A comparator receives a threshold value and compares {HEAD ~ each} of {TAIL ~ the intermediate amplitude values} to the threshold value 
A comparator receives a threshold value and compares { HEAD ~ each } of { TAIL ~ the intermediate amplitude values } to the threshold value
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH