_离散傅立叶变换.pptVIP

Chap 2 review Aliasing effect The Nyquist criterion Band-pass sampling Frequency ambiguity effects of equation aliasing effect of discrete sequences The Nyquist criterion Bandpass Sampling Digital Signal ProcessingChap 3 Discrete Fourier Transform 主讲 ：杨玉红 武汉大学国家多媒体软件 工程技术研究中心 外网邮箱 : ahka_yang@yeah.net 内网邮箱：yangyh@multimedia.whu.edu.cn 傅立叶变换的本质？ DFTs origin - CFT content DFT equation DFT equation - rectangular form DFT equation - example DFT’s analysis frequencies DFT output value DFT example 1 – input signal DFT example 1 – DFT output for m=1 DFT example 1 – DFT output for m1 DFT example 1 – DFT output for m=0 DFT example 1 – DFT results characteristics content DFT symmetry for real signals DFT symmetry for real signals DFT LINEARITY DFT Magnitudes DFT Magnitudes – other DFT expression DFT frequency axis DFT SHIFTING THEOREM DFT SHIFTING THEOREM – comparison between examples DFT SHIFTING THEOREM – comparison between examples content Inverse DFT content DFT leakage – ideal case DFT leakage – ideal case DFT leakage – practical case DFT leakage - frequency response of a DFT DFT leakage - frequency response of a DFT DFT leakage DFT leakage – asymmetrical spectrum? DFT leakage DFT leakage DFT leakage DFT leakage content windows windows Windows – mathematical expression Windows – magnitude response Windows – magnitude response in dB Windows – hanning window Windows – Increased signal detection sensitivity afforded using windowing Windows – summary content DFT SCALLOPING LOSS – rectangular window DFT SCALLOPING LOSS – rectangular window DFT SCALLOPING LOSS – nonrectangular window content DFT resolution Zero padding – magnitude expression Zero padding – windowing Frequency-domain sampling - DTFT Frequency-domain sampling - DTFT content DFT processing gain of a single DFT DFT processing gain of a single DFT DFT processing gain of a single DFT DFT processing gain of a single DFT DFT integration processing gain content The DFT of rectangular functions The DFT of rect