Question

An audio signal υ_m = 20sin2π(1500t) amplitude modulates a carrier υ_c =80 sin 2π (100,000t). The value of percent modulation is ________.

Answer 1

Correct answer is 25  

$v_m=20sin[100\pi t+\frac{\pi }{4}]$

$:v_c=80sin[{10}^4\pi t+\frac{\pi }{6}]$

we know that, modulation index =$\frac{A_m}{A_c}$ 

from given equations, A_m = 20 and A_c = 80 

percentage modulation index =$\frac{A_m}{A_c}\times 100$ 

= $\frac{20}{80}$ × 100 = 25% 

The value of percentage modulation index is =25