Hardware Connection

OneRTK UM982 supports the following two connection methods:

CAN connection (recommended): Use a CAN/I2C cable to connect the OneRTK's CAN port to the flight controller's CAN port. This method is recommended to ensure stable data transmission.
UART connection: Use the [Serial Cable] in the accessories to connect the OneRTK UM982's [UART] port to the flight controller's [Telem] port. This is suitable for situations where CAN connection is unavailable.

Enable OneRTK

Use CAN communication

In Missionplanner, go to [Configuration/Debug] >> [All Parameters], search for the following parameters and set them:

【GPS_TYPE】Set to 9 (GPS1_TYPE=9 for AP4.6 and above firmware)

【CAN_P1_DRIVER】Set to 1

【EK3_SRC1_YAW】Set to 2 (use GPS as the heading source) or 3 (use GPS as the heading source first, with compass as a backup).

Using UART connection communication

If the module is connected to the GPS2 port of the flight controller, configure the following parameters:

【GPS_TYPE】Set to 25: UnicoreMovingBaseline (GPS1_TYPE=25 for AP4.6 and above firmware)

【SERIAL4_PROTOCOL】Set to 5, You need to change serial3_protocol to -1 so that the GPS2 interface will be defined as the first gps.

【GPS_AUTO_CONFIG】Use the default value of 1.

Antenna Installation

To ensure accuracy and avoid signal interference, a minimum distance of 30 cm must be maintained between the master and slave antennas.

Master and slave antenna offset settings

According to the actual installation situation, set the offset of the main antenna relative to the slave antenna:

GPSx_MB_TYPE：Set to 1 (for AP firmware versions earlier than 4.6) or GPS1_MB_TYPE (for AP firmware versions 4.6 and above).

GPSx_MB_OFS_X/Y/Z：Set the X, Y, and Z axis offsets of the master antenna relative to the slave antenna (unit: meters).

(If you can't find the above parameters, search for GPSx_MB_TYPE and set it to 1, then restart the flight controller and the above parameters will appear)

Note:

The X-axis is usually defined as the front-to-back direction of the vehicle. When the primary antenna is located in front of the vehicle, this parameter should be entered with a positive value, indicating that the primary antenna is moved forward by the corresponding distance relative to the secondary antenna.

The Y-axis is typically defined as the left-right direction of the vehicle. When the master antenna is to the right of the slave antenna, a positive value should be entered for this parameter, indicating that the master antenna has been moved to the right by that distance relative to the slave antenna.

The Z axis is usually defined as the vertical direction of the vehicle. When the master antenna is lower than the slave antenna, this parameter should be entered as a positive value, indicating that the master antenna has moved downwards by a corresponding distance relative to the slave antenna.

Positioning offset settings

If the OneRTK main antenna cannot be installed at the center of gravity of the UAV, you need to set an offset from the center of gravity:

GPS_POS1_X/Y/Z(For AP firmware versions below 4.6) orGPS1_POS_X/Y/Z(For AP firmware 4.6 and later): Set the X, Y, and Z axis offsets of the main antenna relative to the center of gravity (unit: meters).

Note:

The X axis usually refers to the longitudinal axis of the drone, that is, the front-to-back direction of the vehicle. When the main antenna is located in front of the center of gravity of the drone, this parameter should be entered as a positive value, indicating the distance the main antenna is offset forward relative to the center of gravity.

The Y axis usually refers to the lateral axis of the drone, that is, the left and right direction of the vehicle. If the main antenna is located to the right of the center of gravity of the drone, this parameter should be entered as a positive value, indicating the distance the main antenna is offset to the right relative to the center of gravity.

The Z axis usually refers to the vertical axis of the drone, that is, the up and down direction of the vehicle. If the main antenna is below the center of gravity of the drone, then this parameter should be entered as a positive value, indicating the distance the main antenna is offset downward relative to the center of gravity.

Failure to set the offset or incorrect offset setting will cause the aircraft to obtain incorrect positioning information, resulting in position offset or inaccurate positioning during heading deflection.

Heading confirmation and calibration

After completing the configuration and calibration of the GPS system, the accuracy of the heading needs to be verified:

Open the MissionPlanner software and switch to the "Flight Data" page.
In the "Flight Data" toolbar, find and observe the "gpsyaw" value. "gpsyaw" represents the drone's heading calculated by GPS. Check whether this value is consistent with the actual heading of the drone.

3.To confirm the accuracy of the "gpsyaw" value, you can manually rotate the aircraft. During the rotation, pay attention to whether the "gpsyaw" value can correctly respond to the rotation of the drone.