Friday, March 4, 2011

What is E1 / T1 ?

The PDH (plesiochronous Digital Hierarchy) has 2 primary communication systems as its foundation.

These are,
T1 system based on 1544kbit/s that is recommended by ANSI &
E1 system based on 2048kbit/s that is recommended by ITU-T.

Common Characteristics :- 
  1. Both are having Same Sampling Frequency i.e. 8kHz.
  2. In both (E1 & T1) Number of samples/telephone signal = 8000/sec.
  3. In both (E1 & T1) Length of PCM Frame = 1/8000s = 125µs.
  4. In both (E1 & T1) Number of Bits in each code word = 8.
  5. In both (E1 & T1) Telephone Channel Bit Rate = 8000/s x 8 Bit = 64 kbit/s.

Differing Characteristics :-
  1. In E1 Encoding/Decoding is followed by A-Law while in T1 Encoding/Decoding is followed by µ-Law.
  2. In E1 - 13 Number of Segments in Characteristics while in T1 - 15 Number of Segments in Characteristics.
  3. In E1 - 32 Number of Timeslots PCM Frame while in T1 - 24Number of Timeslots PCM Frame.
  4. In E1 - 8 x 32 = 256 number of bits / PCM Frame while in T1 - 8 x 24 + 1* = 193 number of bits / PCM Frame. (* Signifies an additional bit).
  5. In E1 - (125µs x  8)/256 = approx 3.9µs is the length of an 8-bit Timeslot while in T1 - (125µs x  8)/193 = approx 5.2µs is the length of an 8-bit Timeslot.
  6. In E1 - 8000/s x 256 bits = 2048kbit/s is the Bit Rate of Time-Division Multiplexed Signal while in T1 - 8000/s x 193 bits = 1544kbit/s is the Bit Rate of Time-Division Multiplexed Signal.
Reference Source: 

4 comments:

  1. international callings cards are accessible in an array of ante and and features. With the advice of such calling cards, you can calmly alarm all-embracing destinations at the every man amount and at the aforementioned time can accomplish bargain and accessible calls from landlines, mobiles and added options.

    conference calls

    ReplyDelete
  2. I live in London (uk) but most of my relatives lives in other countries so i wanted to know how to make cheap international calls from London to reduce my call rates.

    ReplyDelete
  3. Hi.. Please share call and and sms flow... Thanks

    ReplyDelete
  4. Thanks meant for sharing this type of satisfying opinion, written piece is fastidious, that’s why I’ve read it completely.http://www.gmailfaxpro.com/tutorials/google-fax-number/

    ReplyDelete