Contour Plotting by a Sonic Phase Lock Loop

Abstract

The use of a sound wave as a measurement tool is increasing for a number of reasons. Medically it is a benign ray. Scientifically it is a means of measuring with the minimum of disturbance and in an engineering sense it provides digital information which is readily processed by a computer. However, sonic measurements have largely used a pulse-echo technique which has been refined to a high degree by advances in electronic circuitry and components. Effort has been concentrated in the ultrasound region for practical reasons.