Probably first 3DR Quad received ICAO 24-bit address


ICAO address is used as unique airframe identifier for so called Mode-S transponders -


It is likely at least in Europe that beyond line of sight UAV operations in future will require equipping UAVs with such transponder.


So we decided to start working on ADS-B OUT transponders integration with popular autopilots and adding these features to our ground control software UgCS (


As first carrier we have selected 3DR Quad with Pixhawk.


Why Pixhawk? -  This line of autopilots have matured and we expect lot of  commercial applications will be using it. We will be ready for that with our solution for Pixhawk- ADS-B transponder integration.


We selected 3D Robotics Quad because we have lot of them and they are symbolic for getting quads and UAV technology to the masses. :-)


We will use Sagetech XPS-TR transponder because of its small size and weight, which allows equipping even lightest UAVs with it. 


4 months ago we approached Latvian Civil Aviation Agency with request to provide us ICAO 24-bit address for our quad, and now it has happened! 


Latvian Civil Aviation Agency (FAA analogue for us) has issued ICAO address 502С08 for our little bird - 3DR Quad with "tail number" 6 (see picture).


In a month or two it should appear on




UgCS Team

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  • @Alexev NP I make lots of stupid programming mistakes. Alex the frequency is 1090 Mhz transmitters sholud be ok but receivers that close will need some help in the form of filters. I think 10 watts should be enough for UAS we don't need 1000 mile range.

    We will have to see how it goes besides that's a lot of power to have to supply. I bet we get it down to 10 watts.

  • Is there anyway to provide filtering on the input to other RF equipment?  I have used cavity filters for my UHF gear and they are easy to tune but REALLY BIG. 

    Great idea and I hope it becomes standard.

  • Thank you that you pointed me to it. With my software developer background I sometimes do stupid mistakes when it comes to electronics.

    Yes, the transmission power of the transponder is 250 watts.

    So we probably need to do something to insulate other electronic components from the transponder antenna.

    I found a recommendation that the antenna of transponder must be at least 20 inches from the other antennas. We may have to put the transponder antenna on high "legs".

  •  250w is average for an adsb transponder.

  • It's very strange... Below on same page

    we can see: Power Consumption (ON & ALT): 14 watts (max).

    So I think that it is mistake about transmitting power. I think 250 mWt.

    I checked user manual provided with transponder and saw same parameters. I'll write to the Sagetech.

  • Great going. Congrats for receiving you ICAO address.

    Regarding the Sagetech transponder: The detailed technical info indicates 250 watts transmit power! 

    Do you plan to use any shielding for the flight controller ?

    For the Multi-rotor in the OP picture power consumption would likely be 15% - 20% of the flight battery capacity, but after seeing the RF TX power specification, my power consumption concerns give way to concerns about radiated RF energy.

    Now, is that's just a very brief, periodic  'chirp' ?  Right?

    How is the GPS, magnetometer or the flight controller going to feel about that kind of RF power in such close proximity?

    Won't this addle the analog stage internals of the Invensense chips?

  •  I'm doing some interesting things with FllightRadar24. There is a way to use it for avoidance it let's the UAV pilot do the avoiding.

     I'm interested in using the same schema for Cubesat tracking in an amateur worldwide network. But there are implications of the technology of use to UAVs and amateur high altitude balloons as well.

  • Moderator

    The official system will be fed, getting to know ADSB and FlightRadar etc cannot harm. It only costs $20 to start playing.

  • I don't think that simply feeding FlightRadar24 is enough to warn other pilots of your presence.

    If we set the precedent of using a central internet tracking server to publish flight notices then it will put the burden on ATC to use that information.  There's no more public way of sharing your location and flight plan that publishing it publicly on the internet.

    If the FAA and ATC fail to use information that is easily available then they will have to share in the responsibility for avoidable accidents if/when they happen.

    I don't think they really have the option of willfully ignoring safety information that is published and/or conveyed to them.  That would be like the fire department saying they only accept faxes and any calls will be ignored.

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