WHAT IT IS
CIS-11 is a Russian synchronous full-duplex FSK teleprinter with an 11-bit word. Factory / service name on the monitor cards: TORG-11 (also written TORG-10/11). It needs two frequencies — forward and return — and both ends keep transmitting even when there is no traffic, so the pair stays locked. Main published use: CIS aeronautical / meteorological reports in the Russian M2 third-shift Cyrillic ITA-2 alphabet.
The “11” is the frame length, not a tone count. CIS-14 / AMOR is the 14-bit cousin.
WHAT THE WATERFALL LOOKS LIKE
Two FSK rails, one link. Shift on the cards: 400 Hz (Sigidwiki) or 500 Hz (I-56578 / TORG literature). Occupied width about 650 Hz. Continuous — idle is not silence; it is the alpha idle character looping. USB or LSB; polarity is part of the decode, not the PHY.
HOW THE AIR INTERFACE WORKS
Modulation: 2-FSK. Usual on-air rate 100 Bd (Wavecom also quotes 100.05). Other books list 50 / 150 / 200 / 300; Wavecom AUTO span 30–650 Bd. One 11-bit word at 100 Bd is 110 ms.
Word layout (I-56578 / Wavecom):
Bits 1–5 — M2 / ITA-2 character, bit order reversed vs ordinary Baudot.
Bits 6–7 — system state / alphabet (00 idle or RQ; 10 Cyrillic; 11 Latin on the few analysed tapes; 01 unpublished).
Bits 8–11 — four parity bits. Modulo-2 over the seven data+state bits; four checks are enough to locate and flip one bad bit.
I-56578 parity (d0–d4 reversed data, s0 s1 state):
p0 = d1 + d3 + d4 + s0
p1 = d0 + d2 + d4
p2 = d0 + d1 + d3 + s1
p3 = d0 + d2 + d3 + s0 + s1
ITU-R F.342-2 idle pair used on this waveform:
α 01101 00 1100 — keep-alive when there is no text.
β 10101 00 0001 — ARQ request.
Alphabet change on the analysed streams: 00000 10 → Cyrillic, 11111 11 → Latin.
BANDS AND WHERE IT IS HEARD
HF, 3–30 MHz. Meteorological / aero weather nets. RadioReference marked CIS-11 last-seen Feb 2019 and older manuals already called TORG-11 retired. Treat live copies as sparse, not extinct until proven.
HARDWARE
Two HF transmitters and two receivers, or a duplex pair. Baudot / M2 end gear. Wavecom, Hoka, Sorcerer will slice the 11-bit word; they do not unwrap a later cipher if one is applied.
NOT THESE
CIS-14 / AMOR — 14-bit duplex FSK, same job, longer word.
CIS-12 — 12-tone PSK + 3300 Hz pilot, not FSK.
CIS-36-50 / BEE — Navy 36/50 Bd FSK, not 11-bit M2.
CIS-40.5 / T-206 — 40.5 Bd encrypted telegraph FSK.
Ordinary ITA-2 RTTY — 5 data bits, no 4-bit parity frame, bits not reversed.
CAVEATS
400 Hz vs 500 Hz shift is two monitor books, not two services. “Not used for years” is a 2000s FAQ; later logs exist. State-bit table is from a small I-56578 sample.
STATUS
Legacy duplex meteo ARQ. Expect CIS-14 next to it on any remaining pair.
IN ONE SENTENCE
CIS-11 / TORG-11 is the Russian 11-bit full-duplex FSK teleprinter — usually 100 Bd, 400–500 Hz shift — M2 weather text with four parity bits and a continuous idle so both ends of the pair never go quiet.