The ABCs of DSC
— January 2001
By Brad Dunn
The ABCs of DSC
|The latest radio innovation means a lot to your safety--if you read between the letters.|
It seems there are more acronyms in the world of electronics than there are electrons. It's DSL this, DSP that; here a DGPS, there a DSC, everywhere a DDEC.
Though all this technoalphabet soup may seem like BS, one of these letter combos is revolutionizing the way your VHF sends an SOS, which could save your life if you're ever broken down, offshore, and SOL.
The Digital Selective Calling (DSC) label is the must-have acronym for the new generation of recreational boating radios. If you attend the Miami International Boat Show next month, you'll see it on radios from every major marine electronics maker, like Datamarine's latest launch, the SEA 157 VHF, DSC Radiotelephone. But what exactly is DSC, and why is it an abbreviation worth knowing about?
The purpose of the DSC system is twofold: to make distress calling faster and more accurate and to allow you to call individual boats and land-based stations privately, as you would on a telephone. Developed in the early 1990s by the U.S Coast Guard and Merchant Marine, the DSC system has been a central part of the emerging Global Maritime Distress and Safety System (GMDSS).
Because watch stations around the country became swamped with Channel 16 distress calls as the boating industry boomed, DSC's prime objective was to speed up the transmission of calls and change them to a textual format. To that end, signals from all DSC-enabled radios are designed to automatically include vessel identification and location and other vital information. This data can be transmitted over radio waves within seconds.
The best way to understand how DSC works is to take a look at each word in the acronym.
Digital. This means all data signals are sent over radio waves in the computer language of ones and zeros. When you send a DSC message, it automatically includes your nine-digit Maritime Mobile Service Identity (MMSI) number (which you receive when you register the radio), the MMSI of the boat or station you're calling, and the priority of the call. In order of declining importance, they are Distress, Urgent, Safety, and Routine. If you link your radio to a Loran or GPS unit, your message will also automatically contain your position.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.