Raymarine Limited. Registered in England. Company no. 1177969 Page 9
Registered Office: Anchorage Park, Portsmouth P03 5TD
In listen mode the talk/listen relay connects the horn to the input of a small signal amplifier and the
horn acts as a directional microphone. The signal from the horn is amplified and routed to the
handset and speaker.
The loudhailer may also be used as fog horn. The talk/listen relay is switched to talk and, instead of
voice, a fog signal tone, generated by the microcontroller, is routed to the power amplifier. The
standard tone is a square-wave “whistle”, but provision is also made to generate a “bell” sounding
tone.
Telephone Interface
The telephone interface is an optional plug-in board that connects the Ray240 to a standard telephone
line or DTMF controlled device, enabling the Ray240 to be used as a telephone.
The telephone interface comprises:
• 12V and 5V power
• Audio lines to and from the telephone line
• Discrete signals indicating on-hook/off-hook and ringer status
• A spare discrete nominally called “mute”
• An I2C serial communications interface, used for controlling a DTMF generator on the
telephone interface board
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