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