Precise measurement of ultrasonic velocity

In contemporary NDE engineering the application of such sensitive method for researching as measuring of ultrasound velocity gradually increase. Now this method is used in measuring of temperature, evaluating of mechanical strength and fatigue of materials. For all these applications the main problem is high accuracy of measured ultrasonic velocity. This problem is double - precise measuring of time delay of radio-pulsing ultrasonic wave and calculation with such precision of the distance traveling of this wave, especially when it can not be measured mechanically. This is considered the original method of calculation of time delay of ultrasonic wave by measuring of full phase shift of this wave. Number of phase cycles in expression for full phase shift determines from results of measuring of phase shifts on two near frequencies. Value of frequencies is finding under condition of invariability of number phase cycles for two frequencies. Time delay of ultrasonic waves can be presented by full phase shift on one of frequencies. Calculation of distance traveled by ultrasonic waves is a difficult problem too. But we can decide it by using the mentioned method of time delay measurement on two near direction of wave's traveling. The example of distance measurement is presented.