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