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Priyom ID Spectrum image
Enigma ID S28


Name: Buzzer, UVB-76, UZB-76, MDZhB
Frequencies: 4625 kHz with few parasitics and harmonics
Status Active
Enigma ID status Active
Voice Male/female live
Emission mode Varies, read below
Location Russia
Activity pages

Audio Sample: Download sample

Enigma 2000 Control list description
Known counterpart stations S30,S32,Plovets41

S28 carries callsign MDZhB (formerly UZB-76/UVB-76). It is a Russian military station that broadcasts 24/7 for the most of time. Channel marker consists of a 1.85 s buzzing tone followed by 1.25 s pause.

Main, never changing frequency of S28 is 4625 kHz with few parasitic emissions noted around (they are varying): 4585, 4666, 4712, 4753 kHz and also occasional harmonic on 9250 kHz (which is 4625 * 2).

Emission mode
The Buzzer uses at least two transmitters (see: /blog/2-buzzers.aspx) and the emission mode varies by the transmitter and even within the same transmitter due to their instability. It is possible that there is a third transmitter that is responsible for transmitting the carrier while the other two alternate on transmitting the buzz.

One of the transmission sites is located near St.Petersburg. It is the transmission site of the 60th communication hub (located on Palace Square in St.Petersburg). There is document circulating in the net related to the site renovation project, and it has provided us with site antenna field schema

Buzzer has been seen operating on H3E (USB + carrier) and R3E (suppressed LSB, reduced carrier, full USB), some messages on J3E (USB) and some on R3E (suppressed LSB, reduced carrier, full USB) respectively.

The correct emission mode is difficult to determine, it is possible that the Buzzer uses a J3E transmitter that is incorrectly adjusted or overmodulated. Due to the Buzzer having multiple transmitters, all of them very error-prone, it is impossible to attribute one "standard" mode for it's operation.

Old mode seems to be reported as A3E (full carrier two-sideband AM).

Voice messages

S28's channel marker is sometimes interrupted to send voice messages. Usual format of them is:

[callsign] 93882 NAIMINA 7414 3574

There were many speculations about meaning of numbers and a word. First proposed theory by members of Priyom.org assumed first 5 figure group means ID of receiving unit. Now it's believed to be checksum of message. Old theory regarding two 4 figure groups believed they are coordinates. Now they are assumed as instructions in codebook. Currently there isn't any definite theory regarding codeword.

When S28 was called UZB-76, message was read as "93 882 NAIMINA 74 14 35 74, 9 3 8 8 2 Nikolaj Anna Ivan Mihail Ivan Nikolaj Anna 7 4 1 4 3 5 7 4". After starting using callsign MDZhB, codeword was read directly using Russian phonetic alphabet, but numbers were read in same way (93 882...).

There were also logged formats including more than one codeword:

79992 BONGU 9923 7768 BRONShchIK 7117 5770 (for some time very common format - check activity pages - but not heard recently)
28138 KARIAMA 7756 0151 AGGRADACIYa 0551 5597 GLAShATEL' 7678 5508 (very rare format)
48713 BRYaNTA 4893 6991 ORTOLAN 7463 1198 PROKLIZA 6910 4566 HROMATIZM 5954 0194 (extremely rare format, occured only two times)

S28 was reported for first time as early as in 1976 and as late as in 1982. Before first logged voice message ENIGMA group called it XB. Before 1990 it was reported as 2-second tone varying in pitch, then buzzer.

In September 2010 activity of the station has increased a lot, described on activity pages. Since then we have continuous (24/7) observation of 4625 kHz.


The Buzzer Primer 2011 Activity 2010 Activity Pre 2010 Activity


Notes from the Conet Project booklet


The Buzzer
Can be heard in the UK on 4625khz after dark, buzzing relentlessly. Just before the top of every hour, the signal changes, as in this example. The Buzzer has been on the air since at least 1987. The station is not I.T.U. registered, and has no callsign. See Enigma Newsletter number 11.

Tcp d4 32 the buzzer irdial by The Conet Project