[GreenKeys] TTY on ocean cables?

[Duncan Brown]

The original undersea cables used DC signalling.  But because of the 
large amount of capacitance in the thousands of miles of coaxial cable 
used, the DC level could not change quickly and even hand-sent Morse had 
to be sent slowly. This was improved somewhat by using polar signalling, 
but was still too slow for TTY.

Around 1910, they started using audio signals on the undersea cables. 
This allowed faster signalling and Frequency Division Multiplexing.  At 
this time, TTYs, using AFSK, could have been used on the undersea cables.

Have fun,

Duncan
K2OEQ


On 4/26/2025 9:41 PM, Brenda Gentry via GreenKeys wrote:
>
> The mention of Navy RTTY  and water brought out a question- when was 
> the first transatlantic teletype cable system built? What kind of 
> keying did it use?
>
>      B. Gentry,  KA2IVY
>
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