Russian MFSK-OFDM-chirp hybrid modem

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Russian MFSK-OFDM-chirp hybrid modem
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
Emission Designator
Bandwidth 24 kHz,48 kHz,3 kHz,12 kHz,96 kHz
Location Russia, Worldwide
Short Description A supposedly Russian HF data mode with MFSK, OFDM and frequency sweeps, resulting in an interesting spectrogram and sound.
I/Q Raw Recording Download file
Audio Sample

This is an interesting data mode that is believed to be used by Russian military or other agencies. The official name, purpose and equipment used to transmit this signal are not known, and there doesn't seem to be a commonly agreed name among amateur listeners.

The signal is transmitted in bursts. Each bursts starts with a pilot tone and a couple of irregular frequency sweeps, then follows a short MFSKMultiple Frequency Shift-Keying part and then a data transmission which apparently consists of OFDMOrthogonal Frequency-Division Multiplexing blocks 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. In this sample case there is also a continuous carrier slightly below the burst transmission. It's not always seen and it may or may not belong to this transmission.

Bandwidth of this sample is about 3 ... 3.2 kHzKiloHertz (kHz) 10^3 Hz but this signal has been seen with much higher bandwidths of 12, 24, 48 and 96 kHzKiloHertz (kHz) 10^3 Hz as well, see the links and video examples below. Bandwidth of 6 kHzKiloHertz (kHz) 10^3 Hz has been seen in assumed test transmissions.



The examples presented here were observed on the following frequencies, but the complete frequency range is likely much broader.

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

16259 kHzKiloHertz (kHz) 10^3 Hz

Video Examples[edit]

Additional Links[edit]

Additional Images[edit]