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超声传播速度和衰减值的测量,作为超声基本量的测量和超声技术的一些应用,都有着重要的意义。多次脉冲反射法是目前超声测声速、声衰减等工作中最常用的方法,尤其对体积不大的固体材料的测量中,用得更多。用这类方法测声速时,都需要测定超声脉冲在被测样块内在返一次所经历的时间。而对这一时延值的确定,目前来说,有着两种方案,即当超声脉冲往返一次反射后,或者依据它的包络的相应时延直接确定;或者依据它的射频相位的比较来推算确定。前者测量方法和设备较简单,后者测量结果的精度较高。
Ultrasound measurement of velocity and attenuation values, as the basic measurement of ultrasound and ultrasound applications of some applications, has important significance. Multiple pulse reflection method is currently the most commonly used method of ultrasonic sound velocity, sound attenuation and other work, especially for the measurement of small solid materials, more. When using this method to measure the speed of sound, it is necessary to determine the time it takes for the ultrasonic pulse to travel back through the sample being tested. However, there are two schemes to determine this time-delay value. For example, when the ultrasound pulse is reflected once or twice, or directly determined by the corresponding delay of its envelope, or based on the comparison of its RF phases determine. The former measurement methods and equipment is relatively simple, the latter the measurement accuracy of the higher.