A measurement method based on Kalman filtering for ultrasonic time-of-flight estimation

A new digital signal-processing method for ultrasonic time-of-flight (TOF) estimation is presented. The method applies the discrete extended Kalman filter (EDKF) to the acquired ultrasonic signal in order to accurately estimate the shape factors of echo envelope as well as locate its onset. It is so possible to assure reduced bias and uncertainty also in critical TOF measurements, such as those involving low signal to noise ratio (SNR) as well as severe distortion of echo shape. A number of numerical tests ate conducted on simulated signals with the aim of highlighting the good performance of the method when operating in critical conditions. Results attained in TOF based distance measurements finally asses the reliability and efficacy of the method also in the presence of actual ultrasonic signals.