The purpose of this project has been to investigate means for obtaining improved characterization of the size, shape, and location of subsurface discontinuities in metals. This has been done by applying computerized data processing techniques to the signal obtained in conventional ultrasonic pulse-echo systems. The principal benefits are improved signal-to-noise ratio, and resolution.

The received ultrasonic pulse from a discontinuity is combined with a reference function in order to preserve both the phase and amplitude of the received pulse. Processing is performed on the power spectrum of the resultant signal. The reference function is also used to compensate for some of the frequency-dependent scattering caused by the material microstructure. During data acquisition, analog signal averaging improves the signal-to-noise ratio (SNR). After data acquisition, a digital deconvolution procedure improves the transducer longitudinal resolution.