function[signal_out,I_out,Q_out]=mod_msk(data,data_len,sample_number,Rb)
%MSK基帶調制
% data              調制信號
% data_len          碼元個數
% sample_number     每個碼元采樣點數
% Rb                碼元速率
% signal_out        基帶調制輸出
% I_out             I路輸出
% Q_out             Q路輸出
data_len = 10;                %碼元個數
sample_number = 8;            %采樣點數
Rb = 16000;                   %碼元速率
data1 = randint(1,data_len);
data = 2*data1-1;             %傳輸的序列
Tb = 1/Rb;                      %碼元時間
fs = Rb*sample_number;          %采樣速率
%差分編碼
[data_diff] = difference(data);
%并串轉換，延時
I(1) = 1;             %fai0 = 0,cos(fai0) = 1
for i = 1:2:data_len
    Q(i) = data_diff(i);
    Q(i+1) = data_diff(i);
end
for i = 2:2:data_len
    I(i+1) = data_diff(i);
    I(i) = data_diff(i);
end
for i = 1:sample_number
    I1(i:sample_number:data_len*sample_number) = I(1:data_len);
    Q1(i:sample_number:data_len*sample_number) = Q(1:data_len);
end
%乘加權函數
t=1/fs:1/fs:data_len*Tb;
I_out = I1 .* cos(pi*t/2/Tb);
Q_out = Q1 .* sin(pi*t/2/Tb);
%調制信號產生
signal_out = I_out + j*Q_out;