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1、AM调制解调过程仿真精品文档clcfs=1000;fc=20;fm=1;dt=0.001N=5/dt;t=0:N-1*dt;snr=1;g=5*cos(2*pi*fm*t);A=5;s_am=(A+g).*cos(2*pi*fc*t);figure(1);subplot(211);plot(g);grid on;df=fs/(N-1);f=(0:N-1)*df;yg=fft(g,N);mg=abs(yg(1:N/2)*2*pi/N;subplot(212);stem(f(1:20),mg(1:20);grid on;figure(2);subplot(211);plot(s_am);hold
2、on; plot(A+g,r-);grid on;df=fs/(N-1);f=(0:N-1)*df;y=fft(s_am,N);m=abs(y(1:N/2)*2*pi/N;subplot(212);stem(f(1:200),m(1:200);grid on;figure(3)subplot(211);x1=awgn(s_am,snr); plot(x1);grid on;N=1500; df=fs/(N-1);f=(0:N-1)*df;y1=fft(x1,N);m1=abs(y1(1:N/2)*2*pi/N;subplot(212);stem(f(1:150),m1(1:150);grid
3、on;y1 = x1(:);figure(4)subplot(211)t1 = (0 : 1/fs :(size(y1,1)-1)/fs);t1 = t1(:, ones(1, size(y1, 2);z1 = y1 .* cos(2*pi * fc * t1 );num,den = butter(5,fc*2/fs); for i = 1 : size(y1, 2) z1(:, i) = filtfilt(num, den, z1(:, i) * 2;endplot(g);hold onxx=z1-A;plot(xx,r)hold off运行结果：图1 原始信号及频谱图2 已调信号与原始信号对比图及已调信号频谱图3 加入噪声信号及频谱图4相干解调的信号与原始信号对比图收集于网络，如有侵权请联系管理员删除
