Saturday, February 26, 2011

PHP Code Sample : Convert GPS / NMEA Lat Long to Decimal Degrees

This piece of code converts NMEA/GPS Lat -Long to Decimal Degrees. Code comments are self explanatory. The code is not graceful, but it works.
function degree2decimal($deg_coord){
//GPS/NMEA fixes are in Degree Minutes.m format
//for Google maps we need to convert them to decimal degrees
//sample format of GPS 4533.35 is 45 degrees and 33.35 minutes
//formula is as follows//Degrees=Degrees
//.d = M.m/60//Decimal Degrees=Degrees+.d
$degree=(int)($deg_coord/100); //simple way
$minutes= $deg_coord-($degree*100);
//South latitudes and West longitudes need to return a negative result
if (($direction=="S") or ($direction=="W"))
$decimal=number_format($decimal,4,'.',''); //truncate decimal to 4 places
return $decimal;