Eddy current testing is a commonly used method for detecting surface defects in metals,which generally includes sever-al detection methods such as single-coil excitation and reception,single-coil excitation and multi-coil reception,or multi-coil exci-tation and reception.However,under the same frequency excitation,the signal received by the receiving coil is usually very weak and accompanied by strong background noise,so the received coil signal needs to be filtered.In this paper,a frequency band segmenta-tion method and multiplexing idea are used to design two types of active bandpass filters with adjustable frequency using low noise and low distortion operational amplifiers THS4011 and THS4012,namely second-order infinite gain multiple feedback(MFB)and second-order dual operational amplifier(DABP)filters.Simulation and comparative experimental results show that the bandwidth of the de-signed filters is 1 kHz～1 MHz,and the center frequency can be adjusted arbitrarily within the bandwidth.Both can be applied to dif-ferent bandpass filter requirements in complex eddy current testing scenarios.
关键词
涡流检测/有源滤波器/可调带通滤波/无限增益多路反馈/双运放
Key words
eddy current detection/active filter/tunable bandpass filter MFB/DABP
维普
万方数据