qam.m

来自「Matlab时频分析工具箱,希望能对大家有所帮助啊」· M 代码 · 共 60 行

function xo=qam(xi,order)
%QAM  QAM modulation of input signal.
%    Usage:  xo=qam(xi,order);
%
%    xi must be a vector of 0's and 1's. 
%    order must be a power of 2.

% 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/>.

% Verify input

if ~all((xi==0) + (xi==1))
  error('Input vector must consist of only 0s and 1s');
end;

if mod(log2(order),1)~=0
  error('order must be a power of 2.');
end;

% Get the optimal ordering of bits
bitorder=circbitflip(order);

% nbits is number of bits used. Everything will be ordered
% in groups of this size.
nbits=log2(order);

L=length(xi);
symbols=L/nbits;

% nbits must divide L
if rem(symbols,1)~=0
  error('Length of input must be a multiple of log2(order)');
end;

xi=reshape(xi,nbits,symbols);

two_power=(2.^(0:nbits-1)).';

% This could be vectorized by a repmat.
xo=zeros(symbols,1);
for ii=1:symbols
  xo(ii)=sum(xi(:,ii).*two_power);
end;

% xo now consist of numbers in the range 0:order-1
% Convert to the corresponding complex root of unity.
xo=exp(2*pi*i*bitorder(xo+1)/order);