in most digital communication techniques, there is some bits sent at first "called preamble" which used to synchronize both Trans. and Receiv.
these preamble bits always 0101010101,,,,and change in size depending on technology type.
example: Ethernet stations need to synchronize with the signal's frequency; this is done by means of 64 preamble bits.
Token-Ring stations are always synchronous to received frames because there is always a signal passing the ring (idle symbols); they only need a 8-bit starting delimiter in order to get ready for receiving the frame.
yours, Zico©