Digital measuring techniques for high accuracy ultrasonic sensor application

Ultrasonic sensor level measurements are based on the determination of the time-of-flight (ToF). Owing to both the rise time and the time resolution, traditional techniques produce poor estimations of the ToF. Furthermore, the presence of noise is a cause of further inaccuracy. The main aim of the paper is to show how the accuracy of the ToF can be improved by adopting simple interpolation algorithms in conjunction with the wavelet transform (WT) technique. After examining and characterizing the different error components, brief theoretical considerations on the WT are reported and the effects of this choice on the accuracy are examined. It is proved that in this case the accuracy of the level measurements is very high. Finally, the performance of the proposed algorithms has been verified by means of computer simulations and experiments.