Abstract: An apparatus and method for removing noise of an ultrasonic system to improve robustness against noise by removing external noise from a reception signal reflected from an object are provided. The method includes transmitting, by a sensor, a transmission signal to a medium and receiving a reception signal reflected from the medium. A controller is configured to remove noise from a frequency range recognized as a normal signal from the reception signal and calculate a correlation between the transmission signal and a signal in the frequency range recognized as the normal signal in the reception signal. In addition, the controller is configured to determine whether the signal in the frequency range recognized as the normal signal is the normal signal or noise based on the calculated correlation.

Abstract: Embodiments related to a piezoelectric bender that comprises a spring and mass element to provide additional constructive resonance. An embodiment provides an apparatus comprising: a base plate; a piezoelectric body coupled to the base plate; a spring coupled to the base plate; and a mass element coupled to the spring, wherein the base plate, the piezoelectric body, the spring, and the mass element are operable to produce at least two resonance frequencies in the apparatus.