An electromagnetic field which nutates about a pointing vector is used to both track or locate a remote object in addition to determining the relative orientation of the object. Apparatus for generating such a field includes mutually orthogonal dipole radiators, defining a reference coordinate frame, and circuitry for supplying excitations, such that the maximum intensity vector of a vector field produced by these excitations in the radiators nutates about a mean axis or axis of nutation which is called the pointing vector direction of the field. A pointing coordinate frame has the x-axis coincident with the pointing vector and the y-axis in the x-y plane of the reference frame. Mutually orthogonal sensors at the object sense the field and establish a sense coordinate frame, which can be coincident with the coordinate frame of the remote body.
Coordinate transformer means, system and process are used in connection with determining the pointing and angular position of the sense frame with respect to the reference frame. A first error signal relating the sense frame to the pointing frame is transformed into a second error signal relating the sense frame to the reference frame. This second error signal is used to generate the three Euler angles defining the orientation of the sense frame relative to the reference frame and to generate the pointing angles defining the translation of the sense frame from the reference frame.
Means, system and process are described, thus, capable of continuously measuring five independent angles through the use of one field generating means, one field sensing means at the remote object, and signal processing means. Two of the angles specify the direction to, or location of, the remote object and the remaining three angles define the angular orientation of the remote object, the angles defining the sense frame with respect to the fixed reference coordinate frame of the field generating means.