bshape.m

交全面的给出了好几种调制解调方案的matlab代码,又ASK,BPSK,FSK,QAM等的源代码 对通信领域的研究人员很有帮助

function y=bshape(x,fs,fb,N,alfa,delay);
%
% Usage: y=bshape(x,fs,fb,N,alfa,delay); BBI
% 2000;x为数字基带信号,fs为采样频率,fb为比特率,N为升余弦滚降滤波阶数,alfa成为滚降系数<其取值范围在0-1之间,delay代表眼图
% 的观测延迟,y为滤波后的信号
% Baseband shaping with a raised cosine filter
if nargin<6;delay=8;end;
if nargin<5;alfa=.5;end;
if nargin<4;N=16;end;
if nargin<3;fb=1;end;
if nargin<2;fs=16;end;
if nargin<1;x=pulse(randint(1,64));end;
b=firrcos(N,fb,2*alfa*fb,fs);
y=filter(b,1,x);y=y/max(abs(y));m=fs;
%--------------------------------------------------------------------------
if nargout<1;
    dt=1/m;t=0:dt:(length(y)-1)*dt;
    subplot(211);plot(t,x,t,y);
    v=axis;axis([v(1:2) v(3)-v(4)*.2 v(4)*1.2]);
     % ?  set(gcf,'num','off','name',['Baseband Shaping with a Raised Cosine Filter',(alfa='num2str(alfa)'),'blanks(10)','BBI 2000']);
    title('Pulse Signal'); h=get(gca,'children');
    set(h(1),'color','b');set(h(2),'color',[.9 .8 0]);
    subplot(224);n=length(y);eyescat(y(m:n),fb,fs,delay);
    y=fft(y)/n;y=abs(y(1:fix(n/4)))*2;
    I=find(y<1e-04);y(I)=1e-04;y=20*log10(y);
    x=fft(x)/n;x=abs(x(1:fix(n/4)))*2;
    I=find(x<1e-04);x(I)=1e-04;x=20*log10(x);
    f1=m/n;f=0:f1:(length(y)-1)*f1;
    subplot(223);plot(f,x,f,y);h=get(gca,'children');
    set(h(1),'color','b');set(h(2),'color',[.9 .8 0]);
    title('Power Spectrum');xlabel('f/fb');zoom xon;
end;