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
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).
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)
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
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
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
79992 BONGU 9923 7768 BRONShchIK 7117 5770 (for some
time very common format - check activity pages - but not heard
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
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.
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
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