Analysis of ultrasonic waveforms using Shannon entropy

A symbol-oriented information-theoretical approach to signal analysis based on application of thermodynamic concepts is described. Images formed from temperature-dependent thermodynamic analogs of entropy, thermodynamic energy, the partition function, and specific heat at constant volume are considered. It is shown that this can be a preferred alternative to conventional digital signal analysis by making an experimental comparison of these images to images based on a more conventional signal energy approach. In all these images, which were made by c-scanning a family of thin graphite/epoxy laminates containing a foreign object within two plies of the specimen surface, the thermodynamic analogs exhibit significant increases (up to fourfold) in detection sensitivity