Relationship between Fourier series Coefficients and F Transform

In summary, the conversation discusses a DT periodic signal x[n] with fundamental period N and its Fourier transform. The question is how to find the Fourier Series coefficients a_{k}[n] from the Fourier transform X_{n}[e^jω]. It is also mentioned that the Fourier Series coefficients are periodic with period N. The TA suggests using the provided connection between Fourier Series and Fourier transform to solve this problem.
  • #1
ace1719
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Homework Statement



"Suppose x[n] is a DT (discrete time) periodic signal with fundamental period N. Let us define x[itex]_{n}[/itex][n] to be x[n] for n ε {0, 1,2, ... , N-1} and zero elsewhere. Denote the Fourier transform of x[itex]_{n}[/itex][n] with X[itex]_{n}[/itex][e^jω]. How can one find the Fourier Series coefficients a[itex]_{k}[/itex][n] from X[itex]_{n}[/itex][e^jω]? Using the provided connection show that Fourier Series coefficients are indeed periodic with period N."


Homework Equations



None.

The Attempt at a Solution



By "provided connection" I think my TA meant the answer from the first part of the question, ie. finding the relationship between FS and FT.

I am not entirely sure which Fourier coefficients we are supposed to link, those for x[n], or x[itex]_{n}[/itex][n].

I know the expressions for the Fourier coefficients and Fourier transform, but as with much of what this TA gives us, I don't know where to begin otherwise.
 
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  • #2
Anyone? I'm still stuck with this one.
 

Question 1: What is the relationship between Fourier series coefficients and Fourier transform?

The Fourier series coefficients and Fourier transform are both mathematical tools used to represent a periodic signal in terms of its frequency components. The main difference between them is that the Fourier series coefficients are used for representing periodic signals, while the Fourier transform is used for representing non-periodic signals.

Question 2: How do Fourier series coefficients relate to the Fourier transform in terms of mathematical equations?

The Fourier series coefficients are obtained by taking the Fourier transform of a periodic signal and then summing up the complex exponential components over all frequencies. Mathematically, this can be represented as:
               cn = (1/T) ∫T x(t) e-j2πnt/T dt
where cn is the n-th Fourier series coefficient, T is the period of the signal, and x(t) is the periodic signal.

Question 3: Can the Fourier series coefficients be used to reconstruct the original signal?

Yes, the Fourier series coefficients can be used to reconstruct the original signal by using the inverse Fourier transform. This mathematical operation involves summing up the complex exponential components weighted by their corresponding Fourier series coefficients, and the resulting sum will give the original signal back.

Question 4: How does the number of Fourier series coefficients affect the accuracy of the reconstructed signal?

The accuracy of the reconstructed signal using Fourier series coefficients depends on the number of coefficients used. The more coefficients used, the more accurate the reconstruction will be. However, using an infinite number of coefficients is necessary to perfectly reconstruct the original signal.

Question 5: What is the significance of the Fourier series coefficients and Fourier transform in signal processing?

The Fourier series coefficients and Fourier transform are important tools in signal processing because they allow us to analyze and manipulate signals in the frequency domain. This can provide insights into the characteristics of a signal and can also help in filtering, compression, and other signal processing techniques. They are also used in various fields such as communication, image processing, and audio signal processing.

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