Jhung K H, Hong S S, Lee C R, Kim Y H
Korea Research Institute of Standards and Science, Taedok Science Town, Taejon.
J Acoust Soc Am. 1992 Apr;91(4 Pt 1):2025-9. doi: 10.1121/1.403687.
The effect of higher-order harmonic components on phase determination were analyzed to improve the accuracy of transient time measurement in an ultrasonic interferometer with a quadrature detector system. Under ideal conditions the locus of output signals of the phase sensitive detector forms a circle on the phase plane as the frequency changes and any nonideal factor would distort the circle, leading to erratic phase determination. This analysis has shown that the nth-order contribution to the phase is mostly determined by the product of the amplitudes of corresponding components of the reference and echo signals fed to the phase detector. The distortion parameters were obtained by least-squares fitting of the data to the distorted circle in the phase plane, and compared with those roughly estimated from the frequency components of the reference and echo signals. The exemplary numerical phase corrections for the third-order harmonics were carried out, so as to illustrate the improvement in the accuracy of the ultrasonic interferometer.
分析了高阶谐波分量对相位测定的影响，以提高采用正交检测系统的超声干涉仪中瞬态时间测量的精度。在理想条件下，随着频率变化，相敏探测器的输出信号轨迹在相平面上形成一个圆，任何非理想因素都会使圆发生畸变，导致相位测定不稳定。该分析表明，对相位的n阶贡献主要由馈入相探测器的参考信号和回波信号相应分量的幅度乘积决定。通过将数据进行最小二乘拟合到相平面中的畸变圆来获得畸变参数，并与从参考信号和回波信号的频率分量粗略估计的参数进行比较。对三阶谐波进行了示例性的数值相位校正，以说明超声干涉仪精度的提高。
