Raymarine Ray240, User Manual

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Chapter 1: General Information 15
Chapter 1: General Information
1.1 What is the Ray240?
The Ray240 is a combined VHF radio and Class D Digital Selective Calling (DSC)
system, using a phone style handset to access and control all functions. It enables
you to make digitally selected calls, which are quicker and simpler to make than
traditional voice calls using Channel 16. It can transmit and receive on all
available US, Canadian and International Marine VHF channels.
Should a distress situation occur, using the Ray240 you can quickly raise an alert,
automatically indicating your identity and position, and establishing distress
communication on the emergency voice channel.
1.2 What is DSC?
The present VHF radio system requires users to listen until someone speaks, and
then determine whether the call is for them - more often than not, it isn’t. DSC
makes sure that you receive messages, and alerts you to the fact that it is for you.
DSC is part of the Global Maritime Distress and Safety System (GMDSS), a
maritime communication system - not just for emergency and distress messages,
but also for all types of existing ship-to-ship and ship-to-shore routine
communications.
DSC is simply a tone signalling system, which operates on VHF Channel 70 and is
similar to the tone dialling on your phone, but with the ability to include other
information such as your boat’s identification number, the purpose of the call,
your position and the channel you want to speak on.
DSC calls can be divided into four categories:
• Calls to other ships.
• Group calls.
• Safety broadcasts.
• Distress alerts.