second encoder means for binary encoding {HEAD ~ an output signal} from {TAIL ~ said second means} with a single threshold level proportional to a level of said signal from said first means; and 
second encoder means for binary encoding { HEAD ~ an output signal } from { TAIL ~ said second means } with a single threshold level proportional to a level of said signal from said first means ; and
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH