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 the main embedded system components, What are the main embedded sy...

What are the main embedded system components? Main Embedded System Components a. Embeds hardware to provide computer as functionalities b. Embeds major application softw

Discuss properties and uses of glass and glass products, Discuss important ...

Discuss important properties and uses of Glass and glass products. Glass and glass products - Glass is an inorganic material build by the fusion of various metallic oxides. The

Determine the critical load, A rocket on a test stand is modeled as a colum...

A rocket on a test stand is modeled as a column clamped at x = 0 and free at x = L, and subjected to compressive force P applied at the free end. The direction of load P remains

Assembly language, To find out the largest of ten 8 bit numbers. Method: Th...

To find out the largest of ten 8 bit numbers. Method: The numbers are stored in consecutive memory locations. The counter register is initialized with 0A and the address pointer po

Analyse the characteristics of a dc machine, Theoretical calculations T...

Theoretical calculations The characteristics of the d.c. machine you will be investigating are given on the last page of this part. Use 200V DC supply for both armature and fie

Atomic structure, State the postulates of Bohr''s atomic model. Write any ...

State the postulates of Bohr''s atomic model. Write any three merits and demerits.

Determine about the wireless technology, Determine about the Wireless techn...

Determine about the Wireless technology Wireless technology (WiFi) enables connection of a computer to Internet without the need for connecting cables. A router (comprising a m

With the help of the structures explain lcd, Q. With the help of the struct...

Q. With the help of the structures explain LCD. A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in fro

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