电磁超声换能器的换能效率很低，得到的接收信号十分微弱。为了改善接收信号质量，采用了基于谐振理论的选频放大技术、基于互相关理论的锁相放大技术以及平均技术3种方法对电磁超声接收信号进行处理。实验表明，所设计的选频放大电路和锁相放大电路均能将微弱的电磁超声接收信号从强噪声背景中分离，而平均技术则能够有效改善接收信号的信噪比。最后给出了电磁超声系统联调的实验波形，并对3种检测技术的优缺点进行了分析。

Received signal of the electromagnetic acoustic transducer (EMAT) is very weak resulted from EMAT's poor transduction efficiency. To improve the signal quality, the EMAT received signals were proceeded with three methods, which were the frequency selecting technique based on resonance theory, the lock-in amplifying technique based on cross-correlation theory and the averaging technique. Experiments proved that both frequency selecting amplifier and lock-in amplifier were able to separate the EMAT received signal from a strong noise background, while the averaging technique could effectively improve the signal to noise ratio of the received signal. At last, waveforms of the received signal were given, and the strengths and weaknesses of these three methods were analyzed.