This library use the SGP4 orbital model to predict the Satellite Position in Latitude, Longitude. For further information about SGP4 please refer to this link http://celestrak.com/publications/AIAA/2006-6753/
For testing see the main function of the Sgp4Silvio class file.
This library is the core element of my Android App (SatOrbit) for Satellite position that is available on Google Play.