A transmitter puts out a total power of 32 Watts of 28% AM signal. Calculate how much power is contained in each of the sidebands and the fraction of power in the carrier.

The total power in an AM signal when the carrier power and the percentage of modulation are known is $P_T = P_c \big ( 1 + \large\frac{m^2}{2}$$\big ) \Rightarrow 32 = P_c \big ( 1 + \large\frac{0.28^2}{2}$$\big )$
$\Rightarrow P_c = \large\frac{32}{1.0392}$$= 30.793\;W The total power in both side bands = 32-30.793 = 1.207\;W The power in each side band is half of this \approx 0.60\;W \Rightarrow The fraction of the power in the carrier is \large\frac{30.79}{32}$$\approx 0.96$
edited Jul 13, 2014