Communication Basics #17 PDH: Plesiochronous Digital Hierarchy & E-Carrier

Instructor: Dr. Süleyman Burak ÇELİK

This lesson explains how 64 kbps voice channels get bundled into the carrier links that ride between telephone exchanges. We build the E1 frame from 32 time-slotted channels, climb the CEPT (E-carrier) hierarchy from E1 up to E5, compare it briefly with the North American T-carrier, explain what plesiochronous (almost synchronous) really means and why it forces the dreaded multiplexer mountain when you try to drop or insert a single channel. We finish with a worked example that picks the right E-carrier level for a 150-voice-call inter-exchange link. Topics covered: - E1 frame: 32 channels, 256 bits, 8000 frames per second, 2.048 Mbps - channel 0 sync, channel 16 signaling, 30 voice channels - CEPT (E-carrier) hierarchy: E1, E2, E3, E4, E5 - T-carrier comparison - plesiochronous clocking and justification bits - the multiplexer mountain: drop and insert pain - worked example: sizing a link for 150 voice calls Part of the AcEdumy Communication Basics series.