Re: VHF marine radio buys.
...what is GMDSS features?
GMDSS is an acronym for Global Marine Distress and Safety System. Use of radios with digital selective calling (DSC) is part of the "system" of recommended practices.
The movement to use of GMDSS and DSC was explained by the Coast Guard in a statement they issued 15 years ago. The process has been underway for 15 years.
Here is that statement made 15 years ago:
--------begin statement-----------
Commandant (G-TTM)
U.S. Coast Guard 4 December 1995
Washington DC 20593
Why Digital Selective Calling
Background.
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
alert.
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
harbor.
-------------------------
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."
--------------end statement-----------------------
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).
http://www.navcen.uscg.gov/doc/whydsc.txt
For more information on the restrictions on sale of non-compliant radios which take effect in March of 2011, see:
http://www.navcen.uscg.gov/?pageName=mtDsc
