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