通信原理课程设计1.docx

通信原理课程设计1

第一篇：通信原理课程设计1附录Ⅰ：数字基带信号的仿真代码与结果function[f,sf]=T2F(t,st)dt=t(2)-t(1);T=t(end);df=1/T;N=length(st);f=-N/2*df:df:N/2*df-df;sf=fft(st);sf=T/N*fftshift(sf);end%在把序列d插入到序列M中,得到一个新序列function[out]=sigexpand(d,M)N=length(d);out=zeros(M,N);out(1,:)=d;out=reshape(out,1,M*N);%数字基带信号的功率谱密度digit_baseband.mclearall;closeall;Ts=1;%每个码元的长度N_sample=8;%每个码元的抽样点数dt=Ts/N_sample;%抽样时间间隔N=1000;%码元数t=0:dt:(N*N_sample-1)*dt;%1x8000T=t(end);gt1=ones(1,N_sample);%1x8gt2=ones(1,N_sample/2);%1x4?1x8?gt2=[gt2zeros(1,N_sample/2)];%1x8mt3=sinc((t-5)/Ts);%1x8000sin(pi*t/Ts)/(pi*t/Ts)波形gt3=mt3(1:10*N_sample);%截段取10个码元d=(sign(randn(1,N))+1)/2;%1x1000d=??data=sigexpand(d,N_sample);%插入N_sample-1个0gt4=ones(1,N_sample);gt5=ones(1,N_sample/2);gt5=[gt5zeros(1,N_sample/2)];st1=conv(data,gt1);%调用Matlab的卷积函数convst2=conv(data,gt2);d=2*d-1;%变成双极性序列data=sigexpand(d,N_sample);st3=conv(data,gt3);st4=conv(data,gt4);st5=conv(data,gt5);[f,st1f]=T2F(t,[st1(1:length(t))]);[f,st2f]=T2F(t,[st2(1:length(t))]);[f,st3f]=T2F(t,[st3(1:length(t))]);[f,st4f]=T2F(t,[st4(1:length(t))]);[f,st5f]=T2F(t,[st5(1:length(t))]);figure(1)subplot(321)plot(t,[st1(1:length(t))]);axis([020-1.51.5]);xlabel('单极性NRZ波形');gridsubplot(322);plot(f,10*log10(abs(st1f).^2/T));gridaxis([-55-4010]);xlabel('单极性NRZ功率谱密度(dB/Hz)');subplot(323)plot(t,[st2(1:length(t))]);gridaxis([020-1.51.5]);xlabel('单极性RZ波形');subplot(324);plot(f,10*log10(abs(st2f).^2/T));gridaxis([-55-4010]);xlabel('单极性RZ功率谱密度(dB/Hz)');subplot(325)plot(t-5,[st3(1:length(t))]);gridaxis([020-22]);ylabel('双极性sinc波形');xlabel('t/Ts');subplot(326);plot(f,10*log10(abs(st3f).^2/T));gridaxis([-55-4010]);ylabel('sinc波形功率谱密度(dB/Hz)');xlabel('f*Ts');figure(2)subplot(221)plot(t,[st4(1:length(t))]);axis([020-1.51.5]);xlabel('双极性NRZ波形');gridsubplot(222);plot(f,10*log10(abs(st4f).^2/T));gridaxis([-55-4010]);xlabel('双极性NRZ功率谱密度(dB/Hz)');subplot(223)subplot(224);plot(t,[st5(1:length(t))]);gridplot(f,10*log10(abs(st5f).^2/T));gridaxis([020-1.51.5]);axis([-55-4010]);xlabel('双极性RZ波形');xlabel('双极性RZ功率谱