The third circuit stage compares {HEAD ~ the one fourth, one half, and three fourths amplitude values} to {TAIL ~ a threshold amplitude value} and generates a time of arrival adjustment value based on the comparisons 
to
The third circuit stage compares { HEAD ~ the one fourth , one half , and three fourths amplitude values } to { TAIL ~ a threshold amplitude value } and generates a time of arrival adjustment value based on the comparisons
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH