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