  The FTTH (Fiber To The Home) market currently needs new network maintenance
technologies that can, economically and effectively, cope with massive fiber
plants. However, operating these networks requires adequate means for an
effective monitoring cost. Especially for troubleshooting faults that are
associated with the possibility of remote identification of fiber breaks, which
may exist in the network. Optical Time Domain Reflectometry (OTDR) techniques
are widely used in point-to-point optical network topologies. Nevertheless, it
has major limitations in tree-structured PONs (Passive Optical Networks), where
all different branches backscatter the light in just one conventional OTDR
trace with combined signals arriving on the OLT (Optical Line Terminal) side.
Furthermore, passive power splitters used in FTTH networks input large
attenuation, impoverishing the reflected signal. This makes the identification
of the very branch affected by the problem practically impossible, when
considering conventional analyses. The use of constraint-based techniques have
been applied in a large amount of applications for Engineering Design, where
the duties imposed for graphics and equations constraints result in valued
features to CAD/CAE software capabilities. Currently, it provides a faster
decision making capacity for engineers. This work applies the constraint based
approach along with a Differential Evolutionary Algorithm to separate the
superimposed OTDR signals, after the splitters of a FTTH Passive Optical
Networks. This research introduces a new set of algorithms performing a
coupling to an Optical Network (ON) CAD Design with its correspondent OTDR
measurement signal, considering its geographical distribution branches of
different lengths after the splitter. Results of this work are presented in a
FTTN (Fiber To The Node) prototype arrangement, using a 1:8 passive power
splitter.
