Specifications

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To log a feature: Means to save the characteristics of a feature
into the receiver memory. The user is in charge of entering the
description of this feature whereas the receiver is responsible for
saving the GPS position(s) it has determined on this feature.
To describe a feature: Means to give each attribute of the feature
one of the prompted values for this feature.
Feature Library: A file containing all the feature types required for a
given job. (In fact we should say “Feature Type Library”.)
Feature Type: An item present in a feature library. Each feature type
is defined by a geometry type, a name, a certain number of possible
attributes and the list of possible values for each attribute. There are
four different geometries in feature types: point, line, area and grid.
Field: Any area on the receiver screen dedicated to displaying the val-
ue of a parameter. Some fields are user-editable, some others are not.
Fixed: Position solution status achieved by a receiver operating success-
fully in RTK mode. Position accuracy is in the order of one centimeter.
Float: Intermediate position solution status obtained in a receiver attempt-
ing to operate in RTK mode. Position accuracy is also intermediate as it is
only in the order of a few decimeters.
Geographic Information System: A system of digital maps, data anal-
ysis software and a database of features, attributes and geographic lo-
cations.
GIS: See Geographic Information System.
GNSS: Global Navigation Satellite System. GPS, GLONASS and the future
Galileo are each a GNSS.
GPRS: General Packet Radio Service. A mobile data service available to
cell phone users. GPRS data transfer is typically charged per megabyte of
transferred data, while data communication via traditional circuit switch-
ing is billed per minute of connection time, independent of whether the
user has actually transferred data or he has been in an idle state.
GPS: Global Positioning System. Passive, satellite-based navigation sys-
tem operated by the Department of Defense of the USA. Its primary mis-
sion is to provide passive global positioning/navigation for land-, sea-, and
air-based operations.
GPS satellite geometry: The satellite distribution at a given location.
measured by the PDOP index
GPS signal multipath: Occurs when the GPS signal arrives at the an-
tenna by a path other than a straight line. Multipath signals make the
receiver think that a GPS satellite is farther away than it is and the
resultant position is inaccurate.
GSM: Global System for Mobile communications. The most popular stan-
dard for mobile phones in the world.
HRMS: Horizontal Root Mean Square. A statistical measure of the scatter
of horizontal computed positions about a “best fit” position solution. It
gives you a good indication of how well the unit performs.
Initialization: • A process used at power-on to help a GPS receiver more
easily determine its own location. The solution is of the GPS standalone
type (accuracy is a few meters).
• For an RTK rover, once GPS initialization is achieved, a process through
which the receiver can solve integer ambiguity from which it can deliver a
fixed solution with centimeter accuracy.