Integration of Septentrio Receivers with the PX4 Autopilot System
Abstract
This paper provides a detailed introduction to the complete solution for integrating the Septentrio Mosaic-go series receivers with the PX4 autopilot. This solution is applicable to Pixhawk-standard flight controllers. Using the Pixhawk 4 and Mosaic-go in a laboratory environment as an example, the full process of hardware connection, firmware configuration, parameter adjustment, and functional verification is elaborated upon. The core of the integration includes using a dedicated JST cable for physical connection, flashing custom firmware and configuring the SBF protocol in QGroundControl, setting corresponding parameters based on the single/dual-antenna system (such as GPS offset angles and EKF2 heading functionality), and finally verifying positioning data and satellite status through the ground station interface. The solution also emphasizes the importance of web-interface layout calibration in dual-antenna configurations, offering a complete operational guide for high-precision heading applications.
AI Q&A
What are the key hardware connection considerations when integrating a Septentrio receiver?
Hardware connection requires attention to three core aspects:
A JST-GH cable matching the pin definition shown in the diagram must be used to connect the receiver to the flight controller’s GPS module port.
The receiver must be powered with 5V via the VCC pin of the 6-pin connector or the Micro-USB interface.
Antennas should be correctly connected to the RF-IN port(s) according to the receiver model (single/dual-antenna version). For dual-antenna configurations, antenna layout parameters must be precisely set in the web interface.
How should the PX4 firmware be configured to be compatible with the Septentrio receiver’s data protocol?
The following key configurations need to be completed via QGroundControl:
It is recommended to use the custom firmware published on Septentrio’s GitHub repository for full support.
In the parameter settings, change GPS_1_PROTOCOL to the “Septentrio (SBF)” protocol.
Set the serial port baud rate (SER_GPS1_BAUD) to 115200 8N1 to match the receiver’s default baud rate.
What special configuration steps are required for dual-antenna heading functionality?
In addition to the basic positioning configuration, the following are also required:
Enable the dual-antenna heading option in PX4’s EKF2_GPS_CTRL parameter.
Set the GPS_PITCH_OFFSET and GPS_YAW_OFFSET values according to the actual installation angles of the antennas.
Precisely calibrate the spatial layout of the dual antennas in the Septentrio web interface.
How can successful integration be verified?
Successful integration can be confirmed by the following indicative phenomena:
The QGroundControl map interface displays a red positioning arrow, and the number of tracked satellites appears next to the satellite icon.
After modifying parameters, all changed items are displayed in red, and the configuration takes effect after rebooting the flight controller.
For dual-antenna systems, the EKF2 status page should display valid heading angle information.
High-Precision GNSS Technology Empowers UAV Flight Control Systems
In the wave of UAV automation and high-precision operations, a core bottleneck for flight control systems often lies in obtaining real-time, stable, and environmentally robust heading and positioning capabilities. The Septentrio mosaic-H GNSS heading module is a disruptive solution born precisely to tackle this challenge. Leveraging dual-antenna input, it achieves sub-degree level heading and pitch/roll angle measurement within a compact form factor, combined with centimeter-level RTK positioning accuracy. This allows UAVs to obtain reliable attitude information immediately, even when static or at low speeds, completely eliminating dependence on initial motion. Its built-in AIM⁺ anti-jamming and anti-spoofing technology, multipath mitigation (APME⁺), and vibration robust tracking (LOCK⁺) – part of the GNSS⁺ enhancement suite – ensure stable output even in complex electromagnetic environments and harsh dynamic conditions. The modular design supports fully automatic assembly, features extremely low power consumption, and is compatible with multi-constellation, multi-frequency signals, providing UAVs with high-reliability assurance throughout their entire operation, from precise navigation and automated takeoff/landing to complex mission execution. Choosing Septentrio mosaic-H is not just selecting a navigation module; it is endowing UAVs with an all-weather, all-scenario “precision perception hub,” making autonomous flight more intelligent, safer, and more trustworthy.
Introduction to the PX4 Autopilot Septentrio Custom Branch:
This project is a custom branch of the PX4 autopilot, specifically for releasing firmware versions containing Septentrio-specific features. The official project can be found in this GitHub repository; this repository does not conduct independent feature development or issue fixes. Release versions are available on the “Releases” page, named according to a standard convention: the first part of the version number is the official base version, and the second part indicates the Septentrio custom version. For example, v1.14.0-septentrio1 represents a version based on the official v1.14.0 with integrated Septentrio fixes. Subsequent update versions will increment the trailing number, such as v1.14.0-septentrio2 or v1.14.0-septentrio3. You can download the corresponding firmware via QGroundControl and flash it to the flight controller. Once completed, you are ready to fly! To start using PX4 with a Septentrio receiver, please consult the Getting Started Guide. The latest version’s usage instructions can also be obtained in the official User Manual. Septentrio only tests and validates specific versions on specific hardware platforms, which are labeled as “Tested.” All other build versions are provided as-is without systematic testing.
List of Septentrio Receivers Confirmed Compatible with the Autopilot:
-mosaic-go GNSS Heading Module Evaluation Kit
-mosaic-go GNSS Module Evaluation Kit
-AsteRx-m3 Pro
-AsteRx-m3 Pro+
mosaic-go H (Heading) GNSS Module Evaluation Kit
Features of the mosaic-H Heading GNSS Receiver Module:
-Dual-antenna support: Provides reliable and precise sub-degree level heading and pitch angle or heading and roll angle measurement.
-Ultra-compact evaluation kit dimensions: 74 × 59 × 11.5 mm.
-Weight: 62 grams.
-Complete multi-frequency, multi-system GNSS receiver: Supports GPS, GLONASS, Galileo, BeiDou, QZSS systems.
-Accurate and reliable heading measurement, combined with centimeter-level RTK positioning.
-Industry-leading anti-jamming and anti-spoofing technology: Advanced Interference Mitigation & Monitoring system (AIM⁺).
-Ready-to-use interfaces: Provides USB, serial (COM), PPS, and event interfaces.
-Industry benchmark ultra-low power consumption.
-High update rate: Measurement data up to 100 Hz, RTK+ attitude data up to 20 Hz.
-Fully equipped: Includes cable set and intuitive web user interface, easily operated and monitored from any mobile device or computer.
Core Advantages of the Septentrio mosaic-go H Module Receiver Evaluation Kit:
The mosaic-go H (Heading) is Septentrio’s most compact high-precision GPS/GNSS heading evaluation kit, providing industry-leading centimeter-level positioning performance, especially in complex environments. This kit integrates the multi-band, multi-system GPS/GNSS receiver module mosaic-H into a small metal enclosure, designed specifically for the convenient evaluation of mosaic-H applications in fields such as UAVs, robotics, autonomous systems, construction, and agriculture. This unique high-performance module supports all existing GNSS satellite signals and is forward-compatible with future signals and services. The built-in, industry-leading AIM⁺ advanced technology provides interference mitigation, monitoring, and anti-spoofing capabilities, ensuring optimal availability and reliability for high-precision positioning. This evaluation kit provides you with the opportunity to explore and test the mosaic-go H module. You can integrate the mosaic-go evaluation kit into your system via connections such as COM ports, USB 2.0, or an SD memory card for rapid prototyping.
The mosaic-go H Evaluation Kit Includes:
-A mosaic-H module soldered onto an interface board and housed in a metal case.
-1 USB cable.
-1 COM1 open interface cable (6-pin).
-1 COM2 open interface cable (4-pin).
-1 User Aid Card.
Steps to Integrate the Latest Septentrio Receiver with the PX4 Autopilot on a Pixhawk-standard Flight Controller:
The Mosaic-go evaluation kit and Pixhawk 4 flight controller are used as examples for this explanation. This solution is compatible with all Septentrio OEM boards and other Pixhawk-standard flight controllers. The example configuration was completed in a laboratory environment, connecting the Mosaic-go (COM1 interface) to the Pixhawk 4 (GPS module), without involving the actual installation on a drone system. Detailed and complete operational guidelines are provided below:
Mosaic-go and Mosaic-go Heading evaluation kits can be connected to the serial interface (COM1 or COM2 interface can be used) of the PX4 platform via a JST-GH cable. Since this cable is not a standard configuration, it is essential to ensure its wiring matches the diagram shown below exactly.
Figure 1: Pinouts of JST cable to integrate Pixhawk controller and Mosaic-go (Heading)
Once the above cable is ready, make sure the receiver is powered with 5V. You can use the micro-USB connector or the VCC pin on the 6-pin connector. Connect one or two GNSS antennas (depending on the mosaic-go variant) to the RF-IN ports on the mosaic-go. Connect the 6-pin connector (COM1) to the Pixhawk’s GPS MODULE port. This will provide power to the mosaic-go and with this single connection it will be able to send single and dual antenna information to the Pixhawk 4. In the web interface or with RxTools, make sure the receiver’s baud rate is set to 115200 which is the default value otherwise you can do it by going Admin > Expert Control > Control Panel > Communication > COM Port Settings.
Figure 2: Integration of Mosaic-go with Pixhawk 4 through the COM1 port
Both mosaic-go and mosaic-go heading receivers include an intuitive web user interface for an easy operation and monitoring that allows you to control the receiver from any mobile device or computer.
Before configuring the PX4 autopilot, you need to install QGroundControl as you need it to upgrade the firmware and setup the autopilot. Now you can open the QGroundControl software, go to Vehicle Setup and open the Firmware section and plug in the Pixhawk 4 to your Laptop/PC. The firmware setup window will now appear, the pixhawk board will be detected automatically. Uploading the latest stable release of the firmware will have limited support for Septentrio receivers, you can choose to upload a custom firmware that you can find on the Septentrio GitHub release page. The chosen firmware will start downloading automatically after re-inserting the USB connection of the Pixhawk board. When it is finished, the board will reboot and open the Vehicle setup again.
Once the firmware is uploaded successfully, the parameters can be adjusted. Select GPS and change the parameters of GPS_AUTO_CONFIG (enable if desired), set GPS_1_CONFIG depending on the ports used (in this example GPS 1 relates to the GPS module port of Pixhawk 4) and GPS_1_GNSS (select all constellations to use all available GNSS satellites). You need to change the GPS_1_PROTOCOL to Septentrio (SBF) as shown below
Figure 3: Autopilot configuration to receive PVT and Attitude data from Mosaic-go (Heading)
The serial baud rate should also be selected as 115200 as it is the default baud rate set for the serial COM port of the receiver. You can also set the GPS_PITCH_OFFSET and GPS_YAW_OFFSET according to your setup when using the mosaic-Go heading module. With a dual antenna setup you will also need to navigate to EKF2, then you need to enable GNSS heading using parameter EKF2_GPS_CTRL. When everything is configured correctly reboot the Autopilot by clicking Tools and then Reboot Vehicle.
Once rebooted, all the changed parameters will be shown in red and after few seconds you should be able to see a red arrow representing an accurate position. Next to the Satellites icon you should be able to see the number of tracked satellites as shown below:
Figure 4: Position is being received and shown on QgroundControl
The PX4 autopilot will ensure that the GNSS module is automatically configured for the single antenna setup. However, if you have a dual antenna setup, it is required to set the layout as accurately as possible in the web app. For additional configuration of the dual antenna setup, please refer to our Knowledge Base or the hardware manual.
Below is the summary of all parameters which need to be set on Autopilot side with Single and Dual antenna setups:
Single antenna setup
Edit the following parameters in the PX4 setup page:
GPS_1_CONFIG : GPS 1
GPS_AUTO_CONFIG: Enable
GPS_1_GNSS : 31
GPS_1_PROTOCOL : Septentrio (SBF)
SER_GPS1_BAUD : 115200 8N1
Rebooting the Autopilot by going to Tools > Reboot Vehicle
Dual antenna setup
Edit the following parameters in the PX4 setup page:
GPS_1_CONFIG : GPS 1
GPS_AUTO_CONFIG: Enable
GPS_1_GNSS : 31
GPS_1_PROTOCOL : Septentrio (SBF)
GPS_PITCH_OFFSET : Set accordingly
GPS_YAW_OFFSET : Set accordingly
SER_GPS1_BAUD : 115200 8N1
EKF2_GPS_CTRL : Dual Antenna Heading (include)
Rebooting the Autopilot by going to Tools > Reboot Vehicle
For more detailed information about the mosaic-go and the mosaic module inside, please refer to the hardware manual or the Septentrio Support page.
BLOG Post : Keywords
Primary Keywords:Septentrio,GNSS
Supporting Keywords:Septentrio mosaic-H receiver,GNSS positioning,GNSS signal reception,Anti-jamming GNSS,AIM+ anti-interference technology,APME+ multipath suppression,LOCK+ stable tracking technology, Navigation and Positioning Module, ArduPilot Compatible
