8

Discrete Fourier Transform

Discrete Fourier transform (DFT) is a powerful tool for frequency analysis of discrete time signals. It transforms discrete-time signal of finite length into discrete-frequency sequence of finite length. As we shall observe, the DFT can also be used to calculate Fourier coefficients.

8.1 Approximation of Fourier Coefficients of a Periodic Function

Let f be a real-valued periodic function with period T over the interval [0, T]. We divide [0, T] into N subintervals In of equal length T/N. Thus

 

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The linear interpolation ln (t) of f (t) is given by

 

 

Thus the graph (Figure 8.1) of ln (t) consists of the line ...

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