新编文档-DiscreteFourierTransform-DCU离散傅里叶变换方法-精品文档

1、Discrete Fourier TransformMultiply element-by-element6o.4o.2o.2o.4o.-6o.-8o.16o.401o.2.011 o o.08o06 山 o.04 o o.02 o o.Cumulative sum shows:2 signals of same frequency and phaseMultiply element-by-elementNon-zero cumulative sum25020015010050 ； 00.002 0.004 0.006 0.0080.010.012 0.014 0.016 0.018 0.02

2、Same frequency but n/2 phase differenee602 o.01o.00o.002Element-by element product with both sine and cosine wavesCumulative sumsWave: partly sine, partly cosineElement-by-element multiplication1.510.600500.002 0.004 0.006 0.0080.010.012 0.014 0.016 0.018 0.02Cumulative sumdftsimp2demo(fA fsr timele

3、nA amp)dftsimp2demo(200,1000,0.02,1)dftsimp2demo(fA fsr timelenA amp)dftsimp2demo(200, 1000, 0.05, 1)dftsimp2demo(fA fsr timelenA amp)dftsimp2demo(200, 10000, 0.05, 1)300250200150100500010002000 3000 4000500060007000 80009000 100006004003002520151050Use dB scale and frequencies to FsDFT Procedure Gi

4、ven 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 usingComplex 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