Question

Explain with reason :

(i) In amplitude modulation, the modulation index μ is kept less than or equal to 1.

(ii) The maximum amplitude  of an amplitude modulation wave is found to be 15 V while its minimum amplitude is found to be 3 V. what is the modulation index ?

(iii) Why amplitude modulated signal be noisier than a frequency modulation signal upon transmission through a  channel ?

Answer 1

(i) μ is kept less than 1 so that the noise level can be kept small in the signal.

(ii) μ = a(max) = a(min) / a (max) = 18 / 12 = 9 /6 = 3 /2 = 1.5

(iii) Fading of a signal is prominent in case of amplitude modulation and hence noise level is more in AM than FM.