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Published byEleanor Lansing Modified over 2 years ago

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1 Discrete Fourier Transform

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2 Multiply element-by-element

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3 Cumulative sum shows:

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4 2 signals of same frequency and phase

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5 Multiply element-by-element

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6 Non-zero cumulative sum

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7 Same frequency but /2 phase difference

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8 Element-by element product with both sine and cosine waves

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9 Cumulative sums

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10 Wave: partly sine, partly cosine

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11 Element-by-element multiplication

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12 Cumulative sum

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13 dftsimp2demo(f, fs, timelen, amp) dftsimp2demo(200, 1000, 0.02, 1)

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14 dftsimp2demo(f, fs, timelen, amp) dftsimp2demo(200, 1000, 0.05, 1)

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15 dftsimp2demo(f, fs, timelen, amp) dftsimp2demo(200, 10000, 0.05, 1)

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16 dftcomplex2demo(f1, f2, fs, timelen, a1, a2) dftcomplex2demo(200, 400, 10000, 0.02, 5, 4)

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17 dftcomplex2demo(f1, f2, fs, timelen, a1, a2) dftcomplex2demo(200, 400, 10000, 0.02, 5, 4)

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18 dftspeech2demo(wavfile, timelen) dftspeech2demo('atest.wav', 0.04)

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19 dftspeech2demo(wavfile, timelen) dftspeech2demo('atest.wav', 0.04)

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20 Use dB scale and frequencies to F s /2

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21 dftspeech2demo(wavfile, timelen) dftspeech2demo(‘itest.wav', 0.04)

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22 dftspeech2demo(wavfile, timelen) dftspeech2demo(‘itest.wav', 0.04)

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23 DFT Procedure Given the window (frame) length, decide the base frequency Multiply by sine wave at each multiple of base frequency Multiply by cosine wave at each multiple of base frequency Calculate magnitude and phase spectra using

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24 Complex Exponential Given the window (frame) length, decide the base frequency Multiply by sine wave at each multiple of base frequency Multiply by cosine wave at each multiple of base frequency Calculate magnitude and phase spectra using

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25 Compact Formulae DFT IDFT

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