Sideband Power for a multiple tone wave

[marina87]

Homework Statement

I need to find the sideband power in a AM DSB. My book doesn't have an example or explain what to do when you have a modulating signal that has two tones (two cosines).

Homework Equations

Ps=sideband power= 0.5*(mean square value)^2

Carrier signal = A*cos(Wc*t)

m(t)=(4/pi)*[cos(2*pi*f0*t)-(1/3)*cos(2*pi*3*f0*t)]

The Attempt at a Solution

I only know how to do it for one tone using the equation 0.5*0.5*(μ*A)^2. Where A is the amplitude of the carrier and μ is the index modulation. What should I do? Should I look for the meansquare of each tone and add them?

 

[lazyaditya]

You must know that amplitude modulation systems are linear in nature. By being linear they follow superposition theorem, which states that the output response of the system due to the sum of inputs is equal to the sum of the output responses of each input to the system.

So calculate the responses individually and add them.