3_离散傅立叶变换课件.ppt

Chap 2 review;Frequency ambiguity effects of equation;aliasing effect of discrete sequences;The Nyquist criterion;Bandpass Sampling;Digital Signal ProcessingChap 3 Discrete Fourier Transform;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;;;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 rectangular functions;The DFT of rectangular functions;The DFT of rectangular functions - summary;The DFT of symmetrical rectangular functions;The DFT of symmetrical rectangular functions - example;DFT of an All Ones Rectangular Function