GNSS RTK

This manual provides step-by-step instructions for setting up a dual GNSS system with a fixed base for RTK, with a focus on heading applications. In this configuration, the fixed base station communicates RTK corrections to the moving base station via telemetry, while the moving base station sends RTCM messages to the rover over a wired connection.

It is important to highlight that this configuration is specifically designed for the u-blox F9P module. The steps and settings outlined in this manual may differ for other GNSS receiver models.

Additionally, it is worth noting that the same configuration can be applied in situations where a moving base is not utilized. In such cases, the RTCM messages from the fixed base station can be transmitted through the Ground Control Station (GCS) and the flight controller to the rover module. Additionally, telemetry modules can be used to send RTCM messages between Base station and the Rover.

To ensure a smooth and efficient configuration process, we strongly recommend using the u-blox u-center software. u-center provides a comprehensive and user-friendly interface specifically designed for u-blox GNSS modules.

Fixed Base Configuration

To configure the fixed base station for GNSS RTK, follow these steps:

  • Set the navigation rate on the base and rover to 8 Hz (125 ms) and the time source as UTC.

  • Configure UART1 on the base module to the telemetry baud rate, which is used for sending RTCM messages from the fixed base.

  • Enable the following RTCM messages on the base module by setting their values to 1:

    • RTCM 1005: Stationary RTK reference station ARP
    • RTCM 1074: GPS MSM4
    • RTCM 1084: GLONASS MSM4
    • RTCM 1094: Galileo MSM4
    • RTCM 1124: BeiDou MSM4
    • RTCM 1230: GLONASS code-phase biases

  • Perform a survey-in.

Moving Base Configuration

To configure the moving base for GNSS RTK, follow these steps:

  • Set the navigation rate on the base to 8 Hz (125 ms) and the time source as UTC.

  • Configure UART2 on the base module to 460800 baud, which is used for communication with the rover.

  • Configure UART1 on the base module to the telemetry baud rate, which is used for receiving RTCM messages from the fixed base.

  • Enable the following RTCM messages on the base module by setting their values to 1:

    • RTCM 4072.0: Reference station PVT information
    • RTCM 1077: GPS MSM7
    • RTCM 1087: GLONASS MSM7
    • RTCM 1097: Galileo MSM7
    • RTCM 1127: BeiDou MSM7
    • RTCM 1230: GLONASS code-phase biases

Rover Configuration

To configure the rover for GNSS RTK, follow these steps:

  • Set the navigation rate on the rover to 8 Hz (125 ms) and the time source as UTC.

  • Configure UART1 and UART2 on the rover to 460800 baud for communication.

  • Enable the following messages on the rover by setting their values to 1:

    • UBX-NAV-RELPOSNED
    • UBX-NAV-PVT

Note: The Reflex automatically configures the Rover module when connected to the GNSS port, while the base modules need to be manually configured.