ZHANG Haibin WAN Quan JIANG Weikang

(State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University  Shanghai 200240)

Received Oct.31, 2007

Revised Dec.20, 2007

Abstract Cyslostationary sound field is a special kind of nonstationary sound field, in which the pressure signal is modulated seriously and sidebands exist in its spectrum. The reconstructed sound field can??t figure the cyclostationary features in conventional Nearfield Acoustic Holography (NAH) procedure. On the basis of planar cyclostationary NAH, the cyclostationary NAH based on boundary element method is proposed which can be utilized to analyze radiators with complicated surface. Replacing the Fourier??s transform with the second-order cyclic statistics, the Cyclic Spectral Density (CSD) functions is used as the reconstructed physical quantity in the proposed NAH technique, instead of the spectrum or power spectral density of pressure signal. By virtue of the demodulation ability of CSD function, the reconstructed CAD can effectively express the information of modulating and carrier waver respectively. The simulation and experiment illustrate that the validity and accuracy of this cyclostationary NAH technique satisfy the request of engineering.

PACS numbers: 43.60