美国兰利研究中心的Willian T. Yost等人根据超音速的相速度是热动态变量的函数,测量相速度的变化就可以确定金属和其他材料的状态特性这一原理,研制出一种稳频脉冲锁相回路测量装置。与测量相速度技术有关的问题之一是很难实现自动化,如回波脉冲法。而稳频脉冲锁相回路测量装置对 According to Willian T. Yost et al. At Langley Research Center, USA, the supersonic phase velocity is a function of the thermal dynamic and the phase velocity is measured to determine the state properties of metals and other materials. A stable frequency Pulse-locked loop measurement device. One of the problems associated with measuring phase velocity technology is the difficulty of automation, such as the echo pulse method. The frequency stabilization pulse phase-locked loop measurement device pairs