4 ms·

There's a lot of electronics on a little drone that all produces a lot of noise. Depending on the control schema it may be dumping a video feed or telemetry to

by all2 3y ago

There's a lot of electronics on a little drone that all produces a lot of noise. Depending on the control schema it may be dumping a video feed or telemetry to the base station (typically over 2.4Ghz?). There's also an incidental EM footprint put out by the electronics on board. Brushless motors are extremely electronically noisy and shielding is expensive (by weight, aluminum foil works, but to be effective it needs to be wrapped around everything). I'd go hunting for ways to characterize that EM signature at a distance. Do you need to point a big collection dish at the target? Yes, very likely, but it should get you beyond the standard set of false-positive scenarios caused by Not Enough Information (TM). Can we listen for motor noise broadcast by the brushless motors?

dreamcompiler 3y ago
> Brushless motors are extremely electronically noisy and shielding is expensive If we're comparing RF noise quantity, brushed motors generate a heckuva lot more RF because they're spark generators. Of course modern drones don't use brushed motors much. Brushless motors can in principle have their RF noise reduced by careful modification of their controller waveforms. But your point is well taken. Brushless motor RF is probably easy to identify by the presence of a few peaks on the spectrogram representing multiples of the rotation frequency. Brushed motors would look like that too except buried in a lot more white noise.
AHOHA 3y ago
C2 (command and control) and Telem links can be communicated over different means, either cellular, satcom, or even LoRa, how you will differentiate the drone modem from thousands of UEs in the vicinity? what if the drone flying at a low alt, near power lines and other EM noise? one time I made a drone that detect interference sources for a gov agency to detect any violation of the spectrum, a giant LED can cause so much noise more than any brush-less motor, let alone a small drone ones. Maybe if you have a giant drone (plane size) and flying at a high alt in an empty area, maybe, anything else I would say it's impossible or very hard to reliably use EM as way for detection.

by all2 3y ago

dreamcompiler 3y ago

> Brushless motors are extremely electronically noisy and shielding is expensive If we're comparing RF noise quantity, brushed motors generate a heckuva lot more RF because they're spark generators. Of course modern drones don't use brushed motors much. Brushless motors can in principle have their RF noise reduced by careful modification of their controller waveforms. But your point is well taken. Brushless motor RF is probably easy to identify by the presence of a few peaks on the spectrogram representing multiples of the rotation frequency. Brushed motors would look like that too except buried in a lot more white noise.

AHOHA 3y ago

C2 (command and control) and Telem links can be communicated over different means, either cellular, satcom, or even LoRa, how you will differentiate the drone modem from thousands of UEs in the vicinity? what if the drone flying at a low alt, near power lines and other EM noise? one time I made a drone that detect interference sources for a gov agency to detect any violation of the spectrum, a giant LED can cause so much noise more than any brush-less motor, let alone a small drone ones. Maybe if you have a giant drone (plane size) and flying at a high alt in an empty area, maybe, anything else I would say it's impossible or very hard to reliably use EM as way for detection.