The sync pattern selecting unit 33 d may includes a multiplexer and uses a signal from {HEAD ~ the snap shot} determining Unit 33 b as {TAIL ~ a selection signal} 
The sync pattern selecting unit 33 d may includes a multiplexer and uses a signal from { HEAD ~ the snap shot } determining Unit 33 b as { TAIL ~ a selection signal }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL