Raymarine Ray230 Owner's Handbook Manual page 34

Operations
13. ATIS Operation
When operating in inland waterways, many European countries require
automatic identification transmission, in accordance with ETS300 698.
The RAY230E has the capability of activating this ATIS function.
This radio is also equipped with "ATIS Killer" to squelch unwanted
electrical noise associated with ATIS transmissions.
14. SeaTalk Operation
Position data from other Raymarine equipment is obtained using the
SeaTalk line.
15. Remote Operation
Up to three full function handsets can be connected to the RAY230E.
Auxiliary handsets can be housed in the cradle, enabling you to listen
to radio reception from the external speaker.
16. Intercom Function between Handsets
The Intercom function is available when two or more handsets are
connected.
17. Desensitized Reception (Local Mode)
This function decreases receiver sensitivity in high traffic areas to
decrease unwanted reception.
18. Hailer Operation
The Hailer Horn can be used as a loud speaker or a directional
microphone.
19. Fog Horn Operation
The Hailer Horn speaker can sound several types of manual and auto
fog alerts.
20. DTMF Interface Operation (Optional)
If this optional feature has been installed, the handset can be used as
an interface to any DTMF formatted communications device by
connecting that device to the AUX terminal. See section 3.5.19.
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