The information from each satellite is measured by both the GPS-Base and by the GPS in … GPS-Base User Manual Revision: 090917 7 Table 2. Summary of Differential Correction Types … Correction Measurement Accuracy Max Age(typical) Packet Type 2 GPS-Base Model Differential L1 Pseudo-Range 45cm 1 60s RTCA1 GPS-Base-20 GPS-Base-2 GPS-Base-20G GPS-Base-2G L1 L1 Carrier-Phase 20cm 30s RTCAOBS GPS-Base-20 GPS-Base-2 GPS-Base-20G GPS-Base-2G L1/L2 L1/L2 Carrier-Phases 2cm 30s RTCAOBS GPS-Base-2 GPS-Base-2G Note 1: Using the smoothing …

The GPS-Base is a GPS Base Station suitable for transmitting Differential corrections to the RT3000 and other 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. Both models are identical in their operation. 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 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. 6 Oxford Technical Solutions Figure 1. Differential GPS Overview For RTK (Real-Time Kinematic) Carrier-Phase measurements the principle is the same, but the GPS in the car also has to figure out the difference in the number of carrier- phase cycles between the GPS-Base and the car. The GPS-Base measures the carrier- phase of the signals from each satellite and transmits it to the car. Differential GPS works in real-time because the corrections from each satellite vary slowly and predictably. The GPS in the car uses a model to predict the error from each satellite. It can update its model when the radio link transmits new data. It is not necessary for the GPS in the car to wait until the radio has transmitted the correction before it outputs its latest value. Table 2, lists information about the different correction types that are available.

Download GPS-Base User Manual.Pdf