> Brushless motors are extremely electronically noisy and shielding is expensive If we're comparing RF noise quantity, brushed motors generate a heckuva lot mo

> 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.