Glossary - Magellan MobileMapper - GPS Software User Manual

Glossary

Attribute: A description item of a feature.
Attribute value: One of the possible values that can be as-
cribed to a feature.
Base Station: See Reference Station.
B-File: A binary MobileMapper Pro data file containing
GPS measurement data.
Carrier phase data: Phase angle measurements for the 1575
MHz radio wave carrying the GPS coded messages. Using car-
rier phase data greatly improves GPS accuracy.
Datum: A mathematical definition of a surface from which co-
ordinates of a given system are referenced.
D-File: A binary MobileMapper Pro data file created by field
collection software and stored in the receiver.
DGPS: Differential Global Positioning System. Commonly
used to refer to real-time differential correction techniques.
Differential Correction: The process of:
(1) calculating how much to adjust GPS measurements to re-
duce the difference between a location's surveyed coordinates
and the coordinates calculated by a GPS receiver that is kept
stationary over that point; and
(2) the application of these adjustments to the GPS measure-
ments recorded by any number of receivers within a few hun-
dred kilometers of the "reference receiver."
Differential GPS: See DGPS.
E-File: A binary MobileMapper Pro data file containing GPS
ephemeris data.
Ephemeris Data: Information transmitted from a satellite
which allows the GPS receiver to determine the satellite's po-
sition in space.
Export: Converting MobileMapper Pro data files to GIS For-
mats and writing them to any directory visible to the PC.
Feature: Any element located in the field that you wish to
record for further uploading into a GIS database for example.
A feature can represent a real object (streetlight, park, electri-
cal transformer, etc.) or on the contrary, something invisible or
impalpable (gas, noise level, dose of fertilizer, etc.).
Each new feature that you log in the field can only be an "em-
anation" or "offshoot" of one of the feature types described in
the feature type library associated with the job in progress.
The logging procedure will be different depending on the type
of the feature you are logging.
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