The RT-Base S is a portable GNSS base station suitable for transmitting differential corrections (DGNSS) to OxTS' range of GNSS-aided inertial navigation systems, but is not limited to them. In fact, the RT-Base S can be set-up to work with most GNSS receivers capable of receiving DGNSS corrections. This makes the RT-Base S an incredibly useful and powerful piece of equipment for anyone who needs a stand-alone, portable, all-weather base station.
There are two versions of the RT-Base S. The RT-Base S supplies L1/L2 GPS corrections for up to 1 cm position accuracy. The RT-Base S G supplies GLONASS and L1/L2 GPS corrections for up to 1 cm accuracy. Both models are identical in their operation.
The figure below gives an overview of how differential GNSS works. The information from each satellite is measured by both the RT-Base S and by the GNSS receiver in the car. The RT-Base S calculates the error affecting the signal from each satellite and then transmits that information to the car using a radio link. The GNSS receiver in the car then applies the correction to each satellite’s measurement before it computes position and time.
For RTK (Real-Time Kinematic) Carrier-Phase measurements the principle is the same, but the receiver in the car also has to figure out the difference in the number of carrier-phase cycles between the RT-Base S and the car. The RT-Base S measures the carrier-phase of the signals from each satellite and transmits it to the car.
Differential GNSS works in real-time because the corrections from each satellite vary slowly and predictably. The receiver 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 GNSS receiver in the car to wait until the radio has transmitted the correction before it outputs its latest value.
For Pseudo-Range (not carrier-phase) Differential GNSS the corrections can be up to 60 s old (depending on the GNSS receiver in the car). For RTK corrections (up to 1 cm) the corrections can be up to 30 s old (again, depending on the GNSS receiver in the car).
Different countries have different licensing laws and different frequencies for radio transmissions. Many countries have license-free frequencies that can be used for Differential GNSS signals. We can supply a range of different radios that can be used, license-free, in many countries.
DGNSS Correction Type(s)
The RT-Base S firmware allows the differential correction format to be selected from a choice of RTCA, RTCA2, RTCM, RTCMv3, CMR, CMR+.
Internal battery provides a minimum of 24 hours of continuous operation
Broadcast differential corrections over a wide range of popular formats
Large number of DGNSS correction formats to choose from
Start-up option to average position or restore from a list of 10 previously saved positions
Average position data over a wide user-defined time period
Save differential corrections inside the RT-Base S for later retrieval to a laptop or PC
Ideal for automotive testing applications where real-time RTK integer accuracy is required
Works seamlessly with OxTS devices to provide up to 1 cm RTK integer accuracy
Broadcast corrections can be used with other manufacturers’ equipment thanks to number of correction formats
RT-Base S unit
GNSS antenna and cable
Battery suitable for up to 32 hours of operation
Battery charger and cable
Country specific radio modems with antenna and cables