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.

Using as an RTK Base Station

The C-RTK3 X20P supports operation as an RTK base station. When used as a base station:

• Connect the X20P to the flight controller via CAN or UART.
• Set the base station position through the ground station (enter precise known coordinates).
• The base station will broadcast differential correction data via the RTCM protocol.

Flight Controller Parameter Configuration (CAN Connection, Recommended)

• 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

[!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):

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.

Troubleshooting

1. Unable to obtain RTK Fixed solution. Possible causes:
2. The base station is not working properly or the data link is disconnected.
3. Poor satellite positioning quality; place the module outdoors with open sky view.
4. Poor antenna and feeder connection; check the connection status.

5. RTCM data is not correctly received by the module.

6. Position drift or insufficient accuracy in GPS mode:

7. Check whether the GPS position offset settings match the actual installation (GPS_POS1_X/Y/Z).
8. Poor GNSS positioning quality; check satellite count and HDOP.
9. Disable SBAS augmentation. In areas with weak or no SBAS coverage, enabling SBAS may cause position drift.

UART Connection Parameter Configuration

[!NOTE] ArduPilot 4.4.0 and later versions support the C-RTK3 X20P.

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.