Plesiochronous Digital Hierarchy definition communications
(PDH) A transmission system for voice communication using plesiochronous
PDH is the conventional multiplexing
technology for network transmission systems. The transmitter adds dummy information bits to allow multiple channels to be bit interleaved. The receiver discards these bits once the signals have been demultiplexed.
PDH combines multiple 2 Mb/s (E1
) channels in Europe and 1.544 Mb/s (DS1
) channels in the US and Japan.
PDH is being replaced by SONET
and other SDH (Synchronous Digital Hierarchy