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

______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]

>>> Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
>>> 2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
>>> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]

______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]


Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]

______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]


Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]