A subtracting unit subtracts {TAIL ~ the input signal} from {HEAD ~ the first delayed signal} to generate a difference signal 
A subtracting unit subtracts { TAIL ~ the input signal } from { HEAD ~ the first delayed signal } to generate a difference signal
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH