信号与系统第七章课件.ppt

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1、Chapter7Sampling1Chapter7SamplingContinuousSignalDiscreteSignalsamplingCodeDigitalSignalDSPD/AContinuousSignal-T0T2Tt2Chapter7Sampling§7.1TheSamplingTheorem§7.1.1Impulse-TrainSampling-3T-2T-T0T2T3T4Tt3Chapter7Sampling4Chapter7SamplingThereisnooverlap,canberecoveredexactlyfro

2、mIf5Chapter7SamplingThereisoverlap,cannotberecoveredexactlyfrom6Chapter7SamplingSamplingTheorem:Letbeaband-limitedsignalwithThenisuniquelydeterminedbyitssamplesifwhere7Chapter7Sampling§7.1.2SamplingwithaZero-OrderHoldZero-OrderHold-3T-2T-T0T2T3T4Tt8Chapter7SamplingZero-Order

3、Hold9Chapter7SamplingLPFImpulse-TrainSamplingZero-OrderHoldReconstructionFilter10Chapter7Sampling11Chapter7Sampling§7.3TheEffectofUndersampling:Aliasing欠采样混叠Let12Chapter7Sampling1.ConsiderasinusoidalsignalFix,changeFigure(a)13Chapter7Sampling14Chapter7SamplingFigure(b)15Chap

4、ter7SamplingFigure(c)16Figure(d)Chapter7Sampling17Chapter7SamplingWhenaliasingoccurs,2.Considerasinusoidalsignal18Chapter7SamplingPhasereversal19Chapter7Sampling3.20Chapter7Sampling4.StrobeEffect（频闪效应）Figure7.18Thespeedofrotationofthediscisperceivedcorrectly.Therotationappea

5、rstobeatalowerfrequencythanisactuallythecase.Furthermore,becauseofphasereversal,thediscwillappeartoberotatinginthewrongdirection.RotatingdiscStrobe21Chapter7SamplingHomework:7.17.27.37.67.922