数字信号处理MATLAB实验50题.docx

1、数字信号处理MATLAB实验50题1-1 clc; b=1,1;a=1,-0.5;subplot(3,1,1);zplane(b,a);title(因果系统零极图);n=0:50;x=3*cos(pi*n/3);y=filter(b,a,x);subplot(3,1,2);stem(n,x,.);title(输入x的波形);subplot(3,1,3);stem(n,y,.);title(输出y的波形);1-2b=1,1,1;a=1,0.5,-0.25;subplot(3,1,1);zplane(b,a);title(因果系统零极图);n=0:50;x=3*cos(pi*n/3);y=filt

2、er(b,a,x);subplot(3,1,2);stem(n,x,.);title(输入x的波形);subplot(3,1,3);stem(n,y,.);title(输出y的波形);2clear;clc;b=0,1;a=1,-1,-1;x=impseq(0,-5,50);n=-5:50;h=filter(b,a,x);stem(n,h,.);title(单位脉冲响应)sum(abs(h)3b=2;a=1 -0.8 -0.5;subplot(4,1,1);zplane(b,a);title(系统的零极图);H,w=freqz(b,a,100,whole);magH=abs(H);phaH=an

3、gle(H);subplot(4,1,2);plot(w/pi,magH);title(系统的幅频响应);subplot(4,1,3);plot(w/pi,phaH/pi);title(系统的相频响应);n=0:100;x=impseq(0,0,100);h=filter(b,a,x);subplot(4,1,4);stem(n,h,.);title(系统的冲激响应);4b=1 1;a=1 -0.9 0.81;H,w=freqz(b,a,400,whole);magH=abs(H);phaH=angle(H);subplot(4,1,1);plot(w/pi,magH);title(系统的幅频

4、响应);subplot(4,1,2);plot(w/pi,phaH/pi);title(系统的相频响应);n=0:200;x=sin(pi*n/3)+5*cos(pi*n);y=filter(b,a,x);subplot(4,1,3);plot(n,x);title(输入信号X);subplot(4,1,4);plot(n,y);title(输出信号Y);grid;5x11=1 1 1 1;n=0:5;x12=cos(pi*n/4);y11=circonvt(x11,x12,8)y12=conv(x11,x12)y13=y11(1:1:8),zeros(1,1)e1=y13-y12x21=1

5、-1 1 -1;x22=1 0 -1 0;y21=circonvt(x21,x22,5)y22=conv(x21,x22)y23=y21(1:1:5),zeros(1,2)e2=y23-y22n=0:15;x31=cos(2*pi*n/32);x32=sin(2*pi*n/32);y31=circonvt(x31,x32,32)y32=conv(x31,x32)y33=y32(1:1:31),zeros(1,1)e3=y31-y33n=0:9;x41=(0.8).n;x42=(-0.8).n;y41=circonvt(x41,x42,15)y42=conv(x41,x42)y43=y41(1:

6、1:15),zeros(1,4)e4=y43-y426clear;clc;x1=2 1 1 2;x2=1 -1 -1 1;n=0:8-1;y11=circonvt(x1,x2,4)y12=circonvt(x1,x2,7)y13=circonvt(x1,x2,8)y2=conv(x1,x2)%N最小值77-1x=2,2,2,2,2,2,2,2;w=0:1:500*2*pi/500;H=freqz(x,1,w);magH=abs(H);phaH=angle(H);subplot(2,2,1);plot(w/pi,magH);gridxlabel();ylabel(|x|);title(DTFT的

7、幅度)subplot(2,2,2);plot(w/pi,phaH/pi*180);gridxlabel(以pi为单位的频率);ylabel(度);title(DTFT的相角)N=8;w1=2*pi/N;k=0:N-1;X=dft(x,N);magX=abs(X),phaX=angle(X)*180/pisubplot(2,2,3);plot(w*N/(2*pi),magH,-);axis(-0.1,8.1,0,20);hold onstem(k,magX);ylabel(|x(k)|);title(DFT的幅度:N=8);text(4.3,-1,k)hold offsubplot(2,2,4)

8、;plot(w*N/(2*pi),phaH*180/pi,-);axis(-0.1,8.1,-200,200);hold onstem(k,phaX);ylabel(度);title(DFT的相角:N=8);text(4.3,-200,k)7-2clear;clc;x=2,2,2,2,2,2,2,2;w=0:1:500*2*pi/500;H=freqz(x,1,w);magH=abs(H);phaH=angle(H);subplot(2,2,1);plot(w/pi,magH);gridxlabel();ylabel(|x|);title(DTFT的幅度)subplot(2,2,2);plot

9、(w/pi,phaH/pi*180);gridxlabel(以pi为单位的频率);ylabel(度);title(DTFT的相角)N=16;w1=2*pi/N;k=0:N-1;X=fft(x,N);magX=abs(X),phaX=angle(X)*180/pisubplot(2,2,3);plot(w*N/(2*pi),magH,-);axis(-0.1,16.1,0,20);hold onstem(k,magX);ylabel(|x(k)|);title(DFT的幅度:N=16);text(4.3,-1,k)hold offsubplot(2,2,4);plot(w*N/(2*pi),ph

10、aH*180/pi,-);axis(-0.1,16.1,-200,200);hold onstem(k,phaX,.);ylabel(度);title(DFT的相角:N=16);text(4.3,-250,k)8-1N=12;w1=2*pi/N;k=0:N-1;x=1,2,3,4,5,6,6,5,4,3,2,1;X=dft(x,N);magX=abs(X),phaX=angle(X)*180/pisubplot(2,1,1);axis(-0.1,12.1,0,50);hold onstem(k,magX);ylabel(|x(k)|);title(DFT的幅度:N=12);hold offsu

11、bplot(2,1,2);axis(-0.1,12.1,-400,400);hold onstem(k,phaX);ylabel(度);title(DFT的相角:N=12);8-2x=1,2,3,4,5,6,6,5,4,3,2,1;w=0:1:500*2*pi/500;H=freqz(x,1,w);magH=abs(H);phaH=angle(H);subplot(2,2,1);plot(w/pi,magH);gridaxis(0,2,0,50);xlabel();ylabel(|x|);title(DTFT的幅度)subplot(2,2,2);plot(w/pi,phaH/pi*180);g

12、ridaxis(0,2,-400,400);xlabel(以pi为单位的频率);ylabel(度);title(DTFT的相角)N=12;w1=2*pi/N;k=0:N-1;x=1,2,3,4,5,6,6,5,4,3,2,1;X=dft(x,N);magX=abs(X),phaX=angle(X)*180/pisubplot(2,2,3);plot(w*N/(2*pi),magH,-);axis(-0.1,12.1,0,50);hold onstem(k,magX);ylabel(|x(k)|);title(DFT的幅度:N=12);hold offsubplot(2,2,4);plot(w*

13、N/(2*pi),phaH*180/pi,-);axis(-0.1,12.1,-400,400);hold onstem(k,phaX);ylabel(度);title(DFT的相角:N=12);9clear;clc;N1=40;n=0:1:N1-1;t=0.01*n;x=2*sin(4*pi*t)+5*cos(16*pi*t);x1=fft(x);magx1=abs(x1);w=2*pi/N1*n;subplot(3,1,1); plot(w*100)/(2*pi),magx1);title(DFT幅度);axis(0,25,0,200);N2=60;n=0:1:N2-1;t=0.01*n;

14、x=2*sin(4*pi*t)+5*cos(16*pi*t);x2=fft(x);magx2=abs(x2);w=2*pi/N2*n;subplot(3,1,2); plot(w*100)/(2*pi),magx2);title(DFT幅度);axis(0,25,0,200);N3=128;n=0:1:N3-1;t=0.01*n;x=2*sin(4*pi*t)+5*cos(16*pi*t);x3=fft(x);magx3=abs(x3);w=2*pi/N3*n;subplot(3,1,3); plot(w*100)/(2*pi),magx3);title(DFT幅度);axis(0,25,0,

15、400);10clear;clc;N=128;n=0:1:N-1;t=0.01*n;x=2*sin(4*pi*t)+5*cos(16*pi*t);y=x+0.8*randn(1,length(t);x1=fft(x);magx1=abs(x1);w=2*pi/N*n;subplot(2,1,1); plot(w*100)/(2*pi),magx1);title(DFT幅度);axis(0,40,0,400);y1=fft(y);magy1=abs(y1);w=2*pi/N*n;subplot(2,1,2);plot(w*100)/(2*pi),magy1);title(被噪声污染后DFT幅度)

16、axis(0,100,0,400);11clear;clc;N=512;n=0:N-1;t=0.01*n;x=sin(2*pi*5*t)+sin(2*pi*15*t)+sin(2*pi*30*t);X=fft(x,N);magx=abs(X);k=0:1:N-1;w=2*pi/N*k;plot(k/N*100,magx);title(FFT N=512)xlabel(频率（单位：Hz);ylabel(|X|);gridaxis(0,100,0,300)12clear allclcN1=128;n1=0:N1-1;t1=0.01*n1;x1=0.5*sin(2*pi*15*t1)+2*sin(2

17、*pi*40*t1);k1=0:1:127;w1=2*pi/N1*k1;X1=fft(x1);magX1=abs(X1);subplot(2,1,1);plot(w1*100)/(2*pi),magX1);axis(0,50,0,150);title(DFT N=128);xlabel(频率（单位：pi）);ylabel(X(k);grid;N2=1024;n2=0:N2-1;t2=0.01*n2;x2=0.5*sin(2*pi*15*t2)+2*sin(2*pi*40*t2);k2=0:1:1023;w2=2*pi/N2*k2;X2=fft(x2);magX2=abs(X2);subplot

18、(2,1,2);plot(w2*100)/(2*pi),magX2);axis(0,50,0,900);title(DFT N=1024);xlabel(频率（单位：pi）);ylabel(X(k);grid;13t=0:0.001:1;x=sin(2*pi*60*t)+sin(2*pi*200*t);subplot(2,1,1);stem(t,x,.);title(signial x(n);grid;y=x+1.5*randn(1,length(t);Y=fft(y,1024);p=Y.*conj(Y)/1024;N=1:1024;n=N/1000*1024;subplot(2,1,2);p

19、lot(n,p);axis(0,600,0,280);title(signial y(n);grid;xlabel(频率（单位：Hz);ylabel(p);grid14n=0:1:9;x=cos(0.48*pi*n)+cos(0.52*pi*n);X=fft(x);magx=abs(X(1:1:10);k=0:1:9;w=2*pi/10*k;subplot(3,1,1);stem(w/pi,magx);title(N=10点DFT幅度);xlabel(频率(单位:pi);axis(0,1,0,10);n=0:1:9;y=cos(0.48*pi*n)+cos(0.52*pi*n);n1=0:1:

20、99;x=y(1:1:10) zeros(1,90);x1=fft(x);magx1=abs(x1(1:1:50);k1=0:1:49;w1=2*pi/100*k1;subplot(3,1,2);stem(w1/pi,magx1);title(补零到一百点DFT幅度);xlabel(频率(单位:pi);axis(0,1,0,10);n=0:1:99;x=cos(0.48*pi*n)+cos(0.52*pi*n);X=fft(x);magx=abs(X(1:1:50);k=0:1:49;w=2*pi/100*k;subplot(3,1,3);stem(w/pi,magx);title(N=100

21、点DFT幅度);xlabel(频率(单位:pi);axis(0,1,0,60);15n=0:10;x=10*(0.8.n);x1=fft(x);k=0:10;y1=x1.*(exp(8*j*pi*k/11);y=ifft(y1);subplot(2,2,1);stem(n,x);title(原序列x(n);xlabel(n);axis(0,10,0,12);subplot(2,2,2);stem(n,y);title(移位序列y(n);axis(0,10,0,12);n=0:10;y=10*(0.8.n);x=y(1:1:11) zeros(1,4);n1=0:14;subplot(2,2,3

22、);stem(n1,x);title(15点序列x(n);xlabel(n);axis(0,14,0,12);x1=fft(x);k=0:14;y1=x1.*(exp(8*j*pi*k/15);y=ifft(y1);subplot(2,2,4);stem(n1,y);title(15点移位序列y(n);axis(0,14,0,12);16clc;N=31;n=0:N;x=n.*(stepseq(0,0,N)-stepseq(16,0,N);y=stepseq(0,0,N)-stepseq(8,0,N);X=fft(x);Y=fft(y);Z=X.*Y;z=ifft(Z);subplot(3,1

23、,1);stem(n,z);title(线性卷积);axis(0,25,0,100);N1=15;n1=0:31;x1=n1.*(stepseq(0,0,31)-stepseq(16,0,31);y1=stepseq(0,0,N1)-stepseq(8,0,N1);X1=fft(x1,16);Y1=fft(y1);Z1=X1.*Y1;z1=ifft(Z1);subplot(3,1,2);n1=0:15;stem(n1,z1);title(16点圆周卷积);axis(0,20,0,100);N=31;n=0:N;x=n.*(stepseq(0,0,N)-stepseq(16,0,N);y=ste

24、pseq(0,0,31)-stepseq(8,0,31);X=fft(x);Y=fft(y);Z=X.*Y;z=ifft(Z);subplot(3,1,3);stem(n,z);title(32点圆周卷积);axis(0,25,0,100);17Rp=0.5;T=0.001;ws=200*2*pi*T;ws1=(2/T)*tan(ws/2);b,a=cheby1(9,Rp,ws1,high,s);bz,az=bilinear(b,a,1/T);db,mag,pha,grd,w=freqz_m(bz,az);subplot(2,1,1);plot(w/pi,db);grid;axis(0,1,-

25、400,100);title(系统的幅频响应);subplot(2,1,2);plot(w/pi,pha);title(系统的相频响应);18Wn=2*pi*100;fs=1000;b,a=butter(6,Wn,s);bz,az=impinvar(b,a,fs);db,mag,pha,grd,w=freqz_m(bz,az);subplot(2,2,1);plot(w/pi,db);title(系统的幅频响应);axis(0,1,-50,5);subplot(2,2,2);plot(w/pi,pha);title(系统的相频响应);%Filterx=-4,-2,0,-4,-6,-4,-2,-

26、4,-6,-6,-4,-4,-6,-6,. -2,6,12,8,0,-16,-38,-60,-84,-90,-66,-32,. -4,2,-4,8,12,12,10,6,6,6,4,0,0,0,0,0,-2,. -4,0,0,0,-2,-2,0,0,-2,-2,-2,-2,0;y=filter(bz,az,x);N=56;n=0:N-1;subplot(2,2,3);plot(n,x);title(输入波形);subplot(2,2,4);plot(n,y);title(输出波形);19%最高f=30Hz，可取fs=100Hz，即t=0.01n%s(n)=sin(0.1*pi*n)+sin(0

27、.3*pi*n)+sin(0.6*pi*n);%s(n)的样本取301点%注意：这不是双线性变换法，是完全设计法，不过，效果一样。参考PRp=0.1;Rs=40;wp1=0.2*pi;wp2=0.4*pi;wn=wp1,wp2/pi;n=4;b,a=ellip(n,Rp,Rs,wn);%默认时表带通db,mag,pha,grd,w=freqz_m(b,a);subplot(3,1,1);plot(w/pi,db);axis(0,1,-100,5);n=0:300;s=sin(0.1*pi*n)+sin(0.3*pi*n)+sin(0.6*pi*n);subplot(312);plot(n,s)

28、hold ony=filter(b,a,s);subplot(313);plot(n,y)20%可抽象成一低通或带阻滤波器。抽象成低通来设计%抽样频率取fs=1000Hz；%验证看指标fp=100;fs=130;Rp=2;Rs=50;T=0.001; wp=2*pi*fp*T;ws=2*pi*fs*T; wp1=(2/T)*tan(wp/2);ws1=(2/T)*tan(ws/2); n,wn=cheb1ord(wp1,ws1,Rp,Rs,s);b,a=cheby1(n,Rp,wn,low,s); bz,az=bilinear(b,a,1/T);db,mag,pha,grd,w=freqz_m(bz,az);grid onplot(w/pi,db);axis(0,1,-80,5);21b=1,1;a=1,5,6;T=1;bz,az=impinvar(b,a,1/T)bz1,az1=bilinear(b,a,1/T)22Rp