GPS-Base User Manual
Revision: 131025
5
Introduction
The GPS-Base is a GPS Base Station suitable for transmitting differential corrections to
the OxTS RT3000, RT4000, RT2002, RT2004, and OEM products that use
GPS. The position accuracy of differential and RTK GPS receivers is improved when
using the GPS-Base.
Four models of the GPS-Base exist, as listed in Table 1. All models are identical in
their operation but are able to track different satellite signals.
Table 1. GPS-Base Models
Model
Measurement
GPS-Base-20
L1 GPS corrections suitable for 20cm positioning
GPS-Base-20G
L1 GPS and L1 GLONASS corrections suitable for 20cm positioning. Some RT
products can achieve 2cm accuracy using this model.
GPS-Base-2
L1/L2 GPS corrections suitable for 2cm positioning
GPS-Base-2G
L1/L2 GPS and L1/L2 GLONASS corrections suitable for 2cm positioning
The GPS-Base is available with several different radio options. Different radios are
required for license free operation in different countries.
Overview
Figure 1 gives an overview of how differential GPS works. The information from each
satellite is measured by both the GPS-Base and by the GPS in the car. The GPS-Base
works out the error in the satellite’s information and transmits it to the car using a radio
link. The GPS in the car then applies the correction to each satellite’s measurement
before it computes position and time.
