Question

State any two reasons for necessity of modulation.

Answer 1

In the modulation process, some parameter of the carrier wave (such as amplitude, frequency or phase ) is varied in accordance with the modulating signal . This modulated signal is then transmitted by the transmitter .

It is necessary to modulate the signal because-

1. It avoids mixing of signals. If the base band 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 can not separate them from each other .

2. It increases the range of communication.The frequency of baseband signal is low, and the low frequency signals can not travel long distance when they are transmitted . They get heavily attenuated . The attenuation reduces with increase in frequency of the transmitted signal, and they travel longer distance .