Dual-frequency eddy current testing is a hot spot of eddy current testing. This work briefly analyzes the necessity of dual-frequency in eddy current testing, introduces the basic principle of eddy current testing, describe the overall scheme of dual-frequency eddy current testing system, and introduces the design process of dual-frequency eddy current testing system, including the design of the dual-frequency excitation source, the analysis of the signal detection circuit, analysis of the dual-frequency signal extraction circuit and the method of signal processing. This work also verifies the effectiveness of dual-frequency eddy current testing for inhibiting interference factors, which is one of the main interference factors of eddy current testing.
