Ag Leader GPS 5200 User Guide - Manual (Page 16)

2 Overview
14 GPS 5200 Receiver User Guide
GPS positioning methods
GPS positioning systems are used in different ways to provide different
levels of accuracy. Accuracy is measured in absolute terms, that is, you
know exactly where you are in a fixed reference frame.
Table 2.4 summarizes the GPS positioning methods. Imperial units in
this table are rounded to two decimal places. The values shown are
2 sigma.
For more information about each positioning method, see below.
RTK GPS positioning
The GPS 5200 receiver uses the RTK positioning method to achieve
centimeter-level accuracy. To use the RTK method, you must first set up
a base station. The base station uses a radio link to broadcast RTK
corrections to one or more rover receivers. The GPS 5200 receiver is a
rover receiver, so another compatible receiver, such as a Trimble
MS750
™ , AgGPS 214, AgGPS RTK Base 450, or AgGPS RTK Base 900
receiver, must be used as the base station.
The rover receiver uses RTK corrections from the base station to
calculate its position to centimeter-level accuracy. As part of this
process, the rover receiver must calculate an initialization. This takes a
Table 2.4 Absolute accuracy of GPS positioning methods
GPS positioning
method Corrections used Approximate absolute accuracy
Real-Time Kinematic
(RTK) GPS Trimble CMR corrections
broadcast by a local
base station 2.5 cm (0.98 inch) + 2 ppm horizontal
accuracy,
3.7 cm (1.46 inch) + 2 ppm vertical accuracy
Satellite Differential GPS OmniSTAR VBS 78 cm (30.71 inch)
Satellite Differential GPS WAAS/EGNOS 95 cm (37.40 inch)
OmniSTAR HP
Differential GPS OmniSTAR HP 10 cm (3.94 inch) after the signal has fully
converged
1
1 Convergence time can vary, depending on the environment. Time to the first fix (submeter accuracy)
is typically <30 seconds; time to the first high accuracy fix (<10 cm accuracy) is typically <30 minutes.
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