Continuous Wave or A1A CW transmission, produces an audible audio tone from an AM radio receiver equipped with a a BFO control or beat frequency oscillator. Even as late as the 70’s CW communications was the goto backup, in 5 character coded groups, for encrypted HF RTT or High Frequency Radio Teletype communications.
Often, when transmission conditions precluded solid connections and synchronizations with receiving stations due to solar conditions or remote geographical locations or some combination of these in high latitudes, CW became the method of choice and necessity for clearing high priority communications traffic.
We had a book of data to help us optimize frequency selection for the range in nautical miles and the geographical location and Zulu time which we were attempting to communicate over.
In less technologically advanced clubs, like the starved Canadian Navy, satellite communications, etc, were the stuff of science fiction which our American brothers didn’t share with us because of our open affiliation with Communist regimes everywhere.
All courtesy of our Great North Magus, Pierre Eliot Trudeau and his Great Red North socialism. We still suffer from those Communist affiliations under his deviant son Prime Minister Boy Justin.
Anyway, here, for your entertainment, is a little vignette of ancient “CW” competing with modern “Texting” as a communications medium, a little “Blast From The Past” for all the iPhone thumb babies.