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

Use mesh analysis and nodal analysis to determine voltage, Q. Use (a) mesh ...

Q. Use (a) mesh analysis and (b) nodal analysis to determine the voltage ¯V at the terminals A-B of Figure.

Draw the circuit of a 7805 voltage regulator, Q. Draw the circuit of a 7805...

Q. Draw the circuit of a 7805 voltage regulator? Explain the functions of the capacitors used at its input and output sides. Functions of capacitors used at input and outp

Obtain the value of rs, Consider and obtain the values for R S , R 2 , R 1 ...

Consider and obtain the values for R S , R 2 , R 1 , and R D . Apply the rule-of-thumb dc design procedure outlined in this section for a JFET with V P = 3V, I DSS = 20 mA, and a

Pdc, disadvantages of shunt&series clippers

disadvantages of shunt&series clippers

Schrodinger’s wave equation, Discuss the degeneracy of energy of energy sta...

Discuss the degeneracy of energy of energy states. Solve the Schrodinger’s equation for a free particle in three dimensional boxes and find Eigen values and Eigen function of free

Demodulators for FM, Demodulators for FM Figure  shows a block diagram ...

Demodulators for FM Figure  shows a block diagram of a general FM demodulator, which is implemented by generating an AM signal whose amplitude is proportional to the instantane

Determine the voltages vx using voltage division, Q. Determine the voltages...

Q. Determine the voltages Vx using voltage division and equivalent resistor reductions for the circuits shown in Figure.

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