Wind measurement is an important factor for detecting natural phenomena in various industrial fields. Wind measurement can be applied not only to industrial fields but also to environmental monitoring and controlling systems, indoor air conditioning systems, the weather forecasting systems and so on. To improve problems with the previous mechanical sensors, methods that use MEMS- type sensors or ultrasonic sensors [1–3] have been studied. A MEMS-type sensor is a contact type so that the abrasion property is high. It is sensitive to dust, and it is difficult to use for a 2D anemometer in the atmosphere [4]. A method to use ultrasonic sensors is being studied and developed because this method has a distinguished advantage over the non-contact type [1]. For measuring wind velocity using an ultrasonic sensor, there are two methods: transit-time measurement and vortex measurement [5–7]. With vortex measurement it is difficult to measure wind direction. So the method of transit-time measurement is used to measure wind velocity and direction [8].