|Enigma ID||X06, X06a, X06b, X06c||
|Emission mode||USB + carrier, USB, AM|
|Location||Moscow, Russia; Havana, Cuba|
|Known counterpart stations||Serdolik|
Mazielka is a selective call system used by the Russian Diplo/Intel. It is a usually USB + carrier (H3E) mode transmission of a 1998 ms 6-tone string, 333 ms per tone, followed by a 1380 ms pause, repeated. The strings can be written as numbers, with the numbers mapping to the following pitches, in hertz:
Typically strings of only unique digits are sent, allowing 720 unique combinations. However, far fewer, about 50, are actually being used. A Mazielka broadcast can last anywhere between a few seconds and a few hours.
While many of the transmissions are unscheduled, some are being heard regularly on a certain day of the month ("2nd Saturday of the month" type) within a specific time frame on a specific frequency.
Sometimes transmissions are made, which may consist of sequences such as 121212 (an alternating two-tone X06a sequence), 111666, 111111 (consecutive-repeat X06b sequences) or 123456 (the X06c sequence). These can extend for many hours.
The Mazielka system has been used since 1970s. It originally acted as a pre-cursor to diplomatic RTTY and Serdolik broadcasts. Its current purpose is currently unknown. The sequence 111666 is sent about an hour before scheduled transmissions of E07, M12, and XPA.
Until 1990, broadcasts could have been heard where the pause replaced with a high pitched tone: