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 complex-baseband phase shift keying modulated signal
22 ## into an information sequence of integers in the range
23 ## @code{[0 @dots{} M-1]}. @var{phi} controls the initial phase and
24 ## @var{type} controls the constellation mapping. If @var{type} is set
25 ## to 'Bin' will result in binary encoding, in contrast, if set to
26 ##'Gray' will give Gray encoding. An example of Gray-encoded 8-PSK is
30 ## d = randint(1,1e3,8);
31 ## y = pskmod(d,8,0,'Gray');
33 ## d_est = pskdemod(z,8,0,'Gray');
41 function y=pskdemod(x,M,phi,type)
44 usage("y = pskdemod (x, M, [phi, [type]])");
56 index=mod(round((arg(x)-phi)*M/2/pi),M)+1;
58 if (strcmp(type,"Bin")||strcmp(type,"bin"))
60 elseif (strcmp(type,"Gray")||strcmp(type,"gray"))
61 map=bitxor(m,bitshift(m,-1));
64 usage("y = pskdemod (x, M, [phi, [type]])");
67 %!assert (pskdemod([1 j -1 -j],4,0,'Bin'),[0:3])
68 %!assert (pskdemod([1 j -j -1],4,0,'Gray'),[0:3])