Friday, September 15, 2017

fft - In case of Complex DFT spectrum, why the x axis range from N/2 to N point mean a negative frequency?


When we transform a complex signal into frequency signal by using a complex DFT,


The range from N/2 to N point on the X axis of the spectrum mean a negative frequency...


But i cant understand why it is..


In addition, we should not use the range over the N/2 point because of the aliasing issue. But i heard that the negative frequency region is used in case of complex dft spectrum of a complex signal.


Very confused..


Could you clearly explain it for me?


Thank you.




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