31 March 2021

CIS-1200 DBPSK 1200Bd ("Makhovik", T-230-1A)

Good quality CIS-1200 (T-230-1A, DBPSK 1200Bd) transmission spotted on 9073.80 KHz (cf) thanks to the ArcticSDR. The transmission consists of a series of encrypted messages, the 240-bit Initialization Vectors are sent in 8x30-bit groups, each group repeted three times (Figure 2).

Fig. 1

Fig. 2

The transmission ends with a long "idling" part consisting of the 511-bit m-sequence generated by the polynomial x^9+x^5+1 (Figure 3). All is ok with previous CIS-1200 recordings [1].

Fig. 3

[1]  https://i56578-swl.blogspot.com/search/label/Makhovik

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