Categories: Symbian C++ | Location Based Services | How To | Code Examples

This page was last modified 21:13, 1 May 2008.

From Forum Nokia Wiki

The following code snippet demonstrates, how to obtain coordinates of the GPS satellites, that are used for determinate current device location. Class CPositionReader can be used for obtaining coordinates of the satellites. You should:

• implement interface MPositionReaderObserver in your class
• include CPositionReader* iReader as a class member
• activate request:

iReader = CPositionReader :: NewL( this ); // new reader
iReader->ReadSatelliteInfo();   // request satellites info

And process results of reading:

void YourClass :: ReadingComplete( TPositionInfoBase& aPosInfo )
{
   TPositionSatelliteInfo& info = ( TPositionSatelliteInfo& )aPosInfo;
   for( TInt i = 0; i < info.NumSatellitesInView(); i++ )
   {
      TSatelliteData satData;
      info.GetSatelliteData( i, satData );
 
      if( satData.IsUsed() )
      {
         TReal azimuth   = aSatData.Azimuth(),
  	       elevation = aSatData.Elevation();	
         ... 
      }
   }
}

The coordinates of the satellites ( azimuth and elevation ) are presented in spherical coordinates system. This image demonstrates that indicate these coordinates:

And these formulas can be used for transform spherical coordinates to the coordinates in cartesian system:

x =  cos( Azimuth ) * cos( Elevation ) * Radius;
y =  sin( Azimuth ) * cos( Elevation ) * Radius;