or 220 VAC input and 24 VDC as output;
• N. 1 Laptop PC with the GMDSS software necessary to manage the MST-1124 and the MSD-1097;
• N. 1 Direction finder V-UHF to localize distress signals in the VHF marine band (included channels 16, 70, 6, 13) with the addition of the rescue frequencies:
  • 121.5 MHz (civil aviation rescue).
  • 243.0 MHz (military aviation rescue).
  • 406.025 MHz (radio beacon rescue E.P.I.R.B.).

For Control Centres, Marcom provides an integrated software solution designed to provide functions for continuous monitoring and identification of emergencies in GMDSS Area: Marinsys GMDSS.