Ultrasonic detector with frequency matching

摘要

An ultrasonic detector of the type for determining the level of a liquid within a tank or the magnitude of the flow of liquid within a conduit. The detector includes a transducer that generates bursts of ultrasonic energy and receives echoes of the energy bursts. The frequency at which the transducer transmits energy bursts is automatically adjusted to substantially match the ringdown frequency of the transducer. The detector distinguishes between true echo signals and spurious echo signals by determining whether the frequency of the echo signals generated by the transducer substantially matches the frequency at which the corresponding energy bursts were transmitted.