Interesting find here... cannot locate the original source to reference but still a neat video!
The technology of amplitude modulation (AM) radio transmission was developed during the two decades from 1900 to 1920. Before this, the first radios transmitted information by wireless telegraphy, in which the radio signal didn't carry audio (sound) but was switched on and off to create pulses that carried text messages in Morse code. This was used for private person-to-person traffic, similar to telegrams.
