How does getAltitude() of Android GPS Location Works

Question

HI

I tried to implement a simple GPS tracker. Therefore is used

lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
lm.requestLocatio         


        

Answer 1

old post, i rekon, but someone might still be interested. while listening to GPS, you can parse NMEA GPGGA sentence (http://aprs.gids.nl/nmea/#gga), in which there is the geoid height (Height of geoid above WGS84 ellipsoid). just subtract this heigh from the getAltitude returned value, one and you'll have a more accurate elevation value.

Edit after several months of usage and feedback received from users of my app

A better solution is to get directly the elevation value in the GPGGA sentence:

double GGA_ALTITUDE = 0d;
private static final String NMEA_GGA = "$GPGGA";    
private static final int altitude_element_id = 9;

@Override
public void onNmeaReceived(long timestamp, String nmea) {
    foundSats = true;
    // check that this is an RMC string
    if (nmea.startsWith(NMEA_GGA)) {
        String[] tokens = nmea.split(",");
        try {
            // get orthometric elevation
            String elevation = tokens[altitude_element_id];             
            if (!elevation.equals("")) {
                Log.d("NMEA", "ortho elev: " + ortho);
                GGA_ALTITUDE = Double.parseDouble(elevation);                   
            }
        } catch (Exception ex) {
            Log.e("NMEA", "onNmeaReceived: "
                    + ex.getMessage());

            onNmeaException(ex.getMessage());               
            ex.printStackTrace();
        }
    } 
}