PX4 Instructions
The ARK RTK Base is a ground-side base station. It connects to QGroundControl over USB-C, and QGroundControl forwards its RTCM corrections to the vehicle over MAVLink. An RTK rover on the vehicle — such as the ARK RTK GPS — uses those corrections to reach centimeter-level absolute position.
This requires QGroundControl running on a laptop or PC, and a Wi-Fi or telemetry radio link between it and the vehicle. The Android and iOS builds of QGroundControl do not support RTK.
Setting Up the Base Station
Place the base station where it will not be moved, with a clear view of the sky and well away from buildings. Elevating it on a tripod or a roof mount helps.
Connect the ARK RTK Base to the QGroundControl laptop over USB-C. It is detected automatically, and an RTK status icon appears in the toolbar alongside the normal GPS icon.
Power the vehicle and confirm it is connected to QGroundControl.
QGroundControl starts Survey-In, the procedure that establishes an accurate position for the base station. This typically takes several minutes. Click the RTK status icon to watch the progress.
Survey-In is complete when the RTK status icon turns from red to white and corrections begin streaming. The vehicle's GPS status then reads
3D RTK GPS Lock.
The minimum Survey-In duration and accuracy are set in the QGroundControl RTK GPS settings, under Settings > General > RTK GPS. After a survey completes you can select Use Specified Base Position and press Save Current Base Position to reuse that position and skip Survey-In on later flights.
The base station must not be moved while it is in use. Moving it invalidates the surveyed position, and the corrections it sends will pull the vehicle's position with it.
Vehicle Configuration
Serial GPS
No configuration is needed. PX4 forwards the RTCM corrections it receives over MAVLink directly to the GPS on the serial port.
DroneCAN GPS
PX4 has to republish the corrections on the CAN bus, and the GPS node has to subscribe to them.
Flight Controller Parameters
Set the following in QGroundControl and reboot the flight controller.
CAN Node Parameters
Set the following on the GPS and reboot the node. CAN node parameters can be configured using either:
QGroundControl — each CAN node appears as a separate Component X entry under Vehicle Settings > Parameters.
The DroneCAN GUI Tool.
CANNODE_SUB_RTCM
1
Subscribe to RTCMStream messages on the CAN bus. Enabled by default on the ARK RTK GPS
Tuning
The default EKF2 GPS noise parameters assume meter-level accuracy. With RTK, lower EKF2_GPS_P_NOISE and EKF2_GPS_V_NOISE to 0.2.
RTCM streaming needs MAVLink 2, which is the default on recent builds. If corrections do not reach the vehicle over a telemetry radio, confirm MAV_PROTO_VER is set to 2 and that the radio firmware is up to date.
Troubleshooting
RTK status icon stays red — Survey-In has not converged. Check that the base station has a clear sky view and has not been moved, and consider relaxing the accuracy target in the QGroundControl RTK GPS settings.
Vehicle never reaches RTK Fixed — confirm corrections are streaming (white RTK status icon) and that the telemetry link has enough bandwidth. When using a DroneCAN GPS on the aircraft, ensure the flight controller sets
UAVCAN_PUB_RTCMto1and the GPS node setsCANNODE_SUB_RTCMto1.See our GPS Placement guide for mounting best practices, interference sources, and antenna positioning.
Last updated