Patent ID: 8165174

Claim:
A method of demapping a tributary from a first frame into a second frame, said first frame comprising a plurality of tributary words and a synchronization word for synchronizing said second frame, the method comprising: extracting the plurality of tributary words and the synchronization word from the first frame and storing them in a memory; incrementing a master reading counter by a first value at each clock cycle of said second frame; reading the plurality of tributary words and the synchronization word from the memory using a slave reading counter and using them to generate a second frame; generating, by a state control module, a synchronization signal in response to reading said synchronization word from said memory; using said synchronization signal to cause said slave reading counter to change between a first state and a second state; synchronizing, when in said first state, said slave reading counter to said master reading counter at each clock cycle of said second frame; synchronizing, when in said second state, said slave reading counter to said master reading counter at a predetermined instant of said second frame and increasing said slave reading counter by a second value at each clock cycle of said second frame as words are read from said memory; and if a new sequence of first frames is received, causing said slave reading counter to change from said second state to said first state, wherein said first state is a synchronization search state, wherein while said slave reading counter is in said first state, said state control module searches for the synchronization word for said second frame, wherein if said synchronization word is found, said slave reading counter transitions to said second state, and wherein said predetermined instant of said second frame at which said slave reading counter is synchronized to said master reading counter is determined based on the time of state transition from said first state to said second state.