Nowadays, this is usually regarded as illegal radio frequency interference and is suppressed, but in the early days of radio communications (1880–1920), this was the means by which radio signals were transmitted, in the unmodulated spark-gap transmitter.
I dag anses det for at være ulovlig interferens og undertrykkes, men i de tidlige dage af radiokommunikation (1880-1920), var det måden radiosignaler blev udsendt på, i en umoduleret gnistsender.