[Octave-cvsupdate] octave-forge/main/comm pammod.m,NONE,1.1

[cctsim <cc...@us...>]

Update of /cvsroot/octave/octave-forge/main/comm
In directory sc8-pr-cvs3.sourceforge.net:/tmp/cvs-serv4988

Added Files:
	pammod.m 
Log Message:
Initial upload.


--- NEW FILE: pammod.m ---
## 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 2, 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; see the file COPYING.  If not, write to the Free
## Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
##

## usage: y = pammod (x, M, [phi, [type]]);   
##
## Modulates an information sequence of intergers x in the range [0..M-1] 
## onto a pulse amplitude modulated signal y. phi controls the initial phase and 
## type controls the constellation mapping. If type is set to 'Bin' will result in 
## binary encoding, in constrast, if set to 'Gray' will give Gray encoding.
##
##  EXAMPLE: Gray-encoded 8-PAM
##
##	d=randint(1,1e4,8);
##	y=pammod(d,8,0,'Gray');
##	z=awgn(y,20);
##	plot(z,'rx')
##
## See also: 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


%!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])