Control system and method for a magnetic indexer for high accuracy hole drilling

An apparatus for determining a location of a center of a field generated by a device, wherein the device is disposed adjacent a second side of a structure, from a first side of the structure such that a location of the device is not visually perceptible, the apparatus comprising:

• an input for accepting a first signal representative of a strength of the field at a first location on the first side of the structure, and for accepting a second signal representative of the strength of the field at a second location on the first side of the structure;
• a processor responsive to the first and second signals for extrapolating a location of a center of the field being generated by the device from the first and second signals and the first and second locations;
• wherein the processor is further adapted to:
• determine a first distance to the center of the field using the first signal,
• determine a second distance to the center of the field using the second signal, and
• determine a location of the center of the field using the first and second distances.

A machine readable medium for use in locating a device wherein the device produces a field and is disposed adjacent a second side of a structure, from a first side of the structure, and where the device cannot be visualized from the first side of the structure, the machine readable medium including a sequence of instructions executable by a machine that causes the machine to operate to:

• sense the field strength produced by the device at a first location on the first side of the structure;
• sense a second the field strength produced by the device at a second location on the first side of the structure;
• determine a first distance from the first location to the center of the field using the first field strength;
• determine a second distance from the second location to the center of the field using the second field strength;
• use said sensed field strengths and said first and second distance from the first and second to determine a location on the first side of the structure representing a center of the field being produced by the device.