2D Finite Impulse Response filters for surface wave identification

Elliptical areas transfer function Finite Impulse Response filters are investigated (E-FIR). The main axis of the elliptical area is oriented along the selected surface wave dispersion curve. The advantage of such areas is the analytical formulas of the impulse responses as a function of the frequencies bandwidths parameters, k and ω, without the need to use Inverse Fourier transform. E-FIR filters are tested on experimental space-time signals corresponding to the propagation of Lamb waves generated by a pulse and observed by classic transducers on a cylindrical shell and by laser Doppler on a plate. E-FIR filters exhibit their potential to extract Lamb modes and their direction of propagation, even in noisy datasets. Due to their natural round shape energy distribution in k-ω space, E-FIR filtering adds few artefacts to the filtered signals. By using wide k-bandwidth and narrow ω-bandwidth E-FIR filter, Gabor like analysis is also reached.