Convolution encoder MATLAB source code

This section of MATLAB source code covers Convolution Encoder code. The same is validated using matlab built in function.

Specifications

Convolution Encoder (3, 1, 4) specifications
Coding rate: 1/3
Constraint length: 5
Output bit length: 3
Message bit length: 1
Maximal memory order / no. of memory elements = 4
Generator Polynomials: 25 (8), 33 (8), 37 (8)

For basics read our article on convolution encoder implementation.

MATLAB Code

%function [Conv_out] = conv_encoder(Conv_In) 

Conv_In= [1 1 0 1 0 1 1 0 1 1 0 1 0 1 1 0 1 0 1 0];
% x=[1 0 1 1 0 0 0];

m1=0;    

m2=0;    

m3=0;

m4=0;

%% m_in m1 m2 m3 m4

%%[1   0   1  0  1] =x0

%%[1   1   0  1  1] =x1

%%[1   1   1  1  1] =x2;



for k = 1:length(Conv_In)

%%1st polynomial

%%x0= [1 0 1 0 1]



m_in   =   Conv_In(k);



%first polynomial

temp1  =   bitxor(m_in,m2);

x0     =   bitxor(temp1,m4); 



%2nd polynomial

temp1  =   bitxor(m_in,m1);

temp2  =   bitxor(temp1,m3);

x1     =   bitxor(temp2,m4);



%3rd polynomial



temp1  =   bitxor(m_in,m1);

temp2  =   bitxor(temp1,m2);

temp3  =   bitxor(temp2,m3);

x2     =   bitxor(temp3,m4);



Conv_out((3*k)-2)    = x0;

Conv_out((3*k)-1)    = x1;

Conv_out(3*k)        = x2;



%%%Shifiting

m4=m3;

m3=m2;

m2=m1;

m1=m_in;

end

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