Revision as of 13:45, 26 September 2008 by Shamilto (Talk)

Define a Periodic CT Signal and Compute its Fourier Series Coefficients

Let's start this process by defining our signal. For simplicities sake lets use the the signal

$ x(t) = 4sin(3t) + 8cos(7t) $

The Fourier Series can be easily found by treating

$ Asin(\omega_0t) = (A/ j2)*(e^{j\omega_0t} - e^{-j\omega_0t}) $

and

$ Acos(\omega_0t) = (A/2)*(e^{j\omega_0t} + e^{-j\omega_0t}) $

This alows us to to put x(t) in the form of

$ x(t) = \sum_{k=- \infty }^ \infty a_ke^{jk\omega_0t} $

which gives us

$ x(t) = (4/ j2)*(e^{j3t} - e^{-j3t}) + (8/2)*(e^{j7t} + e^{-j7t}) $

Simplifying and distributing

$ x(t) = (2 / j)*e^{j3t} - (2 / j)*e^{-j3t} + 4e^{j7t} + 4e^{-j7t} $

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