Circuit and method for recovering synchronization information from a signal

A circuit, comprising:

• an input terminal operable to receive an input signal that includes a synchronization mark;
• an output terminal;
• and
• a tracking circuit coupled to the input and output terminals and operable to,
• generate a synchronization indicator from the input signal in response to the synchronization mark, the synchronization indicator being different than the input signal and the synchronization mark, and
• generate a synchronization signal in response to the synchronization indicator.

A read channel, comprising:

• an input terminal operable to receive an read signal that includes a synchronization mark and data;
• a synchronization circuit coupled to the input terminal, having a synchronization output terminal, and operable to,
• recover the synchronization mark from the read signal by executing a first Viterbi algorithm, and
• generate a synchronization signal on the synchronization output terminal in response to the recovered synchronization mark;
• and
• a Viterbi detector coupled to the input terminal and to the synchronization output terminal and operable to recover the data from the read signal in response to the synchronization signal by executing a second Viterbi algorithm.

A disk-drive system, comprising:

• a data-storage disk having a surface and operable to store data values;
• a motor coupled to and operable to rotate the disk;
• a read head operable to generate a read signal that includes a data forerunner and data;
• a read-head positioning assembly operable to move the read head over the surface of the disk;
• a synchronization circuit coupled to the read head and operable to,
• recover a synchronization mark from the data forerunner by executing a first Viterbi algorithm, and
• generate a synchronization signal in response to the synchronization mark;
• and
• a Viterbi detector coupled to the read head and to the synchronization circuit and operable to recover the data from the read signal in response to the synchronization signal by executing a second Viterbi algorithm.

A method, comprising:

• tracking an input signal that includes a synchronization mark;
• recovering from the input signal a synchronization indicator that corresponds to the synchronization mark, the synchronization indicator being different than the input signal and the synchronization mark;
• and
• generating a synchronization signal in response to the synchronization indicator.

A method, comprising:

• recovering a synchronization mark from a data signal with a first Viterbi detector;
• generating a synchronization signal in response to the recovered synchronization mark;
• and
• recovering data from the data signal with a second Viterbi detector in response to the synchronization signal.

A method, comprising:

• tracking an input signal that includes a synchronization mark;
• executing a Viterbi algorithm to recover from the input signal a synchronization indicator that corresponds to the synchronization mark, the synchronization indicator being different than the input signal and the synchronization mark;
• and
• loading the synchronization indicator into a path-history register.