Patent ID: 9513396
Filing Date: 2016-12-06
CPC Classification: G01V

Claim Text:
1. An apparatus, comprising: azimuthally orthogonal dipole receiver arrays and azimuthally orthogonal transmitter arrays; logic to record a plurality of acoustic waveforms corresponding to acoustic waves received at the azimuthally orthogonal dipole receiver arrays, the acoustic waves being generated by the azimuthally orthogonal transmitter arrays; and a signal processor to estimate a global minimum of an objective function with respect to an azimuth angle and a set of auxiliary parameters, wherein the azimuth angle corresponds to an orientation of the transmitter arrays and the receiver arrays relative to fast and slow principal flexural wave axes, with the signal processor configured to estimate fast and slow principal flexural waves propagating along the axes and characterized by the waveforms as ordered complex eigenvalues of a waveform matrix diagonalized by a similarity transformation at each data point of the waveforms, and the objective function depending on the waveforms, the ordered eigenvalues, the azimuth angle, and the set of auxiliary parameters, wherein the signal processor is also configured to remove existing ambiguities associated with the fast and slow principal flexural wave axes.