Question

An Am signal is modulated by 50% such that FOM of AM. becomes equal to the Figure of ment (FOM) of FM signal is FM modulated. The modulation index of FM will be _________

• A. 0.272

Answer 1

The correct option is A 0.272
0.272 (0.25 - 0.30)

${\left(FOM\right)}_{AM}=\eta =\frac{{\mu }^2}{2+{\mu }^2}$

${\left(FOM\right)}_{FM}=\frac{3}{2}{\beta }^2$

$\frac{{\mu }^2}{2+{\mu }^2}=\frac{3}{2}{\beta }^2$

${\beta }^2=\frac{2}{3}\left[\frac{1/4}{2+1/4}\right]=\frac{2}{3}\left[\frac{1}{9}\right]=\frac{2}{27}=0.074$

$\beta =\sqrt{0.074}=0.272$