Steven M. Bellovin wrote:
> Does that mean that the new fiber is less tappable?
No change, notwithstanding anecdotal references on fiber
bending
as used for tapping.
Tapping a fiber can be done without much notice by matching
the
index of refraction outside the outer fiber layer, after
abrasion
and etching to reach that layer. There is no need for
bending,
which might not be physically possible (eg, in a thick cable
bundle),
would increase propagation losses beyond that caused by the
tapped
signal power itself, and might create detectable backward
propagating waves (BPWs are monitored to detect fiber
breach).
Low-loss taps are essential. A tap must extract a portion
of
the through-signal. This, however, should not have the
effect of
significantly reducing the level of the remaining signal.
For
example, if one-quarter of the incident signal is extracted,
then
there is a 1.25 db loss in the remaining through-signal,
which
can easily be detected.
Cheers,
Ed Gerck
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