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DEFINITION OF TERMS/ABBREVIATIONS
Due to space considerations, the digital displays use abbreviations for
some names. They are as follows:
ALT ............... Altitude - Your height above sea level.
BRG ............. Bearing - The direction from your present position to a
waypoint.
CLOCK ......... Your local time.
TRK .............. Track - The direction you’re travelling.
DIS ............... Distance - Distance remaining between your present po-
sition and a waypoint.
DNT/UPT ...... Countdown timer (DNT) and Count up timer (UPT)
ETE .............. Estimated Time En route
ICON ............ A symbol you can place on the map, representing a land-
mark.
POSITION .... Your present position.
GS ................ Ground Speed - Your actual speed.
TTG .............. Time To Go - Time remaining at your present speed until
you reach a waypoint.
VMG ............. Velocity Made Good - Actual speed towards a waypoint.
XTE .............. Cross Track Error - Distance to the side of the desired
course line.
GPS - HOW IT WORKS
The Global Positioning System (GPS) is the latest in high-tech navigation
systems. Conceived by the United States military, the GPS system is an
answer to their need of a highly accurate, 24-hour, 365 day a year global
positioning system.
Basically, the system works by using a constellation of satellites orbiting
Earth 11,000 miles in space. As of this writing, there are 25 satellites in
orbit. Before satellites reach the end of their life, new ones are launched.
This keeps at least four satellites in view virtually anywhere on Earth 24-
hours a day. The GPS receiver requires at least three satellites to give a
“2D” fix. (A 2D fix is your position in latitude/longitude. A 3D fix is your
latitude/longitude plus altitude.) When the receiver locks onto at least four
satellites, it displays a 3D fix.
As the receiver locks on to each satellite, it calculates the distance from
the satellite by measuring the length of time it takes the radio signal to
reach it. Each satellite has an extremely accurate clock that tells the re-
ceiver when the radio transmission started. The receiver compares that