[time-nuts] Measuring receiver...

Graham / KE9H ke9h.graham at gmail.com
Tue Jun 21 19:18:56 EDT 2016

This is heavily used in cellular system security and cellular unit
identification and tracking.
Do a google search on patents using the the term "RF fingerprinting" and
you will get quite a few hits.  Mostly recent application to cellular
systems.  You might look at the prior art listings and see if they take you
back somewhere.  Although unlikely any classified methods were patented.

--- Graham


On Tue, Jun 21, 2016 at 4:02 PM, jimlux <jimlux at earthlink.net> wrote:

> On 6/21/16 11:28 AM, Brooke Clarke wrote:
>> Hi:
>> During W.W.II there were secret methods of "fingerprinting" radio
>> transmitters and separately the operators.
>> I suspect the transmitter fingerprinting involved things like frequency
>> accuracy, stability, CW rise and decay time, &Etc. For the operator some
>> from of statistics on the timings associated with sending Morse Code.
>> But. . .  I haven't seen any papers describing this.  Can anyone point
>> me to a paper on this?
>> For "human controlled" stuff, e.g. recognizing someone's "fist", there's
> a huge literature out there on biometric identification looking at things
> like keyboard and mouse click timing - the timing requirements are pretty
> slack, and hardly time-nuts level, unless you're looking to do it with
> mechanical devices constructed from spare twigs and strands of kelp.
> There have been a variety of schemes for recognizing individual radios by
> looking at the frequency vs time as they start up. Likewise, it's pretty
> easy to distinguish radar magnetrons from each other.  Not a lot of papers
> about this, but you'll see it in advertising literature, or occasionally in
> conference pubs (although I can't think of any off hand).  There was
> someone selling a repeater access control system that was based on the
> transmitter fingerprint.
> But the real reason why you don't see any publications is that this stuff
> is pretty classic signals intelligence (SIGINT or MASINT) and it is still
> being used, and is all classified. You're not relying on Betty the receiver
> operator to recognize the characteristic chirp as the agent's radio is
> keyed, it's all done by computer now, but the basic idea is the same.  And
> as with most of this stuff, the basics are well known, but the practical
> details are not, or, at least, are the proprietary secret sauce in any
> practical system. (In a significant understatement, Dixon, in "Spread
> Spectrum Systems" makes some comment about how synch acquisition is the
> difficult part and won't be described in the book)
> You might look at the unclassified proceedings of conferences like MILCOM
> and find something.  Googling with MASINT might also help.
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