2013 Nissan Altima Navigation System Owner's Manual - Page 273

CURRENT VEHICLE LOCATION DISPLAY OF CURRENT VEHICLE LOCATION This navigation system combines the data obtained from the vehicle (by gyro sensor) and from GPS (Global Positioning System) satellites to calculate the current location of the vehicle. This position is then displayed throughout route guidance to a destination. Receiving signals from GPS satellites The reception of GPS signals can be weak, depending on the environment. Vehicles in the following areas/environments may not receive GPS signals. WHAT IS GPS (Global Positioning System)? GPS is a position detecting system that uses satellites deployed by the U.S. government. This navigation system receives radio signals from three or more different satellites that orbit 13,049 miles (21,000 km) above the earth in space, and detects the position of the vehicle by utilizing the principle of triangulation. Positioning adjustment When the system judges that the vehicle position information is not accurate based on vehicle speed and gyro sensor data calculations, the system will automatically adjust the position of the vehicle icon using GPS signals. 10-4 General system information