Fourier Series for real and odd signals

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SUMMARY

The discussion centers on the computation of Fourier Series coefficients for real and odd signals, specifically addressing the integral formulation. The user identifies a consistent issue where the computed coefficients appear flipped on the x-axis. The resolution involves recognizing that the expression e^(-j*w*t) can be decomposed into its cosine and sine components, leading to the conclusion that a missing minus sign in the integral is the source of the error. The correct formulation should involve either correcting the sign in the integral or adjusting the sine function to account for the negative frequency.

PREREQUISITES
  • Understanding of Fourier Series and its applications in signal processing.
  • Familiarity with complex exponentials and their relationship to sine and cosine functions.
  • Knowledge of integral calculus, particularly in the context of signal analysis.
  • Experience with real and odd functions in mathematical contexts.
NEXT STEPS
  • Review the derivation of Fourier Series coefficients for real and odd signals.
  • Study the properties of complex exponentials in relation to Fourier transforms.
  • Learn about the implications of negative frequencies in signal processing.
  • Explore common pitfalls in integral calculations involving trigonometric functions.
USEFUL FOR

Students and professionals in electrical engineering, signal processing, and applied mathematics who are working with Fourier Series and need to understand the nuances of computing coefficients for real and odd signals.

awelex
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Hi,

I have a general question regarding the computation of Fourier Series coefficients for real and odd inputs. In this case, the following should be true:

∫x(t)*e^(-j*k*w*t)dt = ∫x(t)*sin(k*w*t)dt

However, every time I compute my coefficients this way, I get the inverse sign of what it is supposed to be -- my coefficients are flipped on the x-axis. Since this happens every time, I don't think it's a computational mistake, but rather a conceptual problem. What am I doing wrong?

Thanks.
 
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A second after posting this, I think I figured it out:

Since e^(-j*w*t) = cos(w*t) - j * sin(w*t), I'm missing a minus sign in my integral. Correct?
 
It's either that, else or your integral should be ∫x(t)*sin(k*-w*t)dt :smile:
 

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