fsk0.m

matlab下的FSK程序

function [y, fs, fb, fc1, fc2] = fsk(x, Kbase, fs, fb, fc1, fc2);
%
% Usage: FSK调制
% chc 05-3-19(Example from book p288)
% ----------------------------------------------------%
% x: bit stream; Kbase:1/2--（不）采用基带成形        %
% (fs:sampling fre; fb:bit rate; fc:carrier fre)      %
% y: 已调信号                                         %
%-----------------------------------------------------%
if nargin<6; fc2=2.5;   end;
if nargin<5; fc1=2;     end;
if nargin<4; fb=1;      end;
if nargin<3; fs=32;     end;
if nargin<2; Kbase=1;   end;
if nargin<1; 
    x=[0 0 1 1 1 0 0 1 0 1 1 0 0 0 1 0]; end;
T=length(x)/fb;
m=fs/fb;
dt=1/fs; t=0:dt:T-dt;
xx=RecPulse(x, m, 2);                                                      % 基带信号
if Kbase==2; xx=bshapeEx(xx); end;                                         % 基带成形
y= (xx>=0).*sin(2*pi*fc1*t)+(xx<0).*sin(2*pi*fc2*t);                       % FS

% ----------------------------------------------------------- %
if nargout<1;
    subplot(211); plot(t, y, t, xx*.5, [0 T], [0 0], 'b:');
    title('Signal');
    
    n=length(y); y=fft(y)/n; y=abs(y(1:fix(n/2)))*2;
    I=find(y<1e-04); y(I)=1e-04; x=20*log10(x);    
    f1=m/n; f=0:f1:(length(y)-1)*f1;
    subplot(212); plot(f, y, 'r'); grid on;
    title('Spectrum'); xlabel('f/fb'); zoom xon;
    set(gcf,'num','off','name',...
        ['FSK', blanks(10)]);
end;