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本文对原来测量超声声速的脉冲回波重叠法发展改进为交叉触发脉冲回波重叠法.即在示波器上显示脉冲回波时,前一次发射脉冲所产生的一组反射脉冲波列,按正常情况触发显示,而紧随的下一次发射脉冲所产生的一组反射脉冲波列,在触发时刻上,比正常情况延后一个时间值,其值等于超声脉冲在样品中来回一次的时间,如此循环.因而在示波器屏上就可看到整个反射波列相应地一一重叠的波形.其延后的时间值,可由数字式频率计读出.再籍调节示波器的扫描速度及扫描延时,即可很方便地观察重叠波形中的任何部分. 我们还利用这种测量方案,研制成了一种适用于液体的声速仪,可直接读得声速值,使用灵便.
In this paper, the original measurement of ultrasonic sound velocity pulse echo overlap method to improve the cross-trigger pulse echo overlap method that is displayed on the oscilloscope pulse echo, the previous launch pulse generated by a set of reflected pulse train, according to normal circumstances Triggering a display while the next set of reflected pulse trains produced by the next transmitted pulse is delayed by a factor of one from the normal condition at the triggering time equal to the time the ultrasonic pulse traverses the sample once, . So on the oscilloscope screen you can see the entire reflected wave column accordingly one by one overlap of the waveform.The delay time value can be read out by a digital frequency meter.Regularly adjust the oscilloscope scan speed and scan delay, It is easy to observe any part of the overlapped waveform, and with this measurement we have also developed a sonic meter for liquids that reads the speed of sound directly and is handy.