Signals in Natural Domain
Chapter 6 :  Discrete fourier series and Discrete fourier transform
 

Fourier Transform of periodic signals

If is periodic with period N, then we can write

Using equation (5.9) we see that

                                                              

as is periodic with period N.

Example: 
Consider the periodic impulse train
then
    

                                                                             

as only one term corresponding to n = 0 is non zero. Thus the DTFT is

        
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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