@b_jonas Just out of curiosity - what did you refer to when you wrote "that's strange"?

@MartinSleziak History of telegraph and later telephone cables through the Atlantic (telegraph cable was up since 1865 with some interruptions) and later attempts through the Pacific (first cable is in 1950s), as well as radio telegraphy and telephone connections the same way. I've found out most of what I need, but still don't know much about the radio connections.

@MartinSleziak In both cases the main problem until the 1920s was the lack of vacuum tubes, which they need for amplifying signal in cables, or amplitude modulation of radio. I still have questions about the radio comms history part because I found very little. I explain the motivation under chat.stackexchange.com/transcript/message/47171973#47171973 .

Thanks for the response! It seems to be quite an interesting stuff.