The telephone system was born and grew fairly rapidly. Even today voice communication still forms the major part of the total volume of the communication traffic.
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| PCM Cable in Telecommunication |
The aim of communications systems has been to get more and more information transmitted on a signal cable. The involves gathering a number of sources together, transmitting them together and then separating them and passing them to the individual receivers.
One of the methods used is
Frequency Division Multiplexing (FDM). Here a set of telephone channels are modulated with different carrier frequencies to shift the signals into a different frequency range. In this analogue system each channel is separated by frequency.
With ever increasing demands for higher transmission rates with better quality and at lower costs other systems were developed. In the 1960s, digital systems started to appear. Here the telephone channels are separated by time using the method known as
Pulse Code Modulation (PCM).
What is PCM communication systems?
The plesiochronous digital hierarcy (PDH) has two primary communication systems as its foundation. There ase the T1 system based on 1544kbit/s that is recommended by ANSI and the E1 system system based on 2048kbit/s that is recommended by ITU-T.
Do you know which countries use T1 or E1?
The T1 system is mainly in USA, Canda and Japan. European and certain non-European countries use the E1 system.
Common and Differing Characteristics between E1 and T1
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| Common Characteristic E1 & T1 |
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| Differing Characteristics between E1 & T1 |
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