基于MATLAB的二进制数字系统的调制(包括2ask,2fsk,2psk,2dpsk)(6)

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end end; subplot(412); plot(t,st2);

title('基带信号反码st2'); axis([0,5,-1,2]); st3=st1-st2; subplot(413); plot(t,st3);

title('双极性基带信号st3'); axis([0,5,-2,2]);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%载波信号 s1=sin(2*pi*fc*t); subplot(414); plot(s1);

title('载波信号s1');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%调制 e_psk=st3.*s1; figure(2); subplot(511); plot(t,e_psk); title('e_2psk'); noise=rand(1,j);

psk=e_psk+noise;%加入噪声 subplot(512); plot(t,psk); title('加噪后波形');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%相干解调 psk=psk.*s1;%与载波相乘 subplot(513); plot(t,psk);

title('与载波s1相乘后波形');

[f,af] = T2F(t,psk);%%%%%%%%%%%通过低通滤波器 [t,psk] = lpf(f,af,B); subplot(514);

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plot(t,psk);

title('低通滤波后波形');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%抽样判决 for m=0:i-1;

if psk(1,m*500+250)<0; for j=m*500+1:(m+1)*500; psk(1,j)=0; end else

for j=m*500+1:(m+1)*500; psk(1,j)=1; end end end subplot(515); plot(t,psk); axis([0,5,-1,2]); title('抽样判决后波形')

2DPSK调制解调程序及注释 clear all close all i=10; j=5000; fc=4;%载波频率 fm=i/5;%码元速率 B=2*fm; t=linspace(0,5,j);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%产生基带信号 a=round(rand(1,i)); figure(4); stem(a); st1=t; for n=1:10 if a(n)<1;

for m=j/i*(n-1)+1:j/i*n

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st1(m)=0; end else

for m=j/i*(n-1)+1:j/i*n st1(m)=1; end end end figure(1); subplot(321); plot(t,st1); title('绝对码'); axis([0,5,-1,2]);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%差分变换 b=zeros(1,i);%%%%%%%%全零矩阵 b(1)=a(1); for n=2:10 if a(n)>=1; if b(n-1)>=1 b(n)=0; else b(n)=1; end else

b(n)=b(n-1); end end st1=t; for n=1:10 if b(n)<1;

for m=j/i*(n-1)+1:j/i*n st1(m)=0; end else

for m=j/i*(n-1)+1:j/i*n

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st1(m)=1; end end end subplot(323); plot(t,st1); title('相对码st1'); axis([0,5,-1,2]); st2=t; for k=1:j; if st1(k)>=1; st2(k)=0; else

st2(k)=1; end end; subplot(324); plot(t,st2);

title('相对码反码st2'); axis([0,5,-1,2]);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%载波信号 s1=sin(2*pi*fc*t); subplot(325); plot(s1);

title('载波信号s1'); s2=sin(2*pi*fc*t+pi); subplot(326); plot(s2);

title('载波信号s2');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%信号调制 d1=st1.*s1; d2=st2.*s2; figure(2); subplot(411); plot(t,d1);

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title('st1*s1'); subplot(412); plot(t,d2); title('st2*s2'); e_dpsk=d1+d2; subplot(413); plot(t,e_dpsk); title('调制后波形'); noise=rand(1,j);

dpsk=e_dpsk+noise;%%%%%%%%%%加入噪声 subplot(414); plot(t,dpsk); title('加噪声后信号');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%相干解调 dpsk=dpsk.*s1;%%%%与载波s1相乘 figure(3); subplot(411); plot(t,dpsk);

title('与载波相乘后波形');

[f,af]=T2F(t,dpsk);%%%%通过低通滤波器 [t,dpsk]=lpf(f,af,B); subplot(412); plot(t,dpsk);

title('低通滤波后波形');

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%抽样判决 st=zeros(1,i);%%全零矩阵 for m=0:i-1;

if dpsk(1,m*500+250)<0; st(m+1)=0;

for j=m*500+1:(m+1)*500; dpsk(1,j)=0; end else

for j=m*500+1:(m+1)*500; st(m+1)=1;

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