In January we published news that we completed test integration of 3DR copter with Sagetech XPS-TR transponder.


We have received permission from Sagetech to disclose part of their communication protocol in our source codes and can publish all technical information of the solution.

In our experimental project we used Arduino board as communication layer between autopilot and transponder.

Arduino sketch controls transponder mode and decodes telemetry from autopilot.

Source code and schematic available at GitHub - https://github.com/UgCS/sagetech-ardu

Operation of ADS-B solution was monitored using following methods:

- ADS-B receiver Sagetech Clarity + FlyQ EFB application

- Ground control software UgCS with ADS-B receiver support

- Webpage Flightradar24.com

During tests 3DR Quad showed on all types of receivers without interruptions. Thus UAV was seen by nearby air traffic and its presence made known to ensure airspace safety.

Video of results is available here – video on Youtube

We hope that our experience can help you if you want to reproduce same solution.

Safe flights,

UgCS team

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  • Yes, they alive. May be this is error on site?

    We are working in close contact with them.

    In UgCS 2.8 we will provide Sagetech transponders control from UgCS interface.

  • is sagetech still in business? the contact number in their website doesn't work anymore.

  • Yes, arduino can be omitted in case of Pixhawk. But if you want to integrate Sagetech with "closed" autopilots (DJI, Microdrone, ...) you will need intermediate device.

    Yes, all parameters should be send using mavlink.

  • Okay.

    Just some ideas: I think the arduino could also be omitted? Shouldn't be much code in the arduino? Integrate the code from the arduino in the APM code and use one of the apm uarts to talk to the transponder directly?

    And in a next step, the hardcoded parameters could be sent by mavlink commands from the ground station?

  • Hi,

    Yes, GPS coordinates come from Ardupilot.


    - transponder mode (OFF/STANDBY, ON, ALT, IDENT) - defined by RC transmitter switch and translated via autopilot and arduino

    ICAO code

    Aircraft Registration

    Flight ID

    Squawk code

    In our test implementation last 4 parameters hardcoded in Arduino code. For real-world implementation they should be defined from ground station.

  • Which data is shared between the arduino and the transponder?

    The Sagetech XPS-TR has no own GPS - therefore i assume, the GPS data comes from the ardupilot?

    What else?

  • Sagetech one is not cheap especially with customs and VAT if ordered to Europe. It is thousands, exact price shall be requested from Sagetech. But it is lightest one and power optimized for UAV. Next option was about 3x times heavier at 350g and we had no idea about power consumption, considering grille for cooling on it that could be an issue.

  • This is great, Janis. Would you mind sharing a bit more on the micro transmitter? What is the price range?

    Having just received a 333 exemption, as well as an N-number and associated Mode-S code, this is something I've been wanting to look into.

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