Method and apparatus for making spatially correlated eddy current measurements

Apparatus for measuring flaws in an object having both erratic and net axial motions, said apparatus comprising:

• an idler wheel adapted to frictionally engage the object;
• a rotary shaft encoder coupled to said wheel;
• a line driver coupled to said encoder;
• a pulse-on-position circuit coupled to said line driver;
• a bridge circuit having a pair of coils adapted to be disposed proximate the object;
• and
• a triggered analog-to-digital converter coupled to said pulse-on-position circuit and to said bridge.

A method for measuring flaws in an object having both erratic and net motions, said method comprising:

• sensing only the net motion of the object;
• providing an erratic motion complicated flaw signal;
• and
• correcting the flaw signal for the erratic motion, wherein said step of correcting is further comprised of the step of triggering an analog-to-digital conversion of said erratic motion complicated flaw signal responsive to said sensing of the net motion.