2.1. Measuring wind velocity
So far, the measurement of flow velocity using an
ultrasonic sensor is calculated by measuring the transit
time of ultrasonic signals between the transmitter and
receiver, which are located on opposite sites. However, the
proposed system uses the directivity angle of an ultrasonic
sensor as shown in Fig. 1. Receivers are located on the
same axis and they have the same L and y. The proposed
system does not need to use a time-sharing method,
because all receivers can receive ultrasonic signals simultaneously
by a single transmission.
In this study, a method of measuring wind velocity is
developed by using a phase shift based on measuring the
transit time of ultrasonic signals. The delay time, variation
of transit time of ultrasonic signals by the wind is measured
by measuring the phase shift of the receiving signals. This
principle is represented in Eq. (1) [8]