determining {HEAD ~ an instantaneous time difference} between {TAIL ~ a fixed number} of sample clock transitions at a transition of the sample clock, the instantaneous time difference being based upon a time clock having a fixed time clock period, and 
between
determining { HEAD ~ an instantaneous time difference } between { TAIL ~ a fixed number } of sample clock transitions at a transition of the sample clock , the instantaneous time difference being based upon a time clock having a fixed time clock period , and
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH