7 May 2016

CIS 3 x 100Bd/1440Hz VFT system


fig.1
CIS 3x100 waveform consists of three FSK2 channels modulated at 100Bd and a pilot tone at ~3300 Hz (characteristic feature of Russian systems). Every channel has a 1440 Hz shift and 100 Baud speed, channels are separated by 480Hz steps (figs. 2,3) and interleaved as in fig.1
fig. 2 - 1440 Hz shift
fig. 3 - channel separation
The 100 symbols/sec modulation rate, is obtained by highlighting a single channel in the FFT and measuring its speed (fig. 4).

fig.4
update
in this post it has been verified that the system carries up to tree T207/CIS-14 channels for a total of six independent 5-bit channels.

https://yadi.sk/d/SlYz9x6JllZhDg 

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