发布时间 : 星期六 文章MATLAB环境下16QAM调制及解调仿真程序说明更新完毕开始阅读dacc620827fff705cc1755270722192e44365896
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I=filtfilt(b,a,I); Q=filtfilt(b,a,Q);
m=4*fs/fb; N=length(y)/m; n=(.6:1:N)*m; n=fix(n); In=I(n); Qn=Q(n); xn=four2two([In Qn]); %I分量Q分量并/串转换，最终恢复成码元序列xn nn=length(xn); xn=[xn(1:nn/2);xn(nn/2+1:nn)]; xn=xn(:); xn=xn';
bshape.m
%基带升余弦成形滤波器
function y=bshape(x,fs,fb,N,alfa,delay); %设置默认参数
if nargin<6; delay=8; end; if nargin<5; alfa=0.5; end; if nargin<4; N=16; end; b=firrcos(N,fb,2*alfa*fb,fs); y=filter(b,1,x);
two2four.m
%二进制转换成四进制
function [y,yn]=two2four(x,m); T=[0 1;3 2]; n=length(x); ii=1; for i=1:2:n-1;
xi=x(i:i+1)+1;
yn(ii)=T(xi(1),xi(2)); ii=ii+1; end;
yn=yn-1.5; y=yn; for i=1:m-1; y=[y;yn]; end;
y=y(:)'; %映射电平分别为-1.5；0.5；0.5；1.5
four2two.m
%四进制转换成二进制 function xn=four2two(yn);
y=yn; ymin=min(y); ymax=max(y); ymax=max([ymax abs(ymin)]); ymin=-abs(ymax); yn=(y-ymin)*3/(ymax-ymin); %设置门限电平，判决 I0=find(yn< 0.5); yn(I0)=zeros(size(I0)); I1=find(yn>=0.5 & yn<1.5); yn(I1)=ones(size(I1)); I2=find(yn>=1.5 & yn<2.5); yn(I2)=ones(size(I2))*2;
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I3=find(yn>=2.5); yn(I3)=ones(size(I3))*3; %一位四进制码元转换为两位二进制码元 T=[0 0;0 1;1 1;1 0]; n=length(yn); for i=1:n;
xn(i,:)=T(yn(i)+1,:); end;
xn=xn'; xn=xn(:); xn=xn';
constel.m
%画出星座图
function c=constel(x,fs,fb,fc);
N=length(x); m=2*fs/fb; n=fs/fc; i1=m-n; i=1; ph0=(i1-1)*2*pi/n; while i <= N/m; xi=x(i1:i1+n-1);
y=2*fft(xi)/n; c(i)=y(2); i=i+1; i1=i1+m; end;
%如果无输出，则作图 if nargout<1;
cmax=max(abs(c)); ph=(0:5:360)*pi/180;
plot(1.414*cos(ph),1.414*sin(ph),'c'); hold on; for i=1:length(c);
ph=ph0-angle(c(i)); a=abs(c(i))/cmax*1.414;
plot(a*cos(ph),a*sin(ph),'r*'); end;
plot([-1.5 1.5],[0 0],'k:',[0 0],[-1.5 1.5],'k:'); hold off; axis equal; axis([-1.5 1.5 -1.5 1.5]); end;
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