S11a – Cherta Polish Numbers Station Profile

S11a, also known as “Cherta” is a numbers station operated by one of the Polish Intelligence Agencies.  Messages from S11a are not common, mostly null messages are sent.  Messages in the past were usually very short, but now groups of 30+ are common.  Usually at least one message is sent per month.  It was previously given the ENIGMA ID S12 before it was a known variant of S11.

Message Recording


S11a is active twice per week, usually sending null messages.  It changes frequencies every 4 months, and a total 3 of times a year.  The three different schedules are routinely from May to August, another from November to February, and the remaining months have another as well.

Message Format

Preamble Message Repeat End
371 Cherta 32 Vnimanie 47703 47703
91005 91005 …
Vnimanie 47703 47703
91005 91005 …
3-digit ID “/” Group count 5-digit paired groups,
pauses every 10 pairs
5-digit single groups,
pauses every 10 groups
Repeats for 3 minutes
and 10 seconds

Null Format

798 Cherta 00 Konets
3-digit ID “/”
3 minutes and 10 seconds

Uses a variant form of Russian numbers

Nul: Null [ноль] (Zero)
Adinka: Adeen [один] (One)
Dvoyka: Dva [два] (Two)
Troyka: Tree [три] (Three)
Chetyorka: Chyetirye [четыре] (Four)
Petyorka: Pyat [пять] (Five)
Shest: Shest [шесть] (Six)
Syem: Syem [семь] (Seven)
Voysem: Voysem [восемь] (Eight)
Dyevyet: Dyevyat [девять] (Nine)


S11b is an inactive variant of Cherta. It included stutter groups, usually 77777 as beginning and ending groups.  It also always sent 30+ group messages., with pauses after every 10 groups.  This variant was last observed in 2009.

Numbers Station Summary

Nickname: Cherta
Activity: Active
Emission Mode: USB
Voice Summary: Automated woman’s voice w/ Polish accent. Like S11’s but higher pitched.
Believed Country of Origin: Poland
Family Relatives: E11, G11, S11, M03, G10, S26, M20
Station Family: Family 3 “Strich”