It used spark gap technology, but modulated the carrier frequency with the human voice, and later music.
The system takes a carrier frequency and splits it into two identical signals.
In both cases, you tune your radio to the carrier frequency.
It could be noted that sound wave is not a click, but a pulse with a specific carrier frequency.
This range of frequencies is called a carrier frequency.
In 1980, the first atomic clock was installed to regulate the carrier frequency.
The carrier frequency was to be stable to one part in 10 over a month.
The information from the data signal is carried in sidebands on either side of the carrier frequency.
The relative uncertainty of the carrier frequency is 2 parts in 10.
Mitchell waited until he could hear the carrier frequency then replied.