【信号处理】基于2PSK实现信号调制解调含Matlab源码.zip

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));%随机序列,基带信号 st1=t; for n=1:10 if a(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 st1(m)=1; end end end figure(1); subplot(511); plot(t,st1); title('基带信号'); axis([0,5,-1,2]); %%%%%%%%%%%&&&&&&%%%%%%%%%%%%%%%%%产生双极性基带信号 st2=t; for k=1:j; if st1(k)>=1; st2(k)=0; else st2(k)=1; end end; st3=st1-st2;%双极性基带信号 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%载波信号 s1=sin(2*pi*fc*t); subplot(512); plot(s1); title('载波信号'); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%调制 psk=st3.*s1; subplot(513); plot(t,psk); title('2PSK信号'); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%相干解调 psk=psk.*s1;%与载波相乘 [f,af] = T2F(t,psk);%%%%%%%%%%%通过低通滤波器 [t,psk] = lpf(f,af,B); subplot(514); 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')