Using Digital Selective Calling (DSC) Features
24
What is DSC?
Digital Selective Calling or DSC is a standard that allows you to call other
stations using their unique identification code (the Maritime Mobile Service
Identity or MMSI number), just like you would call a phone number. To call
another station, just enter that station’s MMSI number and choose the
voice channel you want to talk on. The radio uses channel 70 to transmit
your MMSI number to the other station along with the voice channel you
requested. If the other station accepts your call, both radios automatically
switch to the requested voice channel so you can talk to the other station.
DSC provides a system for automated distress calls. At the touch of a
button, the radio can transmit your MMSI number, the nature of your
distress, and your current position based on data from your GPS receiver.
The radio repeats the distress call every few minutes until it receives an
acknowledgement.
The DSC standard dedicates a VHF channel—channel 70—to digital
transmissions only. Since digital transmissions require less bandwidth voice
transmissions, channel 70 avoids the problems of busy voice channels.
Advanced DSC features
The UM425 supports the following DSC features:
Feature
Menu Item
Function
Individual Call
Individual
Contact another vessel from your directory.
Group Call
Group
Contact all vessels that share your group
MMSI code.
All Ships Call
All Ships
Broadcast to all vessels within range (used for
safety or advisory messages.)
Position Request
POS Request Request the current location of another vessel.
Position Send
Position Send Transmit your current location to another
vessel.
Test Call
Test
Make sure your radio is working and
configured correctly
Name and MMSI
Directory
Directory
Store a list of 20 names and MMSI
identification codes for DSC calls.
Standby Mode
Standby
Automatically respond to all DSC calls with an
“Unavailable” status.
Received Call Log Receive Log
Display the last 10 distress calls received by
the radio and the last 20 general calls.
Using Digital Selective Calling (DSC) Features
UM425 VHF OM.indd 24
28/9/11 11:55:16 AM
