Optical equivalent circuit of path via line terminals and repeaters

摘要

For each digital optical signal input a transmitter (S1) is provided with a beam splitter (SPL1). A part of the beam passes through a laser safety circuit (LSS1) to a series of repeaters (R11-R1m) on an optical working fibre (OAF). The remainder is taken through an optical transposer (TP1) and wavelength-multiplexed (WDM) on to an optical equivalent fibre (OEF) with distributed amplifiers (WDMV1-WDMVz). The demultiplexer (WDD) feeds the optical 2 x 2 changeover switches (UB1-UBn) connected to optical receivers (OE1) and a combining network (KN) for a test receiver (TE) which monitors the individual optical signals on the equivalent fibre.