Improvements in the Sing-Around Technique for Ultrasonic Velocity Measurements

Abstract

A highly sensitive sing-around system was developed for ultrasonic velocity measurements in solids. In the developed system, a selected cycle of a selected echo is gated out, to retrigger the transmitter. Highly stable circuitry is employed. The timing system incorporates two modified commercial electronic counters and associated circuitry to maximize stability and detection sensitivity. Environmentally induced sample velocity changes of the order one part in 107 may be detected, provided that the accompanying attenuation change is negligible, or that steps taken to compensate for ultrasonic attenuation changes by adjusting electronic attenuation, produce phase shifts which are known to sufficient accuracy.

Ultrasonic velocity measurements in liquids with high resolution—techniques, selected applications and perspectives

“…For velocity data from sing-around systems, a precision near 10 −7 has been stated [120]. In order to achieve this accuracy, however, a high sample temperature stabilization is mandatory [122]; for example, in water at 25 • C (figure 7) a change of the sound velocity by 1 part in 10 7 or 0.15 mm s −1 corresponds to a temperature shift of only 50 µK [123].…”

Metrological support of acoustic measuring devices in the medium frequency range

“…These are the pulse-cyclic method, the correlation method and the direct measurement of propagation time. In systems with a pulse-cyclic method, the accuracy of measuring the speed of sound has been achieved 1•10-7 [7].…”

“…Это импульсно-циклический метод, корреляционный метод и метод прямого измерения времени распространения. В системах с импульсноциклическим методом точность измерения скорости звука достигнута 1•10 -7 [7]. По существу в таких измерителях для получения информации о времени распространения необходимо многократное повторение процедуры передачи и приема акустического сигнала, что уменьшает быстродействие системы.…”