为了提高声速测量时的延时测量精度, 对常用的脉冲反射法声速测量的信号进行了频谱分析。发现声束扩散引起的回波信号畸变, 对判断超声传播时间有一定影响。改用函数发生器的正弦信号, 采用双探头脉冲反射法, 提高了时间测量精度, 降低了对仪器的不良影响。

To improve the precision of time span measurement during measuring sonic velocity, we carried out spectrum analysis on signals of ultrasonic sound velocity got by commonly pulse echo method, and found that the signals were distorted due to beam spread. The distortions took some effect on the measure of time span between echoes. The use of sine wave from function generator as exciting source, and with double probes to excite and receive ultrasonic echoes, can improve accuracy of time span measurement, and reduce harmful effects to instruments.