,J2);axis([030000max(J2)])xlabel('加噪声解调信号频谱')subplot(223)plot(t,Y1)xlabel('无噪声解调信号波形')subplot(224)plot(frqJ1,J1)xlabel('无噪声解调信号频谱')%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%dyi=sn-S;%高斯白噪声s_ni=var(S)/var(dyi);%输入信噪比dyo=YYN-Y1;%解调后噪声s_no=var(Y1)/var(dyo);%输出信噪比dyi1=sn1-S;s_ni1=var(S)/var(dyi1);dyo1=YYN1-Y1;s_no1=var(Y1)/var(dyo1);dyi2=sn2-S;s_ni2=var(S)/var(dyi2);dyo2=YYN2-Y1;s_no2=var(Y1)/var(dyo2);dyi3=sn3-S;s_ni3=var(S)/var(dyi3);dyo3=YYN3-Y1;s_no3=var(Y1)/var(dyo3);dyi4=sn4-S;s_ni4=var(S)/var(dyi4);dyo4=YYN4-Y1;s_no4=var(Y1)/var(dyo4);in=[s_ni,s_ni1,s_ni2,s_ni3,s_ni4];out=[s_no,s_no1,s_no2,s_no3,s_no4];set(gcf,'color','w');figure(3);plot(in,out,'*')holdonplot(in,out)xlabel('输入信噪比')ylabel('输出信噪比')3.1.1调制信号幅度=0.8×载波幅度调用程序,程序中a=0.8。调制信号、已调信号的波形、频谱如图3所示:图3调制信号、已调信号的波形、频谱图解调信号的波形、频谱如图4所示:
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