[GreenKeys] Diversity

[Charles Ring]

> Of course, there's relatively little use of binary FSK on HF compared 
> to just10 years ago, but I have recently heard some frequency 
> diversity FSK systems still in use.  The FSK channels were spaced by 
> some 10s of kc, but they were definitely carrying the same (encrypted) 
> data.  And of course, wide shift FSK (850 or 1000 Hz shift) inherently 
> has some diversity of tone fading which the better modems make use 
> of.  The Russian navy still has a few 1kc or 1.2 kc shift FSK systems 
> in use.
>
> 73,
>
> John K9WT
>
>

There is a wide shift FSK signal on about 4.005 MHz which has been there 
over 45 years that i know of.  For a while it seemed to be gone but it 
came back. Undecodable, at least to me but my attempts were decades ago. 
Assuming it  is military, what if anything is known publicly about it? 
Location maybe?

-- 
*Charles Ring W3NU*
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