function readDrifter (filename)
cd('z:/drifter positions');

startDate = datenum(2020,2,7,7,48,0);
[a,b]=xlsread(filename);
lat = -(a(:,3) + a(:,4)/60);
lon = (a(:,6) + a(:,7)/60);
dateTime = datenum(b(:,1))+a(:,1);

good = dateTime > startDate;
lat = lat(good);
lon = lon(good);
dateTime = dateTime(good);

flt_writeGPX('drifter.gpx', lat, lon, dateTime, 'drifter');

% minlat = min(lat); maxlat = max(lat);
% minlon = min(lon); maxlon = max(lon);
% 
% axesm('mercator','maplatlimit',[minlat maxlat],...
%     'maplonlimit',[minlon maxlon]);
% tightmap;
% framem;
% gridm;
% mlabel;
% plabel;
% plotm(lat,lon,'-o')
plot(lon,lat,'-o')
save ('drifter.mat','lat','lon','dateTime')
deg2nm(distance(lat(1),lon(1),lat(end),lon(end)))
end