{HEAD ~ The digital signals} are introduced to a digital carrier recovery loop and {TAIL ~ a digital symbol recovery loop} 
are introduced to
{ HEAD ~ The digital signals } are introduced to a digital carrier recovery loop and { TAIL ~ a digital symbol recovery loop }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL