采样_采样_MATLAB带通采样_

clear all close all fH=12; fL=9.5; fs=fH*30; dt=1/fs; T=1000; df=1/T; t=[-T/2:dt:T/2-dt]; %ms f=[-fs/2:df:fs/2-df]; %kHz Nf=100; Delta=(fH-fL)/Nf; fc=(fH+fL)/2; x=zeros(1,length(t)); for i=1:Nf fi=fL+i*Delta-Delta/2; x=x+abs(fi-fc)/sqrt(fi-fL+1)*cos(2*pi*fi*t+rand*2*pi); end X=t2f(x,fs); Ns=30; %90 60 30 fsamp=fs/Ns %理想采样 xsamp=zeros(1,length(t)); xsamp([1:Ns:length(t)])=x([1:Ns:length(t)])/dt; %带通滤波 Xsamp=t2f(xsamp,fs)/fsamp; idx=find(abs(f)<=fH & abs(f)>=fL); Y=zeros(1,length(f)); Y(idx)=Xsamp(idx); y=real(f2t(Y,fs)); subplot(3,1,1) plot(f,abs(X)) axis([-20,20 0 400]) subplot(3,1,2) plot(f,abs(Xsamp)) axis([-20,20 0 400]) subplot(3,1,3) plot(f,abs(Y)) axis([-20,20 0 400])