SHI Guangzhi  HU Junchuan 

(Navy Submarine Academy  Qingdao  266071) 

Received Jun.3, 2006 

Revised Nov.8, 2006 

Abstract  The structure law of the ship noise demodulation spectrum harmonic clan feature and corresponding applications to the recognition problem are studied by theoretical derivation and sample analysis. In order to recognize the propeller blade-number, the ship propeller cavitation noise model is established on the basis of five hypotheses. Further, the mathematical expressions of the structure law are deduced by the model. And the class space of the propeller blade-number is analysed mathematically. The results can be applied to target recognition as expert knowledge. Finally, the demodulation spectrum harmonic clans of experiment samples are obtained by using the wavelet packet. The structure law is validated by the statistic analysis of experiment samples. It is shown that the statistical average results of experiment samples are consistent very well with the theory structure law, and 78.6% of the samples basically accord with the theory structure law.

PACS number: 43.30, 43.60