Accurate distance measurement by an autonomous ultrasonic system combining time-of-flight and phase-shift methods

Robust High-Accuracy Ultrasonic Range Measurement System

“…Applying interpolation after the cross correlation was introduced as a solution to achieving subsample accuracy [23], [24], [25]. A combined cross-correlation and phase shift method was proposed in [26], [27] where the cross-correlation is used for a first estimate of the Time of Flight (TOF) and a phase shift method is applied to refine the final result to gain better accuracy. This method gives good results when the accuracy of the cross-correlation stage is within one wavelength of the ultrasonic carrier but if the output of the cross-correlation stage is in error by more than one wavelength of the carrier then the phase shift refining stage can't correct this error and it appears in the final estimate as a significant range error.…”

MEMS Biomedical Sensor for Gait Analysis

“…Several techniques of distance measurement for ultrasound ranging system were proposed in the literature. These include time-of-flight (tof), continuous wave phase-shift method, and also combination of tof and phase (Gueuning et al, 1997). For example, in using tof method as shown in Fig.…”

Inaccuracy of acoustic measurements in dual-frequence method of sounding

“…The use of Hilbert transform to get the echo-signal envelope and further defining of its homepoint requires much calculating which does not take place in hand-held devices [9].…”