Abstract: A digital cross-connection apparatus for use in interconnecting first and second communications network (STM-N) having respective first and second pluralities of data channels, wherein information data and communications management data of the channels in each network is multiplexed together, includes an add/drop unit (TTF, TSAF, LSC), connected to the first network (STM-N) and operable selectively to extract therefrom the data of a selected channel of the first plurality of channels, and a digital switching matrix (LPX) having an output connected to the second network (STM-n) and having an output connected to the add/drop unit (TTF, TSAF, LCS) for receiving therefrom the extracted data including management data from the first network. Thus, the management data can pass through the switching matrix (LPX) to the second network so that end-to-end path monitoring between the two networks is facilitated.

Abstract: An optical receiver incorporating a voltage dependant impedance arranged to shunt excess AC photodetector signal away from the receiver amplifier in response to light level.