ABSTRACT
Global Positioning System (GPS), surveyors use the same sensors as navigators but achieve higher accuracy as
a result of longer periods of observation and more complex post-processing.
In the usual navigation system, the state vector is derived onboard, displayed to the crew, recorded on-
board, or transmitted to the ground. Navigation information is usually sent to other on-board subsystems, for
example to the waypoint steering, communication control, display, weapon-control, and electronic warfare
(emission detection and jamming) computers. Some navigation systems, called position-location systems,
measure a vehicle’s state vector using sensors on the ground or in another vehicle (Section 12.6). The external
sensors usually track passive radar returns or a transponder. Position-location systems usually supply
information to a dispatch or control center.
