The Athena 611 from Collins Aerospace is a fully integrated inertial navigation system (INS), global positioning system (GPS), and an air data, attitude and heading reference system (ADAHRS). The unit incorporates a navigation grade IMU and an embedded pressure altimeter; the data from these sensors is used in the INS/GPS Kalman filter solution. The Athena 611 also gives you an option to accept external static pressure data. It houses a central processing unit (CPU), air data transducers, an embedded C/A GPS receiver and peripheral input/outputs to function as a complete ADAHRS.
The Athena 611 system consists of two cable-connected units: the inertial measurement unit (IMU) and the Navigation and Communications Unit (NCU). The IMU used is the Honeywell HG9900.