Automatic Fault Detection in WDM-PON With Tunable Photon Counting OTDR

An automatic fiber-optical fault analysis system making use of a tunable photon counting optical time-domain reflectometry (OTDR) (ν-OTDR) is proposed and demonstrated in a passive optical network testbed. The employment of the ℓ trend filter as a signal processing tool enables the minimization of the intrinsic coherent random noise impact on the acquired data and also an automatic identification of fiber faults. A feedback loop between an FPGA-based acquisition unit and the filter's selections yields highly accurate automatic results and minute monitoring periods with ITU-T grid DWDM tunability, spatial resolution of 6 m and a measured 32 dB dynamic range.