Methods for GPS-assisted determination of location coordinates of a mobile user or selected position on or adjacent to the Earth's surface with improved accuracy. Elevation readings from an altimeter or barometer are integrated with readings of the GPS-determined elevation coordinate for that location,...http://www.google.fr/patents/US6055477?utm_source=gb-gplus-shareBrevet US6055477 - Use of an altitude sensor to augment availability of GPS location fixes
Use of an altitude sensor to augment availability of GPS location fixes
