Patent ID: 7957225

Claim:
A method for providing a warning for a facility, comprising: receiving an acoustic signal at a set of nodes disposed at the facility; classifying a source of the acoustic signal based upon a spectral analysis of a frequency-based domain signature of the acoustic signal; detecting a bearing of the source of the acoustic signal and an elevation of the source of the acoustic signal relative to each node of the set of nodes; transmitting, from a first node of the set of nodes to a second node of the set of nodes, the bearing of the source of the acoustic signal and the elevation of the source of the acoustic signal relative to the first node; detecting a distance of the source of the acoustic signal from the facility and an altitude of the source of the acoustic signal relative to the facility based upon the acoustic signal; and generating the warning (i) when the source of the acoustic signal is classified as a rotary-wing aircraft and (ii) when the detected distance of the source of the acoustic signal from the facility and the detected altitude of the source of the acoustic signal relative to the facility falls within a defined geographical zone relative to the facility; wherein detecting the distance of the source of the acoustic signal from the facility and the altitude of the source of the acoustic signal relative to the facility based upon the acoustic signal comprises detecting, by the second node, the distance of the source of the acoustic signal from the facility and the altitude of the source of the acoustic signal relative to the facility based upon the bearing of the source of the acoustic signal and the elevation of the source of the acoustic signal relative to the first node and based upon the bearing of the source of the acoustic signal and the elevation of the source of the acoustic signal relative to the second node.