cnv_encd.m

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function output=cnv_encd(g,k0,input)
%  		cnv_encd(g,k0,input)
%  		determines the output sequence of a binary convolutional encoder
%  		g is the generator matrix of the convolutional code
%        	with n0 rows and l*k0 columns. Its rows are g1,g2,...,gn.
%  		k0 is the number of bits entering the encoder at each clock cycle.
%  		input The binary input seq.

%  check to see if extra zero padding is necessary
if rem(length(input),k0) > 0
  input=[input,zeros(size(1:k0-rem(length(input),k0)))];
end
n=length(input)/k0;
%  check the size of matrix g
if rem(size(g,2),k0) > 0
  error('Error, g is not of the right size.')
end
%  determine l and n0
l=size(g,2)/k0;
n0=size(g,1);
%  add extra zeros
u=[zeros(size(1:(l-1)*k0)),input,zeros(size(1:(l-1)*k0))];
%  generate uu, a matrix whose columns are the contents of 
%  conv. encoder at various clock cycles.
u1=u(l*k0:-1:1);
for i=1:n+l-2
  u1=[u1,u((i+l)*k0:-1:i*k0+1)];
end
uu=reshape(u1,l*k0,n+l-1);
%  determine the output
output=reshape(rem(g*uu,2),1,n0*(l+n-1));