Zhao Z, Adenwalla SD, Ketterson JB, Sarma BK. A novel technique to measure the group velocity of sound in dispersive media.
IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 1989;
36:481-484. [PMID:
18290224 DOI:
10.1109/58.31791]
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Abstract
A technique is proposed for measuring the group velocity of sound by a frequency-modulated (FM) continuous wave (CW) technique. Detailed calculations are presented, showing that V(g)=(deltaomega(m)/deltaphi)d , where V(g), deltaomega(m), deltaphi, and d are, respectively, the group velocity, change of modulation frequency, phase change of the received signal detected by a biphase lock-in amplifier, and the distance traveled by the sound. The approach has the advantage of high resolution compared to the conventional time-of-flight measurement technique.
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