WPC GMDSS GOC Exam (India) key terms

An international set of radio and satellite communication requirements and procedures that lets ships send distress alerts and receive safety information automatically, and lets shore stations and other ships coordinate search and rescue.

A sea area covered by at least one VHF coast station with continuous DSC alerting, allowing a ship to send a distress alert on VHF Channel 70 and communicate on VHF radiotelephony.

A sea area outside A1 but covered by shore stations with continuous MF DSC alerting, so a ship can raise a distress alert on the MF DSC frequency and follow up with MF radiotelephony.

A sea area outside A1 and A2 that is covered by an Inmarsat geostationary satellite with continuous alerting, allowing distress alerts and communications through a ship earth station.

The remaining sea areas outside A1, A2 and A3, mainly polar regions, where no Inmarsat coverage exists and a ship must rely on HF DSC and HF radiotelephony for distress alerting.

A priority transmission sent by a ship in grave and imminent danger that identifies the vessel, its position and the nature of the emergency, so rescue authorities can begin a coordinated response.

The spoken radiotelephony signal, repeated three times, that announces a distress message and must only be used when a vessel or person faces grave and imminent danger and immediate assistance is required.

The radiotelephony urgency signal, repeated three times, used when a vessel has a serious problem concerning its safety or the safety of a person but is not in immediate grave and imminent danger.

The radiotelephony safety signal, repeated three times, announcing an important navigational or meteorological warning, such as a gale warning, navigational hazard or search and rescue information.

An automatic digital signalling system used on VHF, MF and HF to transmit and receive preformatted alerting and calling messages, including distress alerts, without requiring a voice operator to be listening.

A unique nine-digit number assigned to a ship or coast station that identifies the station in DSC messages and satellite communications, and is programmed into the ship's radio equipment.

The dedicated VHF DSC channel used only for digital selective calling, including distress alerts; voice communication is not permitted on this channel because it would interfere with DSC signalling.

The international VHF radiotelephony distress, safety and calling channel, monitored by ships and coast stations for initial contact, after which working channels are used for the actual conversation.

Digital selective calling on medium and high frequencies, using dedicated DSC frequencies such as 2187.5 kHz on MF and the 4, 6, 8, 12 and 16 MHz bands on HF, for alerting beyond VHF range.

A dedicated receiver, separate from the main transceiver, that continuously monitors the appropriate DSC distress frequency so a distress alert is received even when the main radio is switched off or tuned elsewhere.

A store-and-forward satellite messaging system used for distress alerting, two-way text messaging and reception of SafetyNET maritime safety information, with a compact terminal that does not need a stabilised antenna.

The shipboard satellite terminal that communicates with an Inmarsat satellite and connects the vessel to shore networks for distress alerting, telephony, fax or data services.

The Inmarsat satellite service that broadcasts maritime safety information, such as navigational warnings and meteorological forecasts, to ships in defined sea areas, replacing NAVTEX where it is unavailable.

A float-free beacon that, when activated in an emergency, transmits a distress signal carrying the ship's identity and position through the Cospas-Sarsat satellite system to rescue authorities.

An international satellite system that detects and locates distress beacon signals from EPIRBs and passes the alert and position to the responsible rescue coordination centre.

The frequency band used by modern EPIRBs to transmit a digitally coded distress message with the beacon's identity, which satellites can process quickly and accurately compared with older analogue beacons.

A low-power auxiliary transmission from an EPIRB or SART that search aircraft use with direction-finding equipment to home in on the beacon during the final stage of a rescue.

A portable radar transponder carried aboard ship that, when interrogated by a searching vessel's radar, produces a series of dots on the radar display to indicate its position.

An automatic narrow-band direct-printing service that broadcasts maritime safety information on MF to ships within about 200 to 400 nautical miles of a coastal transmitter, using a dedicated receiver.

Navigational warnings, meteorological warnings and forecasts, search and rescue information and other safety messages that are broadcast to ships to help them navigate safely and avoid hazards.

A broadcast message about a hazard to navigation, such as a drifting mine, a broken light, a new wreck or a cable-laying operation, classified as local, coastal or NAVAREA warning according to its range.

A shore-based authority that receives distress alerts, plans and coordinates search and rescue operations, and communicates with ships and aircraft taking part in the response.

The person, usually aboard a vessel or aircraft at the scene, appointed by the rescue coordination centre to coordinate the search and rescue activities of all units taking part.

The international treaty rules governing the use of the radio spectrum, including frequency allocations, distress and safety frequencies, licensing and operating procedures that ships must follow.

The authorisation issued by a national administration that permits a ship station to operate radio equipment, usually accompanied by a ship station licence document and a certificate of competency for the operator.

The GMDSS operator certificate that qualifies a person to operate all GMDSS equipment, including satellite and HF systems, on ships that sail beyond the range of VHF and MF coast stations.

The GMDSS operator certificate for vessels operating only within Sea Area A1, covering VHF equipment and related distress, urgency and safety procedures but not satellite or HF operation.

The assignment of radio frequency bands to particular services, such as maritime mobile, broadcasting or aeronautical, so that users in different services do not interfere with one another.

A frequency reserved for distress and safety communications, such as 121.5 MHz, 2187.5 kHz for MF DSC, 406 MHz for EPIRBs and 156.8 MHz for VHF Channel 16, which must not be used for routine traffic.

The continuous monitoring of designated distress and safety frequencies and channels, by a person or automatic receiver, so that distress alerts and safety broadcasts are received and acted upon without delay.

The measured ability of a ship's emergency radio battery to supply the required current for a specified period, checked regularly by discharging it under load to confirm it still meets GMDSS reserve requirements.

A dedicated battery or emergency generator that can power the GMDSS equipment independently of the ship's main electrical system for a required period, ensuring communications survive a main power failure.

A distress alert transmitted by mistake or by equipment malfunction; it must be cancelled immediately through the same service, and the rescue coordination centre informed to prevent an unnecessary search operation.