The invention concerns a method for the measurement of the velocity of ultrasonic oscillations by measurements of the displacement of a radiating element along the sound ray and of the full change in phase shift between a signal which has passed through an acoustic system and a reference signal. The method is distinguished by the fact that, for the purpose of achieving increased accuracy, amplitude-modulated ultrasonic waves are emitted, their passage through the medium is recorded by Toplers optical method, and the received signal is transformed by a photomultiplier into a frequency-modulated alternating current with the variable component fed to a phase comparator. The velocity of the ultrasonic oscillations is determined by the whole number of voltage periods at the comparator output and by the amount of radiator displacement.
Edited trans. of Patent (USSR) 268 048 2p 1970, by R. J. Zeccola.