Remote-field testing (RFT) and remote-field array (RFA) inspection results are especially sensitive to speed. It is particularly important when using this technique to have as much of an accurate maximum pulling speed as possible.
The probeís excitation frequency dictates what low-pass filter is applied to inspection data to lower noise. The frequency of the low-pass filter is directly proportional to the maximum inspection speed.
Simply put, the lower the excitation frequency, the higher the noise from the utility frequency (50 Hz or 60 Hz power outlet). The higher the noise, the tighter the low-pass filter (lower frequency) around the excitation frequency of the probe. Consequently, the tighter low-pass filter can eliminate high-frequency signals. This calls for a lower inspection speed to reduce the defectís signal frequency.
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