APPENDIX > DIGITAL SELECTIVE CALLING (DSC)

Digital Selective Calling (DSC)

Digital Selective Calling (DSC) uses marine VHF radio and Global Positioning System (GPS) technologies to transmit and receive location information. DSC is used by mariners to assist them in two major areas: Distress Calls and Position Reporting.

A non-emergency DSC Position Report allows mariners to exchange and show the locations of one another. When you receive a DSC location, you can create a waypoint or to show the received location on an electronic map.

An emergency DSC Distress Call allows a vessel in trouble to transmit a substantial amount of information in a single transmission or “call,” without the need for voice communication. When any nearby rescuer receives the DSC signal, an alarm sounds and they immediately receive the location of the caller.

The rescuer can choose to navigate (Go To) the caller’s location to assist or forward the call on to the Coast Guard. When the Coast Guard receives the call, they can immediately access the caller’s information (such as who they are and the type of vessel) in their database while they are in transit to the caller’s location.

Any time a vessel receives a DSC call, they can store that location and quickly navigate to that location using a Go To. This makes DSC a time-saver, especially in an emergency situation. In order to use DSC, users must first register their VHF radio with the FCC and receive a Maritime Mobile Service Identity (MMSI) number.

What is a Maritime Mobile Service Identity (MMSI)?

Maritime Mobile Service Identity (MMSI) basically allows a VHF radio to act like a phone. The 9-digit MMSI number acts like a phone number when used in a Position Report and as a unique identifier to the Coast Guard when used in an emergency Distress Call. To obtain a Maritime Mobile Service Identity (MMSI) number, users must register their VHF radio with the FCC (Form 605).

Garmin does not supply this number!

For more information regarding MMSI’s visit http://www.navcen.uscg.gov/marcomms/gmdss/mmsi.htm.

GPSMAP 296 Pilot’s Guide

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