All,
I recently had to create a library replacement of qammod.m in the
communications toolbox, because it doesn't allow for non-square (power
of 4) symbol sets and that was desired for my project. Here is what I
have:
my_qammod.m:
function [y] = my_qammod(x, M, qam_type)
switch(qam_type)
case 1
error('qammod type %d is undefined', qam_type);
exit;
case 3
if (nargin < 2)
usage('y = my_qammod(x,m,type)');
exit;
end
if (M ~= fix(M))
error('m must be an integer power of 2 > 4');
exit;
end
if (any(x >= M))
error('values of x must be in range [0,M-1]');
exit;
end
if (~any(x == fix(x)))
error('values of x must be integer');
exit;
end
c = sqrt(M);
if (c ~= fix(c)|| log2(c) ~= fix(log2(c)))
switch(M)
case 8
a = [ -1, 1, ...
-1, 1, ...
-1, 1, ...
-1, 1];
b = [ 3, 3, ...
1, 1, ...
-1, -1, ...
-3, -3];
c = a + i*b;
y = c(x + 1);
case 32
a = [ -3, -1, 1, 3, ...
-5, -3, -1, 1, 3, 5, ...
-5, -3, -1, 1, 3, 5, ...
-5, -3, -1, 1, 3, 5, ...
-5, -3, -1, 1, 3, 5, ...
-3, -1, 1, 3];
b = [ 5, 5, 5, 5, ...
3, 3, 3, 3, 3, 3, ...
1, 1, 1, 1, 1, 1, ...
-1, -1, -1, -1, -1, -1, ...
-3, -3, -3, -3, -3, -3, ...
-5, -5, -5, -5];
c = a + i*b;
y = c(x + 1);
case 128
a = [ -7, -5, -3, -1, 1, 3,
5, 7, ...
-7, -5, -3, -1, 1, 3,
5, 7, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-11, -9, -7, -5, -3, -1, 1, 3,
5, 7, 9, 11, ...
-7, -5, -3, -1, 1, 3,
5, 7, ...
-7, -5, -3, -1, 1, 3, 5, 7];
b = [ 11, 11, 11, 11, 11, 11,
11, 11, ...
9, 9, 9, 9, 9, 9,
9, 9, ...
7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, ...
5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, ...
3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, ...
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, ...
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, ...
-3, -3, -3, -3, -3, -3, -3, -3,
-3, -3, -3, -3, ...
-5, -5, -5, -5, -5, -5, -5, -5,
-5, -5, -5, -5, ...
-7, -7, -7, -7, -7, -7, -7, -7,
-7, -7, -7, -7 ...
-9, -9, -9, -9, -9, -9,
-9, -9, ...
-11, -11, -11, -11, -11, -11, -11, -11];
c = a + i*b;
y = c(x + 1);
otherwise
error('qammod for M = %d is undefined', M);
exit;
end
else
b = -2.*mod(x,(c)) + c-1;
a = 2.*floor(x./(c)) - c+1;
y = a + i.*b;
end
otherwise
error('qammod type %d is undefined', qam_type);
exit;
end
end
It's basically a copy of what was already there, except I added
special cases for each non-square, like 8, 32, etc. I also added a
"type" which for QAM could be type I, II, or III. Square
constellations are type III and are the most common. However, type
I's can be useful in fading situations, so I may add that
functionality later. Basically, type I's are circular constellations,
and they're useful in fading channels if you use a differential coding
scheme.
You can use the qamdemod that already exists in the communications
package, though you may have to change the reference to "qammod" to be
"my_qamdemod" or rename this file and put it in a path that is at a
higher priority than your communications package.
Please let me know what you think.
Thanks,
Kelly
------------------------------------------------------------------------------
Enter the BlackBerry Developer Challenge
This is your chance to win up to $100,000 in prizes! For a limited time,
vendors submitting new applications to BlackBerry App World(TM) will have
the opportunity to enter the BlackBerry Developer Challenge. See full prize
details at: http://p.sf.net/sfu/Challenge
_______________________________________________
Octave-dev mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/octave-dev
