1、数字信号处理上机答案（含程序及图片）第三版高西全 丁玉美著数字信号处理实验一内容一a=0.8;ys=0;A=1,-0.9;B=0.05,0.05; xn=1,zeros(1,50);x1n=1 1 1 1 1 1 1 1 zeros(1,50); x2n=ones(1,128); xi=filtic(B,A,ys);hn=filter(B,A,xn,xi)n=0:length(hn)-1;subplot(2,2,1);stem(n,yn,.)title(a) 系统单位脉冲响应h(n);xlabel(n);ylabel(hn);y1n=filter(B,A,x1n,xi); n=0:length
2、(y1n)-1;subplot(2,2,2);y=y1(n); stem(n,y1n,.)title(b) 系统对R8(n)的响应y1(n);xlabel(n);ylabel(yn);y2n=filter(B,A,x2n,xi); n=0:length(y2n)-1;subplot(2,2,4);y=y2(n); stem(n,y2n,.)title(c) 系统对u(n)的响应y2(n);xlabel(n);ylabel(yn);内容二x1n=1 1 1 1 1 1 1 1 ;h1n=ones(1,10) zeros(1,10);h2n=1 2.5 2.5 1 zeros(1,10);y21n
3、=conv(h1n,x1n);y22n=conv(h2n,x1n);M1=length(y21n)-1;M2=length(y22n)-1;n1=0:1:M1;n2=0:1:M2;n11=0:length(h1n)-1;n22=0:length(h2n)-1;subplot(2,2,1); tstem(n11,h1n); title(d) 系统单位脉冲响应h1(n);xlabel(n);ylabel(h1(n);subplot(2,2,2); stem(n1,y21n,fill);title(e) h1(n)与R8(n)的卷积y21(n);xlabel(n);ylabel(y21(n);sub
4、plot(2,2,3); tstem(n22,h2n); title(f) 系统单位脉冲响应h2(n);xlabel(n);ylabel(h2(n);subplot(2,2,4); stem(n1,y22n,fill);title(g) h2(n)与R8(n)的卷积y22(n);xlabel(n);ylabel(y22(n);内容三谐振器对u(n)的响应a=0.8;ys=0;xn=1,zeros(1,250); B=1/100.49,-1/100.49;A=1,-1.8237,0.9801;xi=filtic(B,A,ys);yn=filter(B,A,xn,xi)n=0:length(yn)
5、-1;subplot(1,1,1);stem(n,yn,.)谐振器对正弦信号的响应a=0.8;ys=0;xsin=sin(0.014*n)+sin(0.4*n); B=1/100.49,-1/100.49;A=1,-1.8237,0.9801;xi=filtic(B,A,ys);yn=filter(B,A,xsin,xi)n=0:length(yn)-1;subplot(1,1,1);stem(n,yn,.)数字信号处理实验三实验（1）x1n=ones(1,4);X1k8=fft(x1n,8);X1k16=fft(x1n,16);N=8;f=2/N*(0:N-1);figure(1);subp
6、lot(1,2,1);stem(f,abs(X1k8),.);title(la) 8DFTx_1(n);xlabel(omega/pi);ylabel(|(ejomega)|);N=16;f=2/N*(0:N-1);subplot(1,2,2);stem(f,abs(X1k16),.);title(la) 16DFTx_1(n);xlabel(omega/pi);ylabel(|(ejomega)|);实验（1-2，1-3）M=8;xa=1:(M/2);xb=(M/2):-1:1;x2n=xa,xb;x3n=xb,xa;X2k8=fft(x2n,8);X2k16=fft(x2n,16);X3k
7、8=fft(x3n,8);X3k16=fft(x3n,16);figure(2);N=8;f=2/N*(0:N-1);subplot(2,2,1);stem(f,abs(X2k8),.);title(2a) 8DFTx_2(n);xlabel(omega/pi);ylabel(|(ejomega)|);subplot(2,2,3);stem(f,abs(X3k8),.);title(3a) 8DFTx_3(n);xlabel(omega/pi);ylabel(|(ejomega)|);N=16;f=2/N*(0:N-1);subplot(2,2,2);stem(f,abs(X2k16),.);
8、title(2a) 16DFTx_2(n);xlabel();ylabel();subplot(2,2,4);stem(f,abs(X3k16),.);title(3a) 16DFTx_3(n);xlabel(omega/pi);ylabel(|(ejomega)|);实验（2-1，2-2）N=8;n=0:N-1;x4n=cos(pi*n/4);x5n=cos(pi*n/4)+cos(pi*n/8);X4k8=fft(x4n,8);X4k16=fft(x4n,16);X5k8=fft(x5n,8);X5k16=fft(x5n,16);figure(3);N=8;f=2/N*(0:N-1);su
9、bplot(2,2,1);stem(f,abs(X4k8),.);title(4a) 8DFTx_4(n);xlabel(omega/pi);ylabel(|(ejomega)|);subplot(2,2,3);stem(f,abs(X5k8),.);title(5a) 8DFTx_5(n);xlabel(omega/pi);ylabel(|(ejomega)|);N=16;f=2/N*(0:N-1);subplot(2,2,2);stem(f,abs(X4k16),.);title(4a) 16DFTx_4(n);xlabel(omega/pi);ylabel(|(ejomega)|);su
10、bplot(2,2,4);stem(f,abs(X5k16),.);title(5a) 16DFTx_5(n);xlabel(omega/pi);ylabel(|(ejomega)|);实验（3）Fs=64;T=1/Fs;N=16;n=0:N-1;nT=n*T;x8n=cos(8*pi*nT)+cos(16*pi*nT)+cos(20*pi*nT);X8k16=fft(x8n,16);N=16;f=2/N*(0:N-1);figure(4);subplot(2,2,1);stem(f,abs(X8k16),.);title(8a) 16DFTx_8(n);xlabel(omega/pi);yl
11、abel(|(ejomega)|);N=32;n=0:N-1;nT=n*T;x8n=cos(8*pi*nT)+cos(16*pi*nT)+cos(20*pi*nT);X8k32=fft(x8n,32);N=32;f=2/N*(0:N-1);figure(4);subplot(2,2,2);stem(f,abs(X8k32),.);title(8a) 32DFTx_8(n);xlabel(omega/pi);ylabel(|(ejomega)|);N=64;n=0:N-1;nT=n*T;x8n=cos(8*pi*nT)+cos(16*pi*nT)+cos(20*pi*nT);X8k64=fft(
12、x8n,64);N=64;f=2/N*(0:N-1);figure(4);subplot(2,2,3);stem(f,abs(X8k64),.);title(8a) 64DFTx_8(n);xlabel(omega/pi);ylabel(|(ejomega)|);数字信号处理实验四内容一function st=mstgN=800 Fs=10000;T=1/Fs;Tp=N*T; t=0:T:(N-1)*T;k=0:N-1;f=k/Tp;fc1=Fs/10;fm1=fc1/10; fc2=Fs/20; fm2=fc2/10; fc3=Fs/40;fm3=fc3/10; xt1=cos(2*pi*f
13、m1*t).*cos(2*pi*fc1*t); xt2=cos(2*pi*fm2*t).*cos(2*pi*fc2*t); xt3=cos(2*pi*fm3*t).*cos(2*pi*fc3*t); st=xt1+xt2+xt3; fxt=fft(st,N); subplot(3,1,1)plot(t,st);grid;xlabel(t/s);ylabel(s(t);axis(0,Tp/8,min(st),max(st);title(a) s(t)的波形)subplot(3,1,2)stem(f,abs(fxt)/max(abs(fxt),.);grid;title(b) s(t)的频谱)ax
14、is(0,Fs/5,0,1.2);xlabel(f/Hz);ylabel(幅度)内容二Fs=10000;T=1/Fs; st=mstg;%低通滤波器设计与实现fp=280;fs=450;wp=2*fp/Fs;ws=2*fs/Fs;rp=0.1;rs=60; N,wp=ellipord(wp,ws,rp,rs);B,A=ellip(N,rp,rs,wp); y1t=filter(B,A,st); figure(2);subplot(3,1,1);H,w=freqz(B,A,1000);m=abs(H);plot(w/pi,20*log(m/max(m);gridon;title(低通滤波损耗函数
15、曲线);xlabel(w/pi );ylabel(幅度); axis(0,1,0,1.2*max(H)yt=y1(t);subplot(3,1,2); plot(t,y1t);title(低通滤波后的波形);xlabel(t/s);ylabel(y1(t);%带通滤波器设计与实现fpl=440;fpu=560;fsl=275;fsu=900;wp=2*fpl/Fs,2*fpu/Fs;ws=2*fsl/Fs,2*fsu/Fs;rp=0.1;rs=60; N,wp=ellipord(wp,ws,rp,rs); B,A=ellip(N,rp,rs,wp); y2t=filter(B,A,st); f
16、igure(3);subplot(3,1,1);H,w=freqz(B,A,1000);m=abs(H);plot(w/pi,20*log(m/max(m);gridon;title(带通滤波损耗函数曲线);xlabel(w/pi );ylabel(幅度); axis(0,1,0,1.2*max(H)yt=y2(t);subplot(3,1,2); plot(t,y2t);title(带通滤波后的波形);xlabel(t/s);ylabel(y2(t);%高通滤波器设计与实现fp=890;fs=600;wp=2*fp/Fs;ws=2*fs/Fs;rp=0.1;rs=60; N,wp=ellip
17、ord(wp,ws,rp,rs); B,A=ellip(N,rp,rs,wp,high);y3t=filter(B,A,st); figure(4);subplot(3,1,1);H,w=freqz(B,A,1000);m=abs(H);plot(w/pi,20*log(m/max(m);gridon;title(高通滤波损耗函数曲线);xlabel(w/pi );ylabel(幅度); axis(0,1,0,1.2*max(H)yt=y3(t);subplot(3,1,2); plot(t,y3t);title(高通滤波后的波形);xlabel(t/s);ylabel(y3(t);低通滤波器
18、损耗函数及其分离出的调幅信号y1(t)带通滤波器损耗函数及其分离出的调幅信号y2(t)高通滤波器损耗函数及其分离出的调幅信号y3(t)数字信号处理实验五1、function xt=xtg(N)Fs=1000;T=1/Fs;Tp=N*T;t=0:T:(N-1)*T;fc=Fs/10;f0=fc/10;mt=cos(2*pi*f0*t); ct=cos(2*pi*fc*t); xt=mt.*ct; nt=2*rand(1,N)-1; fp=150; fs=200;Rp=0.1;As=60;fb=fp,fs;m=0,1; dev=10(-As/20),(10(Rp/20)-1)/(10(Rp/20)
19、+1);n,fo,mo,W=remezord(fb,m,dev,Fs);hn=remez(n,fo,mo,W); yt=filter(hn,1,10*nt); xt=xt+yt; fst=fft(xt,N);k=0:N-1;f=k/Tp;subplot(3,1,1);plot(t,xt);grid;xlabel(t/s);ylabel(x(t);axis(0,Tp/5,min(xt),max(xt);title(a) 信号加噪声波形)subplot(3,1,2);plot(f,abs(fst)/max(abs(fst);grid;title(b) 信号加噪声的频谱)axis(0,Fs/2,0,
20、1.2);xlabel(f/Hz);ylabel(幅度)2、xt=xtg;N=1000;Fs=1000;T=1/Fs;Tp=N*T;k=0:N-1;f=k/Tp;t=0:T:(N-1)*T;fp=120;fs=150;Rp=0.1;As=60;Fs=1000;wc=(fp+fs)/Fs;B=2*pi*(fs-fp)/Fs;M=ceil(11*pi/B);hn=fir1(M-1,wc,blackman(M);Hw=abs(fft(hn,N);ywt=fftfilt(hn,xt,N);figure;subplot(2,1,1);plot(f,20*log10(Hw)/max(Hw);grid onxlabel(f/Hz);ylabel(幅度（dB）);title(a)低通滤波器的幅频特性)axis(0,500,-160,5);subplot(2,1,2);plot(t,ywt);grid onxlabel(t/s);ylabel(y_1(t);title(b)滤除噪声后的信号波形)
