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OPERATION
4.3 Communicating in DSC (Digital Selective Call) Mode
4.3
Communicating in DSC (Digital
Selective Call) Mode
In DSC mode, digital selective calls (distress, urgent, safety, and routine) are available on
CH70. Distress calls can be made instantly by pressing
DISTRESS
or after editing the distress
message in the DSC MENU. When the message is edited, data such as time and current
position can be added even when no navigation aid is connected.
Other options available in DSC mode are relaying a distress call, displaying and confirming
received messages, and requesting a connection to a public telephone subscribers.
4.3.1
General Information on DSC Calls
In DSC mode, digital codes are used for transmitting and receiving distress or other calls. The specifi-
cations for DSC calls are standardized by RR (Radio Regulation), ITU-R, and IMO, enabling DSC calls
regardless of manufacturer and nationality. A distress message includes ID, position, UTC time, and
the nature of distress. A distress call is first transmitted 5 times consecutively and then it is repeated
in 3.5 – 4.5 minute intervals until it is acknowledged.
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