SPLIT SPECTRUM PROCESSING - DETERMINATION OF THE AVAILABLE BANDWIDTH FOR SPECTRAL SPLITTING

This paper deals with the considerations necessary for the determination of the frequency location of the bank of bandpass filters used for splitting the frequency spectrum in the split spectrum processing applications of ultrasonic NDE. Split spectrum processing has been shown in the past to be an effective method of reducing the material noise content of an ultrasonic signal. However, the success of the technique in obtaining a good signal-to-noise ratio enhancement is critically dependent on proper selection of the signal processing parameters, such as the number of filters in the filter bank, the frequency separation between them, the bandwidth of the filters in the filter bank and the location of the filter bank on the frequency spectrum of received ultrasonic signal. This paper formalizes the determination of the fourth processing parameter namely, the frequency location of the bank of bandpass filters used for the spectral splitting, thereby removing the last remaining ambiguity of the split spectrum processing.