研究了产生超声波的机理及器件性能，分析了超声源驱动电路的组成和工作原理。

Studied the mechanism of how to produce ultrasonic and the functions of the machine, analyzed the ultrasonic driven circuit and its principle of working.

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但由于传统的压电传感器存在着空气与普通的压电材料之间严重不耦合现象，所以压电传感器并不是高效率的超声源。

The traditional PZT, however, is not the ultrasonic source with high efficiency because of the serious non-coupling phenomena between air and ordinary piezoelectric material.

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本文主要介绍了超声多普勒胎心仪超声源检定项目、技术要求及检定方法并介绍了所需要的测量装置，对测量过程进行了阐述。

This paper mainly introduces ultrasonic Doppler baby's heart instrument verification item and technical requirement and verification technique, introduces the equipment and process for determination.

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