High resolution deconvolution using least-absolute-values minimization [US NDE]

A high-resolution deconvolution technique for improving temporal resolution in ultrasonic nondestructive-evaluation signals was investigated. Least-absolute-values (L1 norm) minimization was applied to the deconvolution process for systems whose impulse responses can be modeled as sparsely filled series of spikes. Particular attention was given to the relative performance in the presence of noise of this method as compared to the least-squares (L2 norm) method. There are clear indications that the L1 approach is superior for this type of system. The issue of objectively choosing the damping parameter employed by this technique was also addressed. The method and results from these investigations have been applied to ultrasonic inspection signals from nuclear reactor pressure tubes with good results