Explain how ccitt standards help in building the base band, Electrical Engineering

Assignment Help:

Q. Discuss FDM and illustrate how CCITT stndards help in building the base band?

Ans:

Frequency Division Multiplexing: It is the process of combining numerous information channels by shifting their signals to different frequency groups within spectrum so that they can be transmitted simultaneously over common transmission facility.

Bandwidth of a telephone speech signal is rather less than 4 kHz. While the available bandwidth on unloaded cables pair, is well above 100 kHz. It is consequently possible, using modulation techniques, to divide up cable bandwidth so that anumber of telephone speech paths can be carried simultaneously along a single cable pair. Normal arrangement comprises 24 telephone channels per cable pair, modulation into 24 channels being carried out in two stages. In first stage, 12 channels are multiplexed together to form what is commonly termed as a basic group. Basic group arrangement is demonstrated in figure. Each of the 12 telephone signals are single side-band amplitude modulated on to carriers spaced at 4 kHz intervals from 64 kHz to 108 kHz. Lower side-band (LSB) is used in each case. 12 base-band signals are therefore translated into frequency band from 60 kHz 108 kHz as shown. Block diagram for channel translating equipment is given in figure. To form a 24-channel system, to basic groups are taken together. One basic group (B) is transmitted directly as it stands. Other basic group (A) is amplitude modulated on to a carrier are 120 kHz and lower side-band is taken so as to occupy frequency range from 12 kHz to 60 kHz as demonstrated in figure by using two stages of modulation for basic group A, it is probable to reduce the physical size of component required for LSB filters of the figureas the lowest cut- off frequency required is at 64 kHz rather than 12 kHz if the whole block of 24 channels were assembled together in one stage of modulation.


Related Discussions:- Explain how ccitt standards help in building the base band

Resistance, if the sheet resistance of a tin oxide is 100 ohms, what is the...

if the sheet resistance of a tin oxide is 100 ohms, what is the thickness of the oxide layer?

What is expanded memory system, What is expanded memory system? EMS: Th...

What is expanded memory system? EMS: The area at location C8000H-DFFFFFH is frequently open or free. Such area is used for the expanded memory system into a XT or PC system, or

Write a note on superconductors, Write a note on superconductors. Super...

Write a note on superconductors. Superconductors- The resistivity of most metals rises with increase in temperature and vice-versa. Some metals and chemical compounds are there

Circuit, i need to talk to expert asap.

i need to talk to expert asap.

How to calculate the bus - bar voltage and kilowatt output., Q.   Two shunt...

Q.   Two shunt wound generators running in parallel supply a total load current of 4000 A. Each generator has an armature resistance of 0.02? and a field of 40?. The fiels are exci

Vehicle tracking system, coding for vehicle tracking system using gsm in av...

coding for vehicle tracking system using gsm in avr atmega16 microcontroller

Find the current in resistance, Q. Obtain the Thévenin and Norton equivalen...

Q. Obtain the Thévenin and Norton equivalent circuits for the portion of the circuit to the left of terminals a-b in Figure, and find the current in the 200- resistance.

Quick ratio, Quick ratio A stringent indicator that determines whether...

Quick ratio A stringent indicator that determines whether a firm has enough short-term assets to cover its immediate liabilities without selling inventory. It is calculated as

Design a signal generator, Aims Exploring the analog output capabili...

Aims Exploring the analog output capabilities of the PIC trainer Write PIC assembly code to implement a simple multi-function signal generator Equipment PIC Trainer

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