Alpine NVE-N872A Hardware Manual - Page 7

Preface Gyroscope The gyroscope is a sensor that accurately measures the angle by which the direction of a vehicle or other moving body changes. Gyroscopes are used in inertial navigation systems for airliners and ships. In this navigation system, the gyroscope is used together with the speed sensor, making it possible to display the position of the vehicle even in locations where GPS signals may be blocked. Locations where GPS signals are received easily The optimum locations for receiving GPS signals are locations that command a good view where there are no tall buildings, trees, or other objects to obstruct the signals. Locations where GPS signals cannot be received In the following locations or conditions GPS signals cannot be received. However even in these locations, the gyroscope and speed sensor will provide a substitute means of determining the vehicle's position and the system will be able to continue to track the vehicle's progress along the route. In tunnels and indoor parking lots Locations surrounded by tall buildings Locations surrounded by tall trees On the bottom level of double-decker motorways When a GPS satellite is low on the horizon (angle below 10°), obstructions sometimes make normal reception impossible 7