function Omega=WindMainFreq(x,fs,fmax);
% function Omega=WindMainFreq(x,fs,fmax);
%INPUT: x = signal; fs = sample frequency; fmax = max frequency for
%mainfrequency
% OUTPUT = mainfrequency Omega
% CALSS: spectrum2.m
% PLOT : with no outtput [] generates plot

if nargin<3 || isempty(fmax), fmax = 4; end
 n=10*length(x);
 ws=fix(length(x)/2);
 no=fix(0.99*ws);

[p,f]=spectrum2(x,n,no,hamming(ws),fs,'mean');
 p=p/sum(p);
aa=find(f>0.5 & f<fmax);
[a,b]=max(p(aa));
Omega=f(b+aa(1)-1);
if nargout ==0;  
     ii=find(f(:,1)<=fmax);
    f=f(1:length(ii),:);
    p=p(1:length(ii),:);
 plot(f,p,'b');hold on;
  plot(Omega,max(p(aa)),'m.','MarkerSize', 15); %check w0
end