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a) <math>Y(e{jw}) = frac{1},{N}{X(e^jw)+e^-jwX(e^jw)+.....+X(e^jw)e^(N-1)jw}</math>
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<math>Y(e^{jw}) = \frac{1}{N}(X(e^{jw})+e^{-jw}X(e^{jw})+.....+X(e^{jw})e^{(N-1)jw})</math>
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 +
      <math> = \frac{1}{N} \sum_{k=0}^{N-1} e^{-jwk} X(e^{jw})</math>
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      <math> = \frac{1}{N} e^{-jw(\frac{N-1}{2})} \frac{e^{jw(\frac{N}{2})} - e^{-jw(\frac{N}{2})}} {e^{j(\frac{w}{2})} -e^{-j(\frac{w}{2})}} X(e^{jw})</math>
 +
      <math> = \frac{1}{N} e^{-jw(\frac{N-1}{2})} \frac{\sin \frac{wN}{2}} {\sin \frac{w}{2}}</math>
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<math> \left | H(e^{jw}) \right \vert (Magnitude) = \frac{1}{N} \frac{\sin \frac{wN}{2}} {\sin \frac{w}{2}}</math>
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<math> \angle H(e^{jw}) (Phase) =  e^{-jw(\frac{N-1}{2})}  (when \frac{\sin \frac{wN}{2}} {\sin \frac{w}{2}} > 0)</math>

Revision as of 02:01, 4 February 2009

$ Y(e^{jw}) = \frac{1}{N}(X(e^{jw})+e^{-jw}X(e^{jw})+.....+X(e^{jw})e^{(N-1)jw}) $

      $  = \frac{1}{N} \sum_{k=0}^{N-1} e^{-jwk} X(e^{jw}) $
      $  = \frac{1}{N} e^{-jw(\frac{N-1}{2})} \frac{e^{jw(\frac{N}{2})} - e^{-jw(\frac{N}{2})}} {e^{j(\frac{w}{2})} -e^{-j(\frac{w}{2})}} X(e^{jw}) $
      $  = \frac{1}{N} e^{-jw(\frac{N-1}{2})} \frac{\sin \frac{wN}{2}} {\sin \frac{w}{2}} $


$ \left | H(e^{jw}) \right \vert (Magnitude) = \frac{1}{N} \frac{\sin \frac{wN}{2}} {\sin \frac{w}{2}} $

$ \angle H(e^{jw}) (Phase) = e^{-jw(\frac{N-1}{2})} (when \frac{\sin \frac{wN}{2}} {\sin \frac{w}{2}} > 0) $

Alumni Liaison

Sees the importance of signal filtering in medical imaging

Dhruv Lamba, BSEE2010