GPS GLOSSARY

ACCURACY
A measure of how close an estimate of a GPS position is to the true location

ACTIVE LEG
The segment of a route currently being traveled. A segment is that portion of a route between any two waypoints in the route.

BEARING
The compass direction from a position to a destination measured to the nearest degree; also call an azimuth. In a GPS receiver, bearing usually refers to the direction to a waypoint

COURSE
The direction from the beginning landmark of a course to its destination (measured in degrees, radians, or mils) or the direction from a route waypoint to the next waypoint in the route segment

COURSE TO STEER
The heading you need to maintain in order to reach a destination

DESIRED TRACK (DTK)
The compass course between the "from" and "to" waypoints.

DISTANCE
The length (in feet, meters, miles, etc.) between two waypoints or from your current position to a destination waypoint. This length can be measured in straight line (rhumb line) or great circle (over the earth) terms. GPS normally uses great circle calculations for distance and desired track

ESTIMATED TIME ENROUTE (ETE)
The time it will take to reach your destination (in hours/minutes or minutes/seconds) based upon your present position, speed and course.

ESTIMATED TIME OF ARRIVAL (ETA)
The estimated time you will arrive at a destination.

GLOBAL POSITIONING SYSTEM
A global navigation system based on 24 or more satellites orbiting the earth at an altitude of 12,000 statue miles and providing very precise, worldwide positioning and navigation information 24 hours a day, in any weather. Also called the NAVSTAR system

GOTO
A route consisting of one leg with your present position being the start of the route and a single defined waypoint as the destination

INITIALIZATION
The first time a GPS receiver orients itself to its current location and collects almanac data. After initialization has occurred, the receiver remembers its location and acquires a position more quickly because it knows which satellites to look for

INVERT ROUTE
To display and navigate a route from end to beginning for purposes of returning to the route's starting point.

LATITUDE
A position's distance north or south of the equator measured by degrees from zero to 90. One minute of latitude equals one nautical mile.

LEG (ROUTE)
A portion of a route consisting of a starting (from) waypoint and a destination (to) waypoint. A route that is comprised of waypoints A, B, C, and D would contain three legs. The route legs would be from A to B, from B to C, and from C to D.

LONGITUDE
The distance east or west of the prime meridian (measured in degrees), which runs from the north to south pole through Greenwich, England.

MAGNETIC NORTH
Represents the direction of the north magnetic pole from the observer's position. The direction a compass points.

MAGNETIC VARIATION
In navigation, at a given place and time, the horizontal angle (or difference) between true north and magnetic north. Magnetic variation is measured east or west of true north

NAVIGATION
The act of determining the course or heading of movement. This movement could be for a plane, ship, automobile, person on foot, or any other similar means.

NORTH-UP DISPLAY
A GPS receiver’s map display with north always fixed at the top of the screen

POSITION
An exact, unique location based on a geographic coordinate system.

POSITION FIX
The GPS receiver's computed position coordinates.

RS-232
A serial input/output standard that allows for compatibility between data communication equipment made by various manufacturers

ROUTE
A group of waypoints entered into the GPS receiver in the sequence you desire to navigate them

SELECTIVE AVAILABILITY (SA)
The random error, which the government can intentionally add to GPS signals, so that their accuracy for civilian use is degraded. SA is not currently in use.

STRAIGHT LINE NAVIGATION
The act of going from one waypoint to another in the most direct line and with no turns.

TracBack®
The proprietary GARMIN feature which takes your current track log and converts it into a route to guide you back to a starting position.

TRACK-UP DISPLAY
The GPS receiver’s map display with the current direction of travel at the top of the screen. The map display will rotate as you make turns to keep your track at the top of the screen.

TRACK (TRK)
Your current direction of travel relative to a ground position (same as Course Over Ground).

TRUE NORTH
The direction of the north pole from your current position. Magnetic compasses indicate north differently due to the variation between true north and magnetic north. A GPS receiver can display headings referenced to true north or magnetic north

WAYPOINTS
Waypoints are locations or landmarks worth recording and storing in your GPS. These are locations you may later want to return to. They may be check points on a route or significant ground features. (e.g., camp, the truck, a fork in a trail, or a favorite fishing spot). Waypoints may be defined and stored in the unit manually, by taking coordinates for the waypoint from a map or other reference. This can be done before ever leaving home. Or more usually, waypoints may be entered directly by taking a reading with the unit at the location itself, giving it a name, and then saving the point. Waypoints may also be put into the unit by referencing another waypoint already stored, giving the reference waypoint, and entering the distance and compass bearing to the new waypoint