Détection d'hélicoptères par analyse du bruit acoustique rayonné par leur rotor principal

Abstract
This paper describes a technique for the detection of helicopters based on the farfield acoustic signal produced by their main rotor. This signal may be well modelled as that produced by a point-like rotating source with periodic excitation. The corresponding harmonics may be computed analytically, which allows to define a receiver using both the modulus and the phase of the measured harmonics. Such a receiver may then be considered as a variant of the matched filter, which improves detection capabilities and allows for some rough classification of the detected signal.