Digital ultrasonic pulse-echo overlap system and algorithmfor unambiguous determination of pulse transit time

We report an evolution of an all-digital ultrasonic pulse technique for measurements of elastic constants of solids. An unambiguous analytical procedure is described for determining the correct time delay of echoes without any need for actual echo overlap. We also provide a simple procedure for making corrections for transducer-bond-induced phase shifts. The precision of a measurement made with this system at ambient temperature exceeds one part in 10 7 without the use of mixers, gates, time delays, and other complications normally associated with such measurements.