通信原理课程设计194439new

1、附录：数字基带信号的仿真代码与结果functionf,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.mclear all;close all;Ts

2、=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=gt2 zeros(1,N_sample/2);%1x8mt3=sinc(t-5)/Ts);% 1x8000 sin(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)+

3、1)/2;%1x1000 d=?data=sigexpand(d,N_sample);%插入N_sample-1个0gt4=ones(1,N_sample);gt5=ones(1,N_sample/2);gt5=gt5 zeros(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(

4、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(0 20 -1.5 1.5);xlabel(单极性NRZ波形);gridsubplot(322);plot(f,10*log10(abs(st1f).2/T);gridaxis(-5 5 -40 10);xlabel(单极性NRZ功率

5、谱密度(dB/Hz);subplot(323)plot(t,st2(1:length(t);gridaxis(0 20 -1.5 1.5);xlabel(单极性RZ波形);subplot(324);plot(f,10*log10(abs(st2f).2/T);gridaxis(-5 5 -40 10);xlabel(单极性RZ功率谱密度(dB/Hz);subplot(325)plot(t-5,st3(1:length(t);gridaxis(0 20 -2 2);ylabel(双极性sinc波形);xlabel(t/Ts);subplot(326);plot(f,10*log10(abs(st

6、3f).2/T);gridaxis(-5 5 -40 10);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(0 20 -1.5 1.5);xlabel(双极性NRZ波形);gridsubplot(222);plot(f,10*log10(abs(st4f).2/T);gridaxis(-5 5 -40 10);xlabel(双极性NRZ功率谱密度(dB/Hz);subplot(223)plot(t,st5(1:length(t);gridaxis(0 20 -1.5

7、 1.5);xlabel(双极性RZ波形);subplot(224);plot(f,10*log10(abs(st5f).2/T);gridaxis(-5 5 -40 10);xlabel(双极性RZ功率谱密度(dB/Hz);7附录：数字基带信号接收的仿真代码与结果%数字基带信号接收示意图 digit_receive.mN=100;N_sample=8;Ts=1;dt=Ts/N_sample;t=0:dt:(N*N_sample-1)*dt;gt=ones(1,N_sample);d=sign(randn(1,N);a=sigexpand(d,N_sample);st=conv(a,gt);h

8、t1=gt;rt1=conv(st,ht1);ht2=5*sinc(5*(t-5)/Ts);rt2=conv(st,ht2);figure(1)subplot(321);plot(t,st(1:length(t);axis(0 20 -1.5 1.5);xlabel(输入双极性NRZ数字基带波形);subplot(322);stem(t,a);axis(0 20 -1.5 1.5);xlabel(输入数字序列);subplot(323);plot(t,0 rt1(1:length(t)-1)/8);axis(0 20 -1.5 1.5);xlabel(方波滤波后输出);subplot(324)

9、;dd=rt1(N_sample:N_sample:end);ddd=sigexpand(dd,N_sample);stem(t,ddd(1:length(t)/8);axis(0 20 -1.5 1.5);xlabel(方波滤波后抽样输出);subplot(325);plot(t-5,0 rt2(1:length(t)-1)/8);axis(0 20 -1.5 1.5);xlabel(t/Ts);ylabel(理想低通滤波后输出);subplot(326);dd=rt2(N_sample-1:N_sample:end);ddd=sigexpand(dd,N_sample);stem(t-5,

10、ddd(1:length(t)/8);axis(0 20 -1.5 1.5);xlabel(t/Ts);ylabel(理想低通滤波后抽样输出);附录： 升余弦滚降系统仿真代码与结果 %升余弦滚降系统示意图 raisecos.mTs=1;N_sample=17;dt=Ts/N_sample;df=1.0/(20.0*Ts);t=-10*Ts:dt:10*Ts;f=-2/Ts:df:2/Ts;alpha=0,0.5,1;for n=1:length(alpha) for k=1:length(f) if abs(f(k)0.5*(1+alpha(n)/Ts Xf(n,k)=0; elseif ab

11、s(f(k)1)=0;a=1-2*(rand(1,M)0.5);delta=zeros(1,N);delta(L/2:L:N)=a*fs;S=t2f(delta,fs).*G;s=real(f2t(S,fs);plot(t,s)附录：最佳基带传输系统的仿真1、无码间干扰的的基带传输系统 function s=f2t(S,fs) N=length(S); T=N/fs t=-(T/2):1/fs:(T/2-1/fs); tmp1=fft(S)/T; tmp2=N*ifft(S)/T; s(1:N/2)=tmp1(N/2+1:-1:2); s(N/2+1:N)=tmp2(1:N/2); s=s.*

12、exp(-j*pi*t*fs);end%s为输入信号，S为s的频谱，fs为采样率；function S=t2f(s,fs) N=length(s);T=1/fs*N;f=-N/2:(N/2-1)/T;tmp1=fft(s)/fs;tmp2=N*ifft(s)/fs;S(1:N/2)=tmp2(N/2+1:-1:2);S(N/2+1:N)=tmp1(1:N/2);S=S.*exp(j*pi*f*T);endclear all;close all;N=213;L=16;M=N/L;Rs=2;Ts=1/Rs;fs=L/Ts;Bs=fs/2;T=N/fs;t=-T/2+0:N-1/fs;f=-Bs+0

13、:N-1/T;alpha=0.5;Hcos=zeros(1,N);ii=find(abs(f)(1-alpha)/(2*Ts)&abs(f)=(1+alpha)/(2*Ts);Hcos(ii)=Ts/2*(1+cos(pi*Ts/alpha*(abs(f(ii)-(1-alpha)/(2*Ts);ii=find(abs(f)(1-alpha)/(2*Ts1)&abs(f)=(1+alpha)/(2*Ts1);Hcos(ii)=Ts1/2*(1+cos(pi*Ts1/alpha*(abs(f(ii)-(1-alpha)/(2*Ts1);ii=find(abs(f)=(1-alpha)/(2*Ts1);Hcos(ii)=Ts1;Hrcos=sqrt(Hcos);EP=zeros(1,N);for loop=1:2000 a=sign(randn(1,M); s1=zeros(1,N); s1(1:L:N)=a*fs; S1=t2f(s1,fs); S2=S1.*Hrcos; s2=real(f2t(S2,fs); P=abs(S2).2/T; EP=EP*