西电数字信号处理大作业试题.doc

实验一、信号的采样 clc,clear; dt=0.001;tf=6;t=0:dt:tf; xa=sqrt(t)+cos(t); T=0.5;n=0:tf/T; x=sqrt(n*T)+cos(n*T); figure(1) subplot(2,1,1) plot(t,xa),grid on;title(original image) subplot(2,1,2) stem(n*T,x),grid on,title(digital image) 实验二、信号与系统的时域分析 差分方程为，其中，，。 系统单位脉冲响应 a1=-0.8;a2=0.64;b=0.866;ys=0; xn=[1,zeros(1,49)]; B=1;A=[1,a1,a2]; xi=filtic(B,A,ys); yn=filter(B,A,xn,xi); n=0:length(yn)-1; subplot(1,1,1);stem(n,yn,.) title((a));xlabel(n);ylabel(y(n)) 输入x(n)=cos(n) T=0.1; z=cos(n*T); zn=conv(yn,z); figure(2); n1=1:99; stem(n1,zn,.) 实验三、系统的频域和Z域分析 程序代码（画出dtft的幅度和频率谱） clc,clear; n=0:1:7; x=(0.9*exp(j*pi/3)).^n; w=0:pi/200:pi; X=x*exp(-j).^(n*w); realX=real(X); imagX=imag(X); angX=angle(X); magX=abs(X); subplot(2,2,1);plot(w/pi,magX);grid xlabel(frequency in pi unit); title(magnitude part); subplot(2,2,2);plot(w/pi,realX);grid xlabel(frequency in pi unit); title(real part); subplot(2,2,3);plot(w/pi,imagX);grid xlabel(frequency in pi unit); title(imaginary part); subplot(2,2,4);plot(w/pi,angX);grid xlabel(frequency in pi unit); title(angel part); clc,clear; a=[1,-0.5,0.06];b=[1,1,0]; m=0:length(b)-1;l=0:length(a)-1; w=0:pi/500:pi; num=b*exp(-j*m*w); den=a*exp(-j*l*w); H=num./den; magH=abs(H);angH=angle(H); H1=freqz(b,a,w); magH1=abs(H1);angH1=angle(H1); subplot(2,2,2);plot(w/pi,angH);grid;xlabel(w(frequency in pi units));ylabel(?à??rad/w); subplot(2,2,1);plot(w/pi,magH);grid;xlabel(w(frequency in pi units));ylabel(·ù?è|H|); subplot(2,2,3);plot(w/pi,magH1);grid;xlabel(w(frequency in pi units));ylabel(·ù?è|H1|); subplot(2,2,4);plot(w/pi,angH);grid;xlabel(w(frequency in pi units));ylabel(?à??rad/w); axis([0,1,-0.8,0]); figure(2);zplane(b,a); 实验四、信号的频谱分析 程序代码 clc,clear; n=0:7;k=0:7;N=8;w=n*(2*pi)/8; x=(0.9*exp(j*pi/3)).^n; X1=[x zeros(1,8)];X2=[X1 zeros(1,16)]; XK=x*exp(-j*k*w); k1=0:15;n1=0:15;w1=n1*(2*pi)/16;XK1=X1*exp(-j*k1*w1); k2=0:31;n2=0:31;w2=n2*(2*pi)/16;XK2=X2*exp(-j*k2*w2); w3=0:pi/200:2*pi;X=x*exp(-j*n*w3); magX=abs(X);angX=angle(X); mag