Marine VHF w DSC

Digital Selective Calling

Marine VHF and DSC. Digital Selective Calling DSC is digital signal which is automatically sent (channel 70) when you press that RED button. Included in the signal is your position, and boat name. Not all radios are DSC enabled, some handhelds do have the capacity.

DSC/VHF radios; Class A and Class D.

Digital Selective Calling
Digital Selective Calling

Class A is for professional mariners, Class D is recreational and the most obvious differentiating feature is that Class A receives DSC signals while transmitting. With Class D if you are transmitting you will not receive a DSC call. You will receive a DSC call if you are receiving however.

Who Monitors DSC calls; The US Coast Guard monitors channel 70 DSC. USCG’s navcen site explains. Commercial ships over 300 tons are now required to monitor the DSC radio reserved channel 70, for distress calls.

Register; You need an MMSI number and a GPS connection to your VHF To enable all the features of DSC .

Test your DSC; To test your DSC capability send a “test” transmission to a Coast Guard stations MMSI number.

Cancelling a false alarm a problem with DSC is false alarms, accidentally sending a distress signal. If this happens is no good just turning off the alarm, since the Coast Guard and other vessels have received your distress call. You must broadcast on CH 16 the false alarm. That way USCG and other boats equipped with DSC will know not to respond and send out SAR teams.

Sending DSC distress calls

  • Transmits distress alerts with the RED button
  • Tells Coast Guard who you are & where you are
  • Cost Guard response automatically switches your radio to CH 16
  • Signal is Automatically stored & displayed on every DSC radio in range
  • Relay distress alerts

Receiving a DSC Distress call

  • If you hear a DSC distress call
  • Your radio will beep when receiving a DSC distress call
  • Radio will switch automatically to 16
  • Display calling stations MMSI, lat & lon
  • Store details of call
  • Continue to listen, do not transmit
  • After 5 minutes and you do not hear a response from the Coast Guard
  • Call Coast Guard on CH 16, and relay the mayday

GPS connection

Standard Horizon instruction manual

GPS connection
Standard Horizon instruction manual GPS connection

By connecting your radio to a GPS you can realize the full strength of DSC. Others will automatically know your position, plus you can track friends through position polling.

You can connect your VHF fixed radio to GPS with 2 wire NMEA cables. Check your radios manual for instructions. This diagram of the Standard Horizon GX1600.