UVB-76
UVB-76, also known by the nickname "The Buzzer", is a shortwave radio station that broadcasts in upper sideband mode on the frequency of 4625kHz. It broadcasts a short, monotonous, repeating at a rate of approximately 25tones per minute, 24hours per day. Sometimes, the buzzer signal is interrupted and a voice transmission in Russian takes place. Although the true nature of the transmission has never been revealed, it is speculated to be related to the Dead Hand system, thus the transmission being sometimes referred to as the Doomsday Radio.
Name and callsigns
The station is commonly known as "The Buzzer" in both English and Russian. From its first voice transmission in 1997 to 2010, the station identified itself as UZB-76. The callsign UVB-76 was never used by the station itself, but is rather a mistranscription of UZB-76. However, the station is still often referred to by that name. In the following years of transmission, the main callsign of the station changed regularly.| Callsign | Timespan used |
| UZB-76 | 24 December 1997 – 7 September 2010 |
| MDZhB | 7 September 2010 – 28 December 2015 |
| ZhUOZ | 28 December 2015 – 1 March 2019 |
| ANVF | 1 March 2019 – 30 December 2020 |
| NZhTI | 30 December 2020 – present |
In addition to these main callsigns, The Buzzer also uses other "side callsigns" which are being used less frequently than the main callsign. Whenever the main callsign changes, all previous side callsigns are also discarded.
The station transmits using AM with a suppressed lower sideband, but it has also used full double-sideband AM. The signal consists of a buzzing sound that lasts 1.2 seconds, pausing for 1–1.3 seconds, and repeating 21–34 times per minute. Until November 2010, the buzz tones lasted approximately 0.8 seconds each. One minute before the hour, the repeating tone was previously replaced by a continuous, uninterrupted alternating tone, which continued for one minute until the short repeating buzz resumed, although this stopped occurring in June 2010.
Since the start of broadcasting, The Buzzer broadcasts as a repeating two-second pip.
Voice messages
The buzzing sound is sometimes interrupted by the broadcast of voice messages. These messages are always given in Russian by a live voice, and follow three fixed formats:Monolith
A message in the Monolith format always consists of the following parts:- Callsigns, each of which read out twice in the readout. A callsign always consists of four symbols, each symbol being either a Russian letter or a digit
- Five digit ID groups
- Message blocks, each consisting of one code word and eight digits
Monolith messages can however contain any number of items from each part:
Uzor
A message in the Uzor format always consists of the following parts:- Callsigns, each of which read out twice in the readout
- Message blocks, each consisting of one code word and four digits
Nowadays, Uzor messages are rarely sent on The Buzzer.
Komanda
Komanda is the most uncommon type of voice message. Since it has not been heard for years, messages of this type are most likely not being sent on The Buzzer anymore. They consist of a callsign, a codephrase, and a following number.Example of such a message:
Unusual transmissions
Distant conversations and other background noises have frequently been heard behind the buzzer; this suggests that the buzzing tones are not generated internally, but are produced by a device placed near a live and constantly open microphone. Because of the occasional fluctuating pitch of the buzzing tones, it is supposed that the tones are generated by a tonewheel as used in a Hammond organ. It is also possible that a microphone may have been turned on accidentally. One such occasion was on 3 November 2001, when a conversation in Russian was heard:In September 2010, several unusual broadcasts were observed; these included portions of the buzzer being replaced with excerpts from Tchaikovsky's Swan Lake.
On 15 May 2020, broadcasts from unknown French speaking persons were heard.
In January 2022, various signals with spectrogram-encoded images, visible through a spectrum analyzer, were broadcast on the same frequency. There have also been reports of various songs airing on the station's frequency, many of which were connected to internet memes such as the 2012 K-pop song "Gangnam Style"; a Vice article attributed these broadcasts to pirates hijacking and spamming the frequency. The nationality of the pirates has also come into question by Vice in relation to the 2021–2022 Russo-Ukrainian crisis and Russo-Ukrainian war.
Only on very rare occasions have there been any external civilian communications—unless authorised by the Russian defence ministry—with UVB-76, given its status as a military radio. The most recent event occurred under irregular circumstances. During the night of 4 May 2024 at 21:38, an unknown Russian-speaking pirate infiltrated the frequency and attempted to contact the station whilst the buzzer was not active, if not on standby. The pirate subsequently asked a series of improvised questions to the station, briefly conversing with the station's operator:
Other instances of deliberate hijackings are widely unreported. Another incident occurred one day prior to the above event. An unknown pirate—possibly the same one—attempted to subject the buzzer to interference, prompting the on-duty operator to immediately retaliate, taking preventative measures against the signal incursion. The UVB-76 operator combined three individual transmitters, with one above, one below and the other centre 4625 kHz transmitting MS-5 burst, along with CIS-12 modern audio as well as tones in several states, summarising together a highly dense spectral pattern with the upper-side band. Numerous noticeable transitions were witnessed over the 4625 kHz selected spectrogram section, as the operators frantically fought against the pirates. The incident occurred for around half an hour, until the operators ceased their tactics after the pirate abandoned attempts, as the buzzer was then reactivated.
On 11 November 2025, the station broadcast twenty-four messages comprising thirty different words, the "most verbose broadcast in its history."
On 30 December 2025, the broadcast was again replaced with excerpts from Swan Lake. Also played were many western songs, including ‘Counting Stars’ by OneRepublic. On 31 December 2025 the broadcast was once again hijacked to play Russian rap as well as western pop songs. This interruption lasted for over three hours.
Location and function
The purpose of the station has not been confirmed by government or broadcast officials. However, Rimantas Pleikys, a former Minister of Communications and Informatics of the Republic of Lithuania, has written that the purpose of the voice messages is to confirm that operators at receiving stations are alert. Another explanation is that the broadcast is constantly being listened to by military commissariats.There is speculation published in the Russian Journal of Earth Sciences which describes an observatory measuring changes in the ionosphere by broadcasting a signal at 4,625 kHz, the same broadcast frequency as the Buzzer.
One possible interpretation is that the voice messages constitute military communications. The possibility of the station being a numbers station for intelligence agencies, such as the FSB or the former KGB of the Soviet Union, is considered unlikely by some, since messages occur at seemingly unpredictable times. In addition, the static frequency of 4,625kHz and the low transmitter power are likely unsuitable for reliable long-range communication.
The buzzing functions as a "channel marker" used to keep the frequency occupied, thereby making it unattractive for other potential users. The signature sound could be used for tuning to the signal on an old analogue receiver. The modulation is suitable to be detected by an electromechanical frequency detector, similar to a tuning fork. This can be used to activate the squelch on a receiver. Due to the varying emission properties on shortwave bands, using a level-based squelch is unreliable. This also allows a signal loss to be detected, causing an alarm to sound on the receiver.
Another theory, described in a BBC article, states that the tower is connected to the Russian 'Perimeter' missile system, and emits a "dead hand" signal that will trigger a nuclear retaliatory response if the signal is interrupted as a result of a nuclear attack against Russia. This theory is also unlikely, given that the signal frequently breaks down or is routinely switched off for maintenance.
There are two other Russian stations that follow a similar format, nicknamed "The Pip" and "The Squeaky Wheel". Like the Buzzer, these stations transmit a signature sound that is repeated constantly, but is occasionally interrupted to relay coded voice messages.
The former transmitter was located near Povarovo, Russia, at which is about halfway between Zelenograd and Solnechnogorsk and northwest of Moscow, near the village of Lozhki. The location and callsign were unknown until the first known voice broadcast of 1997. In September 2010, the station's transmitter was moved to the nearby city of Saint Petersburg, near the village of Kerro Massiv.
This may have been due to a reorganization of the Russian military. Since 9 August 2015, the station is not transmitting from the Kerro Massiv transmitter site anymore, possibly due to a reorganization of the Russian military for the particular area which may cause the frequency to be used only in the Moscow Military District. At present, The Buzzer appears to be broadcast only from the 69th Communication Hub in Naro-Fominsk, Moscow. In 2011, a group of urban explorers claimed to have explored the buildings at Povarovo to find an abandoned military base and, in it, a radio log record confirming the operation of a transmitter at 4,625 kHz.