What is Digital Selective Calling?

Digital Selective Calling (DSC) is how vessels connect with shore stations and other vessels via radio communications. It's used mostly in maritime and marine radio systems for distress, urgency, safety, and routine communication. DSC operates on specified VHF, MF, and HF radio frequencies.

Digital Selective Calling

Unlike traditional voice communication, DSC uses digital signals to transmit information. This provides several advantages, including better clarity and accuracy, as well as the ability to automate processes such as call setup and position reporting.

Each vessel or shore station equipped with DSC has a unique Maritime Mobile Service Identity (MMSI) number, which is similar to a phone number. This MMSI is programmed into the DSC equipment.

DSC allows for the transmission of different types of calls:

Distress Calls: Used in emergencies when a vessel requires immediate assistance.
Urgency Calls: Used when a vessel is in a serious but non-life-threatening situation.
Safety Calls: Used for important safety-related messages.
Routine Calls: Similar to making a regular phone call, used for non-urgent communication.

Some DSC systems can automatically transmit the vessel's position along with a distress or urgency call, aiding in quicker rescue operations.

What Kind of Radios Use DSC?

VHF Radios: VHF (Very High Frequency) radios are widely used for short-range maritime communication. DSC is integrated into many modern VHF marine radios, making them capable of sending and receiving digital selective calls.

MF/HF Radios: Medium Frequency (MF) and High Frequency (HF) radios are used for long-range maritime communication. DSC is also integrated into some MF/HF marine radios, allowing vessels to communicate over longer distances using digital selective calls.

AIS (Automatic Identification System) Transceivers: AIS is a system used for vessel tracking and collision avoidance. Some AIS transceivers are equipped with DSC capabilities, enabling them to send and receive digital selective calls in addition to broadcasting vessel information.

Fixed and Portable Radios: DSC functionality is available in both fixed-mount radios, which are permanently installed on vessels, and portable radios, which can be carried by crew members for communication both on board and ashore.