Changes

* A 6DOF tracker using two transmitter coils (instead of three) can be built; Frederick Raab calls this [[6DOF_Two_State_Electromagnetic_Trackers|two-state excitation]] in his 1981 paper referenced above. Two-state trackers are severely limited, as they cannot track near the axis of the missing transmitter coil and cannot track near the plane of the two existing transmitter coils.

* A 6DOF tracker using two transmitter coils (instead of three) can be built; Frederick Raab calls this [[6DOF_Two_State_Electromagnetic_Trackers|two-state excitation]] in his 1981 paper referenced above. Two-state trackers are severely limited, as they cannot track near the axis of the missing transmitter coil and cannot track near the plane of the two existing transmitter coils.