The coordinates of GNSS points are always stored in the WGS 1984 coordi-
nates system. WGS 1984 is a three-dimensional Cartesian coordinate system
with the origin at the centre of the Earth. WGS 1984 coordinates are given as
X,Y,Z Cartesian coordinates, or latitude, longitude and height (above the WGS
1984 ellipsoid).
GNSS points are stored as class
Measured
or class
Navigated
:
•
Class Measured: If there are 5 or more satellites, and the distance to the
reference is not too great for the prevailing ionospheric conditions, Smart-
Station computes a GNSS real-time position. The CQ indicator for this type
of point is about 0.01 m to 0.05 m.
•
Class Navigated: If the reference stops working, or if the communication
link between the reference and SmartStation fails, SmartStation computes
a navigation position. The CQ indicator for this type of point is about 3 m
to 20 m.
Depending on the surveying task and the instruments being used, certain
GNSS surveying techniques are possible. The three existing types of GNSS sur-
veying techniques are:
GNSS survey-
ing technique
Characteristic
Description
Static
Way of working
•
Base set up over a point with accu-
rately known coordinates.
•
Rover set up over a point with
known or unknown coordinates.
•
Data recorded at both instruments
simultaneously at the same data
rate, typically 15 s, 30 s or 60 s.
•
Post-processing is compulsory.
Use
For long baselines, geodetic networks,
tectonic plate studies.
Accuracy
High over long baselines.
Working speed
Slow
Post-pro-
cessed kine-
matic
Way of working
•
Base set up as static over a point
with accurately known coordinates.
•
Rover moves from one point to
another. The instrument remains
turned on while moving.
•
Static and moving raw observations
are collected.
•
Post-processing is compulsory.
Use
For detail surveys and measuring many
points in quick succession.
Accuracy
High for baselines up to 30 km.
Working speed
Efficient for surveying many points that
are close together.
Real-time,
base and
rover
Way of working
•
Base set up as static over a point
with accurately known coordinates
in WGS 1984.
GNSS points
GNSS surveying tech-
niques
Glossary
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