DJI civilian drones broadcast transponder data, as required by the FAA and many other nations' FAA-equivalents. DJI apparently encrypts these signals, and sells an expensive product to receive and decrypt them: <a href="https://www.dji.com/aeroscope" rel="nofollow">https://www.dji.com/aeroscope</a> Decoding transponder data presumably gives better accuracy than regular radio-directionfinding, which militaries have used in combat for 80 years now.<p>(UA has been operating consumer drones on the front lines, because they're suicidal, desperate, or both. Consumer drones use narrowband transmissions on unlicensed radio bands, making them easy to jam and track. Military drones use spread-spectrum transmissions on restricted channels, making them harder to jam and detect, but are generally a hundred or a thousand times more expensive per unit.)<p>Like anything expensive sold to institutions, I assume DJI Aeroscope has some kind of yearly support contract, and the field terminal regularly phones home. It sounds like DJI has remotely terminated UA transponder receivers, and not done that with RU units, which UA is unhappy about. We also see the downsides of installing infrastructure operated by a hostile foreign power.