1 ## Copyright (C) 2006 Charalampos C. Tsimenidis
3 ## This program is free software; you can redistribute it and/or modify it under
4 ## the terms of the GNU General Public License as published by the Free Software
5 ## Foundation; either version 3 of the License, or (at your option) any later
8 ## This program is distributed in the hope that it will be useful, but WITHOUT
9 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 ## You should have received a copy of the GNU General Public License along with
14 ## this program; if not, see <http://www.gnu.org/licenses/>.
17 ## @deftypefn {Function File} {@var{y} = } pamdemod (@var{x}, @var{m})
18 ## @deftypefnx {Function File} {@var{y} = } pamdemod (@var{x}, @var{m}, @var{phi})
19 ## @deftypefnx {Function File} {@var{y} = } pamdemod (@var{x}, @var{m}, @var{phi}, @var{type})
21 ## Demodulates a pulse amplitude modulated signal @var{x} into an
22 ## information sequence of integers in the range @code{[0 @dots{} M-1]}.
23 ## @var{phi} controls the initial phase and @var{type} controls the
24 ## constellation mapping. If @var{type} is set to 'Bin' will result in
25 ## binary encoding, in contrast, if set to 'Gray' will give Gray encoding.
26 ## An example of Gray-encoded 8-PAM is
30 ## d = randint(1,1e4,8);
31 ## y = pammod(d,8,0,'Gray');
33 ## d_est = pamdemod(z,8,0,'Gray');
41 function y=pamdemod(x,M,phi,type)
44 usage("y = pamdemod (x, M, [phi, [type]])");
55 index=genqamdemod(x,[-M+1:2:M-1].*exp(-1j*phi));
57 if (strcmp(type,"Bin")||strcmp(type,"bin"))
59 elseif (strcmp(type,"Gray")||strcmp(type,"gray"))
61 map=bitxor(m,bitshift(m,-1));
64 usage("y = pamdemod (x, M, [phi, [type]])");
67 %!assert (pamdemod([-7:2:7],8,0,'Bin'),[0:7])
68 %!assert (pamdemod([-7:2:7],8,0,'Gray'),[0 1 3 2 6 7 5 4])