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5 Digital selective calling
5.1 General
DSC (Digital Selective Calling) is a semi-automated method of establishing
a radio call, it has been designated by the International Maritime Organi-
zation (IMO) as an international standard for establishing VHF, MF and HF
radio calls. It had also been designated part of the Global Maritime Distress
and Safety System (GMDSS). It is planed that DSC will eventually replace
aural watches on distress frequencies and will be used to announce routine
and urgent maritime safety information broadcasts. This new service will also
allow mariners to initiate or receive distress, urgency, safety and routine calls
to or from another vessel equipped with a DSC transceiver.
5.1.1 Maritime mobile service identity
An MMSI is a nine digit number used on Marine Transceiver capable of
using Digital Selective Calling (DSC). This number is used like a telephone
number to selectively call other vessels. Refer to section 6.12 (USER MMSI
ENTRY).
5.1.2 How can I obtain a MMSI assignment?
A request must be made to Communication Board, Department or similar
(according to the nation).
Warning
This radio is designed to generate a digital maritime distress and safety call to faci-
litate search and rescue. To be effective as a safety device, this equipment must be
used only within communication range of a shore–based VHF marine channel70
distress and safety watch system. The range of signal may very but under normal
conditions should be approximately 20 nautical miles.
5.2 DSC call types
Press the DSC/MENU key to pop up the menu for user to select the DSC call
type to send. Note that only four calls can be shown at any one time on the
screen. Press + /–or rotate the CH knob scroll up and down the call types
until the cursor is positioned at the desired option.
Press the Ch knob the call types are:
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