Method for fault locating by reflectometry in an optical transmission link and locating apparatus using this method

摘要

A coherent detection reflectometer (5) is used with a load signal which has the same wavelength as the measuring pulses employed. The load signal also has an extended bandwidth such that the power developed in the narrow measurement band is negligible compared to that of the measurement pulses. The reflectometer has a measurement pulse generator (8) controlled by a processor (9) and the measurement pulses are transmitted to a coupler (12) where they are combined with externally generated load signals (14) and sent to the transmission line through an interface (7). Reflected signals entering the interface from the transmission line are mixed (13) with measurement signals from the source (8,10) and fed to a heterodyne receiver (6). The resulting signals are used by the processor to supply transmission line fault details through a screen or printer.