Research on the cyclostationary nearfield acoustic holography based on boundary element method

Cyclostationary 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 recon- structed 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 radia- tors 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 CSD can effectively express the information of modulating and carrier wave respectively.The simulation and experiment illustrate that the validity and accuracy of this cyclostationary NAH technique satisfy the request of engineering.