単純なボリュームコード符号化プログラム
1941 ワード
以下は簡単な畳み込み符号化プログラムのMATLAB実装である.
% *****************************************
% * *
% * This function implements the *
% * state machine for a convolutional *
% * code with rate 1/2 and K = 3. *
% *****************************************
function output = conv_code(mssg)
input = zeros(1,length(mssg) + 3);
input(1:length(mssg)) = mssg; % padding message with 0 in the front
output = zeros(1,2*(length(mssg) + 2)); % output of covolutional code
k = 1;
state = 0; % initial state
i = 1;
while i <= length(mssg) + 3
switch(state)
case 0 % state 0
if(input(i) == 0)
state = 0; % next state 0
y = [0 0];
else
state = 2; % next state 2
y = [1 1];
end
case 1 % state 1
if(input(i) == 0)
state = 0; % next state 0
y = [1 1];
else
state = 2; % next state 2
y = [0 0];
end
case 2 % state 2
if(input(i) == 0)
state = 1; % next state 1
y = [1 0];
else
state = 3; % next state 3
y = [0 1];
end
case 3 % state 3
if(input(i) == 0)
state = 1; % next state 1
y = [0 1];
else
state = 3; % next state 3
y = [1 0];
end
end
if(i ~= length(mssg) + 3)
output(k) = y(1);
output(k + 1) = y(2);
end
k = k + 2;
i = i + 1;
end
end