通信原理实验波形图

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1、AM相关解调AM包络检波AM相关解调结果AM相关解调结果AM包络解调结果DSBDSB结果滤波法产生SSB信号滤波法相移法产生SSB信号相移法FM调制时域图figure(1);dt=0.001;t=0:dt:1.5;am=15;fm=5;mt=am*cos(2*pi*fm*t);fc=50;ct=cos(2*pi*fc*t);kf=10;vt=cos(2*pi*fc*t+10*15*sin(2*pi*fm*t)/(2*pi*fm));subplot(3,1,1);plot(mt);axis([0,1500,-20,20]);ti

2、tle('调制信号的时域图');subplot(3,1,2);plot(ct);axis([0,1500,-1,1]);title('已调信号的时域图');FM调制频域图figure(2);am=15;fm=5;mt=am*cos(2*pi*fm*t);fc=50;ct=cos(2*pi*fc*t);kf=10;vt=cos(2*pi*fc*t+10*15*sin(2*pi*fm*t)/(2*pi*fm));subplot(2,1,1)Fs=20;T=1/Fs;N=1024;t=(0:N-1)*T;mt=am*cos(2*pi

3、*fm*t);NFFT=N;Y=fft(mt,NFFT)/N;f=Fs/2*linspace(0,1,NFFT/2);Am=2*abs(Y(1:NFFT/2));plot(f,Am)title('调制信号频谱')xlabel('Frequency/Hz'),ylabel('magnitude')subplot(2,1,2)Fs=200;T=1/Fs;N=1024;t=(0:N-1)*T;vt=cos(2*pi*fc*t+10*15*sin(2*pi*fm*t)/(2*pi*fm));NFFT=N;Y=fft(vt,NFFT)/

4、N;f=Fs/2*linspace(0,1,NFFT/2);Am=2*abs(Y(1:NFFT/2));plot(f,Am)title('已调信号频谱')xlabel('Frequency/Hz'),ylabel('magnitude')FM解调figure(3)dt=0.001;t=0:dt:1.5;am=15;fm=5;mt=am*cos(2*pi*fm*t);fc=50;ct=cos(2*pi*fc*t);kf=10;vt=cos(2*pi*fc*t+10*15*sin(2*pi*fm*t)/(2*pi*fm));sub

5、plot(3,1,1);plot(t,mt);title('调制信号时域图');subplot(3,1,2);plot(t,vt);title('已调信号时域图');vt1=vt;fori=1:length(t)-1diff_vt1(i)=(vt1(i+1)-vt1(i))/dt;enddiff_vt2=abs(hilbert(diff_vt1));zero=(max(diff_vt2)-max(diff_vt2))/2;diff_vt3=diff_vt2-zero;subplot(3,1,3);plot((1:length(

6、diff_vt3))/1000,diff_vt3/400);title('解调信号时域图');