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For the amplitude-modulated signal x_AM(t) = 10(1 + 0.5 sin 2πfₘ t) cos 2πf_c t, with fₘ < B, the average power contained in the sidebands is

1. 25
2. 12.5
3. 6.25
4. 3.125

Correct answer: 6.25

Solution

Carrier power Pc = Ac^2/2 = 10^2/2 = 50. Total sideband power = Pc*(mu^2/2) = 50*(0.5^2/2) = 50*0.125 = 6.25.

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