How speech is transmitted in digital switching environment, Electrical Engineering

Assignment Help:

Q. How speech is transmitted in digital switching environment by using PCM/TDM?

Ans:

A digital carrier system is a communications system which uses digital pulses instead of analogue  signals  to  encode  information.  Figureshows  the  block  diagram  for  a digital  carrier  system.  This  digital  carrier  system T1  employs PCM-encoded  samples from  24  voice  band  channels  for  transmission  over  an optical  fibre  transmission  line  or single  metallic  wire  pair.  Every voice-band channel  has  a  band  width  of about 300 Hz to 3000 Hz. Again, multiplexer is simply a digital switch with  24  independent  inputs  and  one  time  division  multiplexed  output.  PCM output  signals  from  24  voice-band  channels  are  sequentially  selected  and connected through multiplexer to transmission line.

When  a  T1  carrier  system,  D-type  (digital)  channel  banks  perform  sampling, multiplexing  and  encoding  of  24  voice-band  channels,   every channel  comprise an eight-bit PCM code and is sampled 8000 times a second. Every channel is sampled at the same rate. Figuredemonstrates the channel sampling sequence for a 24-channel T1 digital carrier system. As the Figureillustrates each channel is sampled once each frame though not at the same instance. Every channel's sample is offset from previous channel's sample by  1/24  of  the  total  frame  time.  Hence  one  64-kbps  PCM-encoded  sample  is transmitted for every voice-band channel during each frame (a frame time of 1/8000 = 125 µs). Afterwards, an extra bit (known as the framing bit) is added to every frame. Framing  bit  occurs  once  per  frame  (8000-bps  rate)  and  is  recovered  in the receiver, where it's used to maintain frame and sample synchronization between TDM receiver andtransmitter.

837_How speech is transmitted in digital switching environment.png


Related Discussions:- How speech is transmitted in digital switching environment

What are operations performed on data in 8085, What are operations performe...

What are operations performed on data in 8085 The various operations performed are Store 8-bit data Perform arithmetic and logical operations Test for conditio

Determine the current and voltage in given network, Q. For a part of the ne...

Q. For a part of the network shown in Figure, given that i 1 = 4A; i 3 (t) = 5e -t , and i 4 (t) = 10 cos 2t, find v 1 , v 2 , v 3 , v 4 , i 2 , and i 5 .

Sinusoidal analysis by using mesh equations and matlab, This example is con...

This example is concerned with steady-state sinusoidal analysis by using mesh equations and MATLAB. Let us consider the circuit shown in Figure and find the input impedance at the

Ac motors, AC Motors DC motors that have their magnetic fields produce...

AC Motors DC motors that have their magnetic fields produced by coils as described earlier can, in principle,  be powered from AC as well, since if the applied voltage reverse

Calculate the resistivity of an alloy of copper, The resistivity of pure co...

The resistivity of pure copper is 1.56 micro-ohm -cm.  An alloy of copper contains 1 atomic percent nickel has a resistivity of 2.81 micro-ohm-cm. An alloy of copper containing 3-

Determine self inductance of coil, Determine self inductance of coil: ...

Determine self inductance of coil: A flux of 0.5 m Wb is generated by coil A of 600 turns wound on a ring with a current of 2 A in it. Determine (a) self inductance of coil A,

Diploma in electrical engineering, After I complete my diploma how I get a ...

After I complete my diploma how I get a job in goverment

Induced emf, what is the difference between statically and dynamically indu...

what is the difference between statically and dynamically induced emf?

Circuits, Circuits Typical  electronics circuits  are created  out  of...

Circuits Typical  electronics circuits  are created  out  of a basis  set of primitive elements such  as capacitors, voltage sources,  resistors,  transistors and inductors. T

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd