1.例题
2.代码
clear %表示a(t)t=0:0.01:3;a(1:100)=1;a(101:200)=-1;a(201:301)=1;fs=1; %抽样频率fc=0.3; %载波频率%调制y1=modulate(a,fc,fs,'am');%幅度调制y2=modulate(a,fc,fs,'fm');%频率调制y3=modulate(a,fc,fs,'pm',1);%相位调制%解调a1=demod(y1,fc,fs,'am');a2=demod(y2,fc,fs,'fm');a3=demod(y3,fc,fs,'pm',1);%绘出相关波形figure(1);subplot(211)plot(t,a);ylabel('a(t)');grid on;axis([0 4 -1.5 1.5])figure(2)subplot(321)plot(y1);title('幅度调制');grid on;subplot(322)plot(a1);title('AM解调后的信号');grid on;subplot(323)plot(y2);title('频率调制');grid on;subplot(324)plot(a2);title('FM解调后的信号');grid on;subplot(325)plot(y3);title('相位调制');grid on;subplot(326)plot(a3);title('PM解调后的信号');grid on;
