17 February 2016

Unid MFSK 30 parallel tones + pilot tone and service tones

About the unid MFSK 30 parallel tones, reported in the previous post, since the frequency 16553.5 KHz/USB is operated by Japanese Military with their 4xFSK-2 system, it could be that this signal has that same source. 
The spectrum spreads a 2300 Hz bandwidth (pic. 1) and shows 30 tones ~70Hz spaced, in the lower part, after the strong pilot-tone, are visible four distinct tones transmitted at a lower power than the other 30: this could lead to think to a sort of "service" tones but it's a my guess (pic. 2). All the carriers are not modulated so the signal does not carry information. It's difficult to confirm the source (Japanese Mil.) as well as say if they are just testing a new system.

pic. 1
pic. 2

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