a Robertson device coupled to said {HEAD ~ first count signal} and said {TAIL ~ second count signal}, and having as an output a correlation signal 
a Robertson device coupled to said { HEAD ~ first count signal } and said { TAIL ~ second count signal } , and having as an output a correlation signal
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH