Abstract
A method of canceling parametric-effect-induced error in airborne ultrasound Doppler velocimetry is presented. In airborne ultrasound Doppler velocimetry, the received ultrasound signal contains phase modulation due to the nonlinear parametric effect in addition to the direct Doppler effect resulting from the vibration velocity of the specimen. The authors investigate the dependence of the size and frequency of the vibrating surface on the parametric effect. By measuring the acoustic pressure generated by the target vibration, the parametric effect is taken into account to estimate the vibrating velocity. The results show that the measurement error becomes smaller than that without cancellation. For example, for a body of 100 mm diameter vibrating at a frequency of 1.5 kHz, the error reduction is over 50%.
