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[CreaPhase.git] / octave_packages / communications-1.1.1 / apkconst.m

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+## Copyright (C) 2003 David Bateman
+##
+## 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 3 of the License, 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; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} apkconst (@var{nsig})
+## @deftypefnx {Function File} {} apkconst (@var{nsig},@var{amp})
+## @deftypefnx {Function File} {} apkconst (@var{nsig},@var{amp},@var{phs})
+## @deftypefnx {Function File} {} apkconst (@var{...},"n")
+## @deftypefnx {Function File} {} apkconst (@var{...},@var{str})
+## @deftypefnx {Function File} {@var{y} = } apkconst (@var{...})
+##
+## Plots a ASK/PSK signal constellation. Argument @var{nsig} is a real vector
+## whose length determines the number of ASK radii in the constellation.
+## The values of vector @var{nsig} determine the number of points in each 
+## ASK radii. 
+##
+## By default the radii of each ASK modulated level is given by the index of 
+## @var{nsig}. The amplitudes can be defined explictly in the variable
+## @var{amp}, which  is a vector of the same length as @var{nsig}.
+##
+## By default the first point in each ASK radii has zero phase, and following
+## points are coding in an anti-clockwise manner. If @var{phs} is defined then
+## it is a vector of the same length as @var{nsig} defining the initial phase
+## in each ASK radii.
+##
+## In addition @dfn{apkconst} takes two string arguments 'n' and and @var{str}.
+## If the string 'n' is included in the arguments, then a number is printed
+## next to each constellation point giving the symbol value that would be
+## mapped to this point by the @dfn{modmap} function. The argument @var{str}
+## is a plot style string (example 'r+') and determines the default gnuplot
+## point style to use for plot points in the constellation.
+##
+## If @dfn{apskconst} is called with a return argument, then no plot is
+## created. However the return value is a vector giving the in-phase and
+## quadrature values of the symbols in the constellation.
+## @end deftypefn
+## @seealso{dmod,ddemod,modmap,demodmap}
+
+
+## 2005-04-23 Dmitri A. Sergatskov <dasergatskov@gmail.com>
+##     * modified for new gnuplot interface (octave > 2.9.0)
+
+
+
+function yout = apkconst(varargin)
+
+  if ((nargin < 1) || (nargin > 5))
+    error ("apkconst: incorrect number of arguments");
+  endif
+
+  numargs = 0;
+  printnums = 0;
+  fmt = "+r";
+  amp = [];
+  phs = [];
+
+  for i=1:length(varargin)
+    arg = varargin{i};
+    if (ischar(arg))
+      if (strcmp(arg,"n"))
+             try
+               text();
+               printnums = 1;
+             catch
+               printnums = 0;
+             end
+      else
+             fmt = arg;
+      endif
+    else
+      numargs++;
+      switch (numargs)
+             case 1,
+               nsig = arg; 
+             case 2,
+               amp = arg; 
+             case 3,
+               phs = arg; 
+             otherwise
+               error ("apkconst: too many numerical arguments");
+      endswitch
+    endif
+  end
+
+  if (numargs < 1)
+    error ("apkconst: must have at least one vector argument");
+  endif
+
+  if (isempty(amp))
+    amp = 1:length(nsig);
+  endif
+
+  if (isempty(phs))
+    phs = zeros(size(amp));
+  endif
+
+  if (!isvector(nsig) || !isvector(amp) || !isvector(phs) || ...
+      (length(nsig) != length(amp)) || (length(nsig) != length(phs)))
+    error ("apkconst: numerical arguments must be vectors of the same length");
+  endif
+
+  if (length(nsig) == 0)
+    error ("apkconst: first numerical argument must have non-zero length");
+  endif
+
+  y = [];
+  for i=1:length(nsig)
+    if (nsig(i) < 1)
+      error ("apkconst: must have at least one point in ASK radii");
+    endif
+    y = [y; amp(i) * [cos(2*pi*[0:nsig(i)-1]'/nsig(i) + phs(i)) + ...
+                                 1i*sin(2*pi*[0:nsig(i)-1]'/nsig(i) + phs(i))]];
+  end
+
+  if (nargout == 0)
+    r = [0:0.02:2]'*pi;
+    x0 = cos(r) * amp;
+    y0 = sin(r) * amp;
+    plot(x0, y0, "b");
+    yy = [real(y), imag(y)];
+    hold on;
+    if (printnums)
+      xd = 0.05 * max(real(y));
+      for i=1:length(y)
+             text(real(y(i))+xd,imag(y(i)),num2str(i-1));
+      end
+    endif
+    plot (real(y), imag(y), fmt);
+
+    title("ASK/PSK Constellation");
+    xlabel("In-phase");
+    ylabel("Quadrature");
+  else
+    yout = y;
+  endif
+
+endfunction