What is PDH?
PDH is the abbreviation of plesiochronous digital hierarchy. The term plesiochronous derives from two Greek words: ‘plesio’ means ‘near’ and ‘chronos’ means ‘time’. In the plesiochronous digital hierarchy, the clocks are running close but not exactly matched, so signal arrival times may be different when multiplexing, as the transmission rates are directly linked to the...