中文摘要：

通过介绍数字探伤仪内部电路系统的组成和具体的性能指标，进一步分析研究超声发射电路的工作原理和参数要求。在理论推导基础上，详细分析电路中电阻、电容和激励脉冲之间的关系。对发射电路进行了仿真和测试，结果表明设计的发射电路能够产生理想的激励脉冲，具有实用价值。

英文摘要：

Transmitting circuits are introduced at first. And then the system principle is explained. On the basis of theoretical calculation, detailed relations between circuit resistors, capacitors and exciting pulses are concluded. Finally, transmitting circuit is simulated and tested, and experiment results show that the designed circuit can produce ideal exciting pulse and has practical value.