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Optimizing the use of the copper pair as a transmission medium
Authors: Iván Carmona, Carla Vilchez

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Twisted pair has represented, along many years, one
of the most used transmission media by telecommunications
service providers, all over the world. However, it
performance along the frequency spectrum is seriously
affected by the attenuation that signals undergo across
it, within an average distance between 3.3 and 5Km.
Under the hypothetical scenario of a decrease in the
propagation length over telephone twisted pairs, the
levels of attenuation in signals of higher frequencies
than those used by the current telephony and Internet
services, would diminish to the point that signals
would reach the receiver with an acceptable power and
would be recoverable. This would permit the usage of
a broader bandwidth on telephone cables than the one
used nowadays. The approach has been made in spite
of a generalized skepticism in the world about the use of
telephone pairs for frequencies over the 2.1MHz (upper
limit of ADSL2+). In order to determine the feasibility and
conditions under which it would be possible a bandwidth
usage optimization, a documental research was made,
forming a basis to obtain a characterization of the copper
pairs’ behavior, along the frequency spectrum, for a
shorter distance than the average. This characterization
was obtained through a computer simulation of the
line’s behavior, and the subsequent verification of the
results through electric measurements on the cables,
validating and giving reliability to the mathematic model developed. The results obtained verified the proposed
hypothesis, and allowed (in a second part of the research
work) the design of a technological proposal to efficiently
take advantage of the bandwidth among 2,208KHz and
20,000KHz. “AMODT” (assigned name to the proposal),
finally raises the division of the “usable spectrum” in five
sub-bands, with the same width and separation used by
the ADSL2+ technology, moved in frequency looking for
an increase in the spectral efficiency.