Question

What is the modulation index for a single tone modulation, given that positive peak of AM wave is 20V and minimum value is 2V?

(a) 0.81

(b) 0.91

(c) 0.73

(d) 1

I have been asked this question during an online interview.

I want to ask this question from Linear Modulation in section Amplitude Modulation of Analog Communications

Answer 1

Right answer is (a) 0.81

For explanation: Modulation Index (u) = (Vmax – Vmin)/(Vmax + Vmin)

= (20-2)/(20+2) = 9/11 = 0.81.