{HEAD ~ A reference delay unit} delays the first delayed signal by {TAIL ~ a predetermined reference time period} to generate a reference signal 
{ HEAD ~ A reference delay unit } delays the first delayed signal by { TAIL ~ a predetermined reference time period } to generate a reference signal
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH