Design of Weak Signal Conditioning Circuit for Pulsed Eddy Current
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摘要: 分析了铁磁性材料脉冲涡流检测后期微弱信号的特点，在此基础上进行了脉冲涡流微弱信号调理电路的设计。设计采用了阻抗匹配、对称式限幅差分前置放大、浮空的电压源和屏蔽与接地技术，有效地提高了信号的共模抑制比和信号调理系统的信噪比。试验结果表明：设计的信号调理电路改善了接收系统的信噪比，提高了脉冲涡流晚期微弱信号的分辨能力(有效检测信号为几个微伏)，提高了在复杂电磁环境下测量铁磁性材料厚度的检测灵敏度。Abstract: This paper analyzed the weak late stage signal of pulsed eddy current testing of the ferromagnetic materials briefly, and signal conditioning circuit was designed based on the analysis. Techniques of the impedance matching, electromagnetism shielding, grounding, floating empty DC voltage source and limited different pre-amplifying symmetrically are used and the SNR (Signal-to-Noise Rate) of signal conditioning system is improved effectively. The experiment results show that the design of weak signal conditioning circuit for pulsed eddy current improves the SNR and signal of several microvolts can be detected. Effective detection for the small corrosion of ferromagnetic materials in complicated electromagnetic environment is implemented.
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Keywords:
- Pulsed eddy current /
- Signal conditioning /
- Signal-to-Noise Rate /
- Low noise
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