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09/25/02 GPS_field_guide 8:19 A9/P9

GLOSSARY

Accuracy : How close to the real value a measurement is.

Backlight: Selectable on/off illumination that lights the display for enhanced screen at

night and in low light.

Contrast: The difference between the lightest and darkest areas on a display screen.

Coordinates : The unique description of a geographic position using numeric

characters.

Dilution of Precision (DOP): The dilution of precision (DOP) is an indication of the

quality of the results that can be expected from a GPS point position. It is a

measure based solely on the geometry of the satellites in the sky.

Ephemeris: The predictions of current satellite position that are transmitted to the

user in the data message.

Initialization: Refers to the procedure of telling a GPS receiver where it is, when it is

turned on for the first time. Information required for initialization includes

approximate present position in latitude/longitude coordinates, the current local

time and date (information obtained through the satellite signal when using the

eTrex unit).

Map Datums: Since the Earth is not flat a model needs to be used in order for the

GPS receiver to give the coordinates. These models are calls Datums.

Multipath: Mutipath is the phenomena by which the GPS signal is reflected by some

object or surface before being detected by the receptor antenna creating

multipath for a same signal that results in a calculation error when estimating

the distance between the satellite and the receiver

Position: A geographic location on the earth, commonly measured in latitude and

longitude.

Satellite constellation: The arrangement in space of a set of satellites.

Segment: One of several parts or pieces that fit with others to constitute a whole

object.

GPS Control segment: A Master Control Station and a number of monitoring

stations around the world that ensure the accuracy of satellite positions and their

clocks.

GPS Space segment: The network of 24 GPS satellites.

GPS User segment: The receivers of GPS signals such as your eTrex Unit.

Garmin GPS User Manual

Other manuals for Garmin GPS