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In a PCM30 system the frame comprises of 30 timeslots used for traffic and 2
code words that are used for synchronization and signaling purposes.
PDH has two primary communication systems as its foundation. These are the
T1 system based on 1544 kbps that is recommended by ANSI and the E1 system
based on 2048 kbps that is recommended by ITU-T. The T1 system is used
mainly in the USA, Canada and Japan. European and certain non-European
countries use the E1 system.
0
Timeslots 1 to 31
Channels 1 to 31
Frame
Synchronization
0
Frame
Synchronization
16
Timeslots 1 to 15
Timeslots 17 to 31
Timeslots 1 to 15
Timeslots 17 to 31
Signaling