Method and apparatus for determining the instantaneous location, the orientation of an object moving through a three-dimensional space by applying to the object a coil 
assembly including a plurality of sensor coils (20) having axes of known orientation with respect to each other including components in the three orthogonal planes; generating a time-varying, three-dimensional 
magnetic field gradient having known instantaneous values of magnitude and direction; applying the 
magnetic field gradient to the space, and object moving therethrough to induce electrical potentials in the sensor coils; measuring the instantaneous values of the induced electrical potentials generated in the sensor coils; 
processing the measured instantaneous values generated in the sensor coils together with the known magnitude, direction of the generated 
magnetic field gradient, the known relative orientation of the sensor coils in the coil 
assembly to compute the instantaneous location, orientation of the object within the space.