Harmonic frequencies retrieval of helicopter acoustic signal

Based on analysis of spectral characteristic of helicopter acoustic signal, a method of extracting harmonic frequencies from the helicopter acoustic signal via ESPRIT is proposed. These harmonic frequencies can be used as features to identify helicopter. Meanwhile, a method to delete pseudo-frequencies is also given because some pseudo-frequencies are introduced when the model order p is overdetermined. By using it, some harmonic frequencies are extracted from real measured helicopter acoustic signal. The results show that the method presented in the paper can exactly extract harmonic frequencies from helicopter acoustic signals which acquired under various conditions and meet the real-time requirement of the system, so it is an effective method to extract frequency feature of helicopter acoustic signal.