Patent ID: 6360609
Filing Date: 2002-03-26
Classification: G01N

Abstract:
A method of locating discontinuities in a multimode, dispersive medium comprising:exciting at a first position a multimode, dispersive acoustic guided wave in a medium; sensing at a second position both the direct arrival and the reflected multimode dispersive acoustic guided wave; frequency decomposing the multimode dispersive acoustic guided wave using spectrotemporal analysis; selecting a frequency which identifies the group delay, tg, of the direct and reflected guided wave for each mode occurring at that frequency; selecting a mode and determining the time difference, &Dgr;tg, between the direct and reflected signals from the group delays of the selected mode; determining the group velocity, cg, from the dispersion curves; and computing the distance, L, between the discontinuity and the second position L=&Dgr;tgÂ·cg/2.