/usr/share/octave/packages/communications-1.1.1/pammod.m is in octave-communications-common 1.1.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 72 73 74 75 | ## Copyright (C) 2006 Charalampos C. Tsimenidis
##
## 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 <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {@var{y} = } pammod (@var{x}, @var{m})
## @deftypefnx {Function File} {@var{y} = } pammod (@var{x}, @var{m}, @var{phi})
## @deftypefnx {Function File} {@var{y} = } pammod (@var{x}, @var{m}, @var{phi}, @var{type})
##
## Modulates an information sequence of integers @var{x} in the range
## @code{[0 @dots{} M-1]} onto a pulse amplitude modulated signal @var{y}.
## @var{phi} controls the initial phase and @var{type} controls the
## constellation mapping. If @var{type} is set to 'Bin' will result in
## binary encoding, in contrast, if set to 'Gray' will give Gray encoding.
## An example of Gray-encoded 8-PAM is
##
## @example
## @group
## d = randint(1,1e4,8);
## y = pammod(d,8,0,'Gray');
## z = awgn(y,20);
## plot(z,'rx')
## @end group
## @end example
## @end deftypefn
## @seealso{pamdemod}
function y=pammod(x,M,phi,type)
if nargin<2
usage("y = pammod (x, M, [phi, [type]])");
endif
m=0:M-1;
if ~isempty(find(ismember(x,m)==0))
error("x elements should be integers in the set [0, M-1].");
endif
if nargin<3
phi=0;
endif
if nargin<4
type="Bin";
endif
constellation=[-M+1:2:M-1].*exp(-1j*phi);
if (strcmp(type,"Bin")||strcmp(type,"bin"))
y=constellation(x+1);
elseif (strcmp(type,"Gray")||strcmp(type,"gray"))
[a,b]=sort(bitxor(m,bitshift(m,-1)));
y=constellation(b(x+1));
else
usage("y = pammod (x, M, [phi, [type]])");
endif
if (iscomplex(y) && all (imag(y(:)) == 0))
y = real (y);
endif
%!assert(round(pammod([0:7],8,0,'Bin')),[-7:2:7])
%!assert(round(pammod([0:7],8,0,'Gray')),[-7 -5 -1 -3 7 5 1 3])
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