Split spectrum processing: optimizing the processing parameters using minimization

A major limitation to ultrasonic NDE is the noise produced by interfering scatterers such as grain boundaries, etc. effectively masking the flaw. The effect is more severe in some types of material, thereby making it necessary to use some forms of signal processing techniques to improve the signal-to-noise ratio. Split spectrum processing is one such technique introduced about half a decade ago. However, even though the technique has proved useful in signal-to-noise ratio enhancement, its application appears to have been limited perhaps because of the prevailing ambiguity in optimizing the processing parameters. This Paper provides experimental confirmation of a recently postulated procedure for optimizing the choice of processing parameters in split spectrum processing and demonstrates its application to signal-to-noise ratio enhancement in welds, centrifugally cast stainless steel and carbon-epoxy composites.