Question:
For an amplitude modulated wave, the maximum amplitude is found to be 10 V while the minimum amplitude is found to be 2 V. Determine the modulation index μ. What would be the value of μ if the minimum amplitude is zero volt?
Solution:
Maximum amplitude, Amax = 10 V
Minimum amplitude, Amin = 2 V
Modulation index μ, is given by the relation:
$\mu=\frac{A_{\max }-A_{\min }}{A_{\max }+A_{\min }}$
$=\frac{10-2}{10+2}=\frac{8}{12}=0.67$
If $A_{\min }=0$,
Then $\mu^{\prime}=\frac{A_{\max }}{A_{\max }}=\frac{10}{10}=1$