The Raymond-Barker Multi-Tone Transmitter

A device which replaced the 'dit-dah' of conventional morse with sounds of different frequencies. The two-tone transmitter translated the bipolar signals of Cable Code Morse into two distinct frequencies - a high tone for the 'dot' and a lower one for the 'dash'. This meant that the equal-length signals of a cable code message could be deciphered by someone using headphones.

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Click the keys to hear the tones...
(Interactive photo of two-tone transmitter with keys that can be clicked to hear the tones.)

The two-tone transmitter was used for short distance communications during cable repair or laying operations, for instance between a cable ship that had grappled and cut into a cable a few miles off-shore, and engineers at a beach cable hut. Later transmitters had used reversible microphone/speakers so that engineers could actually talk from ship to shore!

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