terminal multiplexer (SDH) (TM)
A terminal multiplexer( TM) is an SDH network component that combines multiple signals, plesiochronous as well as synchronous, into a higher bit rate synchronous transmission mode( STM).
This allows 2-Mbit/s and 34-Mbit/s links from the Plesiochronous Digital Hierarchy ( PDH) to be packaged into synchronous transport modules n( STM-n). The terminal multiplexer acquires and generates the path header parts( POH) on the input side and generates the complete section frame header parts( SOH) for the Synchronous Digital Hierarchy (SDH).
Terminal multiplexers are also called Synchronous Multiplex Terminal( SMT).