The output of {HEAD ~ the sync mark detector} is enabled according to the current state of {TAIL ~ the state machine}, i.e., at a predetermined sample period interval 
The output of { HEAD ~ the sync mark detector } is enabled according to the current state of { TAIL ~ the state machine } , i.e. , at a predetermined sample period interval
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH