Thursday, 20 October 2016

Needs of Modulation

1) Basic aspects:-
A question may be asked as , when the baseband signals can be transmitted directly why to use the modulation?
The answer this that the baseband transmission has many limitations which can be overcome using modulation. It may be explained below.
In the process of modulation , the baseband signal is translated i.e., shifted from low frequency to high frequency. This frequency shift is proportional to the frequency of carrier.

2) Advantages of Modulation:-
1.Reduction in the height of antenna.
2.Avoids mixing of signals.
3.Increases the range of communication.
4.Multiplexing is possible.
5.Improves quality of reception.

3)Reduction in the height of antenna:-
For the transmission of radio signals, the antenna height must be multiple of (pi/4). Here the wavelength. This antenna can be easily installed practically. Thus , modulation reduces the height of the antenna.

4)Avoids mixing of signals:-
If the baseband sound signals are transmitted without using the modulation by more than one transmitter, then all the signals will be in the same frequency range i.e.0 to 20 kHz. Therefore , all the signals get mixed together and a receiver cannot separated them from each other. Thus , modulation avoids mixing of signals.

5) Avoids mixing of signals:-
The frequency of baseband signals is low , and the low frequency signals can not travel a long distance when they are transmitted. They get heavily attenuated(suppressed). The attenuation reduces with increase in frequency of the transmitted signals, and they travel longer distance. The modulation process increases the frequency of the signal to be transmitted. It increases the range of communication.

6) Avoids mixing of signals:-
Multiplexing is the process in which two or more signals can be transmitted over the same communication channel simultaneously. This is possible only with modulation. The multiplexing allows the same channel to be used by many signals. Hence , many TV channels can use the same frequency range , without getting mixed with each other or different frequency signals can be transmitted at the same time.

7) Avoids mixing of signals:-
With frequency modulation (FM), and the digital communication techniques like PCM, the effect of noise is reduced to a great extent. This improves quality of reception.
 

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