T-45C TS, ADV & IUT ENG-24
GINA Operating Characteristics
B.
1.
GINA contains the LITTON A-4 inertial grade model
2.
Triad design: XYZ axes orthogonally mounted on
the laser assembly
3.
Measure linear accelerations
4.
Acceleration data used to calculate aircraft speeds
5.
Nuclear hardened
INSTRUCTOR NOTES
Accelerometers are fundamental INS devices that very
accurately detect when the aircraft is moving, how fast, and in
what axis/axes (direction). That acceleration data, combined
with time to determine speeds and distances, is used to build a
continuously calculated present position plotted from the
original position of the aircraft in the chocks, when the system
was first aligned. A pure INS present position is the result of
those sensed accelerations and the resulting computations.
Keep in mind that when the GINA is operating in HYBD mode,
present position is not a pure INS solution. It is derived from a
blending of INS data with GPS position information,
appropriately weighted by the Kalman filter.
PROGRESS CHECK
Question 3 -- 1.7.7.6.3
How is aircraft movement detected by the laser assembly?
ANSWER: Laser beam Dopple frequency shift patterns,
developed due to motion, are measured on the photo diodes.
That data is then manipulated mathematically to derive
movement values.
Original (9-98)
Page 24-14
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