Showing posts with label CIS-MFSK-5x16. Show all posts
Showing posts with label CIS-MFSK-5x16. Show all posts

21 March 2016

CIS 5 x MFSK-16 + BPSK 250Bd (2)

Just to point out some interesting analogies with a similar MFSK-16 signal, heard in the latest days of the past September 2015.
That signal had the same MFSK parameters, 5 x 16 tones 10Bd 20Hz, but with FSK inserts each 10 seconds rather than the BPSK inserts seen in these days . SOM and EOM shows the same style. While the BPSK version has a fixed lenght of 21:05 minutes, the FSK version had a 33 seconds lenght and was repeated each 15 minutes.
One could say that the BPSK version seen in these days is a sort of evolution of the semptember FSK (test ?) version, but it's probably a speculation.

18 March 2016

CIS 5 x MFSK-16 + BPSK 250Bd


this interesting signal (supposed to be used by "Russian Intelligence") has been heard on 13497.0 KHz and 15812.0 KHz USB on 30 October (from 1300z to 1330z) and on 15845.0 KHz USB on 18 March (from 1300z to 1320z).
The most interesting feature are the BPSK inserts, each 10 seconds, that modulate in turn 6 different 250 Hz spaced carriers at 250 symbols/sec. Apparently there isn't a certain order of choice of the six carriers or a sort of cycle so it's difficult to say something about the scope of these inserts. Since they do not carry informations, they could be sent for tuning filters and equalizing MFSK demodulator purposes, but it's only my guess.



About the MFSK part, it's possible to individuate five distinct MFSK-16 channels with tone separation of 20Hz and 10Bd speed


Most likely the signal is a sort of FTD waveform. All the heard transmissions end with the same ~860 ms sequence  2 frequencies, modulated in some frequency time shifted method.