question_answer

Draw a plot of variation of amplitude versus a for an amplitude modulated wave. Define modulation index. State its importance for effective amplitude modulation.

Answer:

Modulation index \[(\mu )\] Ratio of amplitude of modulating signal \[({{A}_{m}})\] to the amplitude of carrier wave is called the modulation index \[\mu =\frac{{{A}_{m}}}{{{A}_{c}}}\] Importance of \[\mu \] In practice, \[\mu \le \] to avoid distortion. If \[\mu >1,\] then the carrier wave is become over modulated and distortion will take place during reception.

Importance of amplitude modulation

(i) It is an easier method for transmitting and receiving voice signals.

(ii) It requires simple and cheaper transmitters and receivers.

(iii) Its transmission requires low carrier frequencies of \[\text{0}\text{.5-20}\,\,\text{MHz}\text{.}\]