Constrained total least squares based extraction of acoustic resonances of elastic targets

The constrained total least squares (CTLS) method technique is applied to the late time response of the backscattered impulse response function of a large aspect ratio cylinder to estimate the scattering resonances. In the absence of noise, this technique successfully extracted two well-defined sets of poles which could be identified as being associated with the first elastic mode of the cylinder and with an effective Franz mode. In the presence of noise, the elastic poles are perturbed only slightly from their correct values and the technique appears to be fairly robust. The Franz pole positions are somewhat more profoundly affected, but these are of secondary importance in the inverse scattering problem. It is noted that the CTLS is an optimal parameter estimation technique in the presence of Gaussian noise. It is concluded that the CTLS is a robust pole extraction technique that has the potential to lead to improved target classification schemes