Abstract: An interface apparatus for SDH/SONET interconnection includes a transmission interface section provided at a position where an apparatus of the SDH system and an apparatus of the SONET system face each other and adapted to transmit a signal toward an apparatus of a different system. The interface apparatus for SDH/SONET interconnection further includes a mode setting unit for setting a mode suitable for an apparatus of a counterpart system, a frame synchronization information inserting unit provided in the transmission interface section and adapted to insert frame synchronization information corresponding to the mode set by the mode setting unit, and an overhead information inserting unit provided in the transmission interface section and adapted to insert overhead information corresponding to the mode set by the mode setting unit. This structure makes is possible to easily interconnect apparatuses of different systems (apparatuses of the SDH system and the SONET system) so as to operate them.

Abstract: An optical terminal system having self-monitoring function is disclosed, which includes a high-level group loopback section for internally looping back a serial electric signal, a low-level group loopback section for internally looping back a parallel electric signal, a self-loop section for connecting a receiver device and a transmitter device to loop an electric signal received by the receiver device directly to the transmitter device, and a self-monitoring controller for performing a self-monitoring test on respective components of the receiver device and transmitter device by using the self-loop section and either one of the high-level group loopback section and the low-level group loopback section. The optical terminal system can selfcheck the functions thereof through self-monitoring without depending on a network.