4FSK调制和解调
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%--------------------------------------------------- %>>>>>>>>>>>>>>>>>>初始化数据>>>>>>>>>>>>>>>>>>>>>
%---------------------------------------------------
clc,clear,close all;
fs = 30000;
Time_Hold_On = 0.1;
Num_Unit = fs * Time_Hold_On;
one_Level = zeros ( 1, Num_Unit );
two_Level = ones ( 1, Num_Unit );
three_Level = 2*ones ( 1, Num_Unit );
four_Level = 3*ones ( 1, Num_Unit );
A = 1; % the default ampilitude is 1 w1 = 300; %初始化载波频率
w2 = 600;
w3=900;
w4=1200;
%--------------------------------------------------- %>>>>>>>>>>>>>>>>>>串并转换>>>>>>>>>>>>>>>
%---------------------------------------------------
Sign_Set=[0,0,1,1,0,1,1,0,1,0,1,0,1,0,0,1]
Lenth_Of_Sign_Set = length ( Sign_Set ); %计算信号长度
j=1;
for I=1:2:Lenth_Of_Sign_Set %信号分离成两路信号Sign_Set1(j)= Sign_Set(I);Sign_Set2(j)=Sign_Set(I+1);
j=j+1;
end
Lenth_Of_Sign = length ( Sign_Set1 );
st = zeros ( 1, Num_Unit * Lenth_Of_Sign/2 );
sign_orign = zeros ( 1, Num_Unit * Lenth_Of_Sign/2 );
sign_result = zeros ( 1, Num_Unit * Lenth_Of_Sign/2 );
t = 0 : 1/fs : Time_Hold_On * Lenth_Of_Sign- 1/fs;
%---------------------------------------------------
%>>>>>>>>>>>产生基带信号>>>>>>>>>>>>
%---------------------------------------------------
for I = 1 : Lenth_Of_Sign
if ((Sign_Set1(I) == 0)&(Sign_Set2(I) == 0)) %00为1电平sign_orign( (I-1)*Num_Unit + 1 : I*Num_Unit) = one_Level;
elseif ((Sign_Set1(I) == 0)&(Sign_Set2(I) == 1)) %01为2电平sign_orign( (I-1)*Num_Unit + 1 : I*Num_Unit) = two_Level;
elseif ((Sign_Set1(I) == 1)&(Sign_Set2(I) == 1)) %11为3电平
sign_orign( (I-1)*Num_Unit + 1 : I*Num_Unit) = three_Level;
else %10为4电平sign_orign( (I-1)*Num_Unit + 1 : I*Num_Unit) = four_Level;
end
end
%---------------------------------------------------
%>>>>>>>>>>>>>>>>>>产生频带信号>>>>>>>>>>>>>>>>>>
%---------------------------------------------------
for I = 1 : Lenth_Of_Sign
if ((Sign_Set1(I) == 0)&(Sign_Set2(I) == 0)) %00为载波w1 st((I-1)*Num_Unit + 1 : I*Num_Unit) = A * cos ( 2 * pi * w1 * t( (I-1)*Num_Unit + 1 : I*Num_Unit ) );
elseif ((Sign_Set1(I) == 0)&(Sign_Set2(I) == 1)) %01为载波w2 st( (I-1)*Num_Unit + 1 : I*Num_Unit) = A * cos ( 2 * pi * w2 * t((I-1)*Num_Unit + 1 : I*Num_Unit ) );
elseif ((Sign_Set1(I) == 1)&(Sign_Set2(I) == 1)) %11为载波w3 st( (I-1)*Num_Unit + 1 : I*Num_Unit) = A * cos ( 2 * pi * w3 * t((I-1)*Num_Unit + 1 : I*Num_Unit ) );
else %10为载波w4 st( (I-1)*Num_Unit + 1 : I*Num_Unit) = A * cos ( 2 * pi * w4 * t( (I-1)*Num_Unit + 1 :I*Num_Unit ) );
end
end
%---------------------------------------------------
%>>>>>>>>>>>>>>>画初始信号图>>>>>>>>>>>>>>>>>
%---------------------------------------------------
figure
subplot ( 2, 1, 1 )
plot ( t, sign_orign );
axis( [ 0 , Time_Hold_On *( Lenth_Of_Sign + 1),-A/2, 3*A+A/2] );
title ( 'The original Signal' );
grid;
subplot ( 2, 1, 2 )
plot ( t, st ); % the signal after modulation
axis( [ 0 , Time_Hold_On *( Lenth_Of_Sign + 1), -A, A ] );
title ( 'the signal after modulation' );
grid;
%---------------------------------------------------
%>>>>>>>>>>>>>>>带通滤波器>>>>>>>>>>>>>>
%---------------------------------------------------