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