10 May 2017

CIS-40.5 (CIS-81-81, T-206)

CIS-40.5 FSK (T-206 chiper devices family) is the single channel version of CIS-81. It's a quite "old" mil system, most likely in use by some ex USSR republic.
So far, I had CIS-40.5 in three different waveforms:

40.5Bd 120 (supposedly)
Traffic is encrypted and the demodulated stream at my disposal doesn't offer any information. Other samples are needed for further analysis.

Fig. 1
Fig. 2 - CIS-40.5 120Hz shift demodulated shift

40.5Bd 250
It's the most interesting waveform since its demodulated stream exhibits a 12-bit format due to the idle signal (6 mark and 6 space bits). The scrambler x^11+x^9+1 is superimposed to the data block transmitted between idles (Fig. 5). Data blocks are encrypted and consist of 6-bit frames.

Fig. 3
Fig. 4
Fig. 5

40.5Bd 500
Unfortunately the recording at my disposal onsly consists of reversals so it doesn't offer any useful information unless the match of the FSK values (speed and shft). As above, other samples are needed for further analysis.
Fig. 6
https://yadi.sk/d/UTty-5kNJO7b7w (120Hz shift)
https://yadi.sk/d/LYyCXmiP9EQCcQ (250Hz shift)
https://yadi.sk/d/adyKaXEkwL8FdA (500Hz shift)

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