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Author Topic:   Notice Re DSC Radios with RTCM SC101
jimh posted 07-11-2010 11:19 AM ET (US)   Profile for jimh   Send Email to jimh  
The following notice is from the United States Coast Guard regarding federal regulations covering the manufacture and sale of VHF Marine Band radios and their qualification for digital selective calling (DSC) operation:


[Manufacture], importation, sale or installation of RTCM SC101 radios prohibited on March 25, 2011.

The Federal Communications Commission has prohibited the [manufacture], importation, sale or installation of non-portable DSC-equipped radios that do not meet either ITU-R Rec. M.493-11 or IEC 62238 Class D standards effective March 25, 2011. This regulation effectively bans the sale of radios built to the RTCM SC101 standard on that date. A similar prohibition will apply to portable radios effective March 25, 2015 . See 47 CFR 80.225(a)(4).


jimh posted 07-11-2010 11:39 AM ET (US)     Profile for jimh  Send Email to jimh     
For several years the United States Coast Guard has been recommending that recreational vessels that voluntarily equip with VHF Marine Band radios should choose a radio that is qualified to CLASS-D DSC ratings. The ban on manufacture of RTCM SC101 radios after March 25, 2011 (that is, next year's boating season) effectively makes the recommendation of CLASS-D a minimum requirement for voluntarily equipped recreational vessels installing a new radio.These regulations have been in place for some time. Here is a link to the 2009 CFR document which mentions these changes:

"Sec. 80.225 Requirements for selective calling equipment.

"(a) The requirements for DSC equipment voluntarily installed in coast or ships stations are as follows:...

"(4) The manufacture, importation, sale or installation of non-portable DSC equipment that does not comply with either of the standards referenced in paragraph (a)(2) of this section is prohibited beginning March 25, 2011."

Chuck Tribolet posted 07-13-2010 10:02 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Note that this prohibits "[manufacture], importation, sale or
installation". If you have one, you can keep using it.


jimh posted 07-13-2010 01:05 PM ET (US)     Profile for jimh  Send Email to jimh     
Apparently you can keep using an RTCM SC101 radio, but don't ever take it off the boat--you cannot install it again.


pglein posted 07-21-2010 04:03 PM ET (US)     Profile for pglein  Send Email to pglein     
What is RTCM SC-101, and how do I know if I have one? What's the difference between that and Class D?

What does DSC do anyway?

jimh posted 07-22-2010 08:37 AM ET (US)     Profile for jimh  Send Email to jimh     
All of your questions about the difference between RTCM SC101 and Class-D are answered in an article I wrote several years ago. It is available from

DSC is an acronym for digital selective calling. A DSC radio can be called directly from another DSC radio. The two radios can exchange short digital messages, such as the position of their vessels. In more sophisticated DSC radios, printing jobs can be sent from one radio to another, producing printed output.

DSC radio use is part of the GLOBAL MARITIME DISTRESS AND SAFETY SYSTEM, GMDSS, which has been in the process of being implemented for some time. Governing agencies have been lenient is forcing recreational boaters to convert to DSC radio use.

The RTCM SC101 standard for DSC radios required only a small portion of the DSC features to be provided. Permitting radios to be built to RTCM SC101 was a good way to introduce DSC radios to the recreational boater without forcing the cost of the radio to be excessive. As progress was made in manufacturing of radios to better DSC ratings, the cost of a Class-D qualified radio dropped to a very reasonable price. An excellent DSC Class-D VHF Marine Band radio now costs only about $150. The Standard-Horizon company has been the leader in producing Class-D radios at the best price point.

For several years the United States Coast Guard has been telling recreational boaters that they should install a Class-D DSC radio as a minimum radio. The sunset date of March 2011 makes this recommendation a mandatory minimum.

More information on DSC from the USCG at

jimh posted 10-11-2010 12:32 AM ET (US)     Profile for jimh  Send Email to jimh     
In a release dated August 12, 2010 the U.S. Coast Guard issued a clarification on the use of VHF Marine Band radios rated RTCM SC-101 for DSC capabilities after March, 25, 2011. The USCG now says:

"...after March 25, 2011, radios built to RTCM Standard SC-101 can no longer be manufactured, imported, sold or installed; however, previously-installed radios meeting the older standard may continue to be used."


jimh posted 10-11-2010 08:43 AM ET (US)     Profile for jimh  Send Email to jimh     
The Coast Guard has explained their endorsement of digital selective calling for VHF Marine Band radios in this concise statement, which was issued 15 years ago:

Commandant (G-TTM)
U.S. Coast Guard 4 December 1995
Washington DC 20593

Why Digital Selective Calling


On February 1, 1992, changes to the Safety of Life at Sea (SOLAS)
Convention affecting distress and safety telecommunications came
into effect. The SOLAS Convention is a treaty document affecting
cargo, passenger and other ships on international voyages. The
SOLAS Convention has been both an international and national
standard for maritime distress and safety telecommunications for
all of the maritime community, including those vessels not
specifically subject to the Convention.

These changes require ships to carry VHF and MF/HF
radios with digital selective calling capable of initiating
radiotelephone calls. DSC is mandatory on board all ships
of this type. This will allows them to discontinue
watchkeeping on VHF channel 16 and on 2182 kHz on February 1,
1999 (SOLAS regulation IV/12.3 and .4, and 80.1123 and (d) of
the Commission's rules).

DSC also provides the opportunity for reducing or eliminating the
congestion problem on VHF channel 16, alleviating hoax problems,
more rapid receipt of a distress alert, and improved distress
radio watchkeeping on VHF and MF/HF by Coast Guard stations.

Further Reasons for DSC Requirement

Our primary purpose for making this request is for reasons of
safety, to ensure maritime distress and safety communications
remain interoperable among all vessels, as discussed earlier.
There are however additional reasons for granting this petition,
all of which also involve maritime safety:

DSC could reduce or eliminate the congestion problem on the VHF
distress and calling channel 16. The Commission in PR Docket
91-167 (Notice of Proposed Rulemaking permitting VHF Marine
Channel 9 to be used as a second calling channel), stated "the
most common complaint received by the Commission related to
marine radio usage concerns congestion on marine VHF channel 16."
In a study of congestion, FCC staff stated "For a long term
solution (to the problem of congestion on the distress, safety
and calling channel 16), I recommend that the Commission consider
a rulemaking to require Digital Selective Calling on all new
marine radios and set a date when Digital Selective Calling would
be mandatory for VHF marine radios."1

Alleviates hoax problem. Since DSC calls include a unique,
preassigned and pre-entered ship identity, it would be difficult
if not impossible to transmit a distress message without also
identifying the vessel and its owner.2

DSC provides rapid receipt of distress alert. DSC provides a
preformatted distress alert which includes vessel identification,
location and other vital information, which can be transmitted
within a second or less. Vessel location can be obtained
automatically from an existing LORAN C, GPS or other receiver, or
entered manually. With this capability, vessel operators not
having time to send a complete MAYDAY message over radio (e.g. in
the case of the F/V SOL E MAR) could send a complete DSC distress

DSC significantly increases the probability that a call to the
Coast Guard will be received. The FCC noted in their report on
use of VHF Maritime Radio in Boston Harbor 1. that "It was quite
common to observe 400 calls being made per hour on Channel 16 in
Boston Harbor during prime time on weekends" and stated calls
were more than double that on some occasions. The Coast Guard
providers watchkeeping over channel 16 twenty four hours/day
through the U.S. National Distress System, a network of over 300
transceivers with antennas located at high levels to ensure wide
coverage, and remoted to one of 53 Coast Guard Group operations
centers. One radio watchstander guards channel 16 from several
of these sites simultaneously, listening for that one MAYDAY call
to the Coast Guard among a constant background of dozens of
simultaneous conversations. The Coast Guard responds to over
26,000 such distress calls each year. The continued growth in
the amount of traffic on channel 16, in addition to the
constantly increasing duties required of the Coast Guard Group
watchstanders, makes their ability to acknowledge a distress call
increasingly difficult.

The same Coast Guard Group watchstanders who guard VHF channel 16 also guard the radiotelephone distress frequency 2182 kHz.
Watchstanders at Coast Guard Communications Stations also guard
several high frequency single sideband frequencies. These
channels are noisy and difficult to guard, particularly if
traffic on these channels are light. Resource limitations at
Communication Stations as well as Groups require persons
monitoring these frequencies to have other duties as wells.
Consequently, the quality of watchkeeping on these channels is
not high. Discussions with FCC field inspectors and those of the
civil maritime community confirm this fact. However the
Commission and Coast Guard require vessel carry radiotelephone
equipment capable of using these frequencies for distress &
safety purposes.

Unless a solution is found to each of these problems, an
increasing number of distress calls will go unanswered, an
intolerable situation. Digital selective calling is capable of
resolving these problems.

DSC can ensure nearby ships capable of assisting a distressed
vessel receive the distress alert. The current maritime distress
system consisting of ship and shore watchkeeping on voice frequencies of 2182 kHz and
VHF channel 16 ensured that ships in the vicinity of a vessel in
distress could receive the distress alert. In many cases these
nearby vessels can arrive on scene to assist the vessel in
distress much more quickly than can the Coast Guard. Cellular
telephones and satellite communications do not have this
capability. We believe it to be essential that a ship-to-ship
distress alerting capability continue to exist.

DSC improves the ability of the Coast Guard to contact ships in
an emergency. DSC will enable the Coast Guard, public coast
stations or other shore units to contact ships concerning a
marine warning or distress in their area, or for some other
urgent matter, without requiring the ship operator to actively
guard a radio channel.

DSC technology is established in treaty and is recognized
internationally. While other technology could conceivably be
developed to resolve many of these same problems, both the
International Telecommunications Union and International Maritime
Organization, United nations organizations, selected DSC as the
technology for this purpose after ten years of study. No other
similar technology has this recognition.

1. Mr. Vincent Kajinski, Engineer in Chief of the FCC Boston
Regional Office, in his report of December 16, 1991 on Testing of
VHF Maritime Channel 9 as a Secondary Calling Channel in Boston
2. During hearings on July 23, 1990 at Woods Hole, MA, by the
U.S. House of Representatives Subcommittee on Coast Guard and
Navigation, Committee on Merchant Marine and Fisheries, Mr.
Richard M. Smith, Chief of the Commission's Field Operations
Bureau, testified that "Our potential rulemaking solution, and
one which I believe could have a great impact on this problem (of
hoaxes), is a requirement for an automatic transmitter
identification system or 'ATIS'. If adopted, it would eventually
require radio transmitters to automatically send an unobtrusive
identifying signal along with the normal signal. As one form of
ATIS, the FCC and Coast Guard have been developing a digital
selective calling (DSC) system for marine frequencies for use in
the Global Maritime Distress & Safety System. If fully
implemented in this decade as expected, DSC could perform
effectively either to enable identification of hoaxers or help
establish legitimate distress calls...The identifying code of the
transmitter used in a hoax call would be an extremely powerful
piece of evidence in identifying and prosecuting violators."

This text was part of a petition for rulemaking and comments on a
notice of inquiry submitted to the FCC by the Coast Guard
regarding a proposal to mandate minimum DSC capability on marine
radios (PR Docket 92-257).

jimh posted 02-18-2011 09:05 AM ET (US)     Profile for jimh  Send Email to jimh     
I am reviving this article because the sunset date of March 25, 2011 is now only a few weeks away. Many retailers are trying to sell off their inventory of VHF Marine Band radios which, after March 25, 2011, will no longer be compliant with FCC regulations. If you plan to purchase a VHF Marine Band radio in the next few weeks, you should be aware of the changes in regulations detailed above.

I recommend you purchase a VHF Marine Band radio that is rated CLASS-D for digital selective calling. Generally the CLASS-D radios are newer designs and offer improved user interface designs, making the radio easier to operate and use the digital selective calling features.

jimh posted 03-22-2015 09:45 AM ET (US)     Profile for jimh  Send Email to jimh     
I am reviving this article because the statutory date of March 25, 2015 is only a few days away. After that date, the prohibitions on the manufacture, importation, sale, and installation of VHF Marine Band portable radios that are not in compliance with either ITU-R Rec. M.493-11 or IEC 62238 Class D standards will be in effect.

Boaters should watch for clearance sales of older portable radios that are not in compliance. Such sales are prohibited by the FCC rules.

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