实验三 单双极性归零码波形和频谱

实验三单双极性归零码波形和频谱

八、程序代码

%initialize clear;

fs=512*1000; T=1;N=T*fs;

dt=1/fs;

t=-T/2:dt:(T/2-dt); df=1/T;

f=-fs/2:df:(fs/2-df);

L=100;

M=N/L;

Tb=L*dt;

Rb=1/Tb;

SINGLE=zeros(1,N);

DOUBLE=zeros(1,N);

%you decide the length of each sign

emp_rate=input('输入占空比：');

looptime=100;

for kk=1:looptime

%original binary flow

imp=round(rand(1,M));

%generate the actual wave in signal pole form

single=zeros(1,N);

for ii=1:emp_rate*L

for jj=1:M

single(ii+(jj-1)*L)=imp(jj);

end

end

%and in double pole form

double=single;

for ii=1:N

if single(ii)==0

double(ii)=-1;

end

end

SINGLE=SINGLE+t2f(single,fs)/looptime;DOUBLE=SINGLE+t2f(double,fs)/looptim e;

end

%let's plot them out

figure(1)

subplot(2,1,1)

plot(t,single);

axis([-T/2,T/2,-0.2,1.2])

title('单极性NRZ波形')

xlabel('时间(s)')

ylabel('幅度(V)')

subplot(2,1,2)

semilogy(f,abs(SINGLE).^2);

axis([-10*Rb,10*Rb,1e-10,20])

title('单极性NRZ功率谱')

xlabel('频率(Hz)')

ylabel('幅度(W/Hz)')

figure(2)

subplot(2,1,1)

plot(t,double);

axis([-T/2,T/2,-1.2,1.2])

title('双极性NRZ波形')

xlabel('时间(s)')

ylabel('幅度(V)')

subplot(2,1,2)

semilogy(f,abs(DOUBLE).^2);

axis([-10*Rb,10*Rb,1e-10,20])

title('双极性NRZ功率谱')

xlabel('频率(Hz)')

ylabel('幅度(W/Hz)')