Measurement of Ultrasonic Velocity in Liquid Using a Modified Ultrasonic Correlation System Under Low S/N Condition

A new ultrasonic measurement system introducing techniques of cross-correlation and signal averaging for the accurate measurement of the ultrasonic velocity in liquid is described. Improvement in signal-to-noise ratio (S/N) of 35 dB can be readily attained by averaging the correlation output with the new system which uses a S & H circuit and computer-controlled A/D converter. The usefulness of the S/N improvement for the measurement system under various S/N conditions is verified through the experiments.