Inertial Navigation System - INS
An inertial navigation system is an assembly that is used to determine position location information that is calculated from the movement of the INS. An INS system contains an inertial measurement unit (IMU) along with computing systems that can process the acceleration, orientation and rotational information gathered from the IMU to provide relative position information. The INS calculates its position relative to a reference starting point. While the accuracy of INS systems degrades with increases of distance from its initialization reference point, INS systems are immune to jamming so they may be used as backup for other navigation systems such as GPS and LORAN.