WHAT IT IS

CIS-128 is a Russian 128-carrier OFDM data waveform. The waterfall is two 64-tone blocks with the center carrier off, so the grate splits down the middle. I-56578 nickname for the OFDM-128 modem: Corvette (Корвет). Factory stencil unpublished. It sits in the same diplomatic/intel suite as CIS-3000 (the 8-PSK ALE that opens it) and Perelivt / MFSK-68 (the 10 kHz MFSK sibling).

It is also the top mode on the CIS OFDM HDR ladder (45 / 60 / 93 / 112 / 128). Those narrower HDR modes get their own page; this page is the 128-channel split grate.

WHAT THE WATERFALL LOOKS LIKE

Two dense OFDM fences with a dark slot in the center. Narrow book: about 3.1 kHz. Wide book: about 6.1 kHz, same 128 channels, double the baud, still the center hole. USB. CIS-3000 often sits immediately in front. No 3300 Hz Almaz pilot as the ID; no 10 kHz Perelivt slab.

HOW THE AIR INTERFACE WORKS

128 OFDM channels, one suppressed at center → 64 + 64. Per-tone rate on the Sigidwiki card: about 21 Bd. Modulation seen: QAM-16, QAM-4, QPSK / PSK. A Ukrainian survey of the HDR family lists CIS-128 as QAM-16 / PSK, 2688 bit/s in the 3.1 kHz map (spacing ~23.5 Hz) and 5376 bit/s in the 6.1 kHz map (spacing ~47 Hz). Those figures are one published table, not a factory sheet.

CIS-3000 (3000 Bd 8-PSK, ~3.4 kHz) is the calling mode. After the handshake the grate fills. Encrypted payload. No public plaintext decoder.

BANDS AND WHERE IT IS HEARD

HF USB, 3–30 MHz. Diplomatic / intel nets. Same frequency neighborhood as Perelivt and CIS-3000.

HARDWARE

Unpublished HDR / Corvette-class modem. Needs a clean 3 kHz USB path for the narrow map; 6 kHz for the wide map. Not an AT-3004 12-tone box.

NOT THESE

CIS-1280 — OQPSK single-carrier at 1280 bit/s, 1.28 kHz, .081 kHz offsets. Different number, different PHY.
Perelivt / MFSK-68 — 10 kHz MFSK + 40 ms 8-PSK insert.
CIS-3000 — the ALE that opens this grate.
CIS-12 — 12 PSK teeth + 3300 Hz pilot.
CIS-45 / 60 / 93 / 112 — narrower HDR OFDM modes, no center-off 64+64 split.

CAVEATS

Corvette is an I-56578 nickname, not a GRAU index. 21 Bd vs the HDR-table bit rates are two ways of counting the same family. 3.1 vs 6.1 kHz is two maps, not two services.

STATUS

Active as the OFDM traffic mode behind CIS-3000, beside Perelivt.

IN ONE SENTENCE

CIS-128 / Corvette is the Russian 128-carrier OFDM grate — 64 tones, a dead center, 64 tones, 3.1 or 6.1 kHz, QAM/PSK — the file mode CIS-3000 opens, not CIS-1280 and not Perelivt’s 10 kHz MFSK.