Importance

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Abstract

An accuracy control subsystem for an object examination (OE) system is disclosed. The OE system is of typical frequency-based type and includes a drive unit for generating an excitation signal of preselected frequency, a transducer for receiving the excitation signal and for applying it to the object and for generating an output signal indicative of interaction of the excitation signal with the object and a detector for receiving the transducer output signal and for generating first and second output signals respectively indicative of components of the transducer output signal at first and second different phases thereof, typically zero degrees and ninety degrees, i.e., in-phase and quadrature, respectively. The accuracy control subsystem includes circuitry for receiving the detector first and second output signals and self-operable in predetermined pattern for generating first and second phase component correction signals to conform operation of the detector to within a preselected operating subrange thereof and circuitry connected within the detector for combining the first and second phase component correction signals with the transducer output signal.

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First Claim