TXC-03456

m o .c U 4 t e e FEATURES h S a at .D w w w L4M Device Level 4 Mapper TXC-03456 DATA SHEET DESCRIPTION The L4M device maps a 139.264 Mbit/s asynchronous line signal into an AU-4 VC-4/STS-3c SPE signal. The SDH/SONET signal is transmitted via the add bus with timing derived from the drop bus, add bus, or external clock source. The L4M can compensate for up to a frame offset when using external timing and an external C1 pulse. An option is provided to generate TOH bytes, such as the A1 and A2 framing bytes, a C1 byte, and the H1 and H2 pointer bytes only in drop bus and external timing modes. The VC-4/SPE can be fixed to a known J1 reference when add bus timing is selected, or it can be positioned with a pointer value of 0 or 522 when drop bus or external timing is selected. In the drop direction, an optional pointer tracking machine is provided. In this mode, the L4M can compensate for up to a frame in offset. External access is provided for the POH bytes, in addition to internal processing capability. Serial access is provided for the overhead communications bits in the format. An alarm indication port is provided for ring configuration applications. Maps an asynchronous 139.264 Mbit/s tributary into an AU-4/VC-4 STS-3c/SPE. Nibble or byte 139.264 Mbit/s line interface - G.751 receive and transmit performance monitoring (frame alignment, distant alarm indication) SDH/SONET bus access - Drop/add byte buses - Optional drop bus AU-4 pointer tracking with framing delay co...