Here, t is the transit time, t0 is the transit time of the ultrasonic signals when there is no wind, and Dt is the phase shift.
If the ultrasonic path is far away, measuring the delay time can be done easily through the variation of transit time. But, if the ultrasonic path is close, measuring the delay time through the phase shift is more efficient than if the path is far away, because the variation of transit time is too small.
The equation to calculate the wind velocity using the proposed principle is represented in Eq. (2) [3,5,8]. This equation is applied to an ultrasonic anemometer also using time-sharing method