Acoustic Detection: When Microphone Arrays Beat Radar
Radar can struggle with very low, slow and small targets close to clutter, and siting it is expensive. Acoustic arrays fill a narrow gap: short-range, low-altitude detection where the signature is a distinct rotor tone.
Performance depends on background noise, wind and array geometry. At quiet rural sites our nodes held consumer drones beyond 500 m; in dense urban noise the same nodes were limited to a few hundred metres.
Treat acoustics as a cueing layer that points a camera or radar, rather than a primary tracking sensor. Fusion works well with RF because both receivers are passive and reveal nothing to the target.
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We run acoustic nodes on a wildlife reserve and the low false-alarm rate genuinely surprised us. Wind is the main headache, not the drones.
Do you gate by spectrum or by a trained classifier? We still get bird calls slipping through.
Both. A light classifier on top of a spectrum gate removed most of our bird triggers.
How much does array geometry matter in practice? We have a hard limit on pole height and I am worried it kills the range.