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

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

Update of /cvsroot/octave/octave-forge/main/comm
In directory sc8-pr-cvs3.sourceforge.net:/tmp/cvs-serv14589

Added Files:
	pskdemod.m pskmod.m 
Log Message:
Added Files: main/comm/pskdemod.m and main/comm/pskmod.m


--- NEW FILE: pskmod.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 = pskmod (x, M, [phi, [type]]);   
##
## Modulates an information sequence of intergers x in the range [0..M-1] 
## onto a complex baseband phase shift keying 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 QPSK
##
##	d=randint(1,5e3,4);
##	y=pskmod(d,4,0,'Gray');
##	z=awgn(y,30);
##	plot(z,'rx')
##
## See also: pskdemod

function y=pskmod(x,M,phi,type)

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=exp(1j*2*pi*m/M+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 = pskmod (x, M, [phi, [type]])");   
endif


%!assert (round(pskmod([0:3],4,0,'Bin')),[1 j -1 -j])
%!assert (round(pskmod([0:3],4,0,'Gray')),[1 j -j -1])

--- NEW FILE: pskdemod.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 = pskdemod (x, M, [phi, [type]])
##
## Demodulates a complex-baseband phase shift keying modulated signal 
## into an information sequence of intergers in the range [0..M-1]. 
## phi controls the initial phase and type ('Bin' or 'Gray') controls 
## the symbol ordering that was used for encoding.
##
## EXAMPLE: Demodulation of Gray-encoded 8-PSK 
##
##	d=randint(1,1e3,8);
##	y=pskmod(d,8,0,'Gray');
##	z=awgn(y,20);
##	d_est=pskdemod(z,8,0,'Gray');
##	plot(z,'rx')
##	biterr(d,d_est)
##

function y=pskdemod(x,M,phi,type)

if nargin<2
	usage("y = pskdemod (x, M, [phi, [type]])");   
endif    

if nargin<3
	phi=0;
endif

if nargin<4
	type="Bin";
endif

m=0:M-1;
constellation=exp(1j*2*pi*m/M+1j*phi);
[nr,nc]=size(x);
index=zeros(nr,nc);
for k=1:nr
    for l=1:nc
    	[a,index(k,l)]=min(abs(x(k,l)-constellation)); % Minimum distance decoding
    endfor
endfor


if (strcmp(type,"Bin")||strcmp(type,"bin"))
        y=index-1;
elseif (strcmp(type,"Gray")||strcmp(type,"gray"))
	map=bitxor(m,bitshift(m,-1));
	y=map(index);
else
    usage("y = pskdemod (x, M, [phi, [type]])");   
endif

%!assert (pskdemod([1 j -1 -j],4,0,'Bin'),[0:3])
%!assert (pskdemod([1 j -j -1],4,0,'Gray'),[0:3])