西电数字信号处理(三)实验四实验五程序答案.docVIP

信号产生函数mstg清单 function st=mstg N=1600 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*fm1*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) axis([0,Fs/5,0,1.2]); xlabel(f/Hz),ylabel(幅度) 数字滤波器的设计 clear all;close all; Fs=10000; T=1/Fs; st=mstg; fp=290;fs=440 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(2,1,1); [H,W]=freqz(B,A,1000); m=abs(H); plot(W/pi,20*log10(m));grid on; xlabel(\omega/\pi);ylabel(-A(dB)) axis([0,1,-110,5]);title(损耗函数曲线); figure(2);subplot(2,1,2); n=0:length(y1t)-1;t=n*T; plot(t,y1t);grid on; xlabel(t/s);ylabel(yn); axis([0,t(end),min(y1t),1.2*max(y1t)]);title(输出波形); clear all;close all; Fs=10000; T=1/Fs; st=mstg; fp1=430;fpu=570;fs1=280;fsu=900 wp=[2*fp1/Fs,2*fpu/Fs];ws=[2*fs1/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); figure(3);subplot(2,1,1); [H,W]=freqz(B,A,1000); m=abs(H); plot(W/pi,20*log10(m));grid on; xlabel(\omega/\pi);ylabel(-A(dB)) axis([0,1,-110,5]);title(损耗函数曲线); figure(3);subplot(2,1,2); n=0:length(y2t)-1;t=n*T; plot(t,y2t);grid on; xlabel(t/s);ylabel(yn); axis([0,t(end),min(y2t),1.2*max(y2t)]);title(输出波形); clear all;close all; Fs=10000; T=1/Fs; st=mstg; fp=880;fs=550; 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,high);