| 摘要 |
PURPOSE:To enable a high-speed measurement by an ultrasonic wave with a light weight and inexpensive device, by transmitting an ultrasonic wave of a low frequency to an approaching object to be measured while doing an ultrasonic wave of a high frequency to a separating object to be measured. CONSTITUTION:The center frequency of a transmitting vibrator 1 and a receiving vibrator 2 is set at 40kHz, for instance. The oscillation frequency of an oscillation circuit 4 is set at 35kHz with respect to an approaching object to be measured and an ultrasonic wave transmitted from the vibrator 1. As the frequency of the ultrasonic wave received by the vibrator 2 is reflected on the object to be measured and received with the vibrator 2 is higher than the frequency of the ultrasonic wave transmitted by the vibrator 1 due to Doppler effect, the measurable band will be 10kHz and the frequency can be measured up to about 160km/h in the speed. On the other hand, when the frequency of the oscillation circuit 4 is set 45kHz, for instance, with respect to a separating object being measured, the frequency can be measured up to about 160km/h in the speed in the same way as in the case of the approaching object, as the ultrasonic wave reflected with the frequency lower than that of the vibrator 1 due to Doppler effect is received by the vibrator 2. |
