[mdlug] Curious - Phone Tapping Tech

[Ingles, Raymond]

> From: Michael Mol
> On Thu, Jun 21, 2012 at 1:32 PM, Aaron Kulkis <akulkis00 at gmail.com> wrote:

> > Every current travelling "outbound" on one wire of a twisted pair
> > has an equal and opposite "inbound" current on the other half of the pair,
> > making the net current going through the loop = Zero, and therefore, no
> > way to detect ANYTHING  within the cable bundle.
> 
> That assumes the two halves of the pair are coaxial, which they're not.

Right. The further away from the twisted pair, the closer the signal resembles the coaxial case, but there *is* some leakage. In practice, though, differentiating between multiple twisted-pair signals would be quite the chore. I suppose if you had some idea of the signaling protocols involved to establish some heuristics, and an FPGA or similar dedicated hardware to devote to DSP, you *might* be able to extract a signal, but it'd likely be rather noisy.

See: Van Eck Phreaking.

Sincerely,

 Ray Ingles                                      (313) 227-2317

 "The number of your friends is much smaller than the number of
   people you hang out and kid around with." - Stephanie Zvan


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