Clock circuit for use in pulse-echo ultrasonic defect testing

摘要

A clock circuit comprising a synchronizable voltage controlled oscillator in combination with a programmable address means, which address means is adjusted commensurate with the acoustic velocity of the workpiece, provides clock pulses from the oscillator having a stable and accurate acoustic velocity dependent frequency. An entrant surface responsive electrical signal responsive to an ultrasonic search signal entering the workpiece is also provided to the clock circuit for assuring that the clock pulses are synchronized with the receipt of the electrical signal.