Patent ID: 9726640
Date: 2017-08-08
CPC Classifications: G01N

Claim:
1. A circuitry for an eddy current inspection instrument configured to conduct eddy current inspection of abnormality of a test object, the instrument is coupled to an eddy current probe moving at a scanning speed varying in a speed range during the inspection, the circuitry comprises, a front-end circuit for energizing the probe, receiving eddy current response, digitizing and converting the response to response signals with a range of response frequencies related to the scanning speed, a digital processing circuit configured to process the response signals for displaying inspection result, the processing circuit further comprising a filtering circuit configured to filter the response signals from raw detected signals to processed signals, and to apply a phase change of the raw detected signals in a vicinity of 90 degrees while the filtering circuit maintains a substantially constant frequency response within the range of response frequencies, and, wherein the digital processing circuit further comprises a direct digital synthesizer, generating a real component of a reference signal and an imaginary component of the reference signal, a first synchronous detector configured to detect the real component of the reference signal, and a second synchronous detector configured to detect the imaginary component of the reference signal.