Digital Selective Calling (Dsc); Uscg Dsc Watch; Maritime Mobile Service Identity (Mmsi); What Is A Mmsi - Standard Horizon Quest GX1255S Owner's Manual

8.7 DIGITAL SELECTIVE CALLING (DSC)

Digital Selective Calling is a semi-automated method of establishing a radio
call, it has been designated by the International Maritime Organization (IMO)
as an international standard for establishing VHF, MF and HF radio calls. It
has also been designated part of the Global Maritime Distress and Safety
System (GMDSS) and it is planned 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 allow mariners to instantly send a distress call with
GPS position (when connected to the transceiver) to the US Coast Guard
and other vessels within range of the transmission. DSC will also allow mari-
ners to initiate or receive distress, urgency, safety and routine calls to or
from another vessel equipped with a DSC transceiver.

8.7.1 USCG DSC Watch

The USCG has plans to upgrade its VHF National Distress System (expected
by 2005), so at the time of printing only larger vessels that are required to
carry VHF DSC radios will be able to hear your distress transmission.

8.8 MARITIME MOBILE SERVICE IDENTITY (MMSI)

8.8.1 What is a MMSI?

A MMSI is a nine digit number used on Marine Transceivers capable of
using Digital Selective Calling (DSC). This number is used like a telephone
number to selectively call other vessels.

8.9 USING DIGITAL SELECTIVE CALLING FEATURES

8.9.1 Distress Call

Transmits a DSC Distress message to all radios equipped to receive a DSC
Distress call. Some Standard Horizon radios may be connected to a GPS to
also transmit the Latitude, Longitude of the vessel.

8.9.2 Individual Call

This feature allows the user to contact another vessel capable of using DSC
and automatically switch the radio to a desired working channel. This fea-
ture is similar to calling a desired vessel on CH16 and requesting them to go
to another channel.

8.9.3 Urgency Call

This call should be used when a vessel may not be truly in distress, but have
a potential problem that might lead to a distress situation.
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