mod_msk2.m

本程序为通信系统中的MSK调制程序

function [signal_out,I_out,Q_out,phase] = mod_msk2(data,data_len,sample_number,Rb)
%MSK基带调制
%**************************************************************************
% data              调制信号
% data_len          码元个数
% sample_number     每个码元采样点数
% Rb                码元速率
% signal_out        基带调制输出
% I_out             I路输出
% Q_out             Q路输出
%**************************************************************************

% data_len = 10;                %码元个数
% sample_number = 8;            %采样点数
% Rb = 16000;                   %码元速率
% data1 = randint(1,data_len);
% data = 2*data1-1;             %传输的序列

Tb = 1/Rb;                      %码元时间
fs = Rb*sample_number;          %采样速率

%--------------------------------------------------------------------------
%采样
for i = 1:sample_number
    data_sample(i:sample_number:data_len*sample_number) = data;
end
%**************************************************************************

%--------------------------------------------------------------------------
%计算相位
phase = zeros(1,data_len*sample_number);
phase(1) = data_sample(1) * pi/2/sample_number;
for i = 2:data_len*sample_number
    phase(i) = phase(i-1) + data_sample(i-1) * pi/2/sample_number;
end
%**************************************************************************

%--------------------------------------------------------------------------
%I\Q
I_out = cos(phase);
Q_out = sin(phase);
%**************************************************************************

%--------------------------------------------------------------------------
%调制信号产生
signal_out = I_out + j*Q_out;
%**************************************************************************