Virtually zero cross-talk dual-frequency eddy current analyzer based on personal computer

The dual-frequency eddy current technique is a powerful tool for nondestructive testing of conducting materials, well established both for quality control in the manufacturing industry and for inservice inspection of plant components and structures. The common approach aiming at the extraction of two frequency components from a single signal is based on band filtering. A different approach, which contemporaneously carries out component separation and signal rectification, is proposed in this paper; it enables fast measurement response, virtually zero cross-talk, and hardware simplification. The described methodology has been implemented in the form of a card which can be plugged into a personal computer. Together with the managing software, the eddy current card gives the PC all the capabilities of a powerful and versatile eddy current inspection system