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Publicado: 28 May 2015 17:07
por I-56578
this waveform was seen on 14635.0 USB (dial freq) and it seems to me an MFSK 47 tones, 47 spaced, and 47 Baud speed... that's a bit odd.
Maybe I made some wrongs, someone can verify?
A short recording may be downloaded from here:
https://www.dropbox.com/s/87e0e8rxybiok ... z.wav?dl=0


Re: MFSK-47

Publicado: 28 May 2015 19:04
por ANgazu

The speed is 47 b, but something very unusual is taking place.

As you can see in picture, the segment of the signal is synced, but some times there are 3 or 2 tones instead of 1 as is espected in MFSK.

This could point to a transmitter problem or to a very odd signal.
I guess more recordings will help to analyse it.

Saludos cordiales.

Re: MFSK-47

Publicado: 29 May 2015 18:06
por Rapidbit
I get 50 tones. Really, there are some strange areas.
Best regards.

Re: MFSK-47

Publicado: 30 May 2015 13:59
por I-56578
fixed: it was a bad recording due to a narrow filter cutting off part of the signal :(
here a correct recording:
https://www.dropbox.com/s/relrmp58ct8v0 ... 4.wav?dl=0

Signal bandwidth is approximately 3250 Hz. The signals has 68 tones (34 + 34), 47 hertz spaced, plus a visible empty place in the center of the spectrum.
Unlike normal MFSK (1 symbol = 1 tone) the signal sends up to 5 tones per symbol and its synched (1000mS cycle). Manipulation speed (47 Bd) and tone shift (47 Hz) suggest that the signal could be formed using OFDM technology.
Every 1-second cycle the signal transports 45 symbols + 1 sync (2 symbol lenght), so the 47 symbols rate on-the-air.
I do not know who they are, possibly CIS/Russian ?