求矩形脉冲)分x()=上x(的频谱x(O)

SAMPLING We live in a continuous-time world most of the signals we encounter are CT signals, e.g. x(). How do we convert them into Dt signals x[n? Sampling, taking snap shots of x(t) every Seconds

6.1求下列序列的变换X(z),并标明收敛域绘出X(z)的零极点图。 (1)()(k)

一、频域采样点数N,采样间隔 二、频域X)与B)=adv:mDW相乘 三、时域xm7y与FBmr?a或m)卷积

连续信号x(t)=2cos6t+4sin10元t周期为1s, 以不同采样频率对其采样,①f1=16点/周期,② f2=8点/周期,分别求采样后周期序列的频谱,并 与原始信号x(t)的频谱进行比较

连续信号x()=6c0S丌t,以采样间隔T=025对 其采样,求采样周期序列的频谱,并与原始信号 x(t)的频谱进行比较

Last time: Unit circle (=1) in the ROCDTFT X(@) exists Rational transforms correspond to signals that are linear combinations of DT exponentials

例题3－1: 离散信号的加与乘 若 x = [ 1 3 5 7 ], y = [ 2 4 6 8], 则 z = x + y = [ 1 3 5 7 ] +……

Convolution Property 0(t)=h(t)*(t)←→Y(j)=H(ju)X( where h(t)←→H(ju) A consequence of the eigenfunction property

Representation of ct signals Approximate any input x(t) as a sum of shifted, scaled