Ultrasonic Sensing
Ultrasonic sensing is the measurement of the time between an ultrasonic signal being sent and received. The interval between these two signals is typically referred to as time-of-flight (ToF) and depends on the distance the ultrasonic wave travels until it is reflected due to an impedance change and the speed of the ultrasonic wave. The basic equation time = distance / speed can be used to measure fluid level, fluid identification/concentration, flow, or proximity.