fm_modulate.m

程序实现了基带FM调制和解调

function [signal_I,signal_Q,int_v] = fm_modulate(fm,fs,Kf,v,fai_mod) 

%--------------------------------------------------------------------------
% 用matlab中的库函数cumsum可以求累积
int_v = cumsum (v) .* (1 / fs);

%--------------------------------------------------------------------------
% 对音频信号在I,Q两路上进行调制
% fai_mod为一定的相位延迟
signal_I = cos(Kf .* int_v + fai_mod);
signal_Q = sin(Kf .* int_v + fai_mod);

x = cos(Kf .* int_v);
y = sin(Kf .* int_v);

%--------------------------------------------------------------------------
%循环求累积
% int_v(1)=0;
% for i=1:length(t)-1                  	% Integral of v
%   int_v(i+1)=int_v(i)+v(i)*ts;
% end

% ts = 1 / fs;
% % 对此单音信号v(t) = cos(xt)在[0,T]上求积分得到int_v,
% % 以其做为调制过程的调制信号
% 
% sin_wave = sin(2 * pi * fm .* t + fai_v);
% int_v = 1 / (2 * pi * fm) .* sin_wave;