  To plan a rapid response and minimize operational costs, passive optical
network operators require to automatically detect and identify faults that may
occur in the optical distribution network. In this work, we present
DSP-Enhanced OTDR, a novel methodology for remote fault analysis based on
conventional optical time-domain reflectometry complemented with reference
traces. Together with the mathematical formalism, we derive the detection tests
that result to be uniformly most powerful, which are optimal according to the
Neyman-Pearson criterion. To identify the type of fault and fully characterize
it, the detection stage is followed by the estimation of its characteristic
parameters, such as return loss and insertion loss. We experimentally
demonstrate that this approach allows to detect faults inside the event dead
zone, which overcomes the shortage of conventional event-marking algorithms.
