GATE ECE 2014 Set 2 | Question: 23

Question

Consider sinusoidal modulation in an AM system. Assuming no overmodulation, the modulation index ($\mu$) when the maximum and minimum values of the envelope, respectively, are $3$ V and $1$ V, is ___________.

Answer 1

Answer : 0.5

Given: Max Voltage is 3v, Min Voltage is 1v

We know that,

$A{max} = A{c}(1+\mu )$ ---- 1

$A{min} = A{c}(1-\mu )$  ------- 2

Dividing 1 by 2

$(3/1) = (1+\mu )/(1+\mu))$ )

$3*(1-\mu)=(1+\mu)$

$3 - 3\mu = 1 + \mu$

$2 = 4\mu$

$\mu = 0.5$