reaction to Mayday calls from Rescue 21 facilities. Importantly, hailing communication
range may be improved with the use of DSC’s
digital format hailing signal.
The GMDSS Task Force will continue to
pursue further use of DSC, as will the RTCM
(Radio Technical Commission for Maritime
Services), which has an active committee, WC
123, working on standards for data messag-
ing. This application of digitally aided VHF
communication was foreseen some years ago
in the development of what amounted to
bridge to bridge e-mail in the system devel-
oped for the Tampa Bay pilots. In this system
digital messages appearing on the pilot’s lap-
top computer eliminated the need for many
channel calls.
ily defeat the automatic receiver channeling
capability inherent in the DSC radio (CG Alert
DSC—SA0210). This information will be
increasingly important as the Class D versions
of DSC radios (those with full-time Channel
70 receivers) become a larger part of the total
VHF/DSC population. While continuous
monitoring of DSC hailing calls is very positive, having navigation between two vessels
interrupted by remotely initiated changing of
the receiver can create a hazardous situation.
I believe the FCC beginning March 25,
2011, will ban the sale in the US of SC 101
and other DSC radios that lack the ability to
turn off the automatic channels when a radio
is called by another DSC radio. The automatic
channels have caused substantial inconvenience. International Class D VHF/DSC radios
all have the capability of setting the radio to a
busy condition, which inhibits automatic
channel switching.
Design improvements in some VHF/DSC
radios are also possible, such as simplifying
the process used to select the type of message
to be transmitted: undesignated Maydays or
messages to recipients that enhance the ultimate success of the mission and incorporation
of the automatic “test” call option to check
DSC hailing when in range of a Rescue 21 system. Also, improving access to the radio’s
phone number directory will increase the willingness of users to employ DSC hailing.
DSC signaling will become more common
with its use of short message digital signaling
for communication and as part of “e” navigation. DSC is already a vital part of AIS and will
become a component of the message transmitted from future EPIRBs. ME
About the author
Chuck Husick’s current business activities include
technical journalism, consulting in marine and
aviation projects and participation in organizations such as the Radio Technical Commission for
Maritime Services on behalf of recreational boating. Following his service as an officer in the Corps
of Engineers, his work as an electronics engineer
included designing analog computers, program
management for the Gemini Space Program
telemetry system and senior management positions in companies in non-destructive testing,
marine and aircraft electronics and two major aircraft companies. His marine experience includes
serving as chairman and president of the Chris
Craft Boat Co. A sailor and pilot, Husick holds a
Coast Guard Master’s license and commercial
pilot/flight and instrument instructor’s licenses.
