The system 3, wherein the average position is linearly proportional to {HEAD ~ the average} of {TAIL ~ the measured phases} corresponding to the multiple positions 
of
The system 3 , wherein the average position is linearly proportional to { HEAD ~ the average } of { TAIL ~ the measured phases } corresponding to the multiple positions
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 OTH OTH OTH