What is a method to minimize effects from gradual dimensional changes in eddy current testing?

In eddy current testing, gradual dimensional changes can lead to unwanted signals that interfere with the detection of defects. A high pass filter is effective in minimizing the effects of these gradual changes because it allows higher frequency signals (such as those generated by flaws) to pass through while attenuating lower frequency signals, which are typically associated with gradual dimensional variations. By applying a high pass filter, the system can focus on the relevant high-frequency response due to defects, thus improving signal-to-noise ratio and enhancing defect detection.

This method is particularly useful in distinguishing between the signals caused by defects and those resulting from slow changes in material dimensions or surface conditions, ultimately leading to more accurate testing results.