A-013: UVB-76

Status and Warnings

 * Currently considered active.
 * Validity confirmed, purpose unknown.
 * Original article by Jade.

Description
UVB-76 (Russian: УВБ-76), also known as "The Buzzer", refers to a shortwave radio station, broadcasting on a frequency of 4625 kHz from Russia, owned by the Russian Armed Forces. It transmits using AM with a suppressed lower sideband (R3E), but it has also used full double-sideband AM (A3E).

The station is most known for its transmissions of a short buzz tone, lasting 1.2 seconds, pausing for 1-1.3 seconds and repeating 21-34 times per minute. The buzz tone is occasionally replaced by a voice transmission in Russian. Conversations can frequently be heard on the channel, suggesting that the tone is produced not internally, but instead from an outside source and picked up by an always active microphone.

The use of the station is currently unknown and has not been confirmed by government or broadcast officials.

History
The first reports of a station of this frequency were made in 1973 as a repeating two second pip, and changing to a buzzer sound in 1990. On January 16, 2003, the station changed briefly to a tone of longer duration (about twenty tones per minute), but had since reverted back to the original tone pattern.

The repeating tone was previously replaced by a continuous, uninterrupted alternating tone which continued for one minute before the hour, though this stopped occurring in June 2010.

Possible Explanations

 * Rimantas Pleikys, the former Minister of Communications and Informatics of the Republic of Lithuania, has written that the station is used to make sure that the operators at receiving stations are alert.
 * Many have speculated the station is being listened to by military commissariats.
 * It is thought that the voice messages are military transmissions, with the buzz tone being used to keep the channel occupied and undesirable for others to use.