Glossary: communications
16 terms in this category.
- AIS Class AThe mandatory AIS transponder fitted on SOLAS ships transmitting vessel data at regular intervals and responding to interrogations.
- AIS Class BA lower-power AIS transponder used by smaller non-SOLAS vessels, transmitting position and identity data at reduced reporting rates.
- Digital Selective CallingA standard for transmitting pre-defined digital messages over VHF/MF/HF radio to initiate distress, urgency, or routine calls.
- Fleet BroadbandAn Inmarsat satellite broadband service providing high-speed voice and data communications on mobile maritime terminals.
- Global Maritime Distress and Safety SystemAn internationally agreed set of safety procedures and communications equipment required on SOLAS ships for distress and safety.
- GMDSS Sea Area A1An area within range of at least one VHF DSC coast station providing continuous alerting coverage, typically within 20–50 miles of shore.
- GMDSS Sea Area A2An area beyond A1 but within MF DSC continuous coverage, typically up to 400 nautical miles from shore.
- GMDSS Sea Area A3An area beyond A1 and A2 within coverage of an Inmarsat geostationary satellite, covering most ocean areas between latitudes 70°N and 70°S.
- GMDSS Sea Area A4The polar sea areas beyond GMDSS Area A3, not covered by geostationary satellites, where HF radio is used for distress alerting.
- Long Range Identification and TrackingA mandatory satellite-based tracking system requiring SOLAS ships to transmit identity and position to flag and port state authorities.
- METAREAOne of twenty-one geographic areas for which meteorological services co-ordinate the broadcast of marine weather forecasts.
- NAVAREAOne of sixteen geographic sea areas defined by IMO/IHO for the co-ordination of worldwide navigational warning broadcasts.
- Navigational TelexAn automated medium frequency broadcast system transmitting navigational warnings, weather forecasts, and search and rescue notices.
- SafetyNETThe Inmarsat-C broadcast service transmitting maritime safety information including navigational warnings and weather forecasts in GMDSS Areas A3/A4.
- Very High Frequency RadioMarine radio operating in the 156–174 MHz band used for short-range ship-to-ship and ship-to-shore communications.
- VHF Channel 16The international distress, safety, and calling frequency at 156.8 MHz; all SOLAS ships must maintain a continuous watch on this channel.