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} = } pammod (@var{x}, @var{m})
18 ## @deftypefnx {Function File} {@var{y} = } pammod (@var{x}, @var{m}, @var{phi})
19 ## @deftypefnx {Function File} {@var{y} = } pammod (@var{x}, @var{m}, @var{phi}, @var{type})
21 ## Modulates an information sequence of integers @var{x} in the range
22 ## @code{[0 @dots{} M-1]} onto a pulse amplitude modulated signal @var{y}.
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');
39 function y=pammod(x,M,phi,type)
42 usage("y = pammod (x, M, [phi, [type]])");
46 if ~isempty(find(ismember(x,m)==0))
47 error("x elements should be integers in the set [0, M-1].");
58 constellation=[-M+1:2:M-1].*exp(-1j*phi);
60 if (strcmp(type,"Bin")||strcmp(type,"bin"))
62 elseif (strcmp(type,"Gray")||strcmp(type,"gray"))
63 [a,b]=sort(bitxor(m,bitshift(m,-1)));
64 y=constellation(b(x+1));
66 usage("y = pammod (x, M, [phi, [type]])");
69 if (iscomplex(y) && all (imag(y(:)) == 0))
74 %!assert(round(pammod([0:7],8,0,'Bin')),[-7:2:7])
75 %!assert(round(pammod([0:7],8,0,'Gray')),[-7 -5 -1 -3 7 5 1 3])