Providing ATC visibility of a DJI A2 drone using a BeagleBone and Sagetech XPS-TR transponder

The UgCS team has accomplished what we believe is a first – integrating a Mode S/ADS-B out transponder with a small drone, enabling radar visibility throughout the drone’s flight.  A BeagleBone Black computer with CAN bus shield was used to integrate a Sagetech XPS-TR, the world’s smallest transponder, with the A2’s flight controller.  The flight controller continuously sent the drone’s location and commands through the CAN bus shield to the BeagleBone, which passed that information to the Sagetech transponder.  The transponder was powered by the 6S onboard battery, which also powered the drone itself.  The BeagleBone was powered by a separate 2S battery, but with a converter the same 6S battery could have been used for all 3 devices.

With an antenna located about 3m below the drone, the mission was a complete success, with the drone appearing and remaining visible on the website throughout the flight.

Video footage of the flight can be found here: 

UgCS 2.8 will feature a communications interface with the Sagetech ADS-B transponder, enabling configuration of ICAO ID, Flight ID and Squawk Code parameters through the UgCS system.

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Safe flights,

UgCS Team

Views: 2732

Comment by Kevin Goff on January 18, 2016 at 7:36am
Does anyone know how much those transponders cost? I couldn't find pricing. I'm assuming they will be required in commercial use but are they cost effective for hobbyists?
Comment by Darius Jack on January 18, 2016 at 8:23am

Thank you @Kristaps,

could you provide legislation on the use, configuration and operation of that smallest transponder in case of small drones ?

I recall blog's discussion of April 23, 2015

"How it is made" 3DR Pixhawk and Sagetech ADS-B integration

Comment by Darius Jack on January 18, 2016 at 8:29am
Comment by George Kelly on January 18, 2016 at 9:56am

Great work.

ADS-B is not currently accepted by Transport Canada to satisfy sense-and-avoid for commercial drone approvals, but this is the future.

The long, dangling antenna looks a bit concerning. Especially as users will be commercial apps, with a variety of payloads, often close to the ground or other objects.

Could the antenna point up (in a rigid pole) instead of down - empty space above the drone, but often not below.


Comment by Gregory Heide on January 18, 2016 at 10:57am
I have been looking into ADS-b, but weight has been the issue. Why can't the ads-b transponder be ground based and the GCS via telemetry either broadcasts a fixed position or the GPS coordinates from the vehicle? Bigger antenna, and no extraneous power on the vehicle.
Comment by Kristaps Brass on January 18, 2016 at 11:15am

Gregory - there are options such as using usb ADS-B receivers. Obviously, they wouldn't transmit the location of your vehicle, but UgCS has ADS-B integration, meaning that you would get warnings with incoming aircraft that do have ADS-B transponders.

Comment by Lars S on January 18, 2016 at 12:43pm


You are maybe the first with a small quad, but the firm I work for here in Norway, did fly Penguin B fixed wing with the Sagetech, two months ago. :-)


Comment by Darius Jack on January 18, 2016 at 5:08pm


"The fastest and cheapest way to get an own ADS-B-Receiver is the use of an DVB-T-Stick and the free software. This software can convert some DVB-T-sticks into ADS-B-receivers that decode the ADS-B-data and stream this data via network.
AdsbScope can receive this data from the network and visualize it.

Comment by Gary Mortimer on January 19, 2016 at 10:49am
Comment by Alexey Dobrovolskiy on January 20, 2016 at 8:03am

Darius - regarding legislation - we have got temporary permission for transponder use from Latvian CAA. But this isn't common practice now.

George - Sagetech recommended us to place transponder antenna on short mast (50cm) on top of drone. We will try this in near future.


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