Any of these signals can be used as a stimulus while spectrum measurements are made elsewhere in the circuit. 任何这些信号可以作为刺激而谱测量电路是在别处。
This papergives a brief account of an ultrasonic densimeter including its measuringprinciple,measuring circuit,construction and application. 本文简要介绍了超声波密度仪的测量原理，测量电路，仪表结构和应用。
