Eddy current test method with degree of amplification selected in accordance with a compensation signal

US4564809A · kind A · utility

Assignee

• Nukem, LLC · DE

Inventors

• Gerhard Huschelrath · Laufach, DE
• Klaus Abend · Büdingen, DE
• Ursula Orthen · Hanau, DE

Key dates

• Filing date: Jun 22, 1982
• Grant date: Jan 14, 1986
• Expiry date: Jun 22, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/9046
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and an instrument for testing materials using the eddy current principle, at different frequencies depending on the output quantity of a coil system, compensation values are generated being typical of interfering factors. These compensation values are subsequently superposed on the output values in order to remove the influence of the interfering factors on the measuring. In this manner with a favorable setting of the working point of an amplifier charged with the output values, an overmodulation is avoided and the dynamic range of the amplifier optimally utilized. Therefore good measuring results can be obtained even if the percentage of the interfering signals as compared to the signal controlling the detecting of defects, is relatively high.