Re: Fwd: Re: Fwd: Re: FH radios [Dave Emery] [Vaughan Pratt]

[andr0id@midwest.net (Jason Rentz)]

>think I underestimated how hard things could get.  If you're just
>trying to track a frequency-hopping signal where the rest of the power
>in the band is some mix of Gaussian noise and non-hopping signals, the
>carrier should be clearly visible as a spike hopping around in the
>band.  As soon as you have two or more frequency-hopping signals
>however, keeping track of which carrier is which as they hop around
>looks *much* harder.  If they hop at discernibly different times then
>you can correlate a carrier that disappeared with the one that appeared
>elsewhere at the same time.  This easily described and implemented
>approach breaks down when two or more signals hop at the same time.
>Here you might try to associate some sort of signature with each signal
>to allow you to pair up the new carriers with the old, but you'd have
>to know more about the situation to say what signatures would be good.
>
RF finger-printing would do the trick.  Any and all RF equipment has its own
RF fingerprint no matter how closely they are made at the factory.  Now
having equipment to RF fingerprint and identify that fingerprint fast enough
is another story!  

                        Dr0id

(andr0id@midwest.net  callsign: N9XLM)
( Computer Consulting & Management   )
(P.O. Box 421  Cambria, IL 62915-0421)

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