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