A message signal of frequency $8 \mathrm{kHz}$ and peak voltage $12 \mathrm{~V}$ is used to modulate a…
A message signal of frequency $8 \mathrm{kHz}$ and peak voltage $12 \mathrm{~V}$ is used to modulate a carrier of frequency 1.2 MHz and peak voltage $20 \mathrm{~V}$. The modulation index is
0.2
0.3
0.4
0.6
Solution
$\begin{aligned} & \text { Modulation index }=\frac{\mathrm{A}_{\mathrm{m}}}{\mathrm{A}_{\mathrm{c}}} \\ & =\frac{12}{20}=\frac{3}{5}=0.6\end{aligned}$