Apparatus for determining the position of a probe in a sensing volume includes a plurality of magnetic field generating sources for generating different magnetic fields in the sensing volume, where the sources have a planar configuration and are positioned so that they at least partially overlap...http://www.google.es/patents/US5752513?utm_source=gb-gplus-sharePatente US5752513 - Method and apparatus for determining position of object
Method and apparatus for determining position of object
