Glossary
INTRODUCTION
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The GPS 126/128 is a powerful navigation tool that can guide you any-
where in the world. To better understand its operation and capabilities, it may
be helpful to review the basic terms and concepts briefly explained below.
Other navigation and GPS definitions used in the manual are defined in the
appropriate reference sections of the manual.
Almanac Data
Satellite constellation information (including location and health of satel-
lites) that is transmitted to your receiver from every GPS satellite. Almanac data
must be acquired before GPS navigation can begin.
Bearing
The compass direction from your position to a destination.
Course Made Good (CMG)
The bearing from the “active from” position (your starting point) to your
present position.
Crosstrack Error (XTK)
The distance you are off a desired course in either direction.
Desired Track (DTK)
The compass course between the “from” and “to” waypoints.
Differential GPS (DGPS)
An extension of the GPS system that uses land-based radio beacons to
transmit position corrections to GPS receivers.
Estimated Time of Arrival (ETA)
The time of day of your arrival at a destination.
Estimated Time Enroute (ETE)
The time left to your destination at your present speed.
126/128 Manual (new) 6/15/98 9:50 AM Page 2
