function y=O3LPfilter(x)


wp=1.5e-3/5;
ws=0.6*wp;
[n,wn]=buttord(wp,ws,5,10);
[bhigh,ahigh]=butter(n,wn,'high');
[hhigh,fhigh]=freqz(bhigh,ahigh,length(x),10);


y=filtfilt(bhigh,ahigh,x)+nanmedian(x);
