Glossary: communications

16 terms in this category.

• AIS Class A
  The mandatory AIS transponder fitted on SOLAS ships transmitting vessel data at regular intervals and responding to interrogations.
• AIS Class B
  A lower-power AIS transponder used by smaller non-SOLAS vessels, transmitting position and identity data at reduced reporting rates.
• Digital Selective Calling
  A standard for transmitting pre-defined digital messages over VHF/MF/HF radio to initiate distress, urgency, or routine calls.
• Fleet Broadband
  An Inmarsat satellite broadband service providing high-speed voice and data communications on mobile maritime terminals.
• Global Maritime Distress and Safety System
  An internationally agreed set of safety procedures and communications equipment required on SOLAS ships for distress and safety.
• GMDSS Sea Area A1
  An 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 A2
  An area beyond A1 but within MF DSC continuous coverage, typically up to 400 nautical miles from shore.
• GMDSS Sea Area A3
  An 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 A4
  The polar sea areas beyond GMDSS Area A3, not covered by geostationary satellites, where HF radio is used for distress alerting.
• Long Range Identification and Tracking
  A mandatory satellite-based tracking system requiring SOLAS ships to transmit identity and position to flag and port state authorities.
• METAREA
  One of twenty-one geographic areas for which meteorological services co-ordinate the broadcast of marine weather forecasts.
• NAVAREA
  One of sixteen geographic sea areas defined by IMO/IHO for the co-ordination of worldwide navigational warning broadcasts.
• Navigational Telex
  An automated medium frequency broadcast system transmitting navigational warnings, weather forecasts, and search and rescue notices.
• SafetyNET
  The Inmarsat-C broadcast service transmitting maritime safety information including navigational warnings and weather forecasts in GMDSS Areas A3/A4.
• Very High Frequency Radio
  Marine radio operating in the 156–174 MHz band used for short-range ship-to-ship and ship-to-shore communications.
• VHF Channel 16
  The international distress, safety, and calling frequency at 156.8 MHz; all SOLAS ships must maintain a continuous watch on this channel.