本文介绍一种简单价廉的电路，它能在测量超声衰减时自动选择二个相继的回波。当测量超声衰减与某个变化量（例如温度）的关系时，回波脉冲在试样中的传播时间也会改变，结果使回波位置移动，此时要重新调节供取样和保持电路用的取样脉冲。而本文介绍的电路则不需要人工调节。文中给出了详细电路，叙述了脉冲检峰电路和取样保持电路，报导了试验结果。 This article describes a simple, inexpensive circuit that automatically selects two successive echoes when measuring ultrasound attenuation. When measuring the relationship between ultrasonic decay and some amount of change (eg, temperature), the propagation time of the echo pulse in the specimen also changes, resulting in a shift of the echo position where the read and hold circuits are readjusted Sampling pulse. This article describes the circuit does not require manual adjustment. The paper gives the detailed circuit, describes the pulse peak detection circuit and sample and hold circuit, reported the test results.