GMDSS Radio Survey Blog

Category: General

The monopoly of Inmarsat, which has been the only provider of satellite GMDSS services since 1999, is over. In early 2020, Iridium was successfully certified by the IMO. Thus, Iridium GMDSS has become a superior alternative to Inmarsat GMDSS; it covers all GMDSS Sea Areas from A1 to A4 and offers built-in Safety Voice Service. 

Iridium is a global mobile satellite communications system that covers 100% of the Earth's surface, including both poles. It provides real-time voice and data transmitting at sea, in the air, and on the ground. The system enables connection in remote areas which are not provided with traditional land-based communications, and in emergency situations.

The first-generation of Iridium's constellation was deployed in 1997-2002. The technology and most of the funding was provided by Motorola. To get 77 satellites into orbit, Iridium used rockets from the United States, Russia, and China.

Iridium NEXT and Iridium Certus. In 2017-2019, Iridium Communications Inc. launched 75 satellites of the second-generation Iridium NEXT: 66 active and 9 backup ones. They are cross-linked and located in Low-Earth Orbit (LEO) at an altitude of 780 km. New satellites were built by Thales Alenia Space and Orbital ATK and launched by Falcon-9 rockets of SpaceX.

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Category: EPIRB

The phased implementation of the GMDSS began with the mandatory equipping of vessels with satellite beacons. Its introduction made it necessary to manufacture EPIRB testers.

IMO required the inspection of emergency beacons to be mandatory. According to its requirements, EPIRB testers must provide accurate measurement of the parameters and performance of the emergency beacon in volume of:

Annual testing of 406 MHz satellite EPIRBs (Resolution MSC.1/Circ.1040/Rev.1 Revised Guidelines on annual testing of 406 MHz satellite EPIRBs adopted on 25 May 2012);

Shore-based maintenance of satellite EPIRBs (Resolution MSC/Circ.1039 Guidelines for shore-based maintenance of satellite EPIRBs adopted on 28 May 2002).

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Category: AIS

According to SOLAS Chapter V Regulation 18.9, the automatic identification systems (AIS) must be tested annually: “The test shall be conducted by an approved surveyor or an approved testing or servicing facility. The test shall verify the correct programming of the ship static information, correct data exchange with connected sensors as well as verifying the radio performance by radio frequency measurement and on-air test using, e.g., a Vessel Traffic Service (VTS). A copy of the test report shall be retained on board the ship”.

In our historical review, you will find out what the first AIS testers were like, what they were able to do, and what are the features of modern AIS testers. However, the singular is more suitable here, since there is only one tester with such a narrow specialization in today's market. 

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Category: GMDSS Radio

MF/HF radio station is a high tech equipment, designed for receiving and transmitting messages between vessels in the medium and high frequency range. It usually consists of a transceiver, a control block, and an antenna.

For any vessel crossing oceans and seas as well as for those working offshore, an MF/HF radio is an indispensable section of equipment, it ensures long-distance radio communication. MF/HF radio is an important part of GMDSS, that’s why most of the vessels are obliged to install it in accordance to international safety regulations.

MF/HF on board the ship provides radiotelephony, narrow-band direct printing and DSC over long distances. An MF/HF radio installation with DSC should be installed with a TELEX terminal. The system is subject to mandatory annual GMDSS survey.

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Category: SART

The search and rescue radar transponder (SART) is an important part of the GMDSS intended for locating ship or survival craft at sea when it is in distress. 

SART is a small, battery powered, omni-directional radar receiver and transmitter, it can be detected by ship or aircraft radars operating in the frequency band 9.2-9.5 GHz. On receiving a signal from the radar, the device transmits a series of response signals. These signals will be seen on radar screen as a line of 12 dots extending approximately 8 nautical miles away from the SART’s position along its line of bearing. This unique radar signal is easily recognised and allows the rescue vessel or aircraft to locate the survival craft. 

The carriage of the SART on board ships is mandatory, according to IMO requirements. IMO also requires that SART, as a part of the GMDSS, be regularly tested. If the radio survey reveals a malfunction, the vessel may be detained at port.

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