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