{HEAD ~ The frequency} of the back EMF signal is determined from {TAIL ~ the zero crossings} of the EMF signal 
is determined from
{ HEAD ~ The frequency } of the back EMF signal is determined from { TAIL ~ the zero crossings } of the EMF signal
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH