数字基带信号功率谱的MATLAB仿真程序代码

clear all; close all; Ts=1; N_sample=8; dt=Ts/N_sample; N=1000; t=0:dt:(N*N_sample-1)*dt; T=t(end); gt1=ones(1,N_sample); gt2=ones(1,N_sample/2); gt2=[gt2 zeros(1,N_sample/2)]; mt3=sinc((t-5)/Ts); gt3=mt3(1:10*N_sample); d=(sign(randn(1,N))+1)/2; data=sigexpand(d,N_sample); st1=conv(data,gt1); st2=conv(data,gt2); d=2*d-1; data=sigexpand(d,N_sample); st3=conv(data,gt3); [f,st1f]=T2F(t,[st1(1:length(t))]); [f,st2f]=T2F(t,[st2(1:length(t))]); [f,st3f]=T2F(t,[st3(1:length(t))]); figure(1) subplot(321) plot(t,[st1(1:length(t))]);grid; axis([0 20 -1.5 1.5]);ylabel('单极性NRZ波形'); subplot(322) plot(f,10*log10(abs(st1f).^2/T));grid; axis([-5 5 -40 10]);ylabel('单极性NRZ攻略谱密度'); subplot(323) plot(t,[st2(1:length(t))]);grid; axis([0 20 -1.5 1.5]);ylabel('单极性RZ波形'); subplot(324) plot(f,10*log10(abs(st2f).^2/T)); axis([-5 5 -40 10]);ylabel('单极性RZ功率谱密度(dB/Hz)'); subplot(325) plot(t-5,[st3(1:length(t))]);grid; axis([0 20 -2 2]);ylabel('双极性sinc波形'); subplot(326) plot(f,10*log10(abs(st3f).^2/T)); grid; axis([-5 5 -40 10]);ylabel('sinc 波形功率谱密度');xlabel('f*Ts');