Specifications
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Job file: File containing a feature type library and a collection of fea-
tures that grows as you log new features in the field with this job file
open. All the features in the job file necessarily “originate” from the
feature types present in the job file’s feature type library.
Nesting: This word is used to describe a feature that you are logging
whereas another feature is already being logged.
NTRIP: Networked Transport of RTCM via Internet Protocol. A protocol
used by GNSS service providers to deliver corrections from their networks
of reference stations. When setting NTRIP in a receiver, you must specify
the mount point (an IP address) of the NTRIP provider as well as your per-
sonal user profile.
PDOP: Positional Dilution of Precision. An accuracy factor derived
from the geometry of the constellation of GPS satellites used to cal
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culate a position. In general, the more widely distributed the satellites
are in the sky, the greater the accuracy. In general, PDOPs less than
10 are good.
Post-processing: Differential corrections applied to GPS positions in
a PC - after both rover and reference data are logged and downloaded.
Post-processing is slower but more accurate than real-time differen
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tial correction.
Rover: The mobile unit that you carry with you during your field operations.
RTCM: Radio Technical Commission for Maritime Services. Common-
ly refers to a format of real-time DGPS format.
Reference Station: A stationary GPS receiver logging, or broadcasting,
data from a known point. The data is used for differential correction.
Reference Station is synonomous with Base Station.
RINEX: Receiver Independent Exchange Format. A “universal” GPS
measurement data format designed to allow compatibility b tween dif
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ferent brands of GPS receivers.
RTK: Real Time Kinematic. An algorithm run in a receiver that allows its
position to be determined in real time, with centimeter accuracy.
UHF: Ultra High Frequency band. Magellan radio modems use this fre-
quency band.
VRMS: Vertical Root Mean Square. A statistical measure of the scatter of
vertical computed positions about a “best fit” position solution. It gives
you a good indication of how well the unit performs.
Shapefile: A set of GIS files invented by ESRI but published as an
open file standard readable by most GISs. A shapefile consists of a
map file (SHP), a file containg feature descriptions (DBF), a file re
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lating the map locations with the feature description (SHX) and
sometimes a file containing coordinate system information (PRJ).
Waypoint: A pre-determined coordinate point to which a GPS receiver
can navigate. GPS receivers can also log waypoints in the field for lat
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er navigation. GPS for GIS receiver have largely replaced waypoints
with point features.
W-File: A binary data file containing SBAS data.
WGS-84 coordinate system: World Geodetic System, 1984. The coor-
dinate system is used by GPS receivers for computing their positions.