Fourier Transform

Introduction:

This section will discuss the fourier transform and explains the graphical representation of the fourier transform.

The fourier transform:

Let X( t ) be a nonperiodic signal of finite duration, that is,

Such a signal is shown in Fig. (a). Let xT0(t) be a periodic signal formed by repeating x(t) with fundamental period T0 as shown fig (b ). If we let To - , we have

The complex exponential Fourier series of xT0(t)  is given by

The above equ can be written as

Let us define X(w) as

the complex Fourier coefficients ck, can be expressed as



Cosine and sine  Function


Introduction:

This section describes the cosine and sine function Pair mathematically and also explains this in detail.

 

The cosine function pair:

Proof:

 

The f(t) - F(w) correspondence is also shown in fig given below

We know that Cos w0t is real and even function of time, and we found out that its Fourier transform is a real and even function of frequency.

The Sine Function Pair:

Proof:

The f(t) - F(w) correspondence is also shown in figure given below.

 

We know that Sin w0t is real and odd function of time, and we found out that its Fourier transform is an imaginary and odd function of frequency.


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