Unknown Russian HF data mode with MFSK and OFDM and freq sweeps

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Unknown Russian HF data mode with MFSK and OFDM and freq sweeps
Unknown data mfsk sweep ofdm medium.png
Frequencies 12.176 MHz,16.257 MHz,16.259 MHz
Frequency Range 12.176 MHz - 16.259 MHz
Mode USB
Modulation MFSK,OFDM
Bandwidth 3.2 kHz,24 kHz,48 kHz
Location Worldwide
Short Description A supposedly Russian HF data mode with MFSK, OFDM and frequency sweeps, resulting in an interesting spectrogram.
I/Q Raw Recording Download file
Audio Sample

This is an interesting data mode that is believed to originate from Russia. It's transmitted in burst. Each bursts starts with a pilot tone and a couple of irregular downward frequency sweeps, then follows a short MFSKMultiple Frequency Shift-Keying part and then a data transmission which is apparently OFDMOrthogonal Frequency-Division Multiplexing and which is periodically interrupted by upward frequency sweeps, two in this case. The burst ends with a series of frequency sweeps. Frequency sweeps may also be transmitted before the OFDMOrthogonal Frequency-Division Multiplexing part begins.

Purpose of the different modulation techniques is not known. There is also a continuous carrier slightly below the burst transmission. It may belong to this signal but it's not always seen.

Bandwidth of this sample is about 3.2 kHzKiloHertz (kHz) 10^3 Hz but this signal has been seen with much higher bandwidths of 24 kHzKiloHertz (kHz) 10^3 Hz and 48 kHzKiloHertz (kHz) 10^3 Hz as well, see the video examples below.



12176 kHzKiloHertz (kHz) 10^3 Hz
16257 kHzKiloHertz (kHz) 10^3 Hz

16259 kHzKiloHertz (kHz) 10^3 Hz

Video Examples[edit]

Additional Links[edit]

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