Question

$\text{An amplitude modulated signal is given by,}\text{The modulation index of this AM signal is\_\_\_\_\_\_}s\left(t\right)=[20+4cos(2000\pi t)+5sin(5000\pi t\left)\right]cos\left(2\pi f_{c}t\right)$

• A. 0.32

Answer 1

The correct option is A 0.32
$s\left(t\right)=20[1+\frac{1}{5}cos(2000\pi t)+\frac{1}{4}sin(5000\pi t\left)\right]cos\left(2\pi f_{c}t\right){\mu }_1=\frac{1}{5}and{\mu }_2=\frac{1}{4}\mu =\sqrt{{\mu }_1^2+{\mu }_2^2}=\sqrt{\frac{1}{25}+\frac{1}{16}}=\frac{\sqrt{41}}{20}=0.32$