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