xinhaochouyang.rar_multiplexer_信号离散化_抽样定理_混叠现象_连续时间信号

clc,clear for ii=1:3 switch ii case 1 bs=1.5; case 2 bs=2; case 3 bs=3; end dt=0.01; t=0:dt:1; f=8; %信号频率 wm=2*pi*f; ft=cos(wm*t); %时域信号 % bs=1.5; %采样角频率，欠采样 %bs=2; %2倍采样角频率 bs=3; %采样角频率，大于两倍采样 ws=bs*wm; Ts=2*pi/ws; %采样间隔 wc=1/2*ws; %理想低通截止频率 % wc=wm; %理想低通截止频率 nTs=0:Ts:1; f_nTs=cos(wm*nTs); %时域采样信号 % f_guancha=-3*(1/Ts):0.01:3*(1/Ts); ftx=0; for n=1:length(nTs) ftx=ftx+f_nTs(n).*sinc((ws/(2*pi))*(t-nTs(n))); end posplot=['3,1,',int2str(ii)]; subplot(posplot) subplot(221) plot(t,ft); hold on; plot(nTs,f_nTs,'r--'); xlabel('nTs'); ylabel('f(nTs)'); title([num2str(bs),'倍采样频率的采样信号cos(t)']); grid; error=abs(ft-ftx); %求重建信号与原信号的误差 subplot(222); plot(t,error); xlabel('t');ylabel('error(t)'); title(['\omegac=','1/2ws' '重建信号与原信号的误差error']); grid on; subplot(223) plot(t,ft); hold on; plot(t,ftx,'r--'); xlabel('t'); title('原信号与重建信号的比较') subplot(224) f_guancha=0:0.01:12 fnTs_ftf=sig_spec(f_nTs,nTs,Ts,f_guancha); psf1=(abs(fnTs_ftf).^2/1); plot(f_guancha,psf1); hold on ftx_ftf=sig_spec(ftx,t,dt,f_guancha); psf2=(abs(ftx_ftf).^2/1); plot(f_guancha,psf2,'r--'); xlabel('f(Hz)'); title([num2str(bs),'倍采样信号与重建信号的功率谱']); set(gca,'xtick',[0 4 8 12]); end