Essential Components For Quality Surveying - Topcon GR-3 Operator's Manual

A number of differential positioning implementations exist, including
post-processing surveying, real-time kinematic surveying, maritime
radio beacons, geostationary satellites (as with the OmniSTAR
service), and satellite based augmentation systems (WAAS, EGNOS,
MSAS).
The real-time kinematic (RTK) method is the most precise method of
real-time surveying. RTK requires at least two receivers collecting
navigation data and communication data link between the receivers.
One of the receivers is usually at a known location (Base) and the
other is at an unknown location (Rover). The Base receiver collects
carrier phase measurements, generates RTK corrections, and sends
this data to the Rover receiver. The Rover processes this transmitted
data with its own carrier phase observations to compute its relative
position with high accuracy, achieving an RTK accuracy of up to 1 cm
horizontal and 1.5 cm vertical.

Essential Components for Quality Surveying

Achieving quality position results requires the following elements:
• Accuracy – The accuracy of a position primarily depends upon
the satellite geometry (Geometric Dilution of Precision, or
GDOP) and the measurement (ranging) errors.
– Differential positioning (DGPS and RTK) strongly mitigates
atmospheric and orbital errors, and counteracts Selective
Availability (SA) signals the US Department of Defense
transmits with GPS signals.
– The more satellites in view, the stronger the signal, the lower
the DOP number, the higher positioning accuracy.
• Availability – The availability of satellites affects the calculation
of valid positions. The more visible satellites available, the more
valid and accurate the position. Natural and man-made objects
can block, interrupt, and distort signals, lowering the number of
available satellites and adversely affecting signal reception.
P/N 7010-0736
Principles of Operation
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