Raymarine axiom pro 9 RVX Installation Instructions Manual page 138

Please select a sonar channel
The first time you open a new app page that includes the Sonar app
you will need to select a Sonar channel.
Select OK and then choose the Sonar channel you want to use from
the list:
Sonar on and pinging
If your Sonar app has already been set up then when the Sonar app is
opened the Sonar image will be displayed and start scrolling.
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