The method in accordance 1, wherein said two excitation means comprise first and second coils, and said {HEAD ~ exciting substep} comprises {TAIL ~ the further substep} of: 
comprises
The method in accordance 1 , wherein said two excitation means comprise first and second coils , and said { HEAD ~ exciting substep } comprises { TAIL ~ the further substep } of :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH