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1、7 Sampling7.1 Representation of a Continuous-time Signal by its Samples: The Sampling Theorem7. Sampling7.1.1 Impulse-train Samplingx(t)p(t)xp(t)(1) Sampling7 SamplingTime domain:7 SamplingFrequency domain:7 Sampling7 Sampling(2) (Shannon) Sampling theorem Let x(t) be a band-limited signal with X(j
2、)=0 for | M . Then x(t) is uniquely determined by its samples x(nT),n=0,1,2, if s2 M, where s=2/T . 2M is called Nyquist Rate. ( Minimum distortionless sampling frequency ) 7 Sampling(3) RecoverySystem for sampling and reconstruction:7 Sampling7 Sampling7.1.2 Sampling with a Zero-order Hold(1) Sampling system construction:7 Sampling7 Sampling(2) Signal Recovery7 Sampling7.3 The Effect of Undersampling: Aliasings=60s=307 Samplings=1.50s=1.207 SamplingProblems: 7.1 7.2 7.3 7.6 7.9
