UVB-76, a.k.a "The Buzzer"
The nickname that radio listeners have given a radio station. There are two transmitter sites near the town of Novopriozerskoye sh. Leningradskaya oblast', Russia; while another broadcasts the same signal from unnamed Rd, Moskovskaya oblast', Russia 143301.
Sometime in 1982 "The Buzzer " began broadcasting at a frequency of 4625 kHz. It was a repeating 2 second pip, changing to a buzzer in the early 1990's. It changed to a higher tone with longer duration on 16 January 2003; approximately 20 tones per minute where reported. It has since reverted to the previous tone pattern.
The broadcast is a monotonous buzzing tone, repeating at a rate of approximately 25 tones per minute, for 24 hours per day. This transmitted using AM with a suppressed lower sideband (R3E), but it has also used double-sideband AM
(A3E). The sound lasts 1.2 seconds, pausing between 1-1.3 seconds, and repeats 21-34 times per minute.
On November 2010, the tones lasted aproximately 0.8 seconds each. One minute before the hour, the repeating tone was replaced by a continuous, uninterrupted alternating tone, which continues for 1 minute before the short repeating buzz resumes; although this hasn't occurred since June 2010.