Accurate time-of-flight measurement of ultrasonic signals for displacement monitoring applications

A different approach to the measurement of the propagation delay (time-of-flight) of ultrasonic signals is reported in this work. A high speed DSP microcontroller is used to measure directly the frequency of the incoming signal quickly (every single period) and accurately (0.1% error). Frequency variation monitoring is used to determine accurately the arrival time of the ultrasonic signal. The proposed configuration offers a small size and low cost solution to displacement (or generally time-of-flight of ultrasonic signals) monitoring with a remarkable performance in terms of accuracy, range and measurement time