Garmin Sounder GPSMAP 135 Owner's Manual page 103

SECTION
Almanac Data—The satellite constellation information (including location and health of satellites) APPENDIX
E
that is transmitted to your receiver from every GPS satellite. Almanac data must be acquired before
GPS navigation can begin.
Glossary
Bearing (BRG)—The compass direction from your position to a destination.
Course Over Ground (COG)—Direction of movement relative to a ground 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 remaining to your destination at your present speed.
Grid—A coordinate system that projects the earth on a flat surface, using square zones for position
measurements.
Ground Speed (SOG)—The velocity you are traveling relative to a ground position.
Latitude—A north/south measurement of position perpendicular to the earth's polar axis.
Longitude—An east/west measurement of position in relation to the Prime Meridian, an imaginary
circle that passes through the north and south poles.
Position—An exact, unique location based on a geographic coordinate system.
Sensitivity—A measure of how sensitive the sounder is to sonar echoes.
Speed Through Water (STW)—The speed you are traveling relative to the water's surface.
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