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GNSS points
GNSS surveying tech-
niques
Glossary
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-
Characteristic
ing technique
Static
Way of working
Use
Accuracy
Working speed
Post-pro-
Way of working
cessed kine-
matic
Use
Accuracy
Working speed
Real-time,
Way of working
base and
rover
Description
•
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.
For long baselines, geodetic networks,
tectonic plate studies.
High over long baselines.
Slow
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.
•
For detail surveys and measuring many
points in quick succession.
High for baselines up to 30 km.
Efficient for surveying many points that
are close together.
Base set up as static over a point
•
with accurately known coordinates
in WGS 1984.
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