1 April 2015

CIS-45 v1 HDR modem 33.33 Bd BPSK bursts

CIS-45 Ch, Russian 45 tones HDR modem, version 1 http://signals.radioscanner.ru/base/signal46/
This is a Russian 45 tones HDR modem, version 1, formed using the principles of OFDM and here running in burst-mode. Most likely it is a lightweight version of the Russian 93 tone modem. The HDR name is just an abbreviation of High Data Rate.
The transmission heard on 15812.0 KHz USB at 0705z, is composed of two bursts, sent at irregular intervals. Looking at its features it corresponds to the version 1 of the well known Russian 45-tones PSK-2 OFDM modem (also known as CIS-45), here running in burst mode at 33.33 Baud.
The pilot tone also acts as a sync tone at the beginning of each burst. The 45 sub-carriers in the trailer are un-modulated and followed by a PSK-2 modulated segmen. The data-block after the preamble shows a PSK-2 modulation in the channels at the speed of  33.33 baud.

Bandwidth: ~ 3000 Hz
Number of channels: 45 + 1 pilot tone (~ 3350 Hertz)
Manipulation in the channels: 2-PSK
Step between channels (frequency net/grid): 62.5 Hz
Manipulation speed (Baud rate): 33.33(aggregate 1800)

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