Part of the Global Marine Distress and Safety Radio Service

If you see DSC on a button on the face of your VHF radio, that stands for "Digital Selective Calling." DSC was originally designed to broadcast an automated emergency call---a Mayday---so that a boat's crew could take care of emergencies, without having to worry about making a call for help.

Orginally Planned for Ships

Digital Selective Calling was developed in the late 1990s for large ships. All marine VHF radios now are required to have a DSC capability.

Like Using a Telephone

Digital Selective Calling lets you communicate with one specific vessel, much like a telephone. If your boat is equipped with AIS, or Automatic Identification Service-capable radar, you can even see the name of the boat you're calling on the screen.

Distress Calls Have an Alarm System

Emergency calls on DSC-capable marine VHF radios have alarms that are both visual and auditory to let you know that a distress message is coming in. These alarms must be turned off manually, so that they won't remain unseen or unheard by accident.

DSC Can Tell Rescuers Your Location---Automatically

If you connect your boat's GPS to its DSC-capable VHF radio, your DSC radio can automatically broadcast your position if you send a distress call.

Source:

USC Navigation Center: Digital Selective Calling

Resource:

How Digital Selective Calling Works