数字信号处理作业.docx

1、数字信号处理作业实验1 常见离散信号的MATLAB产生和图形显示1.单位抽样序列 x=zeros(1,50);x(1)=1;n=1:50;stem(n,x,.);axis(0,50,0,1);xlabel(n),ylabel(x)2单位阶跃序列 n=-25:25;x=ones(1,51);stem(n,x,.);xlabel(n);ylabel(x(n);axis(-25,25,0,1) 3正弦序列 f=10;Fs=250;fai=0;n=1:499;N=500;x=sin(2*pi*f*n/Fs+fai);stem(n,x);axis(0,100,-1.5,1.5);xlabel(n),yl

2、abel(x)4复正弦序列n=0:0.1:5;w=2;x=exp(j*w*n);stem(n,x,.);xlabel(n);ylabel(x(n) ;axis(0,5-1,1)5指数序列n=0:50; a=2; x=a.n; stem(n,x); axis(0,50,0,10000);xlabel(n),ylabel(x)实验2 离散系统的差分方程、单位脉冲响应和卷积分析1. A=1,0.6,0.09;B=1,-1; x2n=ones(1,25); x1n=1,zeros(1,10); y1n=filter(B,A,x1n); subplot(2,1,1);y=y1(n); stem(y1n,

3、g,.); title(单位脉冲响应) y2n=filter(B,A,x2n); subplot(2,1,2); y=y2(n); stem(y2n,g,.); title(阶跃响应) 2. A=1;B=0,0.5,0.5,0.5,0.5,0.5;x2n=ones(1,15);x1n=1,zeros(1,20);y1n=filter(B,A,x1n);subplot(2,1,1);y=y1(n);stem(y1n,g,.);title(单位脉冲响应)y2n=filter(B,A,x2n);subplot(2,1,2);y=y2(n);stem(y2n,g,.);title(阶跃响应)实验3 离

4、散系统的频率响应分析和零、极点分布num=0.0528 0.0797 0.1295 0.1295 0.797 0.0528;den=1 -1.8107 2.4947 -1.8801 0.9537 -0.2336;z,p,k=tf2zp(num,den);disp(零点);disp(z);disp(极点);disp(p); figure(1) zplane(num,den) figure(2)freqz(num,den,128)零点 -1.5870 + 1.4470i -1.5870 - 1.4470i 0.8657 + 1.5779i 0.8657 - 1.5779i -0.0669 极点 0

5、.2788 + 0.8973i 0.2788 - 0.8973i 0.3811 + 0.6274i 0.3811 - 0.6274i 0.4910 实验4 离散信号的DTFT和DFT1.N=16; n=1:16; x=sin(5*pi*n/16);X1=fft(x,16);X11=abs(X1);subplot(2,1,1);stem(X11); xlabel(频率); ylabel(幅度); title(16点);X2=fft(x,32); X22=abs(X2);subplot(2,1,2);stem(X22); xlabel(频率); ylabel(幅度); title(32点);2.

6、x= sin(5*pi*n/16);X1=fft(x);X11=abs(X1); stem(X11); xlabel(频率);ylabel(幅度); title( DTFT);实验5 FFT算法的应用1：N=64;n=0:2*N-1;x=cos(2*pi*7*n/N)+1/2*cos(2*pi*19*n/N);X=fft(x,128); k=n; stem(k,abs(X)gridxlabel(k);ylabel(|Xk|);2.k=0:63; N=64; X=1./(1-0.6*exp(-j*2*pi*k/N); x=ifft(X,64);stem(abs(x); xlabel(n);yla

7、bel(x(n);title(IFFT)实验6 基于MATLAB的数字滤波器设计IIR:wp=0.4,0.7;ws=0.3,0.8; Rp=1;Rs=40; N,wc=buttord(wp,ws,Rp,Rs)B,A=butter(N,wc) H,w=freqz(B,A);subplot(2,1,1);plot(w/pi,abs(H); xlabel(w/pi);ylabel(magnitude);subplot(2,1,2);plot(w/pi,angle(H); xlabel(w/pi);ylabel(phase)N=9wc =0.3850 0.7127B = 0.0003 0 -0.002

8、3 0 0.0091 0 -0.0213 0 0.0320 0 -0.0320 0 0.0213 0 -0.0091 0 0.0023 0 -0.0003A =1.0000 2.1224 5.1189 7.3007 10.9959 12.0956 13.5601 11.9471 10.6208 7.5869 5.4533 3.1311 1.8194 0.8131 0.3744 0.1204 0.0420 0.0077 0.0018FIR： 由于aS40dB，可选hamming窗，其阻带最小衰减-53dB满足要求。 ws1=0.3*pi;ws2=0.8*pi;wp1=0.4*pi;wp2=0.7

9、*pi;wb=(wp1-ws1+ws2-wp2)/2;wc=wp1/pi-(wp1-ws1)/(2*pi),wp2/pi+(ws2-wp2)/(2*pi); N=ceil(3.3*2*pi/wb);b=fir1(N,wc); n=0:N; hn=b(n+1)H,w=freqz(b,1); subplot(2,1,1);plot(w/pi,abs(H);xlabel(w/pi);ylabel(magnitude);subplot(2,1,2); plot(w/pi,angle(H); xlabel(w/pi);ylabel(phase);hn =0.0013 0.0005 -0.0011 0.0

10、000 -0.0014 0.0009 0.0031 -0.0015 0.0000 -0.0030 -0.0033 0.0081 0.0010 0.0000 -0.0013 -0.0152 0.0084 0.0106 0.0000 0.0102 -0.0286 -0.0114 0.0258 -0.0000 0.0345 -0.0204 -0.0694 0.0339 -0.0000 0.0731 0.0898 -0.2851 -0.0583 0.3994 -0.0583 -0.2851 0.0898 0.0731 -0.0000 0.0339 -0.0694 -0.0204 0.0345 -0.0000 0.0258 -0.0114 -0.0286 0.01020.0000 0.0106 0.0084 -0.0152 -0.0013 0.0000 0.0010 0.0081 -0.0033 -0.0030 0.0000 -0.0015 0.0031 0.0009 -0.0014 0.0000 -0.0011 0.0005 0.0013