实验3

实验3.1w=-4*pi:8*pi/511:4*pi;num=[2.2403 2.4908 2.2403];den=[1 -0.4 0.75]; h=freqz(num,den,w); subplot(2,1,1)plot(w/pi,real(h));grid title('H(e^{j\omega}µÄʵ²¿)') xlabel('\omega/\pi'); ylabel('Õñ·ù'); subplot(2,1,2)plot(w/pi,real(h));grid title('H(e^{j\omega}µÄÐ鲿)') xlabel('\omega/\pi'); ylabel('Õñ·ù');-4-3-2-101234-10-50510H(e j ω的实部)ω/π振幅-4-3-2-101234-10-50510H(e j ω的虚部)ω/π振幅实验3.2w=-pi:2*pi/255:pi;wo=0.4*pi;D=10; num=[1 2 3 4 5 6 7 8 9]; h1=freqz(num,1,w);h2=freqz([zeros(1,D) num],1,w); subplot(2,2,1)plot(w/pi,abs(h1));grid title('Ô-ÐòÁеķù¶ÈÆ×') subplot(2,2,2)plot(w/pi,abs(h2));gridtitle('ʱÒƺóÐòÁеķù¶ÈÆ×') subplot(2,2,3)plot(w/pi,angle(h1));grid title('Ô-ÐòÁеÄÏàλÆ×') subplot(2,2,4)plot(w/pi,angle(h2));grid title('Ô-ÐòÁеķù¶ÈÆ×')-1-0.500.51原序列的幅度谱-1-0.500.510204060时移后序列的幅度谱-1-0.50.51原序列的相位谱-1-0.500.51-4-2024原序列的幅度谱实验3.3w=-pi:2*pi/255:pi;wo=0.4*pi;D=10; num1=[1 3 5 7 9 11 13 15 17]; L=length(num1);h1=freqz(num1,1,w);n=0:L-1; num2=exp(wo*i*n).*num1; h2=freqz(num2,1,w); subplot(2,2,1)plot(w/pi,abs(h1));grid title('Ô-ÐòÁеķù¶ÈÆ×') subplot(2,2,2)plot(w/pi,abs(h2));grid title('ƵÒƺóÐòÁеķù¶ÈÆ×') subplot(2,2,3)plot(w/pi,angle(h1));grid title('Ô-ÐòÁеÄÏàλÆ×') subplot(2,2,4)plot(w/pi,angle(h2));grid title('ƵÒƺóÐòÁеÄÏàλÆ×')-1-0.500.51050100原序列的幅度谱-1-0.500.51050100频移后序列的幅度谱-1-0.50.51-4-2024原序列的相位谱-1-0.500.51-4-2024频移后序列的相位谱实验3.4w=-pi:2*pi/255:pi;x1=[1 3 5 7 9 11 13 15 17]; x2=[1 -2 3 -2 1]; y=conv(x1,x2); h1=freqz(x1,1,w) h2=freqz(x2,1,w); hp=h1.*h2; h3=freqz(y,1,w); subplot(2,2,1)plot(w/pi,abs(hp));grid title('·ù¶ÈÆ׵ij˻ý') subplot(2,2,2)plot(w/pi,abs(h3));grid title('¾í»ýºóÐòÁеķù¶ÈÆ×') subplot(2,2,3)plot(w/pi,angle(hp));grid title('ÏàλÆ׵ĺÍ') subplot(2,2,4)plot(w/pi,angle(h3));grid title('¾í»ýºóÐòÁеÄÏàλÆ×')-1-0.500.51050100幅度谱的乘积-1-0.500.51050100卷积后序列的幅度谱-1-0.50.51-4-2024相位谱的和-1-0.500.51-4-2024卷积后序列的相位谱实验3.5x1=[1,2,3]; x2=[2,4,3,5]; n1=-1:1; n2=-2:1; x3=conv(x1,x2) nb3=n1(1)+n2(1);nc3=n1(length(x1))+n2(length(x2)); n3=[nb3:nc3]x3 =2 8 17 23 19 15 n3 =-3 -2 -1 0 1实验3.6num=[1];den=[1 -0.4 -0.49 0.076 0.048]; [r,p,k]=residuez(num,den)r =0.89510.5342-0.2540-0.1753p =0.8000-0.50000.4000-0.3000k =[]实验4.1函数程序function [Xk]=dft(xn,N)n=[0:1:N-1];k=n;WN=exp(-j*2*pi/N);nk=n'*k;WNnk=WN.^nk;Xk=xn*WNnk;function[xn]=idft(xn,N)n=[0:1:N-1];k=n;WN=exp(-j*2*pi/N);nk=n'*k;WNnk=WN.^(-nk);xn=(Xk*WNnk)/N;结果N=16;n=[0:1:N-1];xn=sin(n*pi/8)+sin(n*pi/4); n=k;[Xk]=dft(xn,N);stem(Xk)246810121416-10-8-6-4-20246810实验4.2N=20; m=10; n=0:1:N-1; x=8*(0.4).^n; n1=mod((n+m),N); xm=x(n1+1); subplot(2,1,1) stem(n,x); title('Ô-ÐòÁÐ'); xlabel('n'); ylabel('x(n)'); subplot(2,1,2) stem(n,xm);title('Ô²ÖÜÒÆλÐòÁÐ'); xlabel('n'); ylabel('xm(n)');原序列nx (n )圆周移位序列nx m (n )实验4.3 函数文件function [y]=circonv(x1,x2) xn2=[x2(1),fliplr(x2)]; xn2(length(xn2))=[]; C=xn2;R=x2; M=toeplitz(C,R); y=x1*M;内容 Ax1=[1 2 3 4]; x2=[4 3 2 1]; y=circonv(x1,x2)结果 y =24 22 24 30 BN=4;n=[0:1:N-1]; x1=[1 2 3 4]; x2=[4 3 2 1]; n=k[X1]=dft(x1,N);[X2]=dft(x2,N);X=X1.*X2;[x]=idft(X,N)x =Columns 1 through 324.0000 + 0.0000i 22.0000 - 0.0000i24.0000 - 0.0000iColumn 430.0000 - 0.0000i实验4.4x=[1 2 4 2 6 32 6 4 2 zeros(1,247)];x1=[x(1) x(256:-1:2)];xep=0.5*(x+x1);xop=0.5*(x-x1);XF=dft(x,256);XEPF=dft(xep,256);XOPF=dft(xop,256);clfk=0:255;subplot(2,2,1);plot(k/128,real(XF));grid;ylabel('Õñ·ù');title('Ô-ÐòÁÐDFTµÄʵ²¿');subplot(2,2,2);plot(k/128,imag(XF));grid;ylabel('Õñ·ù');title('Ô-ÐòÁÐDFTµÄÐ鲿');subplot(2,2,3);plot(k/128,real(XEPF));grid;ylabel('Õñ·ù');title('Æä¹²éî¶Ô³ÆÐòÁÐDFT');subplot(2,2,4);plot(k/128,imag(XOPF));grid;ylabel('Õñ·ù');title('Æä¹²éî·´¶Ô³ÆÐòÁÐDFT')00.51 1.52-5050100振幅原序列DFT 的实部00.51 1.52振幅原序列DFT 的虚部00.51 1.52-5050100振幅其共轭对称序列DFT00.51 1.52振幅其共轭反对称序列DFT。