Navigation Center Logo
Skip Navigation Home | DGPS Advisories | GPS Constellation Status | GPS Testing Notices | LNMs | Almanacs | Nav Rules | AIS | North American Ice Service | Contact Us | Search
Digital Selective Calling
Primary Mission Areas:
Services & Reporting:
Maritime Information:
DIGITAL SELECTIVE CALLING CLASSES

The DSC protocol is defined by ITU-R Recommendation M.493 (series), available from the International Telecommunications Union in Geneva, Switzerland DSC operation is defined by ITU-R Recommendation M.541 (series).

Click the Classes hyperlinks in blue to go to that Class.
A B D E RTCM SC101h ITU-R-Rec:M.825-3

ITU-R-Rec:M.821
Class A:
  • Distress call
  • All-ships call
  • Individual station call
  • Semi-automatic/automatic service call
  • Use of distress, urgency, safety and routine priorities
  • Nature of distress
  • Distress coordinates
  • Time for last (distress) position update
  • Type of subsequent communications
  • Distress relay
  • Distress acknowledgment
  • Test call (for MF/HF only)
  • Radio frequency or channel
  • Display
  • Receive geographical area calls
  • Alarm
  • Optional means for canceling a distress alert
  • Polling
  • Position acknowledgement
  • Test call
  • Test acknowledgement
  • Data
  • Data acknowledgement
All DSC options provided. Required on MF/HF and VHF radios used by SOLAS-regulated ships. Class A includes polling and vessel tracking, data, and numerous other functions in addition to voice.
Class B:

Required on VHF and MF radios used by SOLAS-regulated ships, though most such radios in fact meet Class A. Class B required capabilities include:

  • Distress call
  • All-ships call
  • Individual station call
  • Semi-automatic/automatic service call
  • Use of distress, urgency, safety and routine priorities
  • Nature of distress
  • Distress coordinates
  • Time for last (distress) position update
  • Type of subsequent communications
  • Distress relay
  • Distress acknowledgment
  • Test call (for MF/HF only)
  • Radio frequency or channel
  • Display
  • Receive geographical area calls
  • Alarm
  • Optional means for canceling a distress alert
Class D:

Minimum DSC capability for VHF marine radios carried by recreational boaters, commercial fishing vessels, and other non-SOLAS regulated vessels. Class D required capabilities include:

  • Distress call
  • All-ships call
  • Individual station call
  • Use of distress, urgency, safety and routine priorities
  • Nature of distress
  • Distress coordinates
  • Time for last (distress) position update
  • Type of subsequent communications
  • Radio VHF channel
  • Display
  • Receive distress relay and distress acknowledgment calls
  • Alarm
  • Distress acknowledgement (receive)
  • Geographical area call (receive)
  • Test call
  • Test acknowledgement
Class E:

Minimum DSC capability for HF marine radios carried by recreational boaters, commercial fishing vessels, and other non-SOLAS regulated vessels. Class E required capabilities include:

  • Distress call
  • Individual station call
  • Use of distress, urgency, safety and routine priorities
  • Nature of distress
  • Distress coordinates
  • Time for last (distress) position update
  • Type of subsequent communications
  • Radio channel or frequency
  • Display
  • Receive distress relay and distress acknowledgment calls
  • Test call
  • Test acknowledgement
 
 
U.S. Coast Guard Navigation Center - NAVCEN MS 7310, 7323 Telegraph Road, Alexandria, VA 20598 - 7310 | (703) 313-5900 | Privacy Policy | Last Updated 01/07/2013