The peaks of the forward and rear output pulses are converted into {HEAD ~ direct current voltage levels}, which are then fed into {TAIL ~ a comparator circuit} 
are fed into
The peaks of the forward and rear output pulses are converted into { HEAD ~ direct current voltage levels } , which are then fed into { TAIL ~ a comparator circuit }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL