. . . . "In other preferred embodiments of the present invention, however, other coil designs or antennas of other types known in the art may be used in place of the coils, providing that these coils or antennas define a k,l,m coordinate system that is fixed with respect to the object, and that these coils or antennas generate signals that can be used to determine the position and orientation of the k,l,m" .