联合数字滤波在涡流检测数据采集系统中的应用

Application of multi-digital filter in data acquisition system for eddy current testing

涡流响应信号中时常伴有坏点,通常的FIR滤波难以克服坏点的影响,给后续的特征提取造成困难.在分析了FIR滤波器窗函数设计方法的基础上,提出了一种应用于涡流在线检测的联合数字滤波方法,即先利用中值滤波剔除涡流信号中可能存在的坏点,再利用FIR滤波对其进行在线平滑处理.实验表明:与常规FIR滤波相比,该联合滤波方法可有效地在线剔除坏点,提高涡流数据采集的精度,为后续涡流检测的特征提取及缺陷的定性定量分析创造了良好的条件.

Singular points usually exist in eddy current response signal,and the effect of singular points is difficult to be removed by a conventional FIR filter,which causes difficulties to the follow-up feature extraction.On the basis of analyzing FIR window design method,a multi-digital filter applied in on-line eddy current testing is proposed,in which singular points are removed by median filter and then the filtered data are smoothed on-line by FIR filter.The testing results show that,compared with conventional FIR filter,the multi-digital filter can effectively remove singular points,improve the accuracy of eddy current data acquisition,and create a good condition for the follow-up feature extraction and the qualitative-quantitative defect analysis.