Which of the following is not an eddy current testing method?

Eddy current testing methods involve the use of electromagnetic induction to detect and characterize flaws in conductive materials. Pulse-echo testing, however, is not categorized under eddy current testing; it is a technique more commonly associated with ultrasonic testing. This method uses sound waves that travel through a medium and reflect off boundaries or flaws, making it fundamentally different from the principle of eddy currents, which relies on induced electrical currents in conductive materials.

In contrast, the other listed methods—impedance testing, phase analysis testing, and modulation analysis testing—are all valid techniques within the realm of eddy current testing. They utilize different aspects of the eddy current response to assess material properties, conductivity, and the presence of defects. Therefore, recognizing that pulse-echo testing is a distinct methodology helps clarify its absence from the list of eddy current testing methods.