V Scan the text to fill in the gaps with correct prepositions.1 Navigation software is sometimes embedded __ a central processor __other avionic software or confined __ one or more navigation computers. 2 The navigation software contains algorithms and data that process the measurements made __ each sensor (e.g., GPS, inertial, or air data). 3 It contains calibration constants, initialization sequences, self-test algorithms, reasonability tests, and alternative algorithms __ periods when sensors have failed or are not receiving information. 4 __ the simplest systems, a state vector is calculated independently __ each sensor while the navigation software calculates the best estimate __ position and velocity. 5 Prior __ 1970, the best estimate was calculated __ a least-squares algorithm __ constant weighting functions or __ a frequency-domain filter __ constant coefficients. 6 Now, a Kalman filter calculates the best estimate __ mathematical models __ the dynamics __ each sensor. 7 Digital maps, often stored __ compact disc, are carried __ an increasing number __ aircraft. 8 Algorithms __ waypoint steering and __ control __ the vehicle’s attitude are contained __ the software __ the flight management and flight control subsystems. 9 Specially equipped aircraft are often used __ the routine calibration __ radio navigation aids.
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