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delinka

"... can’t be tracked on radar ..."

Can I voluntarily strap a transponder to my own drone if I buy one? How small can transponders be?

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Looks like tiny ADS-B transponders are readily available: https://uavionix.com/

Measures 3x9x11cm, so likely too bulky for many drones.

Check these ones out, they're the ones designed for drones:

https://uavionix.com/products/ping2020/

20g, 25mm x 39mm x 12mm

The electronics for your typical GA transponder are primitive by modern standards and can be very small, but it would probably need to be paired with a radar reflector or else it would either remain undetected or appear as noise.

After watching a Defcon talk about the idea that transponders self-indicate their position without signature, so it would be possible to clutter ATC and make the panic, I was under the impression that rogue transponders couldn’t safely be dismissed, just in case it were actually the 747 it claims to be.

>After watching a Defcon talk about the idea that transponders self-indicate their position without signature

Older style (I forget the proper name) transponders don't indicate their position, only ID and altitude. Newer ADS-B transponders include GPS position.

It's an interesting point though. Assuming for a moment that a bunch of drone operators equipped their drones with ADS-B transponders, I speculate that there could be a chance of overwhelming an airport approach radar's ability to track targets. Could potentially overwhelm the electronics, or the operators.

While we’re still using secondary radar (which gets an azimuth and range return from the radar site), it’s trivial to ID fake ADS-B outputs. I don’t know if they have filtering in place now or not. The effective bandwidth of ADS-B is limited as well, serving as an effective cap on number of targets created.

Do that and keep doing it, and it would not be hard to find your transmitter.

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