iqam.m

Matlab时频分析工具箱,希望能对大家有所帮助啊

function xo=iqam(xi,order)
%IQAM  Inverse QAM modulation of signal.
%
%    order must be a power of 2.
%    xo is a vector of 0's and 1's. 

% 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/>.

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);

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

% We round the argument of the complex numbers to the closest root of
% unity of order "order"
work=round(angle(xi)/(2*pi)*order);

% work now contains negative numbers. Get rid of these
work=mod(work,order);

% Reverse the optimal bit ordering.
reversebitorder=zeros(order,1);
reversebitorder(bitorder+1)=(0:order-1).';

% Apply the reverse ordering
work=reversebitorder(work+1);

xo=zeros(nbits,symbols);
% Reconstruct the bits
for bit=1:nbits
  xo(bit,:)=bitget(work,bit).';
end;

xo=xo(:);