15 April 2022

Akula: a quite unusual session

Quite unusual session of Rus-Ny "Akula" 500Bd/1000 FSK characterized by the continuous transmission of only the lowest tone before and after the messages (see figure 1), just like some Rus-Ny 50Bd/200 or even FAB broadcasts from PBB Dutch-Ny.

Fig. 1

 Notice in figure 2 the usual structure of the Akula messages:
- reversals
- "sync" group (which never varies and contains 6 code words arranged as 4 x 100101 + 3 x 110001 followed by a separator)
- "preamble" group (7 code words with two different, but varying values arranged as 4 x 1st code word + 3 x 2nd code word)
- data block
- End-Of-Message group + EOT group (which never varies and consists of the five code words 010000 011101 011101 010000 100001)

Fig. 2 - structure of Akula messages



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