For {HEAD ~ the coded data} that was transmitted via a communication channel, a known code portion thereof that is a code portion corresponding to {TAIL ~ known data} is detected 
For { HEAD ~ the coded data } that was transmitted via a communication channel , a known code portion thereof that is a code portion corresponding to { TAIL ~ known data } is detected
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH