Fourier series / calculate power over resistor

[nikki92]

Homework Statement

V(t) = 4 for 0<t< 1 and 0 for 1<t<3 and repeats itself for all t (negative and positive)

Find the first 5 harmonics of the Fourier series in cosine form and find the power if this is the voltage over 100 ohm resistor

The Attempt at a Solution

power = d_dc ^2 / R + .5sum from n=1 to 5 of |v_n|^2 /R = 0.1385 w

This does not seem correct. I am not sure where I went wrong.

 

[rude man]

Where does the sinc come from? Is this some kind of discrete system?

 

[nikki92]

It is a square wave.

 

[rude man]

Why don't you simmply use the integrals for the a_n and b_n coefficients? Then get the series in the form

V(t) = c₀ + 2 ∑_{n=1 to 5} of c_n cos(nω₁t + ø_n)?

And what exactly is x_n?