C-RTK3 X20P User Guide
This chapter applies to the scenario of using the C-RTK3 X20P with ArduPilot vehicles.
[!NOTE] ArduPilot 4.4.0 and later versions support the C-RTK3 X20P.
Setup as Rover (Air Side)
[!TIP] LGC ground station provides graphical configuration and hardware connection guidance for simpler setup. Before configuration, ensure the C-RTK3 X20P is in rover mode (MODE LED flashing green); you can also switch modes by long-pressing the MODE button.
CAN Connection to Flight Controller
- Take out the CAN cable from the accessory package, connect the flight controller to the CAN port of the C-RTK3 X20P; install the antenna and ensure a clear sky view.
- Connect the flight controller to the ground station (such as Mission Planner / LGC) via USB.
- Enter the Full Parameter List, input parameter names in the search bar and set the following parameters.
// Mission Planner path: Configuration/Tuning → Full Parameter List → Search bar on the right
| Parameter | Value | Remark |
|---|---|---|
GPS1_TYPE |
9 | DroneCAN: 9; UART: 26 |
CAN_P1_DRIVER |
1 | Enable CAN1 driver |
GPS_AUTO_CONFIG |
2 | Auto configure DroneCAN GPS |
GPS1_POS_X |
Value (m); set according to installation | Antenna X-axis offset relative to center of gravity, positive forward |
GPS1_POS_Y |
Value (m); set according to installation | Antenna Y-axis offset relative to center of gravity, positive right |
GPS1_POS_Z |
Value (m); set according to installation | Antenna Z-axis offset relative to center of gravity, positive below CG |
[!NOTE] The C-RTK3 X20P is a single-antenna positioning module and does not support dual-antenna heading. There is no need to configure antenna offset parameters.
For firmware versions below ArduPilot 4.6 (exclusive):
| Parameter | Value | Remark |
|---|---|---|
GPS_TYPE |
9 | DroneCAN: 9; UART: 26 |
CAN_P1_DRIVER |
1 | Enable CAN1 driver |
GPS_AUTO_CONFIG |
2 | Auto configure DroneCAN GPS |
GPS_POS1_X |
Value (m); set according to installation | Antenna X-axis offset relative to center of gravity, positive forward |
GPS_POS1_Y |
Value (m); set according to installation | Antenna Y-axis offset relative to center of gravity, positive right |
GPS_POS1_Z |
Value (m); set according to installation | Antenna Z-axis offset relative to center of gravity, positive below CG |
Positioning Verification
- GPS positioning data can be viewed in the status bar of the Mission Planner flight data toolbar.
- Check whether the positioning status is RTK Fixed.
- Observe the satellite count, HDOP value, and other indicators to confirm good positioning quality.
[!NOTE] For RTK positioning, ensure the base station is functioning properly and the data link is working.
UART Connection to Flight Controller
| Parameter | Value | Remark |
|---|---|---|
GPS1_TYPE |
1 | DroneCAN: 9; UART: 1/2 |
GPS_AUTO_CONFIG |
0/1 | Auto configure serial GPS, For AP firmware below 4.8.0, disable auto config |
GPS1_POS_X |
Value (m); set according to installation | Antenna X-axis offset relative to center of gravity, positive forward |
GPS1_POS_Y |
Value (m); set according to installation | Antenna Y-axis offset relative to center of gravity, positive right |
GPS1_POS_Z |
Value (m); set according to installation | Antenna Z-axis offset relative to center of gravity, positive below CG |
SERIAL3_PROTOCOL |
-1 | Disable Serial3 if no GPS is connected to GPS&Safety port; GPS2/UART4 will be recognized as GPS1 |
SERIAL4_PROTOCOL |
5 | Set Serial4 as GPS port, generally no modification required |
SERIAL4_BAUD |
230400 | Set Serial4 baud rate to 230400 |
Setup as Base Station
[!TIP] Use LGC ground station for automated base station configuration. QGC does not yet support C-RTK3 X20P, and Mission Planner cannot configure the base station convergence accuracy and duration.
- Connect the C-RTK3 X20P to your computer via USB cable.
- Confirm the C-RTK3 X20P is in base station mode (MODE LED solid green; long-press the MODE button to switch modes).
- Launch LGC ground station. When the RTK satellite icon appears, the X20P base station has been recognized.
- When the satellite icon shows RTK in red, and the status displays Converging, the RTK base station is performing survey-in convergence positioning.
- By default, the convergence accuracy is 3.0m with a minimum duration of 30s.
- When the convergence accuracy and criteria are met, the RTK text turns white. The status displays RTCM transmitting, indicating base station configuration is complete; the ground station will send differential data to the controller/RTK rover.
[!NOTE] The convergence accuracy can be configured — higher accuracy requires longer convergence time. Under default settings (3.0m accuracy), after the rover resolves, centimeter-level positioning accuracy can be achieved.
Interference Status Display
[!NOTE] The C-RTK3 X20P supports interference status display with built-in CW interference detection and spectrum analysis; this requires compatible flight controller firmware and ground station support. Please contact CUAV technical support if needed.
