摘要:
传感器的设计和信号降噪分析是交流电磁场测量系统中必须解决的关键问题。通过给激励线圈施加磁芯, 缩小传感器的结构尺寸, 对交流电磁场传感器的检测信号部分采用差分式串联结构, 并采用多级放大、滤波和检波电路, 增强对小缺陷信号的检测能力。选取适当的小波, 对采集信号进行小波降噪, 分析由缺陷引起的扰动磁场与缺陷的关系。试验可得, 采用差分式串联结构探头采集的信号峰-峰值较强, 噪声较小, 能够更好地提取微弱的扰动磁场信号; 采用小波降噪后的信号特征能够更明显地定量反映出缺陷特征。
Abstract:
Sensor design and signal de-noising analysis is the key issues of the alternative current field measurement system that must be addressed. Through exerting the coil core, reducing the structure size of the sensor, using differential series structure for the picking-up signal part of the sensor, and adopting the multi-stage amplification, filtering and demodulation circuits, the small defect signals were enhanced. At the same time, the appropriate wavelet mode was selected to denoise the signal acquisition, and the relationship was analyzed about the disturbance magnetic field and the caused defect. Testing results showed that, the stronger peak-peak value and low noise signal could be obtained by the optimized differential series structure sensor, so it was helpful to pick-up the weak disturbance magnetic field signal; the use of wavelet denoising method could help to reflect the signal quantitative characteristics more clearly.
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