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Homework Help: Total power contained in 10.0[cos(160.7*pi*t)]^4 (Fourier Series)

  1. Mar 31, 2013 #1
    1. The problem statement, all variables and given/known data

    Compute the power contained in the periodic signal x(t) = 10.0[cos(160.7*pi*t)]^4

    2. Relevant equations

    3. The attempt at a solution

    Hey guys,
    I have just started Fourier Series and am struggling with this one. Without writing all my calculations, -I start with inverse Euler formula.
    -Then integrate x(t)*e^(-j*ω*k*t) with respect to t. From 0 to (To)
    -Then consider the value of the final exponentials when k is an odd and even number.

    However i calculate that the answer for ak for any value of k to be 15/4?

    Once again I have only started Fourier recently so any direction would be much appreciated.
    Last edited by a moderator: Mar 31, 2013
  2. jcsd
  3. Mar 31, 2013 #2


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    Please show your work.

    Another approach you might try is using trig identities to find the Fourier series.
  4. Apr 1, 2013 #3
    Provided are my calculations in the attachment
    -The function has already been converted using the inverse Euler formula
    - σ is equal to 160.7*pi*t
    - The fundamental frequency is 2*σ/(2*π)

    -Anyway to calculate this equation is fine, inverse euler was just given as a suggestion to begin.

    Attached Files:

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