| 摘要 |
The method consists in analysing the signal received as being a signal corresponding to the acoustic model of Gutin, in calculating (5) a fast Fourier transform of the signal received on the basis of an estimate of the frequency f0 of the main rotor, in projecting (14) the resulting vector onto two subspaces whose basis vectors depend on a number of blades and on the Mach number, in performing an inverse Fourier transform calculation (19, 20) on the two vectors resulting from the projection, in summing (23) the real and imaginary parts squared of the two resulting vectors and in comparing (24) the result obtained with a specified threshold value S, in order to identify the number of blades and rotor speed pairs which gives a result greater than the threshold S. Application: Acoustic recognition of aircraft. <IMAGE>
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