System for determining the location and orientation of an invasive medical instrument

A method of determining the position and orientation of an invasive medical instrument having a distal end, comprising:

• (a) generating a plurality of distinguishable, geometrically different AC magnetic fields such that the AC magnetic fields are generated at a different frequency wherein each different frequency in an integer multiple of a given frequency;
• (b) sensing the AC magnetic fields at a plurality of sensors proximate the distal end;
• and
• (c) computing six dimensions of position and orientation of a portion of the invasive medical instrument responsive to signals representative of the generated magnetic fields and the sensed magnetic fields.

A locating system for determining the location and orientation of an invasive medical instrument having a distal end relative to a reference frame, comprising:

• a plurality of field generators which generate known, distinguishable fields in response to drive signals wherein the field generated by each field generator has a different frequency and each said different frequency is an integer multiple of a given frequency;
• a plurality of sensors situated in the invasive medical instrument proximate the distal end thereof which generate sensor signals in response to said fields;
• and
• a signal processor which has an input for a plurality of signals corresponding to said drive signals and said sensor signals and which computes three location coordinates and three orientation coordinates of a portion of the invasive medical instrument, responsive to said drive and sensor signals.