UVB-76, also known by the nickname "The Buzzer", is a shortwave radio station that broadcasts in upper sideband mode on the frequency of 4625 kHz. It broadcasts a short, monotonous, repeating at a rate of approximately 25 tones per minute, 24 hours per day. Sometimes, the buzzer signal is interrupted and a voice transmission in Russian takes place. Although the true nature of the transmission was never revealed, it is speculated to be related to the Dead Hand system, thus the transmission being sometimes referred to as the Doomsday Radio.