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