Technology Update – Digital Selective Calling Radios
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Digital Selective Calling (DSC) radio is the latest in marine radio technology. Digital Selective Calling is part of a global upgrade in maritime distress communications. Satellite and digital technology used for several years on commercial ships is now available to the recreational boater. DSC radios allow boaters to make ship-to-ship private calls and the DSC distress channel is currently being monitored by commercial ships.
Since 1996 recreational boaters were no longer required to have a ship’s station license issued by the FCC in order to operate a VHF radio. The new DSC radios however have to be registered to work properly in emergency situations. They are also encoded with a unique nine digit FCC identification number that allows the ship-to-ship calling feature. This unique number called a Maritime Mobile Service Identity or MMSI, is much like your cell phone number. Once the radio is registered with the FCC, that information and your boat’s information is entered in the US Coast Guard’s national distress database.
The major advantage of the DSC radio is its ability to send an automatic “mayday” that identifies the vessel and also, when connected to a LORAN or GPS, can send the vessels location. The DSC radio operates much like an EPIRB that sends encoded “maydays” directly to satellites. The DSC radio will also continue sending the emergency signal if the skipper is disabled.
Another feature of the DSC radio is the ability to place private ship-to-ship calls to other vessels equipped with DSC radio. Basically if you know the MMSI number of the radio you are calling only that vessel will receive you message. Just like using your cell phone.
Although commercial ships over 300 tons are now required to monitor the DSC Radio reserved Channel 70 for distress calls, the US Coast Guard is still monitoring Channel 16. As the Coast Guard updates and upgrades there equipment, they should be monitoring DSC Channel 70 in many areas by 2002-3 and be fully functional and compliant by 2005-6. The USCG’s equipment up grade will include:
DSC capability to send or receive calls on channel 70
- Eliminate the 65 gaps in current VHF coverage in the US
- Provide direction finding capability to trace a garbled radio signal to within 25 miles
- Provide playback of VHF voice or digital calls
- Provide automatic tracking of USCG ships and aircraft on search and rescue missions
There have been recent incidences where commercial ships have picked up the “mayday” calls on Channel 70 and relayed them to the USCG.
The DSC radio feature is part of the Global Maritime Distress and Safety System (GMDSS). This system was put in place by international treaty in 1988 and all seagoing nations including the US will be GMDSS compliant by 2005-6.