## [f62e8c]: inst / convenc.m  Maximize  Restore  History

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71``` ```## Copyright (C) 2012 Tony Richardson ## ## This program is free software; you can redistribute it and/or modify it under ## the terms of the GNU General Public License as published by the Free Software ## Foundation; either version 3 of the License, or (at your option) any later ## version. ## ## This program is distributed in the hope that it will be useful, but WITHOUT ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more ## details. ## ## You should have received a copy of the GNU General Public License along with ## this program; if not, see . ## -*- texinfo -*- ## @deftypefn {Function File} {@var{x} =} convenc (@var{m}, @var{G}, @var{k}) ## Compute output of an (n, @var{k}, L) convolutional encoder with vector input ## @var{m} and matrix of generator polynomials @var{G}. ## ## The input vector @var{m} can be of arbitrary length. @var{G} is a matrix with n rows ## and @var{k}*(L+1) columns. The rows of @var{G} are the generator polynomials for each ## of the n output bits (per @var{k} input bits). ## ## The output is a vector whose length is n*floor([length(@var{m})+@var{k}*(L+1)-1]/@var{k}). ## If unspecified, @var{k} defaults to 1. ## ## Example 1: Compute the output from a (2, 1, 2) convolutional encoder ## @example ## @group ## m = [ 1 1 0 1 1 1 0 0 1 0 0 0]; ## g1 = [1 1 1]; ## g2 = [1 0 1]; ## convenc (m, [g1; g2]) ## @result{} [1 1 0 1 0 1 0 0 0 1 1 0 0 1 1 1 1 1 1 0 1 1 0 0 0 0 0 0] ## @end group ## @end example ## ## Example 2: Compute the output from a (3, 2, 1) convolutional encoder ## @example ## @group ## m = [0 1 1 0 0 0 1 1 ]; ## g1 = [1 0 1 1]; ## g2 = [1 1 0 1]; ## g3 = [1 0 1 0]; ## convenc (m, [g1; g2; g3], 2) ## @result{} [1 1 1 1 1 1 1 1 0 1 0 1] ## @end group ## @end example ## ## @strong{Caution:}: this function is not compatible with @sc{matlab}'s convenc(). ## @end deftypefn function x = convenc (m, G, k = 1) if (nargin < 2 || nargin > 3) print_usage (); endif # Use conv2 to do repeated 1d convolutions of m with each row of G. # rem is used to transform the standard convolution result to one # which uses modulo-2 addition. Only cols with index a mult. of k # are in the actual enc. output x = rem(conv2(1, m(:)', G),2)(:,!rem(1:numel(m),k))(:)'; endfunction %% Test input validation %!error convenc () %!error convenc (1) %!error convenc (1, 2, 3, 4) ```