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.