Digital Selective Calling
New Update on DSC

Digital Selective Calling or DSC is an attempt to enhance communications between operators who use marine radios. As recreational boaters our main concern is with the marine VHF radio aboard our boats.

Another part of this enhancement is the USCG long planned upgrade to shore and sea based radio equipment to include include Digital Selective Calling or DSC capability.

Once the USCG finishes their communications upgrade, now called Rescue 21 with a planned completion date sometime in 2011, they anticipate having VHF radio coverage out to 20 miles offshore over 98% of the U.S. coastline. This coverage also eventually include Alaska, Hawaii, San Juan PR, and Guam.

They will also have full DSC capabilities at over 270 shore stations and aboard nearly 700 Coast Guard vessels. As of early 2011 nearly all equipment is installed at coastal locations and in Great Lakes areas.

Currently most regions are fully operational and providing coverage over thousands of miles of coastline. When it is complete, it will be an impressive communication and search and rescue system.

DSC Today

Does Digital Selective Calling benefit boaters today? Yes, in a number of ways.

First and foremost, as a distress-calling device your DSC equipped marine VHF radio will likely be heard by not only the Coast Guard but also get be picked up by other recreational or commercial vessels in your area who are also equipped with DSC radios.

Another benefit available today is the individual ship call. You can use this feature to make a discrete call to a friend (as long as his vessel is also DSC equipped and you know his MMSI number) and advise him electronically to talk to you on another frequency. These days you can also make DSC call directly to Coast Guard stattions as long as have the station MMSI number stored in your radio.

With more sophisticated DSC capabilities even your position can be reported to another vessel or station electronically. So what is the upside of this? You and a fishing or cruising partner could exchange the location of each others boats without actually talking on your marine VHF radio.

Other messages that can be sent via DSC include an all-ships call. This one will send a message to any vessel in your VHF coverage area. Message priority can also be attached indicating whether your message is routine, safety, or emergency related.

Geographical calls cover only a specific area while group calls go out to only a specified group of vessels. You likely won’t use all of these DSC features but some you’ll use everyday once you become familiar with them.

When You Buy a Marine VHF

A couple of things to remember when you purchase a fixed mount VHF radio. Right now most any VHF you find for recreational use will be either a Class D or RTCM SC101.

Basically what these classifications mean is this. Class D radios have two receivers so they can listen on channel 70 at all times for DSC traffic.

Recreational marine VHF radios without this class rating will only have one receiver sharing DSC reception with voice reception.

The bottom line on this is if you can afford it buy a marine VHF that is DSC Class D.

DSC Update on SC101

Originally, the SC101 DSC standard was put in play to let marine VHF radio makers build cheaper recreational boat radios. It was never part of the Global Maritime Distress Safety System.

The GMDSS, by international agreement, sets the standards for DSC and classifies marine VHF radios as Class A, B, or D. The SC101 standard was never recognized for use outside the U.S. and will be officially put to bed here on March 25, 2011.

After that date it will be illegal to build, sell, import, or install a fixed-mount marine VHF radio that only meets the SC101 standard. Any SC101 radio installed prior to that date may be retained in service.

Anyone looking to buy a new marine VHF radio prior to the termination date needs to be aware that makers and retailers will be trying to clean out stock on these radios and likely be offering significantly reduced prices.

However, you may want to forgo the purchase of one of these radios, no matter how low the price goes, and opt for a full Class D radio instead. These radios offer superior hardware and full digital selective calling performance features when compared to their SC101 DSC counterparts.