Abstract: A method offering the capacity for safe in service testing of optical network using time domain reflectometer is disclosed. The network utilizes end equipment devices having filters designed to reject specific frequency range, and preferably a frequency range that lies between two desired frequency ranges. The signal used for the reflectometer is specifically selected to be within the rejected frequency range. The selection of the reflectometer frequency allows for in use testing without effecting the desired frequencies, as well as minimizing damage to sensitive components within the end equipment devices.

Abstract: Locating a fault of an optical transmission line in a system which performs bidirectional optical communication between a wire center Optical Line Terminal (OLT) and plural subscriber devices, Optical Network Terminal (ONT). In this ITU defined topology, a feeder extending from the OLT is branched by a passive (non powered) splitter/coupler device into plural legs each connected to the ONT devices. The present invention encompasses a novel test apparatus and technique for fault location on Passive Optical Networks (PON) and/or Fiber of the premise Networks (FTTP), encompassing APON, BPON and EPON allowing non-service interruptive test, without damage to the ONT or OLT transceivers. The invention provides service providers the ability to locate a fault occurring on an optical transmission line while the system is actively performing bidirectional optical communication between a OLT/head-end device and plurality of ONT/subscriber devices.