《数字信号处理》课程教学课件（2020讲稿）第三章 离散傅里叶变换 §3-5 离散傅里叶变换的性质

延长序列的DFT序列x=sin(0.25*pi*n)+ sin(0.34*pi*n) ; n=0:15;补零到64点，128点，512点，作DFT运算100.10.20.40.50.60.80.90.30x109.0OLo小010.20.30.40.50.60.70.800.10.910e1eolfeeet9eelloe1le0.20.50.10.30.40.60.70.80.9100.20.90.10.50.8100.10.20.30.40.50.60.80.90.7

延长序列的DFT 序列x=sin(0.25*pi*n)+ sin(0.34*pi*n) ； n=0:15； 补零到64点，128点，512点，作DFT运算

延长序列的DFT序列x=sin(0.25*pi*n)+ sin(0.35*pi*n) ; n=0:15;补零到64点，128点，512点，作DFT运算100.80.10.20.60.9040.5110-0ho20.50.20.30.40.60.70.8-109019099tee099909100.50.6100.2100.10.20.30.40.50.60.70.80.9

延长序列的DFT 序列x=sin(0.25*pi*n)+ sin(0.35*pi*n) ； n=0:15； 补零到64点，128点，512点，作DFT运算

x=sin(0.25*pi*n)+ sin(0.30*pi*n)x=sin(0.25*pi*n)+ sin(0.33*pi*n)x=sin(0.25*pi*n)+ sin(0.35*pi*n)x=sin(0.25*pi*n)+ sin(0.34*pi*n)T.alit.中o11411..e

x=sin(0.25*pi*n)+ sin(0.30*pi*n) x=sin(0.25*pi*n)+ sin(0.34*pi*n) x=sin(0.25*pi*n)+ sin(0.33*pi*n) x=sin(0.25*pi*n)+ sin(0.35*pi*n)

n=0:15matlab参考程序：x=sin(0.25*pi*n)+sin(0.34*pi*nL1=0:15dft 16=fft(x,16)L2=0:63dft 64=ft(x,64)L3=0:127dft 128=fft(x,128)L4=0:511dft 512=fft(x,512)nx=0:15K=512dw=2*pi/Kk=0:511X=x*exp(j*dw*nx'*k)subplot(5,1,1)plot(k*dw/(2*pi),abs(X)subplot(5,1,2)stem(L1/16,abs(dft 16)subplot(5,1,3)stem(L2/64,abs(dft_64))subplot(5,1,4)stem(L3/128,abs(dft_128))subplot(5,1,5)stem(L4/512,abs(dft_512))

n=0:15 x=sin(0.25*pi*n)+sin(0.34*pi*n) L1=0:15 dft_16=fft(x,16) L2=0:63 dft_64=fft(x,64) L3=0:127 dft_128=fft(x,128) L4=0:511 dft_512=fft(x,512) nx=0:15 K=512 dw=2*pi/K k=0:511 X=x*exp(j*dw*nx'*k) subplot(5,1,1) plot(k*dw/(2*pi),abs(X)) subplot(5,1,2) stem(L1/16,abs(dft_16)) subplot(5,1,3) stem(L2/64,abs(dft_64)) subplot(5,1,4) stem(L3/128,abs(dft_128)) subplot(5,1,5) stem(L4/512,abs(dft_512)) matlab参考程序：

延长序列的DFT（不是N的整数次幂）序列x=sin(0.25*pi*n)+ sin(0.35*pi*n) ; n=0:15;补零到64点，73点，93点，作DFT运算100.10.20.40.50.60.80.900.30.7100GoO9O0.50.10.20.40.60.70.80.90.310O中Tdole.pioaepeioeeaeriaelob0.20.10.50.70.80.90.30.40.61090999999s?Qf5ellaoilaerte01eae1feap9led0.20.30:0.40.50.60.70.80.91090o0ombeeellaaleaoleaoalled0.10.20.50.80.9C0.30.40.60.7

延长序列的DFT (不是N的整数次幂) 序列x=sin(0.25*pi*n)+ sin(0.35*pi*n) ； n=0:15； 补零到64点，73点，93点，作DFT运算